Loud knocking noise 5.3

Asked by Apr 17, 2011 at 03:42 AM about the 2005 Chevrolet Silverado 1500 Z71 Crew Cab 4WD

Question type: Maintenance & Repair

I have a loud knocking noise coming from the engine . At first I thought it was comin from the top but when i get under it it's alot louder sounds like its comin from the oil pan. I had the transmission rebuilt thinking it was the flywheel or torque convertor and wasn't the problem but transmission was in bad shape. Next I tried taking the coolpack and valve cover off and checked rocker arms , took the main fuse out and tried turnin the motor over to c if they were all movin right so that was good. Then I went and pulled the oil pan off to look at the crank, flywheel, wristpins, and metal shield in the oil pan thinkin it might have broke loose. Everything looked fine and yet i still have this knocking noise anyone have any good advice ???

53 Answers

230

I have an 06 1500 Z71 4wd with 73k miles. I've put 8,500 miles on it and it just started knocking. Started out light and has gotten worse. Does it whether it is cold or hot. I had a shop take a quick look at it and they listened to it with a steth all over the engine, top to bottom, and said it is coming from obove the middle of the oil pan and that it is a rod knock on the crankshaft. I have read a lot about piston slap and knock sensors, etc and not sure what the next step is.

23 out of 23 people think this is helpful.
1,005

for a piston slap you need to pull apart the motor and possibly either re-bore the cylinder with the bad piston or replace the entire block be cause of the damage done to the piston and the cylinder as the piston "slapped" against the walls of the cylinder most likely gouging the cylinder walls

6 out of 6 people think this is helpful.
11,385

You need to tear down the engine. Perhaps do a bottom end rebuild with the motor intact. Once the rods are off the crank shaft you may be able to find your problem. It really sounds like a complete rebuild or motor swap at this time. You also might check the rocker arms to make sure they are fine before tearing into it. Look at everything you can before pulling the motor. If you find metal filings or have internal damage showing, it will need a rebuild to keep it from coming apart because of the damage to the cam and crank and bearings. Pull the filter and have a magnate dipped into the oil and see if it picks up metal.

5 out of 5 people think this is helpful.
355

Did you ever find out what the noise was ? I have the same clicking noise on a 2005 with a 5.3. The stethoscope tells me it is inside the oil pan near the back. It is directly related to RPM. Oil pressure is fine and I drive it everyday but the noise is irritating

20 out of 20 people think this is helpful.
250

Guys! Ive had the same problem for quite a while. So, first I changed my oil to synthetic, thinking it would stop the knocking but it just got worse so I bought this product from O' Reilly's http://m.oreillyauto.com/mt/www.or eillyauto.com/site/c/detail/LUC0/10 063/N2556.oap? redirectkeyword=oil&pt=N2556&ppt= C1941 took my truck for a spin and it stopped the knocking! I guess you guys should try it out maybe it will work for you guys as well. I drive a 2005 chevy silverado 5.3 4x4 crew cab with 200,000 miles on it.

25 out of 25 people think this is helpful.
160

Omiizzyy. How long did you leave this Lucas oil product in for? Till next oil change?

16 out of 16 people think this is helpful.
11,385

MikeG28, Have you fixed your problem? We all would like to know if you found the issue as it will help us when we get another knocking motor question.

9 out of 9 people think this is helpful.
60

I have the same kind of knocking noise but I know what the problem is... i know how to fix it aswell. the knocking noise on mine is the oil draining to the bottom of the oil pan after it sits for a few hours. it only knocks when i start it, but it only knocks for about ten minutes. the knocking noise comes from all the oil draining to the bottom of the oil pan. it goes away because the engine warms up and the oil goes back to the top of the engine. i figured out that synthetic oil keeps it from knocking as much but i hate using synthetic.. 2001 Chevy Silverado 5.3l

6 out of 6 people think this is helpful.
11,385

Is there an additive that will coat the valve train moving parts to keep it lubricated and protect it until the warm oil is pumped back to the lifters? It would appear to either be a design flaw in the Chevy/GM engine or a precursor to an overhaul.

6 out of 6 people think this is helpful.
175

Trust me on this one--# 7 fuel injector ends up full of everything that goes into the fuel rail. REMOVE THE INJECTOR And physically dump it into your palm and you will see what I am saying. the other injectors will not have one spec in them. do your best to get everything out-put it back together and check engine light will stay off (once reset) AND YOUR NOISE WILL GO AWAY. The cylinder is starving for fuel. give it what it wants, and it will shut up. the baffles in the fuel rail seem to divert all of the crap to that cylinder for some reason. Check it out-easy fix if I am right, If not what have you lost?

17 out of 17 people think this is helpful.
370

I recently ran into this same knocking/ ticking issue coming from my 2005 Suburban, 5.3 Vortec. After countless hours of research, multiple engine flushes, oil change, air filter, valve adjustment...etc etc etc...my solution and problem were relatively simple. If you look at your oil pressure and it reads anything under 40 at cold start idle this means your oil pump screen has one of two things: 1) It is clogged and needs to be cleaned, these things are pure metal so a costly replacement wouldn't be worth it, a simple clean will suffice. 2) The oil pump screen o-ring is allowing air into the system keeping the motor from efficiently moving oil through all rockers and rods. Both fixes require removing the oil pan, roughly 10 bolts, and the oil pump screen, 4 bolts. I flushed the engine before draining the oil, replaced the oil pump screen o-ring, cleaned the screen, and installed a new oil pan gasket all in a couple of hours. Low and behold I haven't heard a single tick since doing this, even in cold weather starts, and my oil pressure went from about 30 psi idle to around 45 psi. Take note I had already checked the valves to ensure there they were tight and this may not fix everyones problems but its an easy fix to rule out a few obvious things. One more key note I would like to add is that these motors are KNOWN for breaking the exhaust manifold bolts, typically on the backside of the motor near the firewall. This type of exhaust leak can also give the same noise as a dead lifter when under compression. I had one broken originally and broke another removing it. IF you decided to replace the gasket and pull the exhaust be sure to buy new bolts as the ones they came equipped with are very brittle. I hope this information helps out as many as possible. I spent hours and hours staring at my motor, computer screen, Haynes manuals, and such before finally figuring this out. I have basically compiled a few weeks worth of research as well as trial-and- error on this post. Good luck to all the Do It Yourselfers out there!

37 out of 37 people think this is helpful.
135

my 09 chevy z71 4x4 5.3 had this similar but much quieter knock 60k- 105k that I owned it and NOW my 2006 GMC Sierra k1500z71 slt is knocking. 5.3L with get this, 53k miles! I used 5qts RoyalPurple and 1qt Lucas soon as I bought it with 47k miles.. Ridiculous i say! Freakin madness! Bout to go buy a hemi ram. Stupid GM. NEVER again you useless sums a beaches NEVER

6 out of 6 people think this is helpful.
11,385

Been in the GM family since 1965. Only issues I ever had was bad gaskets and one A/C muffler design flaw on my Buick. Other than that, no issues. Change oil, keep it tuned ever so often, fix what's broken, and it will run great. Two Corvettes, (still have my 69) 4 Buicks, three Pontiacs, and one GMC. Two Ford and one Toyota truck. Oh and an AMC Hornet and a 51 MG, and a beater 57 Ford wagon. I started out with a 51 Plymouth and had a 57 Fiat in college. Never had issues as long as I treated them right. the 57 Ford refused to break, the 51 Plymouth kept spinning rod bearings. Beat you vehicle, and keep shelling out money.

80

The noise is camshaft/lifter roller damage caused by the plastic lifter guide worn on one lifter allowing the lifter to ever so slightly rotate causing the roller to dig into the cam lobe and gaulding both surfaces. To verify this without pulling the heads, the cam can be removed and inspected fairly easily by inserting a piece of 3/8" wooden dowel rod thru the lifter oil galley behind the camshaft retainer plat behind the cam sprocket, after loosening the rocker arms. This can be done in an hour or two, depending on familiarity with those engines.

8 out of 8 people think this is helpful.
30

I have a 2012 silverado 4.8 i have heard it is the oil pump. Mine is knocking or ticking at idle. driving me nuts.

3 out of 3 people think this is helpful.
135

Turns out my camshaft has a chunk busted out of one lobe peak! Wtf GM WTF

1 out of 1 people think this is helpful.
11,385

First, is this still under warranty? Probably not. Second this will be a complete tear down as junk has gone all the way through the engine. I had something similar go wrong in my new rebuilt Corvette engine. I scoured the crank and bearings, but I was able to turn the crank 0.10 and save it, the bearings of course went and the cam was destroyed. Cams are made out of soft metal, and they are susceptible to failure for any number of reasons. Some parts failure, some starting and with a cold engine gunning it before the oil pressure is built up, or metal fatigue. Cams are cheap, engine tear down and cleaned up is a tad bit of money, but if you can save the crank, bearings are not too expensive. It is a 2005, so if the engine can be rebuilt, stay with it as all the parts can be reused and put back together. Good luck my friend.

2 out of 2 people think this is helpful.
11,385

Oh, my Corvette engine was built the second time by a pro NASCAR engine builder. He magnafluxed my original engine with over 325,000 miles on it, and found 3 major cracks in the block. So dump the core, and I got a new short block. 10 grand it cost me. The cracks were from metal fatigue due to the late 60s and early 70s GM engines being made for a lesser strength iron material that could not really take the pressure from high performance builds. GM later changed the metal formula.

3 out of 3 people think this is helpful.
135

My truck is under warranty from one of several "after manufacturer expiration" warranty companies. Its covered under a premium bumper to bumper, roof to tires warranty as long as im paying a note on the purchase of the truck. They wanted to swap my engine out with a higher mileage used engine tho so I'm going with optionB, the GMC dealerships recomendation of a new cam kit job, still sucking $650 outta my pocket but the warranty covered $2850 so it is ultimately better than poke in the eye with a sharp stick.

2 out of 2 people think this is helpful.
30

I had the same problem when I start my truck after about five minutes it would start tapping in the beginning it stop after running for a while then it got worse started continually tapping........I replace my oil pressure switch it continued to tap......tried.....Lucas nothing........tried gummout nothing still tapping . ......so today I was irritated and embarrassed with .......so I went out and paid $8.50 for some justice Bros fast action .......engine tune up (part no.ETU/4 I PROMISE YOU I PUT THIS STUFF IN AND STARTED MY TRUCK AND THE KNOCK IS GONE........I OWN THE 2006 AVALANCHE . ......IF YOUR HAVING PROBLEMS WITH TAPPING NOT SURE ABOUT ANY OTHER ISSUES ITS WORTH IT BEFORE DOING MAJOR WORK.

3 out of 3 people think this is helpful.
60

Camshaft and lifter damaged, it happened on my 2007 5.3L. I replaced oil pump,inspected rod and main bearings,checked pistons all good. removed each pushrods,lifters and founds # 2 lifter and cam lobe damaged.

6 out of 6 people think this is helpful.

I own a 2000 Chevy Slverado Z71 4x4. It has just over 85,000 miles on it. When I first start it I hear the knock. I was told by the Chevrolet Dealership it was piston slap. The truck runs great, never smokes, never low on oil. No engine compression lost. I can run 80mph on a trip. No problem. I know a couple other folks that have these engines with over 200,000 miles. Never a Problem. I just let it warm up a minute, which is really what you should do with any vehicle. The knock goes away. My problem is my body is rusting. I will drive it till it falls apart.

2 out of 2 people think this is helpful.
11,385

The new engine blocks use a different metal material than in the late 60 and 70s so the blocks should be good. The cams always have been soft metal and can get flat spots for any number of reasons. Also gunk deposits can cause a tappet to be sticky until enough hot material is pushed into it to allow it to function. The valve train just may be what is the knocking problem. Some mechanics use a stethoscope to isolate the nocking noise to isolate where or what should be torn down for inspection. A head job and or cam replacement is really cheaper than an entire engine, rusty body or not. If it gets too rusty, make a rat rod out of it. The value goes up then.

2 out of 2 people think this is helpful.

My 1986 with 89000 miles on it GMC S-15 2.8 litre was up to 65 mph , suddenly it dropped to 50 mph, then 40 mph , then 35 mph, then it just quit . We towed it , we took off filter and cut it apart , all clogged up , maybe metal shavings , could not tell . Replaced oil, 5 quarts, and filter , Started it up , then left it run , came back , and the oil pressure gage was up and down . Then we went for ride , it quit again , took it home , my partner checked bottom of oil in pan after I left and said there were metal shavings in it ? Could it have been the transmission instead , I doubt it ! Is it truly a rod or a crankshaft ? If so what is minimum and maximum repair charge ? I bought it at 87000 miles 6 months ago ! The body is excellent , one rust hole thru ! Is this an antique ? I heard on Internet that this 2.8 engine was a "turd "!

11,385

rapplegate: What you have is an engine, not transmission, that is in need of a tear down. Once you have metal filings in the oil, it sends them everywhere oil goes. The metal filings score the bearings and crank, cam, lifters, and other parts. I had a gear driven timing (chain) go out in a newly engine rebuild. I lost the cam, all bearings, had to turn the crank 0.010, all new bearings, and a new double timing chain among other parts. The engine needed to be completely flushed out to remove all the metal filings. This happened after only a few hours on the engine. If it is quitting, you may have spun a bearing, and if you keep running it, a rod may go through the block. (worse case). Either way, you have some major damage inside your engine and it needs a complete overhaul/rebuild. You may find it better to exchange that engine for a rebuilt one. Metal filings in the engine oil does not mix with the transmission. Both are sealed componants and do not exchange fluids. As you engine gets hot, the bearings expand under heat and places added stress on the engine, making it work harder to run, then it will just quit. Sorry, but that is the good news. Bad news is it will cost money to fix.

1 out of 1 people think this is helpful.
60

I have the same knocking noise on a 5.3 vortec engine 04 silverado had the knocking noise for over a year traveling a lot motor has over 200miles, after that long time of period the knocking noise got louder and my oil pressure has dropped and I've now cleaned my oil pan completely and replaced oil strainer O ring and problem is still the same with very low oil pressure. When i accelerate the engine oil level goes up to normal my question is how much longer can i drive the truck I'm still out of town and need to get back to my hometown which is about 9 hrs away. Thanks in advance.

6 out of 6 people think this is helpful.
11,385

If you increase engine rpm, and the oil pressure increases, it should not be an issue to get home. If you are driving at normal speed and you pull out to pass and step on the gas and the oil pressure drops to 0 or near there, than you really may have an issue. If getting home is a desire, put a heavier weight oil in to help keep the pressure up. Also add an additive to help keep the engine together. If the "knocking" is a pounding noise, you may get 100 miles before there is a major issue. If you can slide into a garage, have them listen and advise. Be careful as you may find someone that wants your money. Without hearing the "knock" I can't tell you if a 9 hour drive will hold. Generally a thud, or pounding noise is a bad sign.

1 out of 1 people think this is helpful.
10

I went through a big puddle of water and after I got out of it my truck started knocking and shaking really bad wanting to turn off. Being very late at night and bad weather I drive it home like that but it just made it turning off a couple of times. The next morning I turned it on and the engine was knocking really bad called one of my cousins who knows a bit about trucks and he changed my air filter fuel injectors and oil thinking it might be the problem, the filter did have water and he changed everything correctly but the engine still knocks we turned it on and it knocks really bad then turns off by itself, is there a way to fix this problem I've been looking online and some guy said it my be a broken rod on a piston or something like that do I have to replace my whole engine at this moment?

1 out of 1 people think this is helpful.
11,385

If you take it to a garage that has a listening scope, like the Dr.s use to listen to your heart and lungs, they may be able to isolate the "knocking" sound. Depending on the amount of water you go into your engine it may have caused more pressure in a cylinder than the rods could handle. It may of bent a rod, punched a hole in the piston or bent a push rod. Is there any smoke coming out of the tail pipe? Check and see if any coolant is seeping into the engine. With fuel injection, I don't think there is as much a chance of water being forced into the cylinders as was with carburetors. Still, water compressed and ignited creates steam which expands in an enclosed space, increasing the pressure inside the cylinders. My bet would be a bent rod. Get it scoped ASAP to avoid the possible bent rod from going through the block.

1 out of 1 people think this is helpful.
10

Should I drive it like that it's like it's forcing itself to go it sounds really bad I don't know much about trucks but is it fixable I took a small video of it but i don't know how I can show you sir, I'm sure you would be able to tale, I don't know if I need a new engine or if I it's fixable but there's many mechanics here in Houston tx which one would be the best to go to or any would do?

11,385

If the engine is struggling for power, I'd not drive it. It sounds like some major damage was caused by water entering the intake system. Sometimes do-do happens. I had a friend that had a new Corvette here in So. Cal, and our storm drain system is the roadway itself. So crossing an intersection the nose dipped into the water and the air intake sucked water into the engine. His engine disintegrated due to too much water entering the cylinders. BM told him it was an act of the man upstairs, so his new Corvette got a brand new engine and his bank account went negative. If you take it to the/a shop you may minimize cost of repair. Sorry, but driving it from what you describe will or may cause major damage, then you still have a tow bill. If you have insurance that will pay for towing, use it. Also talk to you agent and see if the insurance company will help. It depends on the coverage you have. An 05 truck engine may be had for around 3 grand put in if your lucky to find one, or have your's repaired for that amount. Ask friends that are car enthusiasts for a good HONEST garage. Good luck my friend.

10

Thank you so much for your help I'll let you know what happens. I really appreciate the advice.

50

alot of yalls problem is piston slap, which isnt a bad thing. the fix for piston slap is to hone your cylinder walls and replace pistons and piston rings. piston slap isnt a problem at all and is completely normal on vortec engines with xxx xxx amount of miles. piston slap usually occurs when the engine is started cold and the noise goes away after a few minutes as the engine warms. if your hearing a louder tic or high knock noise is most likely a worn lifter but in some cases it is caused by the oil pump airating the oil. this concern is fixed by replacing the oil pump and making sure the pick up tube is free of holes, also replaceing the pick up tube o ring. on more rare occasions you can have a low deep knock sounding like knocking on a thick wooden door. this is caused by a spun crankshaft bearing. replacement of the piston rod, crankshaft, and piston is required. but usually on a vortec the problem is lifters. always check cam lobes to make sure they are not grooved/worn or damaged in anyway when replacing lifters. on repeat lifter failure conditions on active fuel managment engines the valve lifter oil manifold would be the issue.

5 out of 5 people think this is helpful.
40

I own an 07 with the 5.3 engine and it's making a taping noise. I was told that its the cam going bad. At the start up there's not noise but once it warms up (at idle) the noise is there. When we change the oil it tends to go away but returns at about the 1200 to 1500 mile mark. It gets pretty loud after about the 2000 to 2500 mile mark. This is happening here lately all the time but there no smoke or oil being burned at all. Is it the cam? If so, how much will it cost me to have this fixed? Should I invest in this engine or just buy a rebuild one or even a new one?

2 out of 2 people think this is helpful.
11,385

It may be push rods, or tappets. I'd get it scooped out by someone with a stethoscope to locate the possible source of the tapping. In the mean time put in some additive to the oil. A good car parts place can suggest the correct additive for what you need. Be careful that there is no something coming apart and filling you engine with metal shavings. It cost me a $10,000 engine when my timing drive went out. Lost the cam, and had to turn all crank shaft, and disassemble the entire engine to get the metal shavings out of the engine. I then hound three major cracks in the engine. It was a 69- 350 with over 350K miles on it anyway. Cost another $10 grand for a new short block, dual timing chain, cam and rebuild. Pull off the oil filter and using a magnate check the oil for metal filings.

1 out of 1 people think this is helpful.
40

Thanks and what I did was change the oil and added Lucas Oil Treatment with Mobil 5W-30 oil. I took it for a ride and the noise went away momentarily. I could still here it after about 15 mins, but then the noise went away. I also inquired about a new 5.3L Vortec engine and was told that it would be about $8000 to replace the old engine. I'll try all before I do this. I may have the engine pulled and rebuild before buying a new one. However, thanks.

40

The noise is still there and seldom heard during acceleration. I've heard that it sounds like a camshaft and pushrods. One maintenance man said that the engine is going to need to be rebuilt. Another says that before rebuilding the engine I should try Marvel's Mystery Oil Additive which should clean the entire engine between oil changes. Hopefully this Marvel's Mystery Oil additive will work.

2 out of 2 people think this is helpful.
11,385

Has any of the mechanics pinpointed the knocking? A camshaft/rod knock is a dull sound and using a stethoscope the sound can be better pinpointed. Rebuild in parts. Do the heads and possibly the cam first. If that does not do it, you're halfway done on the rebuild. Use a magnet to see of there are any metal particles in the oil. If there is, it is a bearing going bad, and since there is metal shavings in the oil, you do need a complete rebuild. There are cheaper engines out there is you use your own parts as replacement, A complete overhaul kit is around the area of $1,000. Labor is about double. Your engine can be rebuilt for $3,500 for a complete rebuild, including heads, cam and pistons, rods, and crank. Oil pump been checked? Might just be that. Good luck. If you are going to get a new engine, I'd say drive it until it disintegrates, but you lose a trade in value for your block.

1 out of 1 people think this is helpful.
40

I'm going to have a dealership use the stethoscope and hopefully they can pinpoint the sound which will help tremendously. I thought that it might be the oil pump but I'm not 100% sure. I'll have it checked as well and if I have anything replaced in the engine I'm just going to have it rebuilt to save time and a headache. I appreciate you assistance.

I have a 2000 LT Silverado 5.3 and it just turned over 170,000 with no problems what so ever. Just replaced my rear brakes for the first time at 160,000 and I purchased the truck with 36,000. So far knock on (no pun intended) wood, it's been the least mx vehicle I have ever owned. I run Mobil 1 5/30 synthetic and change oil every 7,500 miles.

40

The Marvel's Mystery Oil Additive has minimized the noise but I still can hear it. So, I'll give it another 2000 miles and see what happens. However, I believe that I have a piston knocking for sure or a rod.

I have a showroom condition Saab 97x Aero clone with the 5.3 with 102k and its making all kinds of terrible noises..It's an intermittent deep low knock but mostly noticeable when the engine comes off of load between shifts. It's been scoped and driven by mechanics and no one can figure it out.. I'm hoping its a cracked flywheel or a bad lifter but I'm fearing the worst, connecting rod bearing.. Frustrated because its in such perfect condition in and out

11,385

jrtewks4 I fear you may need an engine teardown to locate the bad part. It very well may be a rod bearing from what you describe. Why mechanics can not pin point it I don't understand unless you are not believing them. If it is a deep low knock or pounding sound off load, that usually means a bearing, rod or other.

Have an 06 5.3 vortex 98k just noticed tapping sounds like a belt tensioner. Stopped at dealership tec pulled both belts off still making noise stethoscope leads to believe cam and lifter damaged sound in back of rt bank of engine. Can't afford engine going to go for cam/lifer repair. Son is county mechanic said dextron oil designed for this issue we will see

11,385

If you go the oil route, change the oil first and in the old oil drop a magnet to see if there is any metal in the oil. It there is metal i9n the oil, you need a complete engine rebuild as the metal flake got in all the bearings and scored all of them. Check rebuild vs. crate engine. With that type of damage, you do the quick fix to quiet it down and sell or trade it.

1 out of 1 people think this is helpful.

I have a Chevy Suburban half ton with the 5.3 engine and 108k miles. Two days ago, the engine started knocking. No check engine light, but I noticed that the oil pressure was dropping to the 20's when idling and going up to the 60's when accelerating. Oil was about a quart low. I took it to a Firestone dealer. He looked it over for about 45 minutes and then told me that it was a collapsed lifter and would cost $450. He said that this is a pretty common problem with this engine. Next morning, he called to say that the lifter is under the head, that they would need to do both banks, and the cost was now $2900. I checked around to see if I could get by with doing just one bank, found that I really need to do both, and called Firestone back to give the go-ahead. Now the price was $4600. They cut the price down to $3800 after removing a few extras. I drove it to a mechanic I know. He listened and told me it sounded more like a rod knock to him. He doesn't do engine work anymore, so I took it to a third guy - another I know. He has not diagnosed it yet. Before we tear the engine apart, is it possible that an engine detergent or some other engine treatment could solve the problem? Should we try some other fixes before we look at the expensive repair work? And could it be something else besides a collapsed lifter or a rod?

11,385

Dear Dave, Just from what you tell us here, it sounds like a rod bearing going out. A good diagnostic check should confirm or reject that guess. Do a cylinder pressure test. If it is a bad or sticking lifter, it should have a low reading compared to the others. A stethoscope can tell if it is coming from the heads or deeper down in the crankshaft. A bad bearing will cause a dropping of pressure. Check out a rebuilt or cart engine for replacement. If you re-do the heads, it will build up greater pressure and stress on old and tired bearings and pistons connected to the crankshaft, then that will go next. So look for a crate engine on line or at the chevy dealer for pricing. 103K miles is now-w-days not a lot of milage for a crank bearing to fail. It happens, depending on driving history, and maintenance of the vehicle. A rod knocking, (bearing letting go) will have a low thud or pounding at low RPMs and oil pressure will drip. A lifter going bad will have more of a tap, tap, sound and the noise can be located on the top of the engine. Go to a good engine rebuilder and he will be spot on with a diagnosis. Just the heads alone at $4,000 is more than a complete rebuilt or crate engine BTW. Keep us informed.

I will Thanks for the reply - bad news all around, but it at least gives me an idea what to brace for.

Do you recommend Jegs for crate engines, or can you recommend another site?

11,385

They all are very close in pricing. A lot of mechanics and repair shops utilize Summit Racing. You can call them and they can talk to you or answer on their e-mail site. If cash flow is creating a tight budget, talk to a engine rebuild shop. It may save around a grand. Like I said, your milage is high but in todays engines, it's not ready for the heap. If it is a main bearing, the crank can be turned and new thicker bearings can be used. The cam may have to go, but it is less that $100 for a new one. For peace of mind, a crate engine will work. Chevy dealers also sell the chevy crate engines. Search around. No matter what you are looking for, it's available.

Thank you again for your helpful responses. I have another question. From my research, it seems that the 5.3L engine with active fuel management has a lot of problems. Should I consider getting a different engine, or having the AFM disabled?

11,385

Dave, The EFI requires a higher psi pressure than the mechanical fuel pump needed for carbonated engines. This one is a sump tank that holds fuel in it which eliminates the return line to the fuel tank. It also has a high pressure pump to boost the fuel pressure going into the injectors of the EFI. It is called a fuel command center. Check to see if you decide to go EFI, does your system you have now produces adequate pressure for the EFI system. Everything I have looked at, FiTech, Edelbrock and Holley systems and others do not have issues with the older engines that are or were carb equipped. That is what these systems are manufactured for, to replace the carbs, give better HP, starting and most offer continuous automatic tuning. On mine, I can switch from economy to race mode on the fly. I have spoken to a few people that has switched out to the EFI throttle bodies and they are very pleased and said they have no issues. Some intake manifolds may not work with the set up, but mine has been connected with Edelbrock and Holley to work on all their intake manifolds. Go on line and look at some of the u-tube stuff or do as I did, and contact the manufacturer direct and ask questions. No matter which way you go, have fun and enjoy.

Again, thank you for your advice.

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Used Toyota Tacoma
712 Great Deals out of 32,024 listings starting at $2,995
Used Chevrolet Colorado
298 Great Deals out of 16,518 listings starting at $2,195
Used Ford F-250 Super Duty
450 Great Deals out of 41,610 listings starting at $2,850
Used Chevrolet Silverado 1500HD
10 Great Deals out of 259 listings starting at $4,700
Used Chevrolet Silverado 2500
5 Great Deals out of 213 listings starting at $4,500
Used GMC Sierra 2500HD
134 Great Deals out of 13,438 listings starting at $3,895
Used Dodge Ram 2500
173 Great Deals out of 5,238 listings starting at $2,395

Used Cars For Sale

2017 Chevrolet Silverado 1500 For Sale
31 Great Deals out of 77,998 listings starting at $19,398
2016 Chevrolet Silverado 1500 For Sale
320 Great Deals out of 17,528 listings starting at $18,657
2015 Chevrolet Silverado 1500 For Sale
339 Great Deals out of 7,453 listings starting at $16,000
2014 Chevrolet Silverado 1500 For Sale
451 Great Deals out of 10,925 listings starting at $10,990
2013 Chevrolet Silverado 1500 For Sale
268 Great Deals out of 6,435 listings starting at $9,950