I have an 05 Duramax that runs great. Vehicle is loosing coolant (about 1 gal. per day) and has significant amount of engine oil in coolant reservoir. Pressure tested cold and has no leaks. What's up? I need to see what my next steps should be. Thanks for anybody's input.

20

Asked by Oct 19, 2012 at 07:49 PM about the 2005 Chevrolet Silverado 2500HD

Question type: Maintenance & Repair

29 Answers

30,955

Oil in the Res would lead me to a cracked radiator but I'm lost for the coolant loss. During the pressure test there was no pressure loss, or you just didn't see a leak?

2 out of 2 people think this is helpful.
145

If you getting engine oil into the radiator and coolant,that is usually a sign of a blown head gasket or a cracked head etc. You will see no leaks with a pressure test as its not an external leak, did the pressure drop when you tested it though or did the pressure stay the same over say 5-10 minutes? if it drops that could be a sign of leakage. You will need to get a head check test done, also one other possability is a crack in a transmission cooling line where it runs through the radiator if its auto, it could be trans oil,hows your trans fluid look and level if its pinky white instead of red there maybe water getting into the trans and visa-versa.

30,955

Where in the head is there pressurized oil that will get into the coolant? Oil goes into the lifter from the block and into the push rods and flows down the rocker arms. If the oil was entering the cooling system via the unpressurized heads then as soon as the vehicle was started the coolant would flow into the gigantic hole and into the crankcase. Emptying the cooling system in a matter of minutes. Unless its an overhead cam engine which its not there is nowhere on the head that has pressurized oil.

20

During the pressure test I failed to mention that it was building pressure over 20 psi and then stopped the test. It is definitely engine oil in the coolant reservoir. The trans fluid is perfectly clean and of correct color. This vehicle also has a rear mounted transmission cooler. It is a 3500 Duramax. I am still at a loss.

2 out of 2 people think this is helpful.
575

check to see if there is coolant in the engine oil. the head gaskets have been know to leak on that year of duramax

145

John ,with any engine you have oil and water galleries that pass through the head gasket from the block to the heads and also drain oil back to the sump from the heads so if you blow a head gasket or crack a head near those galleries pressurised oil (eg crank case pressure) gets forced into the water galleries and visa-versa water into oil (check oil if milky or if very milky on oil filler cap.)if your finding on your pressure test its building lots of pressure fairly quickly and blowing water out alot and its not really that hot that can also be a sign of head gasket blown into a cylinder,does it run ok or misfire a bit? but by the sound of it i would get it checked by your local mechanic because if it is loosing alot of coolent you could do worse damage if it is a serious problem.

1 out of 1 people think this is helpful.
30,955

Blown head gasket getting coolant into the crankcase, I have no doubt about that happening. But the pcv valve prevents crankcase pressure. There should be next to ZERO pressure in the crank case and even if there is some it isn't nearly enough to blow oil into the coolant jackets. If the oil was getting into the cooling system via a hole in the head, block, or blown head gasket then the hole would have to be big enough that as soon as you started the vehicle 80% of the engine coolant would escape through that hole and into the crankcase before anything "might" drip back through it. Also I'm pretty sure he would notice a gallon per day in the crankcase.

30,955

What are you even talking about with the pressure test. A pressure test is done with the vehicle NOT running and blowing water out a lot? Where are you proposing its blowing water out from?

575

I agree with brent it sounds like a serious issue and you should probably have a shop look at it. To replace the head gasket on just one bank is a 20 hr job and is probably not that easy to do without good service information. Also John when things go wrong things often don't operate the way they are supposed to.

30,955

If something goes wrong then its obviously not going to operate the way its supposed to. If it did operate the way its supposed to then nothing would be wrong. My point was that if it has a cracked head or bad head gasket, then it would have massive amounts of coolant in the oil not the other way around.

2 out of 2 people think this is helpful.
145

sorry john you are right about the pressure test with the engine not running i was actually thinking and meaning to do a t-kay head check test in which you have the engine running and check those symptoms and believe it or not you do get oil into the water jackets through even some smaller blows in a head gasket in the right place, i have seen this problem quite a number of times before and had to repair vehicles with the problem and a gallon of water or 4 litres is a lot to loose in a short period or even in one day and if it was a cracked radiator as you suggest how would that put oil in the coolant it has to get in somewhere where oil and water can mix eg. head gasket, cracked head or block.So the question is still is the engine oil a milky colour or any water in it?does the oil filler cap have milky substance in it ?and is the substance in the coolant reservoir a milky brown?

30,955

The ONLY place oil gets into the coolant without some unbelievable and very noticeable issue is via the radiator. It happens when the oil cooler cracks into the radiator some have engine oil in the radiator some have a trans oil cooler and some have both. Oil in the cooler will be pressurized in either case and will spew straight into the coolant. Have you ever replaced a radiator, obviously you have and just never payed attention to the steel lines running to it?

2 out of 2 people think this is helpful.
145

john if you have a look at my very first answer you will see i have already suggested that about the trans lines in the radiator as being one possability but then if that is the problem when a pressure test done that should force coolent back into the trans lines eg. coolent in the trans oil.

145

Also that still means its not a cracked radiator its a cracked trans cooling line in the radiator if we wish to split hairs.

1 out of 1 people think this is helpful.
30,955

Look at THE very first answer on this question its mine saying the radiator is probably bad so don't try to take credit for that. "and if it was a cracked radiator as you suggest how would that put oil in the coolant it has to get in somewhere where oil and water can mix eg. head gasket, cracked head or block." Is exactly what you said 10 hours ago, and regardless of what you wish to call it, if the lines are leaking into the radiator, he needs a new radiator. Let's split hairs pops. BTW trans fluid is oil based making it an oil.

4,245

if you (when it's cold) take rad cap off and start truch if the coolant shoots out then there a blown head gasket or cracked head. could also possibly be radiator issues if the engine oil cooler is built into the rad but i've never seen that with engine oil usually only transmision oil.

145

yes John you did say that and i agreed back in the first one but i said about the trans lines into the radiator in my first answer but what i am desputing is you say you cant get oil in the water from a head gasket or cracked head,by the way what is your trade or do you do for a living?

1 out of 1 people think this is helpful.
16,175

I wouldn't mess around with this issue. If it's burning off then you can casue serious damage to your engine. Diesel + water = bad

30,955

True Andrew the engine can turn into a steam engine and run away. Brent I graduated top of my class from Lincoln tech for automotive in 08 and with my associates degree. Its common engine sense as with a cracked head and oil getting into the coolant, and anyone who is familiar with an engines oiling system knows its not happening in this case. Nowhere in the head is the oil pressurized unless its an overhead cam. On a standard engine the oil enters the head through the pushrods and gravity feeds back to the oil pan. Now for this falling or draining oil to be able to enter this hole you make reference to, all of the forcefully flowing coolant would have to exit the system and then maybe if the hole was big enough and conditions were perfect the unpressurized, draining oil would get into the cooling system via this hole. With that said the hole would have to be large enough that you would loose all your coolant before you got to the corner and all this coolant would be in the crankcase. With that said if it was even still running at this point the vehicle would look like a hooker with a severe case of yeast infection wearing no panties. White thick milky yuck would be everywhere within 20 minutes of driving. All I did was simply attempt to rule out the idea of a bad head gasket being the cause of oil in the radiator. I'm not saying the head gasket is good either. You may be right about it being the cause of the coolant loss, but your wrong about it being the source for the oil in the coolant. Also as for the block being cracked it would be the same case. There is no way that an intelligent human in their right mind that also knows an oiling and cooling system could read all this and still have much belief in the whole head putting oil in the coolant theory. Now I'm all about education and if you can figure some idea that makes sense then I'll listen but as of right now you have made no valid argument and I'm tired of reading someone argue a point with no facts or logic.

1 out of 1 people think this is helpful.
30,955

Btw I was born in 88 and started working on cars in 2002. I graduated high school in 07 and college in 08 with a certificate saying i can work for places hiring ASE certified people and a 2 year associates degree in applied science. I showed mine let's see yours;)

1 out of 1 people think this is helpful.
16,175

all arguments aside, a failed head gasket usualy has coolant into oil becasue of the pressure of the coolant is relatively high and oil is lower there. So John has a point. However man, you got some anger issues. Just say your advise and let it go. It's the internet, people just love to push other peoples buttons all the time. With things layed out on the table who is the poster going to belive? 1600 points or 55? NOW USEFUL INFO: Have u mixed any type of coolant? IDK if you use it but DEX-COOL can act funny sometimes. You ARE loseing coolant somewhere, that is clear. But where is the question. If there is an internal oil cooler in the radiator I would agree with John and start there. What is the oil look like? is it milkshake looking after running? I have seen a sludgy build-up in a radiator that didnt have a leak to anything, dont know where it comes from but i have seen it, truck lost no oil or coolant and was a stick so no trans cooler. How are you 100% sure it's oil in there?

145

Well i was born in 64 and started working on cars from the age of 14 started my trade at 16 and have worked as a mechanic for over 25 years in quite a few workshops ,have been service manager,parts manager,owned my own workshop and have seen oil in water from blown head gaskets and cracked heads and repaired the problems and that was from the days when most vehicles were only overhead valve, nothing counts for more than hands on experience and i've seen some strange things happen that your textbook doesnt cover.the thing is this person says there loosing a gallon of water and thats quite a bit of water and has water in the oil ,so if it was a trans line inthe radiator that explains the oil in water but not the water loss so the water has to be going some where he also hasnt said how much oil is in the coolent it may be a brown sludgy mess in there and he hasnt said if there is any water in the oil pan etc. or trans oil.Now depending where your head gasket is blown if between a water jacket and oil gallery and cylinder the compression can push and draw oil and water between the galleries and even into the cylinder believe it or not and it doesn't have to be that bigger blow, i have seen engines still run where you can be filling the radiator and the water is pouring out the exhaust like an outboard just as fast and its still running.I agree with you too Andrew it may not be oil i have seen lots of sludge in cooling systems also that is not oil the just need a good clean out.the fact is we are not there to see for ourselves so its had to say,as for 1600 points against 55 that is only because i dont bother to answer on here very often even though i look at it sometimes because after 25 years of cars i cant be bothered or dont have the time and this is the type of response you get from people.i will leave it to the younger guys to get on with it while they still know it all.

30,955

Aside from the old flat head v8 and maybe a few other designs. Every automotive engine to leave the factory has been an overhead valve since probably the very early 60s. So what days are you talking about. As for a pushrod engine design the oil never flows through the head... it travels up the push rods, flows over the rocker arms, lands on Top of the head and then rolls down the inside of the block under the intake. Let me break this down even further so drink your coffee and get ready. For the engine to blow a head gasket and have that hole connect from the compression chamber to the coolant jacket to the oil in the crankcase running down the inside of the block. So the piston comes down creating around 18-21 inches of vacuum. Pushing around 200+ psi of compression. Pushing air into the coolant and coolant into the oil. Here's the fun part, power stroke is right around 15,000 psi and 2000+ degrees Fahrenheit literally exploding exhaust gases into the cooling system and exploding coolant towards the oil. Finally the exhaust stroke which is probably around 5-20 psi pushing into the coolant which then pushes coolant into the oil. So out of a total 4 strokes lasting 720 degrees at 700 rpm that's approximately 12 revolutions per second which means each of these steps are happening 6 times a second, do you honestly believe that out of those 24 cycles 18 of them having pressure that the vacuum would pull oil into the cooling system. Btw to get the cooling system to pull oil from the crank case, the crank case would by default have to be at a greater pressure than the cooling system. Since the crankcase isn't pressurized that means the cooling system would have to be in some sort of vacuum for the pressure differential to be correct. I'm not a know it all I'm just ot one of those fucking idiots who argue with people about things that I'm not correct about. Anger issues Andrew? No not anger issues I'm just tire of people on here like the lady in this topic ---- --> http://www.cargurus.com/Cars/ Discussion-c8812_ds528581 the person asking the question wanted to know how to remove the PCM from an 89 Buick. Psycho lady said that computers were the size of houses in 1989 so cars didn't have computers. Even after laying all the facts on the table that computers were not in fact a myth and they were real she still argued. Apparently bill gates hadn't invented the computer yet. Like I said before on an over head cam OHC or even a supercharged engine, yea I could see the definite possibility of a head gasket getting oil into the coolant. But not on this stock diesel.

Youre losing water out of your exhaust cooler. Had the same problem with 06 duramax. E valve is bad on your exhaust cooler

What about where the damn coolant meets the oil cooler on the side of the block. These things fail on class eight tractors and do the same shit.

20

John, you are wrong if the gasket is blown by a water jacket causing compression loss into water jacket is where pressure is getting into radiator causing pressure to blow out overflow which in turn is where water loss is coming from an also if it is blown by water jacket an oil Jacke t both it causes a vacuum affect which is where oil is getting into coolant u say u went to school an top of your class then I would suggest goin somewhere else to get updated 99 % of real mechanics know this

2 out of 2 people think this is helpful.

I hate to pop your bubble, I fix four blow head gasket in my life time, best way to tell if it's a head gasket, run engine for a minutes, afterward check your dip stick if it look brown and have bubbles, that will be your answer, if it don,t then it your radiator it one or the other nothing else , I hope this help you and you welcome

10

I have a 2005 2500 diesel and had the same problem. it turned out to be a head gasket leak from the cylinder pressurizing the cooling system. It only lost coolant while towing or going up a steep grade. Replaced both head gaskets and the problem was solved.

1 out of 1 people think this is helpful.
340

Think you have oil cooler element problem (leaking), also possibly injector nozzles jackets leaking, good luck.

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