Blown head gasket?
Well, I bought this truck a few months ago. It's a
2000 chevy silverado 1500 with the 5.3L. I went to
change the oil yesterday and while i didnt see any
coolant in my oil, when i took my oil refill cap off, it
had moisture puddled up on the underside of it and
was gunked up with a chocolate milk/rusty color.
You could literally see moisture in the refill neck
and on the cap and both were caked with that
I've also noticed some little things with it. Ive lost
a little bit of coolant (about an inch out of the res.
and have lost about a half quart to a quart of oil
since i bought it (driven 2000 miles since).
Sometimes it won't start when I first turn the key
and it rolls over a few times, I have to turn the key
back then turn it over again before it will
start(possible compression problem). Also, my oil
pressure gauge gets bouncy when idling and it
doesn't quite idle right, you'll feel a little rumble
every 5 seconds or so.
Besides all that the engine runs fine and idles
decently except for the very slight rumble every 5
seconds. All signs point to a blown head gasket
do they not? I'm also worried about further damage
to the engine because I have a feeling it was like
this before I bought it and I've been driving it this
way and who knows how long it's been driven like
that before hand. If it is a blown head gasket what
kind of repairs will most likely have to be done to it
besides new head gaskets as far as machining,
cleaning, replacing, etc.
I know it's one of the more difficult repairs to
make but I am consider doing it myself with some
help. I'm mechanically inclined I just never tackled
anything this substantial and am not sure what
else will need to be done to the heads or anything
else besides the gaskets. Or what special tools I'll
need. Any advice or thoughts will be appreciated. I
am having my go to mechanic look at it soon I'm
just freaking out here and want to get some
Ok, first off under your oil cap what you see is normal. Its just condensation collecting because of the cold & hot. Your oil usage sounds normal also. If your motor is not overheating, and you don't see any oil in the coolant system, or coolant in the oil, plus no white smoke coming out the exhaust, I don't think it is a blown head gasket. You can do a couple of test to check, 1 by pressurizing the coolant system to see if it holds pressure, 2 by doing a compression test on the cylinders. 1 or 2 cylinders would show. low in compression. The starting thing may be plugs and wires, but I would check the fuel pressure. It should be at 56 to 63 lbs.
I have been working on my own vehicles and changing my own oil since I was a teenager and I've never seen this before. The amount of that gunk on the cap and refill neck was shocking. It covered the rag I used to wipe it off (which I regret now that I'm going to have it looked at). Your probably right that it's not completely blown but something's not right. The bouncy oil pressure gauge can indicate something wrong with the head gasket as well. Also, the little coolant I'm using isn't pudding anywhere so where is it going? My brother who was a marine mechanic on amphibious veh. and has worked on the 5.3s before was the one who pulled the cap off and noticed it in the first place and said I might have some big problems on my hands. Add in the slight rumble while idling and to me there's just no way this is normal.
Also another cause of the moister could be the PCV and breather system. The PCV system takes crankcase gases created by churning oil and cylinder blow-by and directs them into the engine where they are burned along with the air/fuel mixture. This keeps harmful emissions from entering the air we breathe and prevents the buildup of crankcase pressure. The PCV valve regulates the flow of these vapors. A clogged valve can cause pressure buildup, which can in turn cause gasket failure and oil leaks, and also cause sludge buildup, which occurs when moisture remains in the crankcase and contaminates the oil.
I've seen many of these with residue under the cap and sometimes in the tube. Chances are your the first one to clean the fill tube. 1 inch in the overflow isn't hardly anything and 1 quart after 2000 miles isn't bad. How many miles on this truck? If your not getting white smoke out the tail pipe and the oil drained isn't chocolate milkshake then your head gaskets are fine. The starting thing in the morning sounds like the fuel pressure bleeds off overnight. Either check valve in the pump or pressure regulator. I think your getting alittle ahead of yourself.
Did you ever find a fix to this issue? My truck is currently having the IDENTICAL problems. Please help! Thank you!
Well, I had a few issues. The starting problem was my fuel pump, replaced that and have had no problems since. The bouncey oil pressure gauge is likely a faulty oil pressure sensor or a bad seal around the sensor causing oil to leak from there. I have just left it and have had no major issues. Still losing a bit of oil and coolant but nothing I can't keep up with. The fluid and gunk under the refill cap was attributed to condensation from the engine heating up and cooling down. Other than that, no issues.
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