Coolant in Oil - What Now?

[Larryjb]

Nope. Intake gaskets have no coolant flowing through them. Only, sometime, a coolant hose going to the throttle body.

 

[Justinj360]

Nope. Intake gaskets have no coolant flowing through them. Only, sometime, a coolant hose going to the throttle body.

Son of a *****... Excuse me I have a neck to go wring...

 

[swathdiver]

Son of a *****... Excuse me I have a neck to go wring...

Yeah, tis ain't no SBC, no more coolant through the heads and into the intake. Gotta pull the heads.

 

[Larryjb]

I'll have the dealer do that if they will.

This is really easy to do. You could probably have the valve covers off, tested, and back together before you'd drive it to the dealer, wait, drink coffee, wait, pay, then drive home. A coolant pressure test kit is likely cheaper than your visit to the dealer. Because you did the intake gasket, I know you have the skills to pull the valve cover.

 

[Justinj360]

This is really easy to do. You could probably have the valve covers off, tested, and back together before you'd drive it to the dealer, wait, drink coffee, wait, pay, then drive home. A coolant pressure test kit is likely cheaper than your visit to the dealer. Because you did the intake gasket, I know you have the skills to pull the valve cover.

Okay so are you saying the heads all crack in the exact same place? On a side note, could a blown head gasket cause a coolant leak?

 

[Larryjb]

There is a TSB out on this for 2001 - 2006 Tahoes (and others). The crack commonly appears around the oil drains, mostly on Castech heads. Mine is not Castech, but still had the crack in the same area. This may not be your problem, but it is easy to check. A blown head gasket could cause a loss of coolant.

Other areas that cause hard to find leaks:
water pump
thermostat housing
probably lots of others.

The best way to find these to get a coolant pressure tester and leave it on overnight and look for a puddle. When I wasn't finding a puddle, I sent in an oil sample and confirmed I had antifreeze in my coolant. Fortunately it was a slow leak so any water evaporated from the oil. However, the organic buffers used in the coolant stayed in the oil and began to sludge up my oil.

 

[Justinj360]

So today I finished putting it back together and ran it until it reached operating temperature then I changed the oil. When I first started the truck it made the same knocking sound as it did before. It was definitely coming from down low in the engine. Then after about 2 minutes of idling it all of a sudden stopped knocking and then sounded completely normal. I'm not sure what that was about but I ran it for probably 20 minutes total and the knocking never came back. My guess is that the oil wasn't soaking the bearings yet.

Also, while I was changing the intake gaskets I sprayed some Seafoam in the intake ports to help clean them up a bit. So when I started the engine I got the usual cloud of white smoke out the exhaust. Then I noticed that there was white smoke coming from somewhere down by the exhaust manifolds on both sides... This leads me to believe that I have blown head gaskets. Could that be true?
I took this picture looking up at the engine on the passenger side. You can see white smoke towards the front of the engine in the picture however in person you could see smoke along the entire length of the heads.

 

[Tonyrodz]

So today I finished putting it back together and ran it until it reached operating temperature then I changed the oil. When I first started the truck it made the same knocking sound as it did before. It was definitely coming from down low in the engine. Then after about 2 minutes of idling it all of a sudden stopped knocking and then sounded completely normal. I'm not sure what that was about but I ran it for probably 20 minutes total and the knocking never came back. My guess is that the oil wasn't soaking the bearings yet.

Also, while I was changing the intake gaskets I sprayed some Seafoam in the intake ports to help clean them up a bit. So when I started the engine I got the usual cloud of white smoke out the exhaust. Then I noticed that there was white smoke coming from somewhere down by the exhaust manifolds on both sides... This leads me to believe that I have blown head gaskets. Could that be true?
I took this picture looking up at the engine on the passenger side. You can see white smoke towards the front of the engine in the picture however in person you could see smoke along the entire length of the heads.

View attachment 207004

Do you have broken exhaust manifold bolts? Could be leaking from that, and once it warms up, the metal expands some so the smoke will stop.

 

[Justinj360]

Do you have broken exhaust manifold bolts? Could be leaking from that, and once it warms up, the metal expands some so the smoke will stop.

Not that I know of. How would I check for that? It seemed to pour smoke out of both sides the whole time even after it reached operating temperature. When smoke stopped coming out the exhaust it also stopped coming from the engine.

 

[Larryjb]

Broken exhaust manifold bolts are so common, that's almost certainly what it is. Either that, or the bolts have worked loose. I had to tighten exhaust manifold bolts on my Buick 3.8L. I probably should have replaced the exhaust manifold gasket, but there is so much in the way on those FWD engines.

On the plus side, there is an easy fix from Kral Auto parts for the exhaust manifold bolts for the Chevy engines. They are "clamps" that clamp down on the exhaust manifold. However, before investing in this, forgive the broken record, but pop off your valve covers and take a look. I work really slowly on truck stuff. Many guys around here would have had both heads off in an afternoon, with time for beer. I've taken about 2-3 days. It only took me an hour to get the valve covers off to inspect. The head was already "clean" right around the crack, so it was very obvious.

This is what mind looked like:
https://www.tahoeyukonforum.com/threads/latest-oil-change-oil-filters.99646/page-4