Please help with OIL in 250 cooling system

[Matt58]

Hi guys I have a 66 c10 with the original 250 and 3speed. It needed an exhaust gasket and the manifold resurfaced. To get the exhaust off, I had to remove a bracket (old aftermarket A/C) that was held on by the front two head bolts on the driver side. I removed it and replaced the bolts. Got it all back together and running but now have oil in the radiator. I removed the valve cover and made sure all bolts torqued to spec, flushed out the radiator, heater, and head. Got it goin again but still have oil in the coolant. Did I wreck the head gasket ? or worse? Would it take a while to get all the oil out of the system even though I ran a lot of water through it? I left the radiator cap off and when the thermostat opened it was like chocolate milk again. Sorry so long but please help. Matt…. Also no water in crankcase, only oil in cooling system

[blown240]

Sounds like you may have blown your headgasket. Why did you need to resurface your exhaust manifold? Did it warp from heat?

Also, when you pulled the valve cover off, how did it look inside? No chocolate milk under the cover?

[TJ's Chevy]

Does the truck smoke at all? If the head gasket was blown you could tell by either seeing smoke out the exhaust or by the spark plugs. You could do a compression check to see if the gasket it blown. When you run it with the rad cap off...does the water bubble?

[Matt58]

Yes the exhaust manifold was warped. Under the valve cover was normal. Dipstick looks fine too.

[Matt58]

No smoke and no bubbles in the radiator...just chocolate milk. Will check the plugs...

[blown240]

Its possible that you blew the gasket between the coolant passages and oil passages. If so, its where there is oil pressure and that keeps the coolant out of the oil.

[vince1]

I'd pull those two head bolts and put some sealant on the threads. Could be that they extend down into a water jacket.

[Wrenchbender Ret]

Is it an automatic trans.?

[Matt58]

3 speed tranny

[Wrenchbender Ret]

Some of the early models of those engines had a problem with cracks in the lifter galley that caused oil to get into the cooling system. There is no way to tell without a complete teardown. If you exhaust all other possibilities that may be what the problem is. There is no repair for it. If that's the case you have to look for another engine.

[pritch]

Another thing to look at is that front D side head bolt. There ain't much meat there on the block, and in Leo's book he recommends not tightening that one quite as much as the recommended torque, as it's easy to crack the block right there. I'll try to find a picture of that area.

Here:


This is a 250 I tore down a while back. See how there is just not much metal around that front head bolt(the one on the top of the picture) and it's a direct route to the water jacket.

[Matt58]

Thanks everyone.. I am going to pull the head this week. Will report back.

[Matt58]

Well got the head off and could see nothing really obvious except a small gas leak between two cylinders. I took the head and had it checked for straightness and the guy said the same about oil in the coolant would be coming from below the head......got a new head gasket and put it all back together. Cleaned and flushed, flushed and cleaned. Ran it through a bunch of heat cycles, flushed and cleaned. The oil keeps coming...especially at higher rpm.....anyone have a good block for sale?