'85 Blazer 2.8 recurring head gasket problem

[283ci]

I Have a 6x,xxx orginal mile 2.8 Auto 4x4 '85 Blazer I bought with a blown head gasket. The machine shop guy told me the first blown gasket was probably from sitting so long and the antifreeze "dissolving" the old gaskets and blowing upon return to street use. I had the old heads checked for warp (negative) and repaired it.

About 6k miles later I have milky looking coolant pointing to an apparent newly re-blown head gasket. Anybody else have recurring head gasket problems? IS the block deck likely warped? Any thing else i should look for? I would love to just drop a V8 in it but don't want to track down new trans and T-case. The truck is cosmetically like new in and out. I don't want to do another head gasket job that may only last another couple thousand miles.

As I was investigating this I noticed that the lower radiator hose never warmed up. I checked the thermostat and found it to open just fine in hot water on the stove just before boiling. I was also able to pour water freely through the radiator from filler to bottom port and petcock indicating no real blockage in radiator. Does this sound like pump failure? I don't know if it ever overheated. Could never get the temp gauge to work even after replacing all sensors/sending units. Has been running fine and still does. Only noticed problem because I was adding a 1/4 quart of oil and saw milky residue under oil filler cap.

[betterthanyou]

Coolant flow seems like a problem. But overheating or freezing while sitting most likely killed the heads. My bet is the heads are cracked between the valves.

[854x4s15]

You say milky like on the oil filler cap? Sounds more like your getting some blow by caused from sticky rings or valves.

[283ci]

Took the heads to the machine shop a while back and they were fine. Machinist told me, and it makes sense, that oil in the coolant shouldn't be a head problem anyway being that the only pressurized oil path in that area would be the pushrods. Other than there the oil only passes back down through the heads by gravity and wouldn't have the pressure to push into the water jacket. This leads me to believe there is a crack in an oil galley somewhere in the block. In the process of pulling the block but it's a real bitch to get to the bellhousing bolts/converter cover.

[Ed Mc]

Be sure to inspect the intake manifold carefully for cracks. Another source of water to the oil passages.

Maybe it's time for a 3.4 upgrade!!!!! ............ed

[283ci]

I looked the manifold and gaskets over pretty good and saw nothing suspect. The other thing is the problem was 98 percent oil into the cooling system and no coolant into the oil or combustion chambers.

[betterthanyou]

A leaking manifold will never cause oil to get into the cooling system. Could the oil slick in the cooling system possibly be gas?

[283ci]

No, it's oil. It was accompanied by a noticeable dip in crankcase levels per the dipstick, like about 3 quarts. No oil cooler lines running to the radiator either, only tranny cooler lines.

[85firstgen]

I would think that for you to get that much oil into the cooling system then there would have to be a pretty big crack somewhere in the block. The milky substance on the inside of the oil filler cap means that it had gotten water into the oil when the head gasket blew before more than likely but I have never heard of coolant disolving a head gasket and blowing out from being put back into service. My truck sat for almost five years without being cranked and I drive it everyday now and no problems other than having to rebuild the carb.

As far as the bottom radiator hose never getting hot it sounds like your pump has completely stopped working but I would think that even just the heat from the coolant rising to the highest point is going to cause a very minor bit of circulation which the bottom hose should get at least pretty warm if not hot. Does the top hose ever get unbelievably hot? If it does not then maybe you just have the worlds most efficient radiator! Seriously I do not know that this motor is going to give you more and more problems because it blows a head gasket again in 6k miles then something is seriously not right. It means that either there was a problem with the heads that the machine shop did not see or there is a pretty serious problem with the block and more than likely it would need to be replaced because a crack that is going to let that much oil into the cooling system probably cannot be repaired and actually stay together. The only other chevy motor I have seen do this with the oil getting into the coolant was a 350 with a hole inside the block from where it had frozen and somehow did not push out the freeze plugs!
Good luck!