Another bad engine?

[marktara]

What do you guys think is wrong? Engine starts good(a little white smoke and uneven idle for about 30 seconds), top rad hose will get hard after a couple minutes of running, it will get up to operating temp and if you let it idle it will idle for a long time the all of a sudden start pushing out coolant through over flow. If you take it on the highway you can drive as long as you want and have no problems but when you slow down for a corner or stop light it will spit out the coolant. Heres what I have down so far: i pulled off both heads and had them pressure ckecked and were fine, put back together with new gaskets and bolts. Truck went from lots of white smoke all the time to present codition. Then narrowed it down to no. 8 hole as problem so pulled off that head and had it rechecked and reinstalled with new gaskets and bolts thinking I might have damanged gasket first time. Also no antifreeze in oil and blow by seems normal. I've come to the conclusion that my block must have a small hole in it, does this seem possible?

[ejk2352]

Did you have the cylinder heads magnafluxed?? Fel-Pro head gaskets?? New head bolts?? The heads could be cracked, but the crack might not open till you get some heat in the engine. You could have a cracked block. The #8 cylinder area is common. I had 2 cracked heads on my truck a couple of months ago. My heads were cracked between all the valves and in the combustion cambers. Benny Avant did me up two nice heads. I checked the block deck and looked over the cylinder bores, I didn't find any cracks so I put it back together. Truck has been running great for the last 4000 miles. You might want to go to a GM dealer and get some coolant seal tablets. I know a few guys that swear by these.

[marktara]

Not sure if they manufluxed the heads, but used new bolts and FelPro gaskets and yes I tried the tablets from GM. If block were cracked would I not get antifreeze in oil?

[eracers999]

Have you properly bled the air from the system??

[twaddle]

Hi there,
First of all, is the water temperature actually getting too high or is the system definitly pressurising due to cylinder pressure getting into the system?
Have you carried out a pressurising/bubble test to check that it definitly is cylinder pressure getting into the cooling system?
This may be a long shot but you never know...
If the pressurising is caused by an overheating problem, Have you changed the water temperature regulater (thermostat)?
If it is not opening enough it could cause overheating when there is little air flow compared to when the truck is moving.

Good luck

Jim Twaddle
Biggar, Scotland

[marktara]

What is the proper way to bleed the air from the system? I did a pressure test on the coolant system and it took about 5 minutes of idling before the pressure gauge got above 17 psi.

[charliepeterson]

Try replacing the surge tank cap. The system is supposed to hold 15#. If you had a head failure you should see LOTS of white smoke. The top radiator hose really shouldn't get hard after running only a minute.

[Hubert]

Bleeding air out of the system:

There is a bleed screw in the double thermostat cross over housing of 97+ trucks. Some air came out when I was refilling my system after replacing a stuck open thermostat. But I am not sure how much air.

Any other ways to bleed system?

[marktara]

I've tried a new cap, how hard should the top rad hose get?