Coolant Leak Problem GM 366

[jaredg]

Have any of you guys had trouble with steam coming from the engine after the temp gauge hits roughly the mid way point (180 degrees)?

I am its driving me crazy. I can not seem to fix the issue. I first thought it was a bad water pump, so I replaced it. I then thought it was a bad gasket in the thermostat housing, I replaced that and put in 2 new thermostats. Still no progress. I then put a pressure test on the radiator and instantly found a leak in the upper radiator hose. Replaced it and no more leak or steam however I noticed the temperature gauge on dash was way high. Added coolant and drove the bus 80 feet out of my garage onto my drive way. Then noticed the dreaded steam again coming from front of engine! I thought maybe another hose on the upper radiator was bad so replaced that. At this point I had to refill coolant fluid and got some on engine block. I got the steam thing again! It may be from all the previously leaked coolant burning up on the block which would be great. I then let the bus sit for about an hour then re-pressure checked to find the system held at 7 psi (the correct psi called out on the cap). I started her up and backed her into the garage with no problems but am not really sure yet if im out of the woods. I'll go back tomorrow and re pressure check and start her up. hopefully its good but i am not convinced its fixed. If its not hoses or water pump, what else could be doing this? I heard bad head gaskets can lead to this? What are other signs I need to look for?

Anyway, thanks for reading my frustrating rant. I really need some help here.

[jaredg]

Thanks for the reply CheeseWagon.
I had a rather succesfull day yesterday. I pressurized the system with the test tool again and instantly spotted leaking down by the lower gasket of the water pump that I had recently installed. Since I'm a newbie at this I wasnt as thorough with the gaskets and using sealant when I installed the water pump 2 weeks back. So I took out the pump and spent a bunch of time cleaning the mating surfaces and got brand new gaskets. I then sprayed the gaskets with adhesive and stuck them to the block and inserted the bolts just to keep them in place. Let them dry and then applied the gasket sealant to both the gasket and the surface on the pump, re installed. Then I re-pressurized and everything was great!! I started her up and let her run with no leaks or steam! The only thing I noticed was that the temp gauge on the dash went all the way up to hot. Rather strange though. The engine didnt shut off or anything as if it was over heating. I very well could have air pockets in the coolant flow. I'll check them this afternoon.

[the_experience03]

It'd be nice to know what the actual temperature of the engine is instead of just somewhere between C and H. I think you're on the right track though. Bleed is of the utmost importance. Sometimes it is necessary to drill a hole in the thermostat if it doesn't have a toggle valve or even to leave the housing loose during the initial bleeding.

Hopefully you won't have to do the water pump again for a very long time. It's going to be tough with that adhesive holding the gaskets to the block. I like to use 3M weatherstripping adhesive and put a thin layer on the water pump. I spread it out into a nice, even layer and let it tack up for a few minutes. I then lay the gasket on it, pull it up once (the adhesive will get stringy, not unlike contact cement), and then slap it down once and for all. It will hold it in place and assure that there are no leaks on that side. As long as the block side is perfectly clean you won't have leaks there installing it dry either. The best part is that the next time you have to remove it the gaskets stay (mostly) attached to the water pump you're either chucking or returning as a core and not to the block.

[jaredg]

It was most certainly air pockets in the coolant flow! You got it. I burped the radiator and now all is well again! Thanks for all your help! Now I can get started with pulling the seats and the floor up.