Thread: Cooling system issues.

This is going too far:

3 weeks ago I do my intake gaskets and coolant elbows, coolant started appearing as if its boiling because its getting to hot. (Like water boiling in a stove was like my coolant resivoir) Thought it when away but 2 weeks later after a long trip i get a 'knock in the engine' We figure it was the head gasket that was getting air into the coolant but either way, engine is now garbage.

Today i replaced my engine with a used one with way less kilometeres. Take it for a few short trips and get home and can hear the coolant boiling again! Get out, pop the hood, exact same thing but not as bad because it wasnt a long trip. As the car cools down it stops bubbling.

Notes:
-The guy that owned the car before me put *tons* of sealant in the cooling system to stop the intake leak
- Brand new Thermastat
- Brand new Rad Cap
- Swapped the old coolant temp sensor to the motor i have in my car now because old one was a different style
- Heat gauge doesnt even seem to be abnormal when this happens
- Flushed the rad and heater core with hose many times to try and get old sealant out (seemed to have normal flow)

Bad coolant temp sensor?
Sealant clogging something still?
Possible two bad head gaskets in a row?

No clue what to do! Please give me any ideas

I also just purchased a new rad cap. So thats not the prob either :/

Honestly, I would just swap the radiator and hoses altogether. You cant solve an intake leak problem with tons of stop leak, and if it's properly gunked up, you're not going to simply flush it out. If you coughed up the dough to swap in a new motor, I'd get rid of that gunked up radiator and hoses, too.

Originally Posted by RareGMFan

. If you coughed up the dough to swap in a new motor, I'd get rid of that gunked up radiator and hoses, too.

Yes thats exactly what happened, i coughed the money up Im broke as hell right now! But the hoses and rad are still getting flow. The flow MAY be restricted a bit because of the stop leak but would it really take it to the extend of boiling?

Just because water flows through while running a hose through it doesn't mean it's flowing enough under full pressure from the cooling system. To be on the safe side, I'd get rid of it, because if it has gunk from the sealant crap in there, you don't want anything breaking loose and getting back into the new motor you just put in there.

Changed your title to get you more hits. Bubbling coolant is normally a head gasket, which is not very common at all with these engines.

I dont think i wanna get rid of this car but thanks for the advice. I guess i will try new hoses, temp sensor, rad and try to see if my fans are actually coming on or not. Just dont know where to start

New hoses are not expensive, and certainly not a bad idea given the age of these cars. You can grab a junkyard radiator pretty cheap, of find someone selling them on one of the GP/w-body related message boards. I would do those first regardless, because even if the radiator itself isn't causing the majority of your problems, I would not be comfortable with all that crap the previous owner had running through the cooling system. I wouldn't want it to find its way back into the replacement motor where you CAN'T do anything about it without some serious headaches and money, where as right now, it's isolated, so you can eliminate that possibility simply by replacing the hoses and radiator.

Then, I'd check to make sure the fans work, which is obviously free. Just a matter of running the car till the engine gets hot enough for the fans to kick on. IF that doesn't happen, then I'd check relays, fuses, fan motor to see if it's working, etc. If all that checks out OK, but the fan still doesn't work, THEN I'd go after possibly the temp sensor.

Originally Posted by TheOtherNick

Changed your title to get you more hits. Bubbling coolant is normally a head gasket, which is not very common at all with these engines.

Thank you! and yes i realise head gaskets are VERY rare on these vehicles. So what are the chances there are 2 bad headgaskets in a row? lol. So i have an update. Yesterday after the coolant had been boiling i waited for it to cool down, i unplugged the temp sensor which automatically turn on the fans. Took it for a hard drive and it was fine. So maybe it is a bad temp sensor.

Originally Posted by RareGMFan

New hoses are not expensive, and certainly not a bad idea given the age of these cars. You can grab a junkyard radiator pretty cheap, of find someone selling them on one of the GP/w-body related message boards. I would do those first regardless, because even if the radiator itself isn't causing the majority of your problems, I would not be comfortable with all that crap the previous owner had running through the cooling system. I wouldn't want it to find its way back into the replacement motor where you CAN'T do anything about it without some serious headaches and money, where as right now, it's isolated, so you can eliminate that possibility simply by replacing the hoses and radiator.

Thanks! I think i will deff be relacing the hoses and rad. Even though it may not be the problem it wont hurt to eliminate any possiblities. I appreciate the help.

Yeah sounds like a bad temp sensor.

Thats what im thinking. Took if for a longer drive today with the temp sensor unplugged and she ran fine. No coolant issues whatsoever.

So it could be my heater core. i had thought about it maybe being plugged. But like i said i took both lines of that went to it and flushed it back and forth many times to get anythingi could out. But the flow could be restricted i guess. Mabe i will look ito gettig a new one than. Thanks!

You guys know what else can cause boiling sounds and incorrect temp on the gauge.

Lack of coolant in the motor.

Once in a while I get one that reminds me that our systems can be a pain to get coolant into. Had one myself this weekend. Front was jacked up in the air, down etc etc it wouldn't take coolant. Pull your thermostat housing and thermostat. Fill through there if it's low. Give it a while then see if it hasn't burped a little air up and can be filled further. Do this with the cap off the radiator.