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Overheating Car. Running out of parts to change!

2K views 30 replies 7 participants last post by  royce gibbs 
#1 ·
Hey everyone,
I have a 95 Oldsmobile Cutlass Supreme with a 3.1. Its a long story but I'm running out of things to try.

The head gasket or intake gasket blew a few months back and I know these motors are infamous for that. So I changed the head gasket and intake gaskets and sealed everything all the way up. I chose to put 10W40 in it for the first change to help clean out all the gunk from the leak, so I am getting a slight amount of smoke from the tail pipe but not a bunch. I changed the thermostat and both temp sensors during the rebuild too.

Neither of the two fans would kick on so I got a Lil frustrated and ran them both to a toggle switch on the dash so the are both running now. Didn't feel like dealing with a computer issue yet.

I bled the coolant system (first time ever doing that so I may have done it wrong, was unsure in what order two open and close the two bleeder screws).

With both fans running at idle the car wants to level out at about 225 to 230. I believe normal temp should be 200 or a Lil above. And when I have idled it up it wants to redline. Scared to drive it in case it blows a gasket again...

Any ideas after what I've changed?
 
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#4 ·
But like I said earlier I tried to bleed the system and I'm not sure if I did it right... I opened both bleeder and started it and waited till they both poured fluid and I didn't see anymore air bubbling out of the screws. But I wasn't sure if I did it right so I let it cool off and repeated and I got one big burp out of the radiator and then a smaller one and then then the lower bleeder had pretty decent pressure coming out but not so much out of the other. I don't know if I need them to give me a pin stream or spray like theyll strip paint
 
#5 · (Edited)
I have seen people put the thermostat in the wrong way a very easy thing to do. You might want to try testing the radiator for a small leak in the system. There might be something going on in the engine besides the head gasket, which causes the it to heat the antifreeze to the point that it can not cool down enough before going back into the engine. One other thing if you have used tap water when adding antifreeze to the aluminum radiator that you most likely have it might be clogged which would result in the systems you are describing. Tap water has minerals in it that tend to restrict the coolant due to clogging the tubes in the radiator. I would remove the radiator and have it tested at a good radiator shop. Even though coolant is flowing through the system it might not be enough to cool it down or it might not have cooled down enough to keep the engine cool.
 
#8 ·
OK that makes sense. I did a little online digging and I guess the way the housing on the intake is made on the 3.1, its impossible to mount the thermostat backwards. How would I go about seeing if the coolant channels are blocked or cleaning them?
 
#10 ·
I believe in the first post you said you ran both fans to a toggle and the were on when you ran the engine and the gage still redlined. If the gage is working properly and the coolant is in fact circulating though the block than the problem is IHO the radiator. There are 2 ways to check the temp, 1) insert a thermometer into the radiator and see what it goes up to, 2 get a laser gun and point it at the radiator and see what you get than look at the gage and see what it says. You have already blown a head gasket and do not want to repeat doing it again. As for a blockage in the coolant passages I have a hard time seeing that. If it was something like my 54 Studebaker I would agree, but a 91 I can not see it. I would check the gage and then pull the radiator if the gage is working.
 
#11 ·
Clem: Don't know how long you've had the car, but there was a class action suit on your problem. I have no idea if you're entitled to any money. Maybe worth looking into. Also, is the smoke black, blue or white?
 
#12 ·
the car has two sensors one for the PCM to signal for the fans. I bypassed that with the toggle switch. The other runs the dash gauge. I replaced both during the rebuild. The dash gauge didnt even work until I replaced the sensor. Ill try the thermometer. Does it have to be anything special?

Is there a chance that I bought a bad thermostat? I bought one for 195 degrees. Considering taking the thermostat out and running it without one to see if it will stay colder. I know it will constantly circulate but that would tell me if the new one isn't opening right... Or not all the way. And while I had it out I could try putting it in a pot of boiling water... I just changed the thermostat on the rebuild because it was easier to get to then. I still have the old one and I can compare them in the pot...
 
#13 ·
And the smoke out the tail pipe is white. But its slowly going away as I let the car run and work on the problem...I'm sure there's a chance some of the water ran into a few places when I had the heads off and I'm thinking the smoke is just it working its way out
 
#17 ·
If it opened at the temp it was rated for it is working. You can check the temp of the coolant either of the 2 was I posted to check your gages. If everything else is working than either you have a problem with the engine or the radiator. I do not know if yours is aluminum or copper/brass, but I would have it checked out. Assuming the engine is good and all the gages and sensors are good that would be the last thing.
 
#20 ·
I haven't ever changed it. What should I look for once its out of the car to check for damage?

And back to the bleeding of the system. How much air am I looking to bleed off? And should I leave the cap on during the process to maintain system pressure?
 
#22 ·
OK. So update. I flushed the heater core. Checked the water pump. And started pulling hoses and starting it to see if it would flow out further and further along the line. This might sound crude but I had flow all the way to the thermostat housing. So I said screw it and ran the car without the thermostat. ( I boiled it in a pot of water earlier and it did open and its brand new) the car sits perfectly at 200 to 210 and I have heat. So I'm guessing that means its the thermostat?
 
#26 ·
Took it off. It spins with the pulley. And I have pressure in the system up to the thermostat. With the thermostat in there's no circulation to the upper hose. Without it I do. I did run the coolant mixture really light doing this too because I got sick of wasting anti freeze
 
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