Overheating olds

[84dragcutlass]

I have a strange problem with my 85 cutlass salon with the 307. After about a 30 minute drive the car goes fine down the highway but when you have to stop at a stoplight it hits 3rd and bogs down and will barely run. It hasnt boiled over that ive noticed, has a new thermostat, but when i get home the upper hose is super pressurized and you can tell its hot. I have a feeling i know what the answer to whats wrong with it is but i want to get all your imput first

 

[olds307 and 403]

Is the bottom of the rad cool? I have had a bad new thermostat. Could be a plugged rad too.

 

[84dragcutlass]

Every part of the radiator and hoses are hot as heck, when it cooled down i got the cap off and watched the radiator circulate and it seemed to flow good, at least at the top where i could see. Not real sure about the rest

 

[olds307 and 403]

Do you have a shroud? A fan clutch may be in order too.

 

[84dragcutlass]

Yeah i have a shroud, car is all original, 75,000 miles. Would the clutch fan cause it to overheat just at stop or would it do it going down the road? I have about 5 of them so if its that simple i could change that out pretty easy

 

[olds307 and 403]

Yes, speeds up the fan under load. Give it a try. The 307 is easy to cool. My 403 was a challenge.

 

[84dragcutlass]

Ill give that a shot, would be better than what i was thinking. I was thinking head gaskets or a cracked head from the pressure in the cooling system but that could also be caused by the heat.

 

[olds307 and 403]

I have had good luck with Olds and head gaskets, despite multiple over heating's.

 

[84dragcutlass]

So have i, the olds engine is built like a tank. It overheated to the point of boiling over once because of a bad thermostat and its been a battle ever since

 

[DeltaDevil88]

After Texas brutal summer last year I became a expert at the 307 cooling system.

My best guess is a fan clutch especially because you notice it most at a stop.........Its a cheap easy fix I would suggest getting the HD fan clutch for a couple extra bucks.

Now what brand and degree thermo you use? I had great results with my Mr Gasket 180.

As always suggest a yearly flush of the rad, inspect it for calcium deposits also check if you have a 2 or 3 row rad....... this was the culprit of the overheating on my 307 got so hot I blew the weep hole on my water pump. Luckily no intake damage thank god for the durability of the 307.

Just to be on the safe side I gave my 307 a whole new cooling system

AC delco 3 row radiator
new water pump
New fan clutch
New Mr gasket 180 tstat
New rad hoses.