Coolant thermostat question

[bhw33191]

A few months ago i upgraded to the "extra cool" thermostat (160 degrees i think) thinking it would make my engine run cooler, and it does during normal driving conditions. The problem is, if i'm on the highway in traffic the temp creeps up around 200 and doesnt go below 190, and on hot days if i have the AC on the temp goes up even more! I just like the piece of mind having some buffer room before the overheat or "caution" temperature you know?

The question is , could the thermostat be allowing so much coolant to flow through the radiator that it doesnt get a chance to cool it down? If thats the case then i'll replace it with something like a 180 degree therm.

I just want my car to be reliable because i'm going off to college soon.

[j cAT]

Originally Posted by bhw33191

A few months ago i upgraded to the "extra cool" thermostat (160 degrees i think) thinking it would make my engine run cooler, and it does during normal driving conditions. The problem is, if i'm on the highway in traffic the temp creeps up around 200 and doesnt go below 190, and on hot days if i have the AC on the temp goes up even more! I just like the piece of mind having some buffer room before the overheat or "caution" temperature you know?

The question is , could the thermostat be allowing so much coolant to flow through the radiator that it doesnt get a chance to cool it down? If thats the case then i'll replace it with something like a 180 degree therm.

I just want my car to be reliable because i'm going off to college soon.

the thermostat will regulate the temp only if the coolant system is working correctly. if you get temps above the thermostat rating of more than 15 deg this tells me you have a problem. if at slow speeds the temp creaps above 180 in YOUR case then this would be most likely the fan clutch , or the radiator is corroded/too small. with the 350 I would use the 3 core radiator.

[Blt2Lst]

Originally Posted by j cAT

with the 350 I would use the 3 core radiator.

Good advice ^.
Have the radiator checked and replace if needed or the cooling system will not work properly. And as also mentioned, check the fan clutch for proper operation.

[bhw33191]

Originally Posted by j cAT

the thermostat will regulate the temp only if the coolant system is working correctly. if you get temps above the thermostat rating of more than 15 deg this tells me you have a problem. if at slow speeds the temp creaps above 180 in YOUR case then this would be most likely the fan clutch , or the radiator is corroded/too small. with the 350 I would use the 3 core radiator.

The radiator is brand new though. Its only 2 core bUt it should still be sufficient..my mechanic gave it to me anyway so im sure its the right one.

You think this could be a clogged rad though? There was a bit of rusty sludge in the water pocket before i installed this motor. I did flush the system before I put in the new rad but im not sure I did a good job..ill have to try flushing it again

[j cAT]

Originally Posted by bhw33191

The radiator is brand new though. Its only 2 core bUt it should still be sufficient..my mechanic gave it to me anyway so im sure its the right one.

You think this could be a clogged rad though? There was a bit of rusty sludge in the water pocket before i installed this motor. I did flush the system before I put in the new rad but im not sure I did a good job..ill have to try flushing it again

2 core too small. 3 core is for big engine. the 305 is the little guy which can use the 2 core.

more HP means more heat...

[bhw33191]

Originally Posted by j cAT

2 core too small. 3 core is for big engine. the 305 is the little guy which can use the 2 core.

more HP means more heat...

Huh, i just find it hard to believe the mechanic who i know very well would give me a 2 core and think its ok. At this point i'm stuck with the damn thing though. You think if i got an auxiliary electric fan (or maybe 2) then that would help? I mean the only time it gets hot is in traffic so I'd think the fan would "solve" it.

[Blt2Lst]

I believe a 2 row core is standard for the std V8 caprice.
Thats what was in my 89 from the factory, I replaced it with a 3 row core when I needed to replace it.

[CD Smalley]

Valid suggestions all here. But I think you are possibly right in your diagnosis of the thermostat being open too much. I've seen numerous people think they could get away without one, putting a washer of some kind in it's place. Switch back to at least a 180*F one, it's quick , it's easy and it's cheap. See if that fixes your concern first.

Secondly, 200*F in sitting traffic with AC on isn't something I would worry about anyway. My truck will sit in 90*F and idle at over 200*F with no issues whatsoever.

[bhw33191]

Originally Posted by CD Smalley

Valid suggestions all here. But I think you are possibly right in your diagnosis of the thermostat being open too much. I've seen numerous people think they could get away without one, putting a washer of some kind in it's place. Switch back to at least a 180*F one, it's quick , it's easy and it's cheap. See if that fixes your concern first.

Secondly, 200*F in sitting traffic with AC on isn't something I would worry about anyway. My truck will sit in 90*F and idle at over 200*F with no issues whatsoever.

Ok thanks. JUST the answer i was looking for! I was 90% sure my theory was right about it being open too much, i'm no mechanic but it seemed to be plausible. And i actually DID pickup a 180* today so i'll post a reply on how that goes. I'm going to school in Maine this year so the 160 is much too cold for winter use right? I was told in a post a while back that if i used a 160 in the winter i'd get carbon buildup.

[silicon212]

FWIW, I run a 190 degree t-stat and here in the Arizona sun it's not uncommon to see running temps in the heat of 220 or more. I've been running my engine that way since I built it back in '93 - 340k miles later it still keeps plugging along ...

And yes, the two core is too small. My own car originally had a 305 in it, and when I put the 350 in it, it was fine for running around town but was a guaranteed pukefest on the highway. The 4-core in there now solved that problem, but the running temps are the same. just my $.02.

[j cAT]

Originally Posted by bhw33191

Ok thanks. JUST the answer i was looking for! I was 90% sure my theory was right about it being open too much, i'm no mechanic but it seemed to be plausible. And i actually DID pickup a 180* today so i'll post a reply on how that goes. I'm going to school in Maine this year so the 160 is much too cold for winter use right? I was told in a post a while back that if i used a 160 in the winter i'd get carbon buildup.

if you lived in phoenix the 4 core is with higher HP the only way to go. with 110deg in the shade under the hood and on the road its hotter than 110 deg F...

so your friend the auto mechanic is not too smart , with these engines/vehicles.. I think I mentioned I got rid of my 2 core shortly after buying my 1983. the 3 core in our area works great. when paired up with the large tranny cooler mounted in front of the ac condensor you will never have your hot engine issues..180 deg f themostat should be the lowest temp to use. With this the temp THERMOSTAT should indicate about 185-190deg f.on guage.

since you are going to maine the coolant needs to be at the max . go for 60% coolant 40 water. also when the coldest months are here use the 5-30wt oil. if it goes to 10 below or colder 10-30wt or higher will cause starting problems..

have a can of starting fluid just in case .