3800sc running hot when idling (Page 1/2)
pontiacfierokid1985 JUN 30, 01:08 AM
3800sc L67

Ok here is my problem I got a 3800sc 4 speed fiero. Not running the fiero T stat housing using the stock 3800 one. I just installed a new 180 t stat water pump is new also, intake gaskets have been done with 04+ series 3 intake manifold gaskets so not the plastic ones. When driving the car it runs perfectly fine right at cool temps no over heating at all. When I’m idling or in heavy traffic the temp gauge creeps pass the 220 mark. Stock fiero fan using a Derale adjustable fan switch screwed into the lower intake manifold water outlet so I know that it’s accurate. If I read the scanner I can see it getting to 220 that’s when I have the fan switch turn the fan on. It will stay on but the temps won’t come down it will just keep fluctuating. Soon as I drive off or rev the motor the temps come right down does this sound like a air pocket situation? I bled the system from the back keeping the bleeder open car jacked up til all air came out. Overflow bottle up front is half full also When warm.
Spoon JUN 30, 09:54 PM
Pull your radiator and have a shop that repairs radiators check it out. Emphasis on Radiator Shop. They see this stuff daily and can fix or replace if needed. Classical problem, Car heats up while sitting in traffic.. They probably hear this quite often.

Spoon


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"Kilgore Trout once wrote a short story which was a dialogue between two pieces of yeast. They were discussing the possible purposes of life as they ate sugar and suffocated in their own excrement. Because of their limited intelligence, they never came close to guessing that they were making champagne." - Kurt Vonnegut

phonedawgz JUN 30, 10:58 PM
I would get a better fan with a proper shroud and set the temp the fan comes on to at a lower point.
Patrick JUN 30, 11:39 PM

quote
Originally posted by pontiacfierokid1985:

I just installed a new 180 t stat... I can see it getting to 220 that’s when I have the fan switch turn the fan on.




quote
Originally posted by phonedawgz:

...and set the temp the fan comes on to at a lower point.



Yeah, that's a no brainer for sure. Set it to perhaps 210° on 200° off... or with the relatively low temp thermostat that's been installed, 195° on 185° off.
pontiacfierokid1985 JUL 01, 12:20 AM

quote
Originally posted by phonedawgz:

I would get a better fan with a proper shroud and set the temp the fan comes on to at a lower point.



I saw something or someone on here bought some fan that screws to the existing fiero fan shroud. It is able to pull up to 1300-1600 cfm of air through the radiator. I just don’t know the part number or the link can you possibly help out with this?
pontiacfierokid1985 JUL 01, 12:22 AM

quote
Originally posted by Patrick:

Yeah, that's a no brainer for sure. Set it to perhaps 210° on 200° off... or with the relatively low temp thermostat that's been installed, 195° on 185° off.



I was thinking of going with a lower pressure radiator cap too. I have a 16 pound vented cap up front on the radiator and a 18 pound non vented on the rear in line radiator fill port do you think I should change the rear one?

I’ll definitely lower the temp of the fan controller to come on at a lower temp. I totally forgot to do that anyway thanks for reminding me about it
Patrick JUL 01, 01:30 AM

quote
Originally posted by pontiacfierokid1985:

I was thinking of going with a lower pressure radiator cap too. I have a 16 pound vented cap up front on the radiator and a 18 pound non vented on the rear in line radiator fill port do you think I should change the rear one?



I don't know anything about the rear rad cap used with a 3800sc swap... but you need a 15-16psi non-vented cap up front. Check the Cooling section (under Powertrain) at The Ogre's Fiero Cave.
ignorant prodigy JUL 01, 08:17 AM
I think you just need to adjust when the fan comes on.
pontiacfierokid1985 JUL 01, 11:38 PM

quote
Originally posted by ignorant prodigy:

I think you just need to adjust when the fan comes on.



You maybe 100% right on this fan is coming on after it gets passed 220 degrees I’ll lower the adjuster on the controller while looking at the scanner and dial it in to come on at 200 degrees and turn off at 180. I’m also installing a non vented 16 lbs cap in the rear so I’ll have 2 of the same pressure caps hopefully this solves the problem
Patrick JUL 02, 12:00 AM

quote
Originally posted by pontiacfierokid1985:

I have a 16 pound vented cap up front on the radiator



Okay, now you're confusing me.


quote
Originally posted by pontiacfierokid1985:

I’m also installing a non vented 16 lbs cap in the rear so I’ll have 2 of the same pressure caps


[This message has been edited by Patrick (edited 07-03-2021).]