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Just posted in the generic engine issue area but Im back with another issue. My car is as follows:
1988 Iroc body
350hp (possibly bored out before we owned) w/ Edelbrock Carb
Wrapped heads with header wrap
700R4 Transmission
Champion 3 Core Aluminum Radiator
Base (NAPA) water pump
160 Degree Thermostat
50/50 Coolant mixture with Distilled water
Great coolant flow, no pinched hoses, can feel heat in hoses
Dual fan setup from 97 Silverado for main cooling
Auxiliary fan to aid when gets too hot
New Air Dam
New front grill w/ license plate holder since in IL(I hear some guys run w/o the grill and it helps cool while driving)
I think this is the basics of what you guys will need to help. I have a new Edelbrock high flow water pump and high flow 180 degree thermostat on the way in hopes that will fix me up.
The car runs great. Starts fine, seems to be in time as we vacuum gauge timed it. If you let it set at idle with the above setup it will get really hot. Operating temp seems to be around 180 to around 210. When driving down the highway I really have no issues keeping it below 220. Slow backroad or in town driving can drive the car up to 240 depending on how hard it was driven before that point. That is usually when I kick on the auxiliary fan and help it cool or not get any hotter. I added the new radiator thinking that would fix it but it didnt. It did help a little but not much over a stock Autozone radiator. I know these cars run hot since there is little engine compartment space and a bigger engine tossed in there but I know guys run higher horse engines than this one and have way less heat issues. You guys have any idea what may be going on or do you think that the new water pump plus putting the 180 tstat will help?
Did your car have 1 or 2 fans stock? 100% sure the gauges are working properly?
The factory dual fans and rad can keep these cars cool up around 6-700hp without AC sooo I'm guessing you may have a low speed airflow problem. Something seems off with the fans to me.
This is a tricky one, I too am wondering when your fans come on, it's almost like e engine is getting to hot and you are fighting to bring it back down, when if you can prevent the temps from getting that hot to begin with, you would struggle as much to maintain. My fan runs constant, not sure if PO wired it that way or if my switch is faulty, but at any rate mine has never hit 200 deg. Mine is a stock LB9 5.0 TPI so that might have something to do with it. Best of luck with this issue
I need to check on exactly when the fans kick on. From stock I know they were supposed to kick on around 180.
I know the temp gauge is correct as we installed a different one just to check becuase we couldnt believe it was getting that hot.
I think the stock 1990 RS had a single bigger fan and as said above I am using a dual fan setup from a Silverado. Could be an issue. Also I have no fan shroud if that makes that big of a difference.
I definitely need to get a temp gun to do some checking. That is a great idea.
edelbrock carburetor conversion. no telling when the fans turn on now, although I inferred from "when I kick on the auxiliary fan" that at least one of them is now controlled manually. "a dual fan setup from a Silverado" also leads me to believe that any comparison to DrBob's cooling system and one from an Fbody may be distant.
Stock gages are inadequate indicators of the state of nature at the sensor, even when swapped with another. If your cooling system isn't boiling over, it's not getting too hot. Confirm temps with an alternate means.
If I had cooling issues with that setup I'd look at the efficiency of the cooling system and the tune of the motor. Probably look at tune of motor first.
Motor runs great, new distributor, plugs and wires.
There is a dual fan setup on the motor side of the radiator and a single auxiliary fan on the front side which is manual controlled.
I am in the process of getting a temp gun to verify temps.
New Rad plus new water pump and tstat may do the trick, which is what I was thinking. Will get additional info and get back to you.
Now that I think about it, I believe the dual fans are wired direct. meaning they fire up when the key is in the On state. Not sure if that is a hindrance in any way.
Correct me if I'm wrong, but the 3 core radiators require much higher CFM/pressure fans for low speed flow. The radiator absorbs more heat, and can dissipate it, but the 3 rows reduces flow. So that might explain your low speed overheating issue.
Without the use of a shroud I don't think the stock thirdgen fans can pull enough air through the radiator to keep it cool.
I don't have a 3 core rad, just going by what I've read on the forums.
Water pump is correct. The flow seems to be decent with the crappy "stock" one from Autozone. I just got my high flow Edelbrock water pump and will install and see if it makes a difference.
The "stock" 2 corre radiator that was installed before the new 3 core I installed had the exact same issue. I do agree that it could still have something to do with the lack of a shroud and possibly the main fans are not "big" enough to handle the heat.
Back on after finally getting around to making some changes........
I have added a radiator shroud and two new electric fans, removed the smog pump and put in a bypass pulley, new high output Tstat rated at 180, added a new Edelbrock water pump to go with the 3 core Champion rad. I haven't had extensive testing yet to see if this setup will fix all of my overheating so I will post back when I do.
A quick question, do we know of a spot to buy chrome or polished upper radiator covers for Third gens? I cant seem to find any and my stock upper radiator support cover doesnt work with my new fan/shroud setup.
I posted a radiator fan control solution in your other thread. Also, you may want to pickup a Holley radiator cap with a round thermometer built in (available at most auto parts stores in the "mods" section (the section with the chrome plug wire guides and chrome breather caps). Came in handy when I was trouble shooting my overheating including a suspect coolant gauge-sender system. Excellent sanity check.
I will definitely get one of those. I didnt even know that was a thing. Ill look over your wiring diagram and see what i can do. Seems pretty straight forward.
what are you running for a distributor? If an HEI,...what are you using for vacuum advance? I switched from ported vacuum to full manifold vacuum and it dropped my temps by about 10 degrees.
