TropicalVette

So I got brave and decided to undertake a major upgrade on my Vette, which is way over my knowledge level on car mechanics. I pulled off a heads and cam swap, changing and/or upgrading many other components, such as the oil pump, timing chain, damper, a/c compressor, all new heads components and many other parts and tasks. So far most of what I've done has been right on, but made some mistakes. The first one was that I didn't tighten the damper correctly which lead me to upgrade to a Super Damper that wasn't needed, and when I wanted a different look I installed aftermarket aluminum fuel rails which my Vetted didn't like at all and after tinkering with the fuel system I reached the conclusion that the OEM fuel rails had to come back on.

This brings us to my new problem. Now that it's starting and running like new the engine cooling system isn't working. I took it out yesterday for a test run after installing back the factory fuel rails and when I returned home temperatures were over 220 degrees. I have a good idea on how to troubleshoot it but I would love to get some advise on how to really do it right. Please help!

sunchaser73

Did you refill the coolant system in accordance with the factory service manual?
Have you looked at the radiator to see if there is dirt or debris trapped in the fins?

FWIW, 220 isn't hot. May be hotter than you would like, though...

If you haven't already done so, fill and bleed the coolant system using the service manual procedure. Check you radiator and A/C condenser for dirt and debris. Clean it out using low pressure air and/or a vacuum cleaner.

You said you had some ideas for troubleshooting...what are they?

jrp1588

When does the cooling fan kick on on these things? Isn't it at like, 230 degrees or something? Mine regularly goes up to 230 when I'm idleing, as soon as I start moving, it cools right back down to 180 or so.

Mr. Jones

Did you upgrade injectors and has it been tuned yet?

these are the right items to check.

TropicalVette

I'm going to find the filling procedures in the service manual and follow the instructions. After I did the cam swap I just poured antifreeze into the reservoir without doing anything other than a regular fill up. It seemed strange that I drained almost three gallons of antifreeze and when I filled it back it took less than half of that. I surely did it wrong. I hope this is the cause of the problem. I had been looking into checking the fuses and relays governing the fans. I didn't do it today for lack of time. Now I have more possible causes. I finished the engine upgrades over a year ago but since I was doing paint and body work I had to wait until now to try tuning. Every time I've been at the dyno I've had to return home with my limping Vette with a new diagnosis of something not letting the tuner guy do his job.

TropicalVette

Relay number 43 was the culprit. Got it replaced and the fans are ok now. Two of the holes were the pins go into are burnt, the other two are ok. I'm a little worried with the burnt holes and I wonder why it actually got burnt.

Mr. Jones

you might have a fan going bad. It can draw more current then it should. The weakest like will show its face.
You can try some type of electrical contact past at the relay.

leadfoot4

Sounds like you've got a HUGE air pocket in the cooling system.... When the engine is COLD, pull the cap off the reservoir, start the engine, let it run for several minutes, and let the air escape. You'll know, as the coolant level in the reservoir will drop, and you'll need to top it off.

Silverbullet00

Best bet!

CactusCat

I might add here that virtually every thread I've read that have had heads/cam installed, the user has changed the thermostat. Since the OP is in PR, I'd suggest going to the 180 at a minimum. Easy to do, not expensive. Will help the cooling on the modded C5 for sure.

jrp1588

That's not going to help him stay cool while he's idleing though. I believe you can get it tuned and have the fans come on at a lower temp.

GCG

It definitely seems like you have trapped air in the system. If you drained 3 gallons you should have been able to put back 3 gallons. The difference is air.

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CactusCat

It's all relative. It does help a little but not without tuning. And if you install H/C, etc... you must get a tune. A competent tuner knows how to tune the fans. My H/C/I install was tuned with a 180 thermo and I seldom get above 200-205, even when idling. Hottest of days with AC going, stuck in traffic, I might see 210-215.

Chicago1

235 or 236


..op your temps are normal

leadfoot4

But.....the OP stated he drained 3 gallons of coolant, but only got about half of that back in. He has air trapped in the cooling system.

Chicago1

^ I didn't see that part...one way to get the air out is crack the line from the heads

k24556

is this what you are looking for?:

The low speed cooling fan is commanded on when the coolant temperature reaches 108°C (226°F). It is turned off if the coolant temperature lowers to 104°C (219°F). The high speed cooling fan is commanded on when the coolant temperature reaches 113°C (235°F). It is turned off if the coolant temperature lowers to 108°C (226°F). When the A/C is on and the coolant temperature reaches 85°C (185°F), the low speed cooling fan will be turned on at vehicle speeds less than 56 kPh (35 mph).


Normal driving with driving speed that flows sufficient air across the radiator with the AC off, the coolant temperature with a factory thermostat is 190°F, The fans will be off. The factory setting will not let the first cooling fan come on until the coolant reaches 226°F.

Unless you tune the fan start points, this is the factory setting. One thing that will mess you up is dirt in the radiator, or a baggie sucked up and blocking the radiator air flow..