I have an 89 IROC, with the 305 TBI with 700r4. The issue i've been having is that the coolant just seems to disappear. I've filled the reservoir multiple times, however there seems to be no real coolant loss in the radiator. There are also no noticeable leaks around the reservoir. The oil isn't milky, and the trans fluid isn't pink. Just asking for ideas if anyone has run into this issue before, or something i'm missing and should be looking at.

 

Have your cooling system pressure tested. You can do it yourself; DIY parts stores rent such a tool. Pressurize the system at the radiator and look for the leak(s).

 

Is there a certain pressure i should be looking for? just wanna know before i try it so i know what to look for

 

Just realized that its on the cap

 

Look around the weep holes on the waterpump for evidence of a leak. Sometimes a slow leak there will be missed since it'll drip on the pulley and be scattered to the wind. Look around the edges of the intake and around the tstat housing. Check the passenger's floor vent and carpet for an oily discharge from the heater core. Keep in mind you can leak coolant into an intake port where it'll be burned off while running, or a head gasket can leak into the combustion chamber. A small leak can be hard to detect. Personally if you can't find the leak, and everything seems to work OK, I'd put a tube of Alumaseal in it and keep topping off the reservoir. If it's a significant issue, it'll make itself known soon enough. No sense in tearing into the engine looking for a phantom.

 

Good eye. Should be 16lbs. If there's a visible leak, it should make itself evident before you reach this pressure.

 

if you can't find a leak, you can have your coolant tested for by products of combustion, rule out a head gasket or crack

 

So just pressure tested it, small leak at 16lbs from the Heater Control Valve and the bottom of the radiator it seems. Guess that's the issue

 

If you have worm gear hose clamps, make sure they're tight. But don't over-tighten them (~15 in-lb).

 

I was losing coolant and couldn't figure it out at first casue' I couldn't find a leak. Checked the dipstick a couple times and never saw any "milkshake" in the oil and no oil in the coolant so I was at a loss,...... until I DRAINED the oil. In my case the missing coolant got into the oil due to a failed head gasket. While I suspected it was a head gasket ( because I couldn't find a leak ) I would not have known by just looking at the dipstick. Let it sit for a while ( not running ) before your next oil change,.. if there's coolant in the oil it will need time to separate & settle to the bottom of the pan.

 

Thought I'd drag this thread out for kicks and grins. Just acquired one of those cheap cooling system pressure/leak testers. Needed it for another car where I cant find the source of a coolant leak. I had also had a leak on the Formula, but it was random and wasn't too worried. Threw the new tool on the bird, and man was I enlightened. Found leaks I didn't even know I had. A few small adjustments to the hose clamps. leaks all gone. next time I replace hoses on any car, this bad boy will be the last step. highly recommended tool you didn't know you couldn't live without.