woodcrest

I just finished a head gasket job on my 89. Started up and ran just fine, but coolant temp quickly went to 200+ I shut the engine down and felt the radiator hoses. they were not warm. So I am thinking stuck thermostat, but it is new and best I could find. I drained the radiator, about 1/2 gallon drained out (radiator was full when I started the car). The radiator took only 1/2 gallon to fill up. Maybe my radiator is clogged? I did use head gasket sealant in the engine before the head repair. So...first, how much should the radiator hold? What would cause it to take 1/2 gallon? Any insights on replacing the radiator? thanks, you guys got me this far!

84 4+3

At half a gallon there is either a gigantic air pocket somewhere or it could be clogged like you speculate. When I fill mine I usually end up massaging the hoses to get it to burp out the air. I haven't experienced a clogged radiator before so I don't really know how to check for one though...

bjankuski

No water in the block, pull the thermostat fill the radiator until you see water at the top of the thermostat housing. Then put the thermostat back in and fill the radiator full. Also drill a 3/16 hole in the thermostat flat surface to purge out trapped air while the car is warming up. Car should take around 3 gallons to fill.

You can also start the car and while it is idlng add coolant to the radiator until it is full and then put the cap back on. Obviously do this while the engine is still cold.

383vett

the thermostat can't open if there is no coolant below it. A half gallon fills only the radiator.

woodcrest

When you say..."You can also start the car and while it is idling add coolant to the radiator until it is full and then put the cap back on. Obviously, do this while the engine is still cold......would this be done without removing the thermostat?

bjankuski

You could try that, and see if it works.

Ed Ramberger

Having numerous vehicles to maintain, I plan on investing on a vacuum filler. It will eliminate all of these kinds of issues.

RalfKramden

I have a vacuum filler and used it on my "88 and it worked like a champ. Easiest coolant change I ever did!

Black_C4

Your hose from the passenger side top of the radiator that goes to the surge tank is prolly clogged.

Literally just spent a week or trying to figure this exact prob out on my new project. Which just had HG's done as well.

Good luck!

Tom400CFI

I've got a question that may contribute to the OP's issue. On my '89 (which is the Kart, now), my radiator cap is lower than the T-stat housing and lower intake. That being the case, I can't see how it's possible to fill the system with the car sitting on level ground. Can anyone else?

I jack my car's front end about 2' off the ground to get the radiator fill above the t-stat, hoses and intake...then I fill it and end up with no air in the system on the first try. Short of that, IDK how you'd fill an '89 and not still have air in it.


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65Z01

When refilling the coolant system on my '88 I warm the engine with cap off.
When I see coolant flowing I add fluid and blip the throttle (carefully of course) to "burp" the system of air.
When coolant level doesn't drop install the cap and done.

84 4+3

I get that. I've always just filled the rad and than kept topping off while it was idling until it stopped taking fluid. once the t-stat opens it takes the last little bit down and then it gets one more top off. Any remnants of air will be taken care of by the puke tank after that. Been doing that for 6 years now and have yet to have a problem. I have tried that on LS style engines (or engines with top down cooling for that matter) however and that never works. Those things are a pain to burp no matter what you do. And if you bring up the rpms a little with the stat open, all the air will be forced into the radiator anyway in my experience. My garage is level, so that's how I know it can be done.

Tom400CFI

Copy. Thanks for that tip. I'll give that a try next time. I'm definitely not "all about" the jacking routine...that's a hassle.

VikingTrad3r

this.

and as dogs says u could put a 1/8th hole in the flange of the tstat. that works. to make it even quicket yet, do as tom says and jack the front passenger side.

and u need to ensure the cap is sealing. and that the overflow hose isnt cracked or comprimised. or plugged.

if u need to clean inside of your overflow tank here is my trick ive used on three early c4’s. grab a few handfulls of playground gravel. no debris just stones. the more angular the better. put them in the tank with hot soapy water and start shaking. tank comes out like new. gets ride of the all-too-common staining from either rust or even more common bars leak residue!!!

good luck.