Re: Instant overheating

Posted by Mike Flanagan on October 07, 1997 at 14:38:09

In Reply to: Re: Instant overheating
posted by Bob Johnson on October 07, 1997 at 09:48:04

I suspect there are several things going on here. Number one the relief tube is probably to low and when you stop the residual heat causes the water to expand and run over the top of the tube and out on the ground. It doesn't have to be boiling for this condition to occur if the tube is to low. This can be a never ending cycle. It runs over and you fill up, it runs over.... (Put a piece of rubber vacuum hose on the top of the relief tube to extend to within 1/2 inch of top of radiator then monitor the water level until you reach a happy median level.

After letting the car idle for 5 minutes feel the face of the radiator at both the top and near the bottom. Mine is pretty warm at the top but not so warm at the bottom. Means the radiator is working gooood. If hot at both top and bottom then possibly a problem. One possible problem is to much circulation. If the water is circulating through to fast it doesn't have the time in the radiator to be cooled sufficiently and will progressively become hotter. I resolved this with a 160 thermostat above the top of the inlet and have had no problem since. My four row passes the water like corn through a goose, it has never really "overheated" but feeling the radiator told me there was very little differential in temp from top to bottom. Has to be some.

I agree with the other fellows, I know people that would kill for an operating temp of 140.

The Model A Fool.

I do not think that your radiator is "boiling over".I would guess it is one of the two following things.The Model A cooling system is not like modern cooling systems. It is an open system and is not pressurized.The radiator should not be filled up to the top.You should fill only up to the top of the baffle (if you do not have a baffle you have found your problem).If it is filled too high it will spill over until it is at the right level.The other possibility is that the water pump is moving water faster than it can flow through the radiator.So either there is a restriction in the radiator or the pump is pumping too fast. You should flow test the radiator.To do this disconnect the lower radiator hose and put run water through it with a garden hose. Adjust the flow of water coming out of the hose so that the radiator is kept full but does not overflow (all the water is comonig out the bottom of the radiator).At this point fill a 5 gallon bucket with the hose and time how long it takes to fill.It sould take around 9 seconds. (5 gallons in 9 seconds is 33 gallons per min. I think that is the correct flow rate)If it take more than 10 seconds the flow through the radiator is not fast enough.

: Are you using anti-freeze in your car.If so try plane water since anti-freeze can cause floaming which will look like boiling over.Hope this helps.

: Bob




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