By January 18, 20070 Comments Read More →

1994 Mitsubishi 3000GT – Cooling System Pressure Test

Reader Question: I have 1994 Mitsubishi 3000GT Non-Turbo with 140,000 miles. After replacing the timing belt and tensioner, I notice there was a leak that seems to come from my water pump, which was not there before. Therefore, I just bought a new gasket for the water pump, thinking that it is just that since I bought a new pump just a year before.

After everything was put together, the leak was still there but just not as bad, then it disappeared when the engine was turned on. Everything was ok for a few days, until the temperature got higher and the leak was noticed again. So I went and bought some radiator and water pump leak seal, hoped that it would stop the leak. But now the leak did stop, just that the temp for the car seems to get hotter even faster than before.

I assume I clogged the radiator or water pump. So my questions are how do I go about testing to see if the water pump is working correctly? If I have a clogged radiator, is there a way I can unclog it without going to a shop?

Lastly, if I have to change the water pump is there an easier way of doing it than taking off the timing belt and all the other stuff?

Thanks for any help or advice to this problem.


Hey Paul,

Thanks for checking your auto insurance and for your e-mail. I would really like to see you get a “cooling system pressure test” FIRST before you do anything else. This simple and inexpensive test can determine if you have a coolant leak somewhere…and we need to address that problem first.

If you have a leak still, get it fixed. The only way I know how to replace the pump is to remove the timing belt…that is why it is always a good idea to replace the pump when servicing the timing belt.

If you replaced the pump, but still had a coolant leak in that area you might have a crack in the timing cover, engine block, or from a hose that is allowing coolant to run down the timing cover and appear to be from the water pump.

On the radiator stop leak, I really do not think you restricted your radiator using it. I would pressure test the cooling system first, check the cooling fans and make sure they are working properly and check the thermostat operation.

You can feel the upper and lower radiator hoses and see if you can feel a major temperature change between them. That would indicate a restriction in the radiator, a thermostat that is not working, low coolant level inside the radiator or a lack of circulation problem with the water pump.

With the engine at normal operating temperature, open the radiator cap and watch the coolant circulation within the radiator. If you don’t see coolant flowing from the upper radiator hose I would suspect a thermostat issue, a water pump that is not circulating (you did check to make sure the water pump rotated the same as the old one did right) or a restriction in the bottom of the radiator.

If the top of the radiator is HOT and as you run your hand down the middle of the radiator, you can feel a drastic temperature drop, you probably do have a radiator restriction.

If that is the case, I would buy a cheap after market radiator and replace it…along with a new thermostat.

Austin Davis

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