626pr

Reservoir starts leaking coolant if fan doesn't run

11 posts in this topic

I have a 1999 626 2.5L, upon the needle reaching the half way point on the interior gauge, is just when the car starts to leak coolant from the reservoir tank. At this point the cooling fan finally kicks in and it no longer leaks coolant out. I can see the coolant go all the way up on the inside of the reservoir and once the fan kicks in after a short while the coolant level drops to the low level. I just had the radiator cleaned also about a year ago I replaced the thermostat and the ect sensor. Any ideas or suggestions. Thanks

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It's currently not leaking from the cap nor from a crack in the reservoir but was at one point from the seems. I have used epoxy to seal the seems since then. So now when coolant does overflow it comes out from the pressure release hose on the reservoir. 

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I would test and check your radiator cap and see if it's holding proper specified pressure. I think it's supposed to be able to 15psi?

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I have cleaned the radiator, changed the thermoswitch for the fan, replaced the thermostat and the radiator cap with a 16psi one. The fan turns on really late to the point that the reservoir starts leaking out coolant through the release tube. If I use the ac, both fans will turn on. I just can't get the cooling fan to cycle on it's own, properly and on time. I had previously bypassed the heater core hoses too. Also, the temperature gauge goes up to and near the half way mark and never passes that.

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Pressure test the cooling system and see if there any pressure drop. If there is a pressure drop and you don't see it leaking anywhere externally,  then you might need to looking at a possible headgasket job. 

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Upon further testing the engine cooling fan does not come on by itself, only when I turn the ac on, it works in conjunction with the ac fan.

Also, with the ac off, when I disconnect the cooling sensor plug the fans come on and function at high speed. Once I plug it back in, they turn off. When the engine cooling fan is working I never see the coolant spewing out of the reservoir. I had replaced said sensor about a year ago. 

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Today I installed a new CTS. I found that the engine fan does turn on but late. Too late because by the time the engine fan turns on, the coolant is spewing out the coolant reservoir release tube. Once the engine fan starts the spewing stops and all is normal. All this while idling. And the interior gauge never goes pass near the half way mark. I haven't tested the car running yet. Don't know if the bypass that it has for the heater core has anything to do with it but can't get the why of the coolant spewing nor for the late engine fan operation. Anyone else with this problem or similar?

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Time to check for headgasket leak. Possible that there may be exhaust gas leaking into the coolant system and creating more pressure.

 

There's the normal engine compression tester and there's a headgasket testing tool that comes in a blue liquid.

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Looks like I'll have to look into that. Hoping for the best. Thanks for the advise Tiberianx.

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Currently waiting for the mechanic to perform the compression test. Until then I want to change the radiator cap since it's been a few years and the radiator has already been cleaned profesionally, installed a new cts, checked the cooling fan relay and it is working, and had changed out the thermostat about a year ago. Only thing not changed...the water pump. The car only has 59k miles. I get no smoke from the tail pipe and the oil is clean. Other than the reservoir coolant spewing coolant until the engine fan turns on, I get normal operation.

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