Hi - I got an unusual coolant leak.

Coolant level sits 2" below full in overflow tank. Car operates fine. If I fill the reservoir to full level it will leak coolant even when standing still until it is down to about an inch below full level again.

The leak seems to be coming the water pump area. Does not seem to leaking at the reservoir.

Does not leak during a long 150 mile drive - just wants to sit 2" below full.

Any thoughts?

Also - I have had water pumps leaks after mechanic changes the timing belt. Any tips about how best to seal the water pump thermostat housing?

Thanks,

Dean

What happens if you just leave it at 2" down and check it often?

We had an '88 745 GLE (118K) that would lose fluid until it was an inch under full. We checked our fluids every week and it never went down from that level.

Our dealer would top it off and within a week, it would be low again.

After a year of this, I marked the level that the car liked, and labeled it -full- , the car ran to 235K without an issue. I added a bit now and then, but nothing like the amount that would disappear if it were topped off.

Owning many cars since '63, I have seen a couple that exhibited this behavior.

Thanks everyone. I do preventative maintenance - the water pump is likely 3 years old. Seems like I have some seals not good - maybe weep hole. I will examine it following the suggestions in thread.

I looked like the pump to me but I was not aware of all the details exposed in thread - thank you.

Thank you again!

https://www.brickboard.com/FAQ/700-900/Cooling.htm#Water_Pump
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Post Back. That's whats makes this forum work.

Hi,

I've tried replacing the "mushroom" rubber seal when mine leaked many years ago. And it worked. In the process you'll have to replace the pump to engine block gasket too. Your pump may be reused if there's no leak at the weep hole (a small hole located near top of pump behind the pulley). The only issue is that these parts usually comes as a package with a new pump. If you have access to a Volvo parts shop near your place you might get these parts minus a new pump.

Otherwise you may try to get these at:
http://www.volvopartswebstore.com/showAssembly.aspx?ukey_assembly=243619&ukey_make=865&ukey_model=20180&modelYear=1994&ukey_category=7072&ukey_driveLine=394&ukey_trimLevel=24661

Look for item 2 (water pump gasket) and item 8 (sealing ring) at the web page. If you go this route you may use a bit of RTV on the new "mushroom" seal to help it seal better plus you must force the pump upwards to squish the new seal against the cylinder head while tightening pump nuts and bolts. However its not advisable to use any RTV on the pump gasket as this would make it harder to remove them during future replacement. The gasket just seals nice without any RTV.

That being said if the car is high mileage with pump still original or the last replacement was done about 100k to 150k km ago then this MAY be the time for a new pump set even without weep hole leak (if you're into preventive maintenance). Furthermore if you haven't been using the OE blue-green coolant all this while.

I think a faulty coolant cap is spot-on diagnosis for that coolant level rise during hot - just like Chris mentioned.

Regards,
Amarin.

If you put a pressure tester on the system and it comes out the weep hole, pump going bad. Top of water pump is a rubber seal where the water pump gets levered up against the eng block. Those are known to seep.
But you got me confused on a "water pump thermostat housing". I know a water pump. I know a thermostat housing, but not what you wrote.
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Post Back. That's whats makes this forum work.

Well, this problem sounds familiar...:)

Yes, the "infamous" mushroom seal is above the pump. As aleekat mentioned, they are levered up against the engine block. My 90's mushroom seal would leak when the engine was cold. Once warm, I believe heat expansion would seal the leak as I never saw it leak when the engine was warm. Or the heat burned off the antifreeze before I saw it. I'm guessing you might have the same problem. It was a slow leak so I lived with it for years until I sold the car.

Some options:
1. You can replace the seal and refit the existing water pump.
2. Do as I did, live with it and plan on replacing the seal and properly seating the water pump the next time you replace it.

If you're filling the reservoir to the "Full" mark when the engine is cool, then you're over-filling it. It should only go to the full mark when it's warmed up to normal operating temperature. You may also, by chance, have a faulty or out-of-spec reservoir cap, causing an over-pressure situation.

But it's likely you just have a water pump that is starting to show its age. Sometimes they last for many years and sometimes they fail within a year. Over-tightening the belt can cause premature failure.

Also, it's not uncommon that you can run the car all day long without losing a drop of coolant, but then when you shut it off and it cools down, it will leak and leave a nice little puddle under the car. If it's leaking in the garage/driveway, examine the pump with a flashlight and mirror and see if you can find wetness before you start it up and it dries out. If it looks like the coolant is dripping from the rear lip of the pulley then it's probably leaking from the weep hole, signaling it's time to replace the pump.
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Current rides: 2005 Volvo S80 2.5T, 2003 Volvo V70 2.4NA, 1973 Volvo 1800ES (getting ever closer to road worthiness)