s70 glt - intermittent coolant leaks
 

I appreciate any insight as to what this could be. I'm still new to volvos, and I really don't understand how the cooling system works in this car yet. It's quite a bit different than my old rx-7.

The car has had coolant leaks since I bought it. First it was the radiator, which I replaced. About a week later and a few miles of really hard driving it blew off the cap on the expansion tank and for the first time, started to overheat. Fortunately I caught it the moment I saw the gauge move from center. I had one of the coolant temp sensors replaced and it seems to have helped.

It doesn't leak while running anymore. If I drive it conservatively it will go weeks without losing a drop of coolant. But sometimes it will dump the all of the contents of the expansion tank on the ground. It leaks out of the hose that comes from the bottom of the tank, and its usually only when I drive it a bit fast. By fast I don't mean constantly redlining it, just hurrying onto onramps and passing. It hasn't overheated since I had the temp sensor replaced.

What could be causing this? If the turbo in this car is water cooled, the leaky line be going to that? Its starting to stay in the 90s all day now and I'm starting to worry about this. Thanks for any help.

Intermittent leak
 

My Volvo S70 GLT, year 2000 model also behaves similar. It runs fine with temperature gauge in the middle of the dial. All of sudden coolant from the expansion tank leaks out. I don't know where the leak is from. I suspect it should be from hose.

This happened twice. After refilling it runs fine.

Please share with me how to check the hose/pipes connecting the expansion tank.

I had my mechanic run a pressure test on the system and the cap. He couldn't find any leaks. He doesn't seem to have any idea.

Heater core?

I've considered that. I do get a coolant smell whenever I have the heat on, which is never. I live in texas. The smell is really faint. I seem to be the only one that smells it. It's likely the smell is simply coolant flavored air from the engine compartment. If it were the heater core, wouldn't it be leaking inside the car? In my case it's leaking from somewhere underneath the expansion tank onto the ground.

Ok is the bottle cracked?

If its a turbo, check you lines... go to a Volvo dealer and ask them for a turbo diagram.

volvo intermittent coolant leak - heater
 

With my s70 (2000) I noticed intermittent coolant leaking because every few weeks it needed a little topping up, without a trace of the lost coolant.
Then the front window started to become steamy after having driven 10 km or so. Now I suspect that coolant is leaking in the heater part and the misty fron window is because of the evaporated cooling liquid.

I still have to have a look at this but it seems rather a tough job to remove the dashboard and stuff.
Anyone experience with this?

IT might be the heater cores,behind the radio somewhere.

Pull back your carpet and check the heater core, I just replaced my heater core and i had a small amout of colant that was leaking outside of the car aswell as inside.

It is not located on the firewall(thank god for that) and only takes a couple of hours to change it without removing the dashboard,at least on a my '98 i didn't have to remove it when i changed it few years back.
But when had to do it my '91 940...holy mother of god... i almost committed suicide that day,lol

so what did u have to remove exactly to get to it.

It's not that hard, just a pain in the...
http://volvospeed.com/vs_forum/index...b8e1962b6aa580

Just thought of updating others. Earlier I posted about my coolant leak. That time I could not find the crack in the coolant expansion tank. May be it was too tiny, which opened up under high pressure. Few months back I could visibly see the crack.

Then I sealed the crack with JB Weld paste and let it dry for 2 days. But it lasted only for a day or 2. Now I replaced with new after market part made by OES Genuine part #W0133-1660981. Will update if I find anything new.

FYI: My car is Volvo S70 GLT SE year 2000.

Looks like some leak at the point where return hose connecting back to coolant reservoir. Tried tightening the clamp. No use. I think probably I should replace with a new clamp. Any suggestions/advice please?

You can try a new clamp but the bottle might be cracked there as well.

If you've replaced the bottle and tightened the clamp, it's probably the hose that is bad.

Another problem spot in the cooling system is in the hose fittings though the fire wall. The key to identify this failure is the coolant ends up on the driver's side floor rather than under the heater core on the passenger side. also no smell in the vents. Same slow leak (10-20ml / wk) and usually is noticed in the winter when cold outside. The o-rings shrink in the cold temperatures letting coolant leak onto the carpeting but only during warm up. No problems in the summer.

I originally found this problem when my 98 S70 GLT was new and I was having electrical problems behind the dash. It took 3 years for the dealer to find the problem ( 3 stereos, most of the dash lights and panel switches). The o-ring on the fire wall fitting had been pinched when installed and because all the tests were on a warm cooling system, the failure wasn't evident.

After about 7 years I had the same symptoms. O-rings changed and all was well again.

Just turned 260K !!!

PS - Also replaced the expansion tank because of that nasty hairline crack as well as the radiator because of a seam failure.

A failed radiator can cause major engine damage, almost as bad as a timing belt failure. Should a radiator be a time change item? They seem to last between 12 to 15 years.

I think I'm going to replace the one in our S70 and 960 within the next 6 months. We're talking $150 to $200, really not a bad price to pay to avoid being stranded somewhere and trying to avoid major engine damange from an overheated motor.

Sorry for not updating the forum in time.

History
======
I actually changed the coolant reservoir after finding a crack, which opens and leaks only at high temperature. After changing the coolant reservoir leak still continued. Then when I looked closely the leak was at the point where return hose connecting back to coolant reservoir. That confirmed that reservoir was good and no leak from its walls.

Then I checked hose for any crack. None found. But the hose itself was little old and did not get tighten up. So I put 2 clamps one at the middle of the nose (where we put a clamp usually) and second one at the tip of the nose.
And that solved the problem. Still it is holding good after 1 and 1/2 years.