Coolant issues, no overheating and can’t find leak

[Stalledvolvos90]

In hope of some good news because I would be shattered if it’s the head gasket.
First up, I drive a 1997 Volvo S90.
When I got the car about 2 months ago coolant was always sitting at max, every time I checked.
I drove the car for about a month and had no troubles until one day I got a coolant warning light. I stopped the car within 20 seconds and left it there. Came back a few hours later with generic green coolant and filled it to the max line.
Didn’t drive the car after that really, I just let it idle looking for leaks and the odd short trip. In about a months time I got hit with the cool t light again. I was constantly monitoring my levels and a friend told me my car should have coolant at Min when cold and Closer to Max when hot.
I got hit with the coolant light again after a start up and because the engine wasn’t too hot I crack the reservoir cap and coolant flushed back in just above the min line. I’ve only used my car a few more times since then but feel like I’m definitely loosing a bit of coolant almost every trip. I can’t see any puddles on the floor my engine bay looks clean. I do have some rusty pipes where hoses meet behind the engine.
I can’t have this car die so I would love advice on what to do next, semi freaking out about it.
There are some cracks in the reservoir tank but they don’t look like they go all the way through, I have heard my cap hissing when the cars hot. And to be honest, I have felt the slightest vibrations when stopped at traffic lights but I kind of hope it’s from low fuel levels.

[Stalledvolvos90]

Added photos of the rusty pipe I suspect could be causing issues and the reservoir tank, pretty sure It will be hard to see the crack near the clamp but like I said it does not look all the way through.

[Rversteeg]

The connection in the bottom of the expansion tank has a metal insert. This insert starts to rust. The expanding rust cracks the plastic around it and causes the tank to loose coolant. Definately worth a check.
The cap of the tank could also be defective and letting out coolant under pressure too soon. Especially when filled to the max when cold there is very little room for expansion, so more likely that coolant will be pushed out through the cap.
Rob

[Stalledvolvos90]

Thabks Rversteeg that’s a good suggestion. This is my first older car so a lot of things I’m not used to going on here!
If coolant was evaporating out of the tank because of the cap how would one diagnose that? There is a small white circle under the bonnet where the cap rests on the lining which is what made me think that was a possibility.

[TonyS9]

On the red blocks you can usually run without a pressure cap, especially in winter and driving gently/normally. Its not ideal as the coolant might boil in parts of the engine, but I've done it with some leaks to reduce them. You won't loose much coolant from evaporation.

[Laird Scooby]

Originally Posted by Stalledvolvos90

In hope of some good news because I would be shattered if it’s the head gasket.
First up, I drive a 1997 Volvo S90.
When I got the car about 2 months ago coolant was always sitting at max, every time I checked.
I drove the car for about a month and had no troubles until one day I got a coolant warning light. I stopped the car within 20 seconds and left it there. Came back a few hours later with generic green coolant and filled it to the max line.
Didn’t drive the car after that really, I just let it idle looking for leaks and the odd short trip. In about a months time I got hit with the cool t light again. I was constantly monitoring my levels and a friend told me my car should have coolant at Min when cold and Closer to Max when hot.
I got hit with the coolant light again after a start up and because the engine wasn’t too hot I crack the reservoir cap and coolant flushed back in just above the min line. I’ve only used my car a few more times since then but feel like I’m definitely loosing a bit of coolant almost every trip. I can’t see any puddles on the floor my engine bay looks clean. I do have some rusty pipes where hoses meet behind the engine.
I can’t have this car die so I would love advice on what to do next, semi freaking out about it.
There are some cracks in the reservoir tank but they don’t look like they go all the way through, I have heard my cap hissing when the cars hot. And to be honest, I have felt the slightest vibrations when stopped at traffic lights but I kind of hope it’s from low fuel levels.

Is it automatic? If so, have you checked the ATF level recently? A big clue here is the vibration at idle, if water/coolant is getting into the ATF, it could be boiling off and causing cavitation within the torque converter which won't do the auto box any failures.

In case you're wondering how the coolant and ATF could mix, the ATF is cooled by (usually) two heat exchangers, one in each radiator end cap.

I've had it happen before on a V8 SD1 and similar symtpoms of vibration at idle followed a few weeks later by loss of forward drive.

[Stalledvolvos90]

Thanks lairdscooby. I’ll do some research and check out the atf in the next hour or so. Thanks for this tip. ATF stands for auto transmission fluid or something else. Sorry I’m just a beginner.

[Laird Scooby]

Originally Posted by Stalledvolvos90

ATF stands for auto transmission fluid

Yes!

[Stalledvolvos90]

So a sad day.
Started car and fuel gauge bounced like it was at rave.
Pressure tested the car to find the leak and didn’t find a drop anywhere not even in the car. Trying to hang in there with it.
No coolant in the atf either looked like a red colour

[Laird Scooby]

Originally Posted by Stalledvolvos90

Started car and fuel gauge bounced like it was at rave.

Standard issue Volvo and the hot climate probably accelerated the inevitable. It'll probably settle down tonight when it's cooler. Meanwhile have a read of this thread, although for a 760 facelift, the 9xx.x90 ranges used similar instruments.

https://www.volvoforums.org.uk/showt...ght=fuel+gauge

With luck your fuel gauge fault is as simple as that.

If the cooling system checks out on a pressure test, i'd strongly suggest the cap is faulty. I've had an unexplained coolant loss on my Rover for a while, discovered the other day the cap pressure valve has detached itself from the actual cap which is a prime example of a failed cap! Will have to buy a new Volvo one for it!

For a few bucks, it's worth a try on yours, if nothing else it will eliminate it from the search!