Hi there!

I'm not so good with Volvo's so i decided to seek advice here.

Car: Volvo 745 GL -88 255kmiles

Symptom: My girlfriend drove it until it started cutting out and steaming. Hole in the radiator. I changed radiator and waterpump. Filled with coolant and took a short drive. Radiator exploded again! !!@@$##!!

I don't thing it's head gasket as expansion tank isn't bubbling (except first time i started it after i refilled it) and oil isn't watered down.
It seems like there is overpressure in coolant system than cracks the radiator. What can be the potential cause of this?

My next step is to change thermostat and radiator, refill and warm up the engine without puting on the cap on expansion tank. If it starts bubbling or smoking then i know it's head gasket that went after she overheated it. If not, then something was blocking the passage and cracked the radiator.

Anyone?


Cheers!
Goran from Sweden

Gas bubbling up into coolant tank can be a severely leaking heater core, instead of a bust headgasket. Know from own experience.

hi there i saved a post about the pressure rating on the resivoir caps but i dont know how to put it up here. here is basicailly what is says.

grey cap= 150 kpa
green cap= 150 kpa
white cap= 100 kpa
black cap= 75 kpa

this was posted from fitz fitzgerald. the way i understand it the caps will let of pressure at different pressure levels . so it looks like the in towing you might want the green cap. but for my average driving i might want a black cap. i guess i want the cap to let off pressure before the radiator takes the brunt of the pressure. and possibly the head gasket. this is something to think abut. good luck.

It's the white cap.

There are some interesting symptoms that you might find usable:

Before i started the engine, i filled it to "MAX" and let the cap off. As I started the engine it started to spew out coolant out of expansion tank until it finally quit and sucked in the rest of coolant from the tank. I topped it off to "MAX" and let it idle. I didn't see any bubbles coming from the expansion tank so i tought "OK, it's not the gasket then", put the cap back o and took a short drive. Bang, radiator cracked.

It might be the radiator too, as i bought it used. It's sounds little far-fetched as i flushed it before use.

Thanx for all help!

Regards,
Goran

You are on the right track (I believe that the thermostat is gone) but you might consider changing all the coolant hoses and the water valve as well, since they are certainly not long for this world.

The expansion tank cap. Always good to replace it with a new,working cap that will not allow excessive pressure to build up in the cooling system. Yes?

Did you change or check the pressure cap?
--
David Hunter

Pressure cap? What's that?

the cap on the overflow resivor.