745 exploding radiator syndrome

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

 

Have a leakdown test done, I would bet the cylinder head is warped and is
allowing combustion gasses into the coolant at higher engine load.

 

This doesn't sound Volvo specific.

A radiator cap that isn't venting under pressure like it should, or
a clogged overflow line--although I'd expect the line to blow off
before the radiator should burst.

A thermostat stuck closed would cause the engine to overheat while the
radiator remains relatively cool. Your problem is that expansion due
to temperature increase has nowhere to go. The problem is in the overflow
system; the cap, hose, or something, perhaps where the overflow hose
is attached to the radiator...

If you had a cracked head, blown gasket, etc., and the pressure relief
components were working, you'd see the combustion/exhaust gas bubbling
out through the overflow tank, cap or no cap.


Gary

 

If you mean the radiator is exploding due to the coolant overheating
than it probably is related to a cracked head or block. This allows
the exhaust gasses to heat up the coolant.

 

TRY TRIMING THE RUBBER ON THE RADIATOR CAP THIS EXPANDED ON A FORD I ONCE
HAD CAUSING MANY RADIATOR BLOW OUTS ALL IT NEEDED WAS THE RUBBER TRIMMED SO
THE WATER COULD GET PAST BETTER STILL BUY A NEW CAP IF THE RUBBER IS LARGER
THAN THE BORE OF THE FILLER ON THE RADIATOR .

 

Try fixing your caps lock key