Engine: 850 T5/R Boiling over

[puffernutter]

1995 Volvo 850 2.4l 5cyl estate
Yesterday on a short trip the temperature gauge started climbing, its happened before and has meant I need to top up the water. I did that this morning. My wife took the dogs to the park (and back) no issues (approx. 1 mile each way) A second run (more dogs!) and at the park the temperature gauge rocketed up and steam from under the bonnet.

I went out to have a look, filled it up with another 2 litres of water and took it very gently home. Towards the end of the trip - steam pouring out from under the bonnet.

Parked up, refilled (3 litres this time) no sign of hose leaks. Started and watched. After about 30s there was a rush of water from the expansion bottle filler cap. Stopped when the engine was switched off.

I checked the dipstick and oil filler and no sign of water, however is this suspiciously a head gasket gone pressurizing the water system?

Could it be anything else?

Cheers

Peter

[Darth Vol]

3 things:

Thermostat
Blocked radiator
Head gasket leaking out exhaust side with no oil-water mix.

Bring to garage and get sniff test done. Only way to rule out head gasket failure.

[cheshired5]

When it overheats, is every hose too hot to hold?

[Thanatos]

has it a green cap or the old grey cap that have a habit of failing bearing in mind the pressure in the system is what stops it boiling as when the needle in the temp gauge starts to rise its at 125 deg c iirc

check the thermostat and see if its stuck a new one is £20 from volvo when mine failed it had been in 16 yrs and was the original

are you adding any coolant as that will bring the boiling point down as well

are you getting bubbles in the water

[puffernutter]

Black cap

Will check thermostat (to the left of the engine?) Is it an easy job to get at? I may just take it out and see what happens!

Anti-frozen at 33% (well it was until it started spitting it out!)

Cheers

Peter

[puffernutter]

Progress (I think!)

This evening I removed the thermostat. Re-installed the housing with some blue hylomar, topped up and started the engine.

I initially left the expansion bottle cap off. On starting the engine there as no sign of bubbles/pressure in the water, in fact it was still. So that (I think) rules out the head gasket - is that a correct assumption.

As it warmed up I put the cap back on.

The bottom hose was much cooler than the top hose, so the radiator is having some effect.

As the engine warmed up and got towards normal (mid way) there was evidence of water escaping from the rim of the expansion cap, as the engine ran longer the water escape became greater.

So, is this as simple as a new expansion cap?

Cheers

Peter

[cheshired5]

Originally Posted by cheshired5

When it overheats, is every hose too hot to hold?

I'll ask again.....

[Thanatos]

peter get a green cap as it superceded the grey/black cap you have which in my opinion has failed

[puffernutter]

Sorry, I missed the question. Top hose is hot, bottom hose is much cooler. I can hold the top hose (but only because I don't let it get too hot!)

Cheers

Peter

[Luxobarge]

Sounds like you're nearly there. As above, get a green cap as a safety measure, even if the new stat does fix it.

If it's any help, H/G failure on these is VERY rare, I can only remember maybe one case on here, and that was because the driver had continued to drive the car after total coolant loss (for another reason) and had massively overheated the engine IIRC.