hello, since I put a new coolant cap on my 850 2.5SE 1995 it started to leak antifreeze at enormous speed. I replaced old coolant cap because it had some cracks BUT: COULD IT BE that the old cap had some kind of valve, like a hole inside of it, thet regulated air flow within cooling system that is under pressure? because as soon as I started using the new cap, the problems begun at a great speed.

my old cap was grey and my new one is like this 1993-1997 Volvo 850 Coolant Reservoir Cap - Gates W0133-1638910 - Direct OE replacement

thanks

 

Have you tried putting the old cap back on to see if it stops?

 

I threw away the old cap...I've been to the mechanic now and he tells me that this green one is the only proper cap for volvo and that previous owner probably improvised with some other cap since he couldn't find original one. if I unscrew the cap a little bit it stops leaking but the mechanic says that antifreeze must be under pressure to do the cooling properly and the cap should be tightened hence. but interesting, even when cap unscrewed or total antifreeze missing, it still doesn't alarm me about temperature, it seems normal.

 

you may need to try and source a genuine one second hand.......I know they do have a pressure relief valve on them.

Mine looks nothing like the one you showed, and mine is a grey one, and is genuine volvo

 

crap...does your one have like a small hole on top of it...? thanks for help...

 

The older caps are grey, the newer caps are green. You want the newer cap style.

When you say you started 'leaking'...where? Out the cap? Caps have a built in pressure ratings, around 14psi. If it is making a good seal and your still leaking then I can think of two options. One, the cap is defective or Two, there is something else going on that is making the pressure in your system exceed the rating on the cap (i.e. blown head gasket, low coolant level causing overheating). Make sure the fluid is indeed coming from the cap and not the return line from the water jacket or hose under the reservoir.

 

Maybe I missed it but I don't see where you say it is leaking from. What is it that is leaking coolant ?? Is it the cap itself or some thing else ??

 

I changed the whole coolant tank and thermostat, since they were faulty...I hope I'll resolve the problem. thanks people