heater core to pipe o-rings - square or round?

Post by **erikv11** » 22 Nov 2010, 23:52

The title says it all. I want to replace the o-rings where the heater pipes connect to the heater core, one of them is leaking. The o-rings on there now look like they are square, but I don't know if that is because they are some kind of special o-ring, or because they have deformed over the years.

Anyone ever replaced these? What did you use?

VolvoTurbo850 · Post by **VolvoTurbo850** » 23 Nov 2010, 02:31

They are round. You can buy them from FCP.

The unit is made up of some rubber o-rings and some plastic washers. Do a search and you might see it on Matt`s site or on FCP`s site.

Just be careful down there as the older the unit is, the more chances there is that the `quick connect`unit can break on the opposite side of where your connecting up the core (in the firewall).

Post by **jblackburn** » 23 Nov 2010, 05:15

Don't buy the FCP ones - they LEAK! Worse than my old ones. Go to a dealer and get the OEM ones.

VolvoTurbo850 · Post by **VolvoTurbo850** » 23 Nov 2010, 07:18

Ive used the FCP on five 850`s and no leaks, what`s everyone elses record .. and don't forget, we have pretty cold weather up here.

Post by **jblackburn** » 23 Nov 2010, 08:04

It's possible I pinched the one that was leaking when reinstalling it, though I didn't see any folds when I removed it. The other one seemed fine, so it may have just been me. I removed them and re-installed the Volvo ones and didn't have a problem until the heater core itself sprung a leak a couple weeks later. I figured at 183K miles it was time to just suck it up and replace it.

Post by **erikv11** » 23 Nov 2010, 08:33

Thanks all for the replies.

Not the o-rings in the coupler unit, the ones where the pipe fits into the bottom of the heater core. I have an unused, genuine Volvo o-ring and clip kit for the coupler, and I can see those o-rings in the kit are definitely smaller than the ones currently on the pipes at the heater end.

Problem is, I don't want to mail order (takes too long to get here) and the closest dealer is over an hour in a direction I rarely travel. But the local hardware store has a complete selection of round o-rings ...

jablackburn I presume the genuine Volvo o-rings you bought for the heater core junction were round?

wurkin4it · Post by **wurkin4it** » 23 Nov 2010, 10:20

The O'rings are round. I bought the set from IPD. If you can get t he correct size (nominal) at your local hardware store, go for it. Applied Industrial Technologies is a terrific source for o'rings and hydraulic hoses. They can provide the correct material for the fluid as well as the correct size. Check the internet to see if they have a store close to you.
Good luck.

Post by **jblackburn** » 23 Nov 2010, 10:38

Yep, they were round. They sorta smash though when you install them, perhaps why they looked square. I second the idea (or third it?

) of trying to find some at a hardware store - I doubt there's anything special about them.

Post by **cn90** » 23 Nov 2010, 13:20

Yes and NO!!!

99% of rubber O-ring at hardware stores these days are from China.
The quality is bad seriously.
How do I know? I bought some rubber caps for my Volvo vacuum tree. One year later, it breaks from the heat!!!
The OEM vacuum cap lasted 12 years!

Get the OEM O-rings, unless you enjoy doing this job every year!

nwhitney · Post by **nwhitney** » 23 Nov 2010, 14:14

I work in the field of mechanical seals and 99% of our seals use o-rings. There are a couple of reasons why your old o-rings are now squared. Different applications call for different types of o-rings. AIT (Applied Industrial) is a good source and they are one of my customers. However if you tell me the size and quantity you need I'll ship you some overnight free as we have many extras. As long as you don't need Kalrez o-rings those are spendy little buggers.