I drive a 1994 850 Turbo with 150,000 miles. Here's the deal: the heater core leaks on the regular. But it isn't a slow, constant leak. When it leaks, it goes crazy. I've noticed that it doesn't do this while I'm driving, only when I'm idle or when I stop the car. Then I can hear it spewing out and it gets worse and louder and the windows fog up and steam comes out from behind my dash. When I bought the car in February, the heater core had just been replaced. And when I take a look at it while it's spewing out water, it leaks in only one spot, from one of the black pipes coming out of the heater core. It's easily visible if I take off the carpeting on the driver's side. Does this mean it's the O rings? What should I do?

P.S. the heat still works. It'll blow hot when I turn the heater on, if that matters.

 

#1 - Stop driving it. Your going to overheat and blow the head gasket.

You can get a replacement heater core on ebay for about $40. They take literally about 30 minutes to replace.

Volvo Heater Core 850 S70 V70 C70 1994 through 2000 MADE IN EUROPE 9144221 NEW | eBay

 

You need to fix the leak before the leak is the least of your worries !!

One trick to knowing when you are in trouble cooling system wise is to have the heater on and monitor for heat. As long as you can feel hot air you know you still have water circulating and cooling the engine. If it suddenly goes luke warm or cold you know you just ran out of circulating coolant and you need to immediately turn the engine off.

This is no way to operate a vehicle daily but it is a way to get it home in an emergency if you have to and just can't bring yourself to have it towed.

 

If you can see that the leak is coming from the connection, change the seals. You have a $3 problem that can easily turn into a "I no longer have a car" problem. If the coolant leaks out and the motor overheats because it has no coolant you will blow the motor.

*** This is your 3rd warning ***

 

How/what would I use to change the seals? Do you know or could you give me a link that would show me how to do that? Thank you! I'll attempt it tomorrow.

 

Or instead of asking us for a link you could do a little of the leg work and look yourself as all you need to do is google 850 heater core or go to Matthewsvolvosite or Volvospeed.

But ... http://www.matthewsvolvosite.com/vol...-tutorial.html

and ... http://www.matthewsvolvosite.com/for...hp?f=1&t=40240

Take care of it soon so Rspi can sleep at night and you aren't listing it as a "parts car" with a bad engine.

 

Amen!

 

Sorry to hassle y'all. But thank you very much! Got the O-rings from the dealership today, we're good to go.

 

You are welcome and I'm sorry but I "poke" people occasionally to let them know there's info out there for the finding.

A lot of the time I don't know a specific answer and the hunt for an answer is how I learn more about my Volvo's quirks and specific mechanicals.

 

Hurrah!!! I was up at 2:30 am worrying about it. Phew!!!

I don't know why people don't change the seals when they do the core, or at least make sure it's not leaking.

 

misterbrooke, have you looked at it yet? The chances of the seals being bad is very slim. The chances of the heater core leaking is very high. I know you want or are hoping for the least amount of work but dont mess with this thing, do it right. Your going to take the core down anyway to change the seals.

 

That's a refreshing change! Only half an hour to do a core?

I changed the heater cores on a '99 Honda Odyssey, and I had to take out the ENTIRE DASH. EVERYTHING! The only things still connected to the fire wall were the PEDALS! And the same with the rear heater core. All the plastic and upholstery down to bare metal on the passenger side rear and over the sliding side door tracks. Gad, what a job.

Lynn B.

 

I think he seen where it was leaking from.

 

I would agree with you but I went back to the first post and saw that the core was just replaced so it's likely just a bad seal that might have been damaged or neglected when the core was done.

 

Well folks, I tried my hardest but it just didn't work out. I just made it worse. I don't know whether the core was already bad or whether I destroyed it trying to take thing apart. Anyway, I just decided to connect the pipes outside of the firewall and bypass the heater core altogether. I'll be okay, I live in Phoenix, Arizona.

 

Sorry to hear it went from bad to worse.

If you reconsider there are economical alternatives. They haven't had anyone complain about their quality and they've sold a few hundred. It's a better design similar to the way they make radiators and crimp the core to the end tanks. I haven't tried one but I went through their ebay feedback and there wasn't one complaint about a heater core.
Volvo Heater Core 850 S70 V70 C70 1994 through 2000 MADE IN EUROPE 9144221 NEW | eBay

 

I pulled a Nissin core out of a car the other day and it appeared to be built like that as well.

 

Isn't there an issue with the supply & return lines to the heater core?
It is my understanding that the OEMs have been known to corrode & thereby leak coolant.

 

The eBay link explains it. IMO, anything will leak after 12+ years.

 

Don't get me wrong. I'm not debating the facts, heater cores will go bad.

I was under the impression that in addition to the heater core the supply & return lines corrode as well on these 850s. These lines are often overlooked & if one is going to spend the time to replace the core they might as well consider changing the supply & return lines. just my 2 cents.