Steam heat!

[PeterH]

Driving home last night, all of a sudden I hear a hissing sound from under the dash, coolant leaking onto the drivers floor, getting steamy inside the cabin....'this is not good' I tell myself!
Lucky for me i was almost home, made it back ok with no temperature rise on the gauge.
But coolant leaking everywhere, out from under the door, making a big mess on the driveway.
I released the pressure from the expansion tank which did help a lot.
On inspection this morning, I could see the coolant appears to be leaking from the o ring area on the heater core.
I did replace the o rings about 4 1/2 years ago, it's hard to see exactly where the leak is coming from.
I know the matrix can fail and also the plastic where the screw is can crack as well.
If it is not an o ring failure, I'm going to have to replace the matrix, (which I do happen to have a new one on hand).
Has anyone replaced the heater core on a RHD model?
Does the entire dash really need to come out to replace the heater core on a RHD model?
I have seen the short cut method which works for LHD models without removing the dash, but I've read the steering column gets in the way for this job on a RHD model.
I need some direction on this one, I'm a bit stumped on how to tackle it, any thoughts will be appreciated.
Thanks, Pete.

[Hammer H]

Can be done without removing the steering wheel and dash. Just requires cutting and bending the frame and riveting back together. Not sure if that's the same as the LHD shortcut.

[PeterH]

Thanks Hammer H, I'm very glad to hear that.
All the guides I found are LHD specific, couldn't confirm if that applies to RHD as well.
On another forum, someone said it couldn't be done without removing the entire dash and the heater box as well.
The internet is a bit like the drunk guy down at the pub, some things are right, others are just plain waffle.

I've got it mostly apart up to where the o rings could be done, but I didn't fancy taking the whole dash out if I didn't have to.
It is pretty cramped trying to work under there, as I read elsewhere, you need the strength of an ox and the small hands of a ballerina!
I couldn't tell if the steering column was going to be a problem or not.
I'll be back under there today, hopefully I can get it sorted.
Cheers, Pete.

[redandy3575]

Well Pete, I'm still wrecking my old p38, and am at the stage of removing the dash. If you feel like a drive one day you're welcome to come down and have a look. I still haven't removed the matrix as yet, and the steering column is still in place.

[PeterH]

Thanks for the kind offer redlandy, it would be interesting to have a look, I might take you up on that if I get stuck!
When I got under there yesterday, I could see evidence of coolant leaking around the o rings, so I decided to try replacing the o rings first, then pressurise the system and see if that was the problem. That would save me a lot of mucking around if it was only the o rings.
So I got it back together and started it up, I pulled the air bleeder hose off the top of the radiator to bleed the air off and promptly broke that hose.
It seems they get brittle with age, then I read some people like to remove the end on the expansion tank instead of the radiator to avoid that very thing happening.
So this morning I'm off to find a replacement hose, then I can test if the heater matrix is really the problem.

[PeterH]

I have an update for anyone interested, I got a new radiator bleeder hose and fitted that, then fitted new o rings to the existing heater matrix and started her up.
Looked ok, went for a short drive to see what happened and before I got to the first corner, the hissing steam sound returned and coolant leaking all over the drivers footwell again.
Bugger!
So I took it apart again and following PaulP38A's excellent guide, I carefully cut the frame in the right places using a dremel, cut the ducting in the right spot, bent the frame out of the way and removed the old heater core.
It seemed the old heater was split somewhere, allowing coolant to escape and steam to fill the cabin, trouble is, you can't see it until you remove it.
It's very tight working under there and the steering column does hinder things a bit.
But I can confirm the job is possible on a RHD vehicle without removing the whole dash.
I had a practice run at fitting the old heater core back in, you have to get around the brake pedal, steering column and wiring looms in the way, but I worked out how to get the matrix in and then put the new one in.
I connected the heater pipes back up and started her up again, noticed a leak from the top o ring, so I tightened that up a bit more, still leaking, a bit more and the leaking stopped. I have read you can crack the plastic around the screw if overtightened, so I was being careful to not do that.
Went for a drive with everything still apart and it all looked good at last.
Back home and the reassembly took quite a while, but it all went back together fine, looks like I have it sorted.
It's a bugger of a job really, but I did pretty well, the heater failed on Friday night, I had it back on the road by Tuesday night, (probably would have been quicker if I didn't have to wait until Monday for the bleeder hose), not too shabby!
Hope this helps someone,
Cheers, Pete.

[redandy3575]

Sounds like a ***** of a job. Though not as bad considering you didn't have to remove the dash.
I don't know why the o-ring and matrix syndrome has chosen the P38 as a target.
Don't really hear to often of these types of issue in most other car brands, except old volkswagen beetles where you get gased instead!!

[benji]

I've got this same job coming up.
The orings were leaking, and I had to change the dash anyhow.
The heater core itself had a bur where the orings seal up against and I thought I'd be okay with new orings, but they're still leaking.

I ended up getting a core made up with metal end tanks and pipes on it, as I wanted to eliminate any failures in the future.
He's done a great job ( actually a forum member), all going well I should pick it up today - then the fun begins!

Hopefully you've got it sorted out, sounds like you have.




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[PeterH]

Sounds like a good plan Benji, custom made heater core!
I checked my carpets this morning and they are dry, I was very happy to see that.
I didn't want to remove the whole dash if I didn't have to, but if you are changing the dash anyway, it's a perfect opportunity.
PaulP38A.com has some great guides with photos for dash removal and heater core change, well worth a look before you tackle the job.
Good luck with it, hope it goes well for you.

[TheTree]

I went with the Audi heater core and did it with the Dash out... much easier

Steve

[benji]

I did start with Paul's indestructables when I pulled the first dash out, they're a very good resource. Unfortunately this'll be the third time I've taken a dash out. It doesn't necessarily make you knowledgeable about it, just annoyed that you know how much work it is. ...

I picked it up today, looks fantastic.
On a mental calculation there's double the surface area of the tubes, and less restriction through the core - so it should be good.

Hopefully this is a permanent solution.



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[PeterH]

Wow that looks like a work of art! Nice one Benji. I'll be interested to hear how you go with it.