Heater O-ring replacement in progress.

[PeterH]

I finally took the plunge today and had a go at replacing my leaky heater core o rings.
I got into it ok following the short cut methods on this forum.
Getting the ducting out of the way was a bit tricky, but I got there without cutting it in half.
I am up to the point where I have the o ring clamp screw undone, was getting too dark so I've called it a night.
I'd love any tips from anyone who has done this job, my next task is to get the original o rings out and clean it all up.
Do I need to use any type of sealant on the new o rings, or do they just go in on their own?
Any advice is appreciated, you might save me some headaches tomorrow!
Thanks, Pete.

[p38arover]

Clean the pipes thoroughly. Dip the O-rings in straight coolant, e.g., glycol, to lubricate them before fitting.

Don't overtighten the screw on reassembly as it may cause the heater core to crack and thus leak. I used a stainless steel allen head cap screw.

http://www.aulro.com/afvb/attachment.php?attachmentid=46060&stc=1&d=1334836694

http://www.aulro.com/afvb/attachment.php?attachmentid=46059&stc=1&d=1334836694

[PeterH]

Thanks Ron, your contributions to the Range Rovers.net forum have been a huge help to me tackling this job for the first time.
I was tempted to cut the ducting, but I thought better of that and followed your method of flexing it out of the way.
Do you recommend pulling the pipes right out to clean them, or leave them where they are?
Thanks, Pete.

[rovercare]

Rons thorough explanations about p38s are absolutely brilliant:)

His corrections on the England language on the other hand.....:D

[p38arover]

Do you recommend pulling the pipes right out to clean them, or leave them where they are?

They are damn difficult to clean in situ. Mine had a solids encrustation around the raised section on the pipe where it was not visible and it leaked after I put it all back together. :(

I'd never thought of pulling them out. I see no reason why you shouldn't. If you do that, do one pipe at a time and mark them "top" or "bottom" as appropriate. I knew of a P38A where a chap had got them reversed and could not get a seal because the pipes just didn't seat properly as the angles were wrong.

Whether overtightening causes the crack in the heater core is not known. Suffice to say that both jsp (on this forum) and I both had the heater core crack in exactly the same place. John (jsp) sent me his heater core to compare with mine.

Should sealant be used? I don't know. I used glycol to lube the O-rings and they don't leak. One thing I try to avoid is moving the other end of the pipes under the bonnet as I don't wish to disturb the O-ring seal.

[PaulP38a]

I ended up having to do mine the long way (dash out) as the screw head on the clamp plate was stuffed
https://www.aulro.com/afvb/

Upon the advice of folks on this forum, I also replaced the screw with an Allen head cap screw.
https://www.aulro.com/afvb/

I don't think I did a write up of it, but I did take lots of photos and uploaded them to
Heater O-Rings (http://paulp38a.com/gallery/v/99RR/heaterorings/?g2_page=6)

Might be something in there that is of some use.

Cheers, Paul.

[PeterH]

Those photos are excellent Paul, thanks for sharing, I can see how the clamp slides back now, the very thing I'm just about to do!
Very helpful, I'll be able to refer to those while I do mine.
I'll let you know how it goes!

[Bigbjorn]

I ended up having to do mine the long way (dash out) as the screw head on the clamp plate was stuffed
http://paulp38a.com/gallery/d/2451-1/IMG_1410.JPG

Upon the advice of folks on this forum, I also replaced the screw with an Allen head cap screw.
http://paulp38a.com/gallery/d/2497-1/IMG_1437.JPG

I don't think I did a write up of it, but I did take lots of photos and uploaded them to
Heater O-Rings (http://paulp38a.com/gallery/v/99RR/heaterorings/?g2_page=6)

Might be something in there that is of some use.

Cheers, Paul.

Is that stripped screw head accessible to a hand held reversible drill? With this and a left hand helix drill bit the stripped screw will simply wind out. No need to remove the dash.

[PeterH]

Have an update for you, I was doing a few jobs at once, new radiator, new hose (off the bottom of the thermostat), new coolant temp sensor on the heater pipe, as well as the o rings. I got it all back together and started her up. Wouldn't you know it, coolant still leaking from the o rings!
Not happy Jan.
Thought I may have been a bit too careful doing up the heater clamp screw, so I very carefully did it up a bit tighter. Started her up, hey presto, leak gone! Very happy with myself right now.
The pipes were actually pretty clean, but I did give them a once over to be sure.
Was tricky getting the o rings back on, then getting it all back together, half the battle is getting yourself in the right position so you can see what's going on.
All seems well now, thanks once again for your help Ron and Paul.
Now to reassemble the drivers side, then tackle the blend motor on the passenger side.

[PaulP38a]

Is that stripped screw head accessible to a hand held reversible drill? With this and a left hand helix drill bit the stripped screw will simply wind out. No need to remove the dash.

With an extension I would say yes. I used a left hand helix to unscrew it. Was not easy, even with the dash out of the way. Don't want to do it again anytime soon.

Peter - glad you got it sorted.

Cheers, Paul.

[PeterH]

Ahhh, seems I may have spoken too soon, I have coolant puddles under the car now and the carpet underneath the drivers mat is soaked in coolant.
I ran the car up to temp yesterday (after doing the o rings) and went for a drive, all seemed fine, no detectable leaks.
This morning I pulled the trims off to check the heater o ring connections and the bottom of the clamp is bone dry.
I hate to think its a cracked heater core, not too keen on doing that job.
It COULD be the top pipe not sealing properly, I'm hoping that's all it is.
What would indicate a leaking heater core? Not sure what I'm looking for here.
The coolant appears to be seeping out from the black side section of the heater core, below the o ring joins, or possibly from the same place your heater core was cracked Ron?
In the photo you can see the heater o ring clamp is dry on the bottom.
What am I looking for to diagnose a leaky heater core?
Thanks, Pete.

[redandy3575]

It just slips on, no need for any specific sealant. If anything just coat the new seals with some coolant before you fit them. I did mine almost 2 years ago and was amazed how straight forward the process was. Also be carefully not to over tighten the centre bolt on the o ring bracket as its a fairly weak metal compound and easy to strip. Another tip when completed is the importance of not mixing coolant type, just pick a brand and stick to it as the net effect can be a chemical reaction which can eat into the seals.

[poleonpom]

Sometimes the new O rings take a little time to seal

[PeterH]

Interesting finding poleonpom, have you had seals take a day or two to seat in?
I had a closer look today, the seals do appear to be doing their job, I'm scared to say it looks like there is a leak from the heater core in the area where the pipes join, possibly as Ron B described.

[jsp]

horrible design.

if your going to the effort of dash out i would replace the heater core with a unit from another car with fittings for rubber hose to be clamped on. The design in my classic which is the same as the disco is a bit better with a clamp on each pipe, but is still a poor design.

I have done my O-rings at least half a dozen times now, and have replaced the core twice.

Last time I did them I put a little bit of red RTV sealant inside the bores for the pipes/orings (very small amount) and clamped down the pipes. Hasn't leaked in the 6-7 thousand k's since but may just be luck.

This is where my first core leaked from and cracked - where the bolt head seated:

https://www.aulro.com/afvb/images/imported/2012/04/510.jpg

Took me a while to work it out and was thanks to Ron actually, he saved me ALLOT of time.

Also the thread stripped on the ally plate behind the pipes on mine, so in the end I filed down a bolt to fit between the pipes and put a longer bolt through the whole arrangement.

I found the heater core connections to be the weakest point in my car when I was having overheating issues, as they seemed to leak and fail under pressure than any other part of the system.

Also be careful as I bent my pipes unknowingly at one stage and I think that might also have led to sealing issues, and I replaced them once also.

https://www.aulro.com/afvb/images/imported/2012/12/132.jpg

Two years ago I drove home Canberra to Adelaide with the heater core bypassed as the o rings went on the morning I was comming home and boy was that a cold trip home, on the other hand I had a major failure where both pipes came out under pressure and my feet nearly got burnt and it took a week to dry the car out.

[PeterH]

Thanks for those photos jsp, I'm fairly certain that is the exact point mine is leaking too.
I got under there today with a mirror and torch, the heater pipe clamp is still bone dry, the o rings are doing their job, the leak is definitely coming from the same point you have arrowed.
Oh well, at least I know what it is now!
I'll be ordering a new heater core tomorrow.
Will have to put up with the leak for the week though, next weekend will be my first chance to do the heater core replacement.

[poleonpom]

Interesting finding poleonpom, have you had seals take a day or two to seat in?
I had a closer look today, the seals do appear to be doing their job, I'm scared to say it looks like there is a leak from the heater core in the area where the pipes join, possibly as Ron B described.

When I first changed the seals I was really careful about cleaning the seating area etc. i took it slowly and thoroughly and when I tightened the connection and re-charged the water I couldn't believe the amount of water coming out. I have a really long phillips screwdriver and I carefully increased the torque in the connection, but with no result. Only after 3 attempts did the leek result in a drip - I'd had enough and thought I'd leave it until I could source some better O rings, and then after 2 days not a drop of coolant

[PeterH]

I had a similar experience, I was a bit too tentative at first, with coolant running out of the connection after the first tighten, I increased the tension a bit more and it stopped on the second go. My new heater core has arrived, will be picking that up tomorrow and fot that on the weekend, fingers crossed that sorts the problem out!

[Hoges]

horrible design.

.....if your going to the effort of dash out i would replace the heater core with a unit from another car with fittings for rubber hose to be clamped on. The design in my classic which is the same as the disco is a bit better with a clamp on each pipe, but is still a poor design....



Substitute heater cores from various Audi models (manufactured by Valeo) seem to be the flavour of the month on rangerovers.net. Requires an adaptor or two, to accommodate different hose diameters ...