Heater core replacement on Delanair III

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fergolf
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Heater core replacement on Delanair III

Postby fergolf » Sun Feb 05, 2017 12:21 am

Hello:

I think my '89 XJS 3.6 has a leak of coolant by the heater matrix (or heater core). When I turn off the engine, the windshield begin to get a lot of condensation by inside. It comes from the upper dash. Meanwhile the engine is running, there's no problem. It only comes when engine has been running and then turn off.

I don't see any other leak in the floor, and no rare smell either. But coolant level decreases too. So I almost sure it's a leaking heater core.

My car has the Delanair Mk III system. I've readed this about replace the heater core:
"Those who must replace the heater core should thank their lucky stars if they have the Delanair MkIII system. A major design feature of this system is the ease of replacing this core, a major task on the earlier cars. The Delanair MkIII system has bolt-on pipes for the heater core, eliminating the need for the "shortcut" pipe-cutting procedure devised for the earlier system. The heater core is removable from the right side. There is a large piece of black tape, similar to electrical tape, that covers the access panel. Removal of the core is simple as unbolting the pipes, pulling the glovebox and access cover and removing the core. This eliminates the need for removing the instrument panel and dropping the steering column, as on earlier models."

But I'm not sure about what's the part I need, because I've seen for sale two heaters: JLM11342 and JLM11343. In the Jaguar EPC only appears the JLM11342, but I don't know if it's the heater for Delanair Mk II or Mk III. So I would be grateful to know which one is the heater core for my car.

Has anyone had the same problem with a Mk III? Replacing the heater it's in the way explained above?

Thank you in advance

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poprivet

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Re: Heater core replacement on Delanair III

Postby poprivet » Sun Feb 05, 2017 8:18 am

A few things to check first, is the A/C providing chilled air and are the recirculation flaps operating correctly.

If either of these are not as they should be the car will be in re-circulation mode and will mist the windscreen badly. With the engine operating (to provide vacuum) and the heater controls set on normal settings you will be able to feel the flap in the footwell, it should be closed.
1988 3.6 XJ-S coupe
'Remember that the value of your investment can plummet as well as fall'

davidr

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Re: Heater core replacement on Delanair III

Postby davidr » Sun Feb 05, 2017 12:10 pm

Hi - there is only the later type available now, the reason being that the early type has the pipes fixed and requires a major strip down of the dashboard to replace where as the later one has the pipes bolting onto the side meaning that they can be undone, moved aside and the matrix pulled out easily. The earlier cars can be adapted to the later matrix by changing the pipes so that's what people do. As yours is the later one then I don't think you can go wrong.
However as pop rivet says there are a couple of questions to ask first.
Do you smell antifreeze in the cabin? I changed the matrix on my 1989 V12 Coupe a while back and that was definitely leaking because I could smell it. If you can't smell anti freeze then it suggests that maybe that's not the issue. (The coolant loss could well be something else)
Have you checked that the drains for the condensate from the air conditioning are working properly and aren't blocked? Do you get a puddle of water under the car when it's stood still with the air conditioning running? It may be that the condensate from the air conditioning evaporator isn't draining away quickly enough and so mists up your screen when you stop? If you can get underneath the car then you will see the 2 drains either side of the transmission tunnel. Try poking some wire up them to see if any water comes out. Be careful- if they are blocked be ready to step aside quickly or you'll get a shower!
Replacement of the heater matrix is pretty easy. Didn't take me long. Just had to take the glovebox out to get access. I guess in your case you will have to take the instrument cluster out?
Hope that helps
XJS FORUM COORDINATOR
1996 XJS Celebration Conv. (shown on the JEC stand at NEC Nov 2015)
2001 XKR Convertible

Previously enjoyed!
1989 XJ-S V12 Coupe. 2006 XJ TDVi Sovereign. 1995 XJ6 3.2. 2013 XF 2.2d. 2009 X Type 2.0d Sovereign estate

davidr

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Re: Heater core replacement on Delanair III

Postby davidr » Sun Feb 05, 2017 12:18 pm

Just realised that I hadn't answered all of your questions.
The correct part number is JLM11342. Jaguar list it as no longer available but David Manners have a replacement part (which was what I used). Price is about £84 plus VAT and shipping. You may find cheaper on eBay.
Hope that helps
David

fergolf
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Re: Heater core replacement on Delanair III

Postby fergolf » Sun Feb 05, 2017 12:36 pm

Hello, and thank you very much for your answers:

There's no strange smells inside the cabin, sure.

The mist on the windshield comes always after turn off the engine, althought I have not used the air or heat. Usually I don't use the AC because I've another problems with it (I did R134a conversion, new compressor, receiver drier.... and still leaking gas!! seems impossible to find where the loss is...oh my God...but this is another history).
So with the AC off, when I turn off the engine, windshield comes with mist quickly. No leaks in any other place (passenger's feet, etc). The coolant system is Ok, so I can't find any other reason to explain the loss of coolant.

I was convinced that was a heater core problem, but first I'll check all the things you said: drains for condensate, recirculation flaps, and so on... I hope translate it right to Spanish so in my garage they can understand me.

About part, yes daviddr, I've seen the JLM11342 in David Manner's.
I just wanted to be sure this was the right part, and not the JLM11343 (maybe this is for XJ40? ... I don't know). SNG Barratt sells the JLM11343 as equal/replacement part for JLM11342... so I can't understand what's the difference between these two parts.

smudge56
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Re: Heater core replacement on Delanair III

Postby smudge56 » Sat Aug 04, 2018 7:11 pm

Hi All - just to add to this looking under my newly acquired Celebration 4.0 1996 (and having recharged an empty AC system) with a Jag trained mechanic he pointed out the green coloured flow of liquid from above the exhaust approximately midships and opined that the heater matrix may be the leak issue for the AC system as this is the position of the discharge pipe for condensate - is this easily fixed? Any experiences of similar leaks would be appreciated.....
Thanks
Steve

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poprivet

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Re: Heater core replacement on Delanair III

Postby poprivet » Sat Aug 04, 2018 8:39 pm

What a shame Fergolf never explain the outcome of his problem.
Some feedback would be of use to others.

-------------------------
Edit:
I've edited my original post as with some thought I think I was being too harsh, there could be be genuine reasons why someone fails to return.
Last edited by poprivet on Mon Aug 06, 2018 7:22 am, edited 1 time in total.
1988 3.6 XJ-S coupe
'Remember that the value of your investment can plummet as well as fall'

davidr

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Re: Heater core replacement on Delanair III

Postby davidr » Sat Aug 04, 2018 10:40 pm

I agree with Pop. This is a community and not a one way street.
I've learned so much on the forum over the years that has helped me save an awful lot of time and money and it's only right to share that with people who were just like me when I started.
It's also nice to know if the advice given was of any use!
XJS FORUM COORDINATOR
1996 XJS Celebration Conv. (shown on the JEC stand at NEC Nov 2015)
2001 XKR Convertible

Previously enjoyed!
1989 XJ-S V12 Coupe. 2006 XJ TDVi Sovereign. 1995 XJ6 3.2. 2013 XF 2.2d. 2009 X Type 2.0d Sovereign estate


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