Heater matrix leak / replacement

[k10]

Hello
I've just purchased another MR2 MK1 and the heater matrix is leaking coolant into the passenger footwell.

I've read the posts about this on IMOC and it appears to be accepted that the easiest method is to cut an access panel out of the bulk head, I certainly prefer this idea to removing the dash etc...

Are there any other options for example.
1. If I don't turn the heater fan on the leak seems to stop or at least be less severe.
2. Could I bypass the heater matrix all together, as it's primarily a summer use car, T-bar. Would this have a negative effect on the engine temperature in terms of overheating?
3. I have heard of the fabled 'template' for removing a section of bulkhead so I can slide the matrix out and then make a panel for easy access thereafter, does anyone have the template, or any good tips on what is required to remove the matrix this way?
Many thanks

[k10]

Just thought of option 4. What about radweld or it's equivialnt to block the hole? Has anyone had much experience with rad weld or similar products as it seems to be a marmite product. Will this block the coolant system for example?

Thanks

[System-G]

Avoid Radweld - it can get in places you don't want it getting into causing loads more issues.

Temporarily (and best option until it's sorted as you don't want air getting into the system causing head gasket faults) you can bypass the heater feeds in the engine bay - you'll see the two thinner coolant hoses disappearing into the tunnel toward the front of the car. Where the rubber pipes join to the metal pipes engine end, find the most suitable hose to use and make one metal hose connect to the other - so they are not feeding the metal pipes dissappearing into the tunnel (If that makes sense!) Scuze the rough temrinology

[cabbydave1]

If you need one I can get one out for you this weekend as im taking the interior out of the one im breaking
Dave

[kaiowas]

Bypassing the heater is simple enough and won't do any harm. You can either bypass it in the engine bay as Garrick suggested or where the pipes come up into the frunk and then into the bulkhead. I'd go for the frunk as access is much easier.

[k10]

Thanks for replies, few questions.
1. What's the frunk?
2. To bypass I assume I just connect one pipe going to the matix to the pipe that would be coming from the matrix, thereby bypassing the matrix altogether.
3. Does anyone have the diagram for the cutting out of the bulk head where the matix is??
Thanks

[k10]

Oh and how much for the matrix from the reply who said they are removing htis weekend?
Thanks

[System-G]

or where the pipes come up into the frunk and then into the bulkhead. I'd go for the frunk as access is much easier.

I hadn't thought of that. Good for future useage, Cheers Phil

[kaiowas]

Thanks for replies, few questions.
1. What's the frunk?

The "front boot", or in american "front trunk" hence "frunk".

And yes to bypass the heater just remove the rubber hoses from the top of both metal pipes where they come up into the frunk area then loop a short length of hose from one to the other. You'll need to remove the spare wheel and the large piece of plastic trim which lines the rear of the frunk to access the pipes then it should all become clear.

you can see the pipes in this picture:



They're the pair of bent black ones with a white stripe on them coming up together through a rubber grommet, ours have nothing connected to them as this is our track/sprint car and the heater has been removed entirely. (Plan is to reuse those pipes as part of our chargecooler install, hence the pump bolted in but not yet connected to anything)

[k10]

Okay thnaks for info.
I may just bypass the heater matrix for now at the 'fronk'.....as suggested.

Has anyone removed the matrix via cutting a hole inthe bulk head and what should I look out for.
My initial concerns are.
1. Where to cut and how big, I hear a template is around but cannot locate.
2. How to cut? Won't a grinder have the possibility of setting passenger carpet on fire or burning through wiring in dash area etc...
Anyone done this job?
Thanks

[cartledge_uk]

There is a knowledge base article, but the pics are no-more

http://www.imoc.co.uk/forums/kb.php?mode=article&k=5

[Lauren]

I did the original knowledge base article when I did it to my MK1 some 5 odd years ago.

Even without the pics (which have dissapeared for some reason) the guide still applies, it's simply a matter of just cutting the hole for the size of the matrix, then it just slides out. Really quite easy to do.

You can as others have said blank off the matrix and bypass it. This obviously works but then you'll get no heat into the car and you really will notice it.

[PW@Woodsport]

I thought Laurens idea and template were so good at the time that i saved a copy of the drawing in case i ever had to remove a matrix, it's in my docs somewhere which look like a library with all its books on the floor so bear with me, i may be gone some time!

EDIT : found it... and hosted on my PB account so it will stay here forever.

[Lauren]

Cheers Paul.

Though I'm not sure I can take the credit for the template as I think Tom did it.

[PW@Woodsport]

Oh right! I thought it was yours? Good work Tom , Lauren you're demoted to peasant

[Lauren]

Oh right! I thought it was yours? Good work Tom , Lauren you're demoted to peasant

I cut the hole, changed the matrix and made a panel. IIRC Tom made a drawing afterwards.

[cabbydave1]

As if by magic I fell over whole heater box in my garage pm your address to me and I can get it posted as long as you send me the postage and a small donation I'll be happy to send you a matrix
Dave

[ulysess1966]

Not sure if this is relevant, but might be encouraging.

About 18 months ago I swapped out the heater matrix in an Audi 80. There wasn't really an option to cut a hole in the bulkhead so I dismantled the dash and went in that way. Everyone said I was mad, but I managed it in about 5 hours with plenty of coffee. The trick was to break the job down and keep all the fixings separate and marked for re-fitting. Of course actually changing the matrix took all of 5 minutes once the dash was out.

One word of advice. Don't risk driving in winter time with a clearly damaged matrix because you'll end up breathing antifreeze fumes and there are a handful of fatalities every year in the US from this (usually people trapped in snowdrifts).

[System-G]

Oh right! I thought it was yours? Good work Tom , Lauren you're demoted to peasant

I cut the hole, changed the matrix and made a panel. IIRC Tom made a drawing afterwards.

IIRC, Tom made the template when he changed the matrix on his own car

[PW@Woodsport]

LOL Lauren's been busted!

I must admit though i thought for years it was Laurens mod.