Another coolant leak.... heater matrix???

Post Mon Mar 23, 2015 2:53 pm

Got yet another coolant leak on my 2.7 - seems to be the most regular/common problem on my car for some reason!!!

This time, water is leaking into the passenger footwell.

I've got a local garage that do all my work for me and they've reported that it could be a hose, could be the heater valve, or looks like it could even be the heater matrix!!!
They obviously don't wan to confirm 100% without spending the time stripping it all apart!!!

So how likely is it the heater matrix would leak??? Does that happen often???

I'm fairly sure I had the heater valve replaced, maybe 3-5 years ago!!! Would/could it fail that quick???

I'm hoping it will just be a hose, but they suggest I maybe get a second hand heater matrix to have on standby, in case they need it when they've pulled it all apart!!!

Any suggestions or advice???

Post Mon Mar 23, 2015 3:01 pm

had similar problem recently, turned out to be leaking hose on heater connector (soft with age). Renewed hoses £48!! problem solved.

Post Mon Mar 23, 2015 6:49 pm

Heater valve is likely to fail quickly if the original cause of its failure was a radiator cap that has escaped the recall. Blowing the valve is what the faulty caps do.
There's no need to panic, getting parts on standby, since the two heater hoses under the bonnet can simply be hooked together with a bit of 15mm copper pipe to keep the car on the road.
Failing matrices aren't that unusual, but it's far more often the valve that has failed.
Could also be one of the O rings, or even an inadequately tightened hose up against the bulkhead, as scallyally said.

Post Mon Mar 23, 2015 8:05 pm

Fingers crossed then - I won't go mad trying to get a matrix yet!!!

Definately has the correct cap on, but the cooling system does seem to run at a very high pressure!!!
Have always thought it seemed a lot more pressurised than previous m20's I've had!!!

Post Mon Mar 23, 2015 8:39 pm

had the same problem with my m20, started to panick, only to find out it was a failed O ring, pennies from the local hardware shop, been fine ever since.

fingers crossed yours is as simple.

Post Tue Mar 24, 2015 4:00 pm

Bugger!!!

Apparently needs the small plastic pipe out of the matrix replacing!!!
The garage doing it for me have been told that when you replace that pipe, it will 90% still leak, as the outlet on the matrix tends to mould/mis-shape to the old pipe over time, with the heat - therefore it will be wise to change the matrix at the same time!!!

Does that sound likely/reasonable???

They're usually pretty good and keep costs low for me, so I've no reason to doubt them - they have suggested second hand parts, as these are pricey from the main dealer!!!

I'll stick up a wanted ad in the meantime, but if anyone has any thoughts or suggestions, I'm all ears!!!
Need to get this sorted asap!!!

Post Tue Mar 24, 2015 7:15 pm

miniblob wrote: Does that sound likely/reasonable???

New one on me! What's wrong with the pipe? It's just a short piece of pipe joined to the matrix by a flange and O ring, the same as the electric valve.
Only dealings I've ever had with this pipe is to rotate it through 180 degrees to give more clearance to a M50 inlet manifold, and they certainly haven't leaked afterwards.
The joint is identical to that of the valve, and I've never had leak problems after changing many of these.
http://www.e30zone.net/e30zonewiki/inde ... 300366.jpg

Post Tue Mar 24, 2015 7:30 pm

You need to pull out the glovebox trim and centre console, get your head under the dash in the passenger footwell, wipe all the joints with tissue paper and then run it up to temp with the heater on. The source of your leak should then be obvious. Mine was the heater valve - a bit fiddly but not impossible.

Post Tue Mar 24, 2015 7:34 pm

You dont need to replace anything apart from the O ring

Post Tue Mar 24, 2015 10:25 pm

Hmmm, interesting!!!
The guys doing this for me are going on what someone they know at the local bmw dealers has told them, when they tried to order the new plastic pipe!!!

Not a problem having a second hand spare on the way - had a few offers at sensible prices, so I'll get one as a standby anyway!

I've not seen it myself, but I can only assume if they say the plastic pipe needs replacing, it must be cracked or won't re-seal? These guys are never keen on ordering parts and always fix what they can!!!

I have no glove box, trim, carpet, etc, so it was obvious it was coming from that area!!!
Only put in a centre console a couple of weeks back!!!

Heater valve was replaced a few years back with a new bmw part!!!