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Heater Matrix Replaced And Still Smokey


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#1 JimMPI

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Posted 18 October 2020 - 06:45 PM

Hi there, been on the forum a while but this is my first post...

 

I have a 1999 MPI and when I bought it the heater valve had been bypassed and the heater seemed to be leaking.  I've recently replaced the heater valve and the matrix (plus pipes and o-rings) but each time I've used the heater since I'm getting mist/steam out of the vents for a few seconds (I've only been out in it 3 times so far).

 

I can't find any evidence of water leaking, but I suppose it could be evaporating off.  It seems to produce this steam once it gets to full temperature but after 5-10 seconds it seems to disappear again.  I have read that new matrixes (matrices?) can be coated with oil at the factory which burns off - could this be the cause of my problems?  Or is there something I've missed?

 

The rest of the cooling system seems to be fine - I've previously flushed it all through, and fitted a new thermostat and expansion cap.  Temperature gauge sits at the halfway point and never seems to go above this (although I guess that's no guarantee that it's not actually overheating) but the rad fan seems to but in and out as you'd expect.

 

Thanks for any tips!

 

Jim



#2 bpirie1000

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Posted 18 October 2020 - 07:02 PM

Difficult to say i know but is the smoke blue or white..

Burning oil from the smell of it or usi g any fluids?

Piston rings worn? Miles? En

#3 Revd

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Posted 19 October 2020 - 09:56 AM

if it's steam (not smoke) it could be water vapour from a leak around the screen seal - a known rust trap on later cars



#4 JimMPI

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Posted 19 October 2020 - 02:44 PM

Difficult to say i know but is the smoke blue or white..

Burning oil from the smell of it or usi g any fluids?

Piston rings worn? Miles? En


I would say it's a greyish mist. Interestingly it didn't happen on the way to work this morning, but I'm not sure if the engine got that hot as there was no traffic.

I haven't done a compression test but the engine seems to run ok and no visible oil burnoff from the exhaust. It's done 88k miles.

#5 JimMPI

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Posted 19 October 2020 - 02:47 PM

if it's steam (not smoke) it could be water vapour from a leak around the screen seal - a known rust trap on later cars


I'm not sure if it's steam or smoke but I can confirm that behind the dash is dry as a bone as I've just replaced the dashboard. Car is garaged and doesn't usually come out in the rain.

What are the odds of a brand new matrix having a leak? I thought it might be leaking where I installed the new metal pipes but there's no sign of any water there at all.

#6 Chris1275gt

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Posted 19 October 2020 - 04:06 PM

I had a nearly new matrix on my 75gt on cold start it used to condense on the windscreen above the demister vents ever so slightly then disappear. Never could see any leak at all on it. Changed the matrix and no more condense. Mine doesn't go out in the rain either.

#7 mrmeds

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Posted 21 October 2020 - 07:16 PM

I had steam come out of mine the other day, when it was raining, also had loads of condensation on the headling and dripping on my head. The windscreen was out recently due to a respray and had a new larger seal put in, but it looks like sealants been used, so still assuming mines the 30 year old matrix, which gives out very little heat. Had the car two years and only had the heater on in the summer before, with the window open for cooling purposes !  Hoping to swop the matrix around with new one next week- pray for no more steam



#8 Steve220

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Posted 22 October 2020 - 04:39 PM

You may have residual water in the heater itself. Will take a while to evaporate.

#9 JimMPI

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Posted 24 October 2020 - 10:13 AM

Thanks all for your advice.  I haven't seen any more smoke/steam for the rest of the week, so I'm assuming it was some sort of oily coating burning off.  I've also noticed on the screen above the vents is a slightly greasy residue which supports this theory.

 

Just need to get hold of a suitable resistor to reinstate fan speed #1 now, and the job's complete  :-)






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