Hi Everyone,
I have a '91 1.6 Driver that I got in July. I've just discovered no heat comes from the heater (first time using it!). Any ideas why?
Thanks.
I think its a blocked heater matrix.
scs
Are the water pipes hot that go through the bulkhead? If not you may need to get rid of an airlock.
If that is the case then squeezing the various water hoses whilst the engine is idling should do the biz.
Thanks for the info'. Absolutely bucketing down here, and I don't have a garage. I'll give that a go tomorrow and see whats, what.
Maybe not blocked matrix, more likely if you still have the bypass valve fitted it will be that blocked. Either way probably wise to replace the matrix so it doesn’t pop then remove the bypass, no longer needed with a new matrix and replace the 2 heater hoses that will have been cut for the bypass with mk3 ones available new.
The bypass is an 90s recall that vw did as a quick fix to poorly designed matrix that would burst and spray occupants feet with boiling hot coolant.
Matrix design was changed so all new ones shouldn’t need the bypass. But make sure you get a reputable brand.
Or could be the foam has all gone, so water system is fine, does it get hot when stationary?
I hope for your sake it isn't the heater matrix. But if it is you will learn all about what is behind the dashboard.
It's raining here too. Just been under the Caddy on the drive. That wonderful sensation of rain dripping on my bottom half whilst trying to replace the big ends.
Where did summer go!
Recent GOV.UK survey cited 91% of people are satisfied with their lives.
The other 9 percent own a Volkswagen.
I would get out more but it’s raining cats and dogs here as well.
I've half dismantled the dashboard, and the foam is all gone from inside the heater box. Should be dry tomorrow so going to try and cover the adjusters with heat proof aluminium tape.
Thanks for all the advise.
Will keep you updated... ;D
So...
There was no foam on the heat box adjusters, so I've covered them with heat proof tape and cleaned out all the foam bits.
I ran the engine while doing this, and when I first put the heater on, the air was hot for maybe 20-30 seconds.
I've just used the car for 30 minutes and the heater is warmer than before, but still not really warm.
Yesterday I checked that all the pipes to the heat matrix were hot (they are), ran the car with the expansion tank lid off and massaged various hoses while the engine was running. I've recently had the thermostat housing replaced and since then the temperature gauge is significantly lower/cooler. I'm also fairly sure the heater was warmer before the housing was replaced, but I've not really used the heater since having the car.
Any ideas?
Thanks.
Is the temp gauge in the middle when fully warm?
Re replacing the foam. Just clarify which foam you have replaced. It's the foam on the flaps in the heater box that disintegrates and needs replacing.
Hi, yes it's the foam on the flaps in the heater box I've replaced.
No, the temperature guide never moves above 1/4 hot. Before the thermostat housing was replaced it would go above half when in traffic, but since the repair it doesn't go anywhere near that high. Not sure if the garage replaced the thermostat when they did the housing, or if the coolant system was flushed. I will check when they open tomorrow, but I'm thinking maybe the thermostat is stuck open and/or it needs a coolant flush (or 3!).
I had this issue on a previous car any selection of fan speed above one and the air would start warm but quickly blow cold even though the engine temperature was normal. I was convinced it was a blocked matrix. I never cured the problem even following flushing and loads of fiddling. note I did not replace the matrix.
When the engine is fully warm do the water pipes get very hot to touch? The bottom rad pipe from the thermostat should be very hot to touch proving water is getting to the radiator. Obviously be careful putting your hand near the drive belt (might only be an issue if you have PAS).
It also might be worth flushing water through sections of the cooling system (hose pipe) to ensure no blockages before flushing with distilled water and re-filling.
Have just checked, all radiator hoses get very hot. Checked paperwork from garage and it wasn't the thermostat housing that was replaced it was a housing elsewhere, so I'm still thinking it could be the thermostat stuck open?
Am currently running a coolant flush through to see if this does anything, can't say I fancy flushing things with the hose, I can see that going very wrong :o
I wasn't meaning a hose on full blast :D
However you could check water is free flowing through the matrix by testing the in out section only
Thanks for the info. Will be tinkering again on Friday.
Hopefully update at the weekend 👍
The temp gauge should go to half way point. if it's not I suspect the stat is not operating properly, however it could be a red herring caused by a faulty temp sensor. I always check a thermostat in a pan on the hob before fitting to comfirm it opens and closes as required.
It's probabbly the coolant flange on the side of the block that was changed. I looks like it should be the termostat housing, and it's a sad state of affairs that a mechanic dosen't know. I have a slight leak from the coolant flange on mine and it came up in the MOT as an advisory, 'leak from thermostat housing'. That would have had me looking in the wrong place.
The thermostat housing is plastic and warps, so I treat them as a single use item. And every time I've done the job the bolt on the water pump sheers also. so I treat the water pump as a replaceable item too.
So new stat, water pump and stat housing and you'll be ready to takle it. If the car is PAS that adds an extra level of pain as the PAS pump needs to be moved out the way.
A test you can do, when running the car from cold the bottom radiator hose should stay cold for quite a while. It's not until the stat opens and lets hot water freely flow into the rad that the bottom hose will get hot.
Make sure car is cold, start car, hold bottom radiator hose, if it gradually gets warm from the start then Stat is stuck open.
If it never gets warm stat is stuck closed.
If it stays cold for a while then suddendly gets hot, stat is working as expected.
The flaps, did you do all of them? Did you do it with the heater box in situ or did you remove and dismantle the heater box? If the later, then makes sense to fit a new matrix while you're there.
If you didn't dismantle you might had missed the bottom flap that shuts off cold air from outside, so even when coolant system is working right you'll still only get slighty warm air inside when vehicle is moving as the cool air feed over powers any heating benefit.
Hi,
Thanks for all the info, it is really really helpful. I’ve just driven about 3 miles in the car. The top radiator hose is very hot, bottom hose warm. Bottom hose does get hot, I remember when I was massaging them on Saturday evening. I repaired 3 heater box flaps while it was in the car, I did the one at the front that moves with the heater direction control and the two that are hinged together, further back inside the box. These moved together when moving the hot/cold control. I’m currently running a radiator flush and will back flush the heater matrix on Friday. Thanks to your info I’m not going to touch the thermostat as it appears to be working and the car does have power steering.
I’m a bit out of practice doing these kind of car jobs as I’ve not done anything for about 34 years, but I am loving the challenge,
Thanks again 👍
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Have you managed to get all the sticky cr4p off your hands from doing the flaps ? :D
Well done for fixing the flaps in situ you must have small hands or a "cunning" technique/fix.
There wasn't any sticky stuff in the heater box, just lots of small bits of foam.
Not sure about the small hands, but I have lots of cuts/scratches and today they really ache :( .
Must be getting old...
Like the car!
So I've back flushed the heater matrix for about an hour and flushed the whole coolant system.
I've run the car and made sure there are not air locks etc and the heater is slightly better, but still on the cool side.
The in and out hoses to the heater matrix get very hot and the bottom radiator hose gets hot at the appropriate time, so the thermostat is working OK.
Any ideas??
Cheers.
Does your heater pipes still have the bypass valve in?
https://www.vwgolfmk2.co.uk/clubforum/index.php?topic=20.0
Hi,
Thanks for your reply.
Is this the valve? It goes back into the engine, so I assume (quite possibly incorrectly) it’s a proper part of the coolant system.
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Also the out hose from the matrix has this copper pipe in it. I have paperwork to confirm a new matrix was fitted in about 2011/12, can’t remember the exact date without checking so it’s not 30 years old. I’m reluctant to dismantle all the heater if it could be something other than the matrix.
🚗
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The copper pipe is where the bypass parts would have been
The inlet manifold will also have a
Hi,
Thanks for your reply.
Is this the valve? It goes back into the engine, so I assume (quite possibly incorrectly) it’s a proper part of the coolant system.
Looks like this connects onto the inlet manifold, which is standard for a carb engine
Ok thanks.
Any ideas about getting more heat?
Get your car up to temperature and check both pipes to the matrix. Are they both hot hot? If so get the heater box out and replace your tape with foam.
If they are not hot or if there is a significant difference between them think about flushing or replacing the matrix.
Blockages before or after the matrix feed and return pipes is unlikely so I think the long term fix is box out, new matrix, foam the flaps.
Thanks for the info'
Looks like matrix out is the next step.
Cheers
Well, I’ve got around to changing the matrix and the heater is now tropical 🌴.
Bit of a fiddly job but inexpensive, as the matrix was only £30 and available from my local Eurocar Parts.
Thanks for all the advice and knowledge, you have all been invaluable.
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Excellent and without taking the dash out?
Removed the under dash shelves from both sides and the centre console. Then the 3 bolts under the bonnet and is sort of dropped out (with a bid of persuasion). I thought lining it up to put it back would be the hardest bit, but it all lined up great. I only intended to start removing some of the interior ready to do it at the weekend. It turned out to be much easier than I expected! Having had lots of advise beforehand was really helpful though. :)
Fair play to you, well done... we'll have you stripping the engine down soon!
I hate doing the heater matrix, doesn't help with wide shoulders, when I did one on an 86 KJet the bloody nuts on the bulkhead were rusted solid, took ages with a hacksaw cutting them off with lots of swearing!!!