Heating problems

[skinnyman9000 0]

I've got some issues with my heating. When you start the car the heating slowly warms up with the engine, as you would expect. But then after 5-10 mins the air gets colder as the engine gets warmer. As the water temperature increases the air temperature decreases, until eventually there is no difference between hot and cold settings on the heater controls.

 

What on earth is going on? Its a 1990 valver, incase that makes any difference.

[Toad 0]

Is your water level ok? Have you got the bypass valves (2 alloy blocks) in the heater lines? How is the cooling on the car?

[Valerian 0]

Did you ever find out what was causing it?

I'm having the same problem now and this is the second Corrado i've had this trouble with.

[Supercharged 2]

Deffo faulty bypass valves and maybe a leaking matrix

[Valerian 0]

Bit of an odd day with my C.

This morning when i drove to work my coolant level light was flashing.

I let the car cool at work then checked the coolant level and it was ok.

Restarted the car and no warning light :shrug:

 

Just drove 40 miles and all of a sudden the heater started blowing cold air.

Pulled over, checked under bonnet and found that coolant was being forced past the expansion tank lid.

Unscrewed the lid to release excess pressure and drove another 40+ miles stoppeing a couple of times to check no coolant was being forced past the lid but both times things looked normal.

Still only have luke warm air from the heater.

i've checked all over the car and there is no water leaking from anywhere.

 

Just letting the car cool down then i'll check the coolant level again.

[Rustynuts 0]

Sounds like a potentially sticky thermostat, can't remember now whether I put a new one in when I built that engine. Also if it has the bypass valves and the pressure has built up with the rising temp the valves shut off.

 

One thing to be careful of is that the header tank cap has it's little rubber seal located properly.

 

Did it ever overheat on the temp needle?

 

The only other thing I could think off is that the anti freeze is weak and some parts of your system have got frozen up causing a blockage. This usually causes the head gasket to blow or even the block to crack. Hopefully yours is a minor issue.

[Valerian 0]

Temperature guage stayed normal reading......Antifreeze was changed 6 months back and i mixed it 50:50.

I have known some of the cheaper quality thermostats to fall apart before.

If the bypass valve was to shut off, would it re-open by itself or does it mean having buy another one?

Both heater in and out pipes get hot as normal.

[Rustynuts 0]

Very strange, the pressure valves should reopen hence why people get the heat whilst the engine warms up syndrome. If I was you I would remove the bypass valves as they are a pain in the arse. I reckon that has what has caused your temporary overheating problem. If you look at the valves there is a small pipe connecting the 2. If that was to block it would cause a major pressure build up. I reckon your valves are part closing anyway so water is bypassing your heater. Get rid of them and you will be warm again.

[Valerian 0]

I had the problem of no heat from the heater on a white valver i had. Even taking the valve off made no difference. Tried everything in the book and forum.

Anyhew....will MAYBE have a gander tomorrow if i can stand the cold for long enough.

[Valerian 0]

Just had a look at the car and found that the valve inside the expansion tank cap had come adrift from it's clips.

When i took the lid off, the valve had come out of the lid and was wedged in the filler neck.

Anyhew....no coolant has been lost , however, i'm still getting no heat from the heater.

I suspect that the bypass valve may be shot because the right hand feed pipes before and after (the metal bodied portion of the) valve are hot.

The small bore pipe between the valves/large bore pipes is also hot.

The left hand heater pipe with the black plastic portion of the valve is hot before the valve but after the valve (between the valve and bulk head) is cold.

I assume that because the small bore bypass pipe is hot that water is being bypassed between the main large bore heater feed pipes.

The engine is not losing any coolant and is running at normal temperature.

The radiator fan cuts in when it's supposed to as well.

[Rustynuts 0]

Yes spot on, whip them valves out and you are warm again. If you don't want to renew you pipes use some copper heating tube to connect the broken pipes

[Valerian 0]

Starting to get some heat now but nothing like it used to be.

I managed to get hold of another bypass valve and also bought a new expansion tank, expansion tank top and top rad hose.

The top rad hose is getting rather soft so best replace it i suppose.

Hope to get this sorted at the weekend.

[bigray 0]

Iv got a similar problem on my g60, after finding nearly every coolant pipe to and from heater matrix had split, the neck of the heater matrix broke off after being a bit vigerous trying to remove rubber pipe. Dash out, replaced matrix, boxed it all back up, connected pipes to heater matrix, ran up as normal, nothing. Coolant was red hot before and between valves, but not after. The techs at work agreed with me that it must have an air lock, que hours of me running the car up trying to force air out. A week and a half without a heater in this weather is annoying. :censored:

 

Took car into work this morning, had the car red hot, fan cutting in etc, undid the jubilee clip that holde the return pipe onto heater matrix, pulled it off slightly so water was being forced out, after 5mins of this the water being forced out went from stone cold to red hot, slid pipe back on, did up. Thaught to myself, job done, hot water going into heater matrix, hot water coming out of matrix, surely theres gotta be heat. Alas nothing. :brickwall:

 

My only conclusion is that when iv had the dash out to change matrix, one of the heater controll cables has become jammed/trapped and is unable to open the vent to allow the heat from the matrix into the car? The car isnt over heating, the coolant temp is as it was before i started faffing with it, fan is cutting in ok.

 

Anyone have any other ideas?

 

Sorry to hijack your post by the way, but seemed pointless to start my own when theyre similar issues. :wave:

 

Cheers for any thaughts, ideas, remedies (iv allready thaught on the petrol and lighter idea) in advance,

 

Ray

[Valerian 0]

Ray.....Have you changed your heater bypass valve?

[bigray 0]

Do you mean the valves between the engine and matrix? Didnt see the point as the pipes after the valves were hot both feed and return.

 

Just stripped dash down to see if the heater cables were trapped, the direction cable has a clip missing meaning it wont stay on the screen setting but the hot/cold cable works fine. When you push it to cold, the air gets noticeably colder, slide to hot and it warms up a degree or two.

 

Lose the bypass valves? Thaught they were in there as the matrixs melt and spray boiling coolant at you thru the vents, haha?

[Valerian 0]

Might be worth you taking the bypass valve out just to see if it has any effect.

A Corrado i owned a few years back had the same heater problem as yours and i'm sad to say i couldn't seem to cure it either no matter what i did.

[bigray 0]

Hmmmm, think thats gunna be my last resort. Not keen on removing them as if i do put them back in its an absolute :censored: to get run up and rid of all the air locks.

 

Most of the techs at work said get rid of the valves, mate whos into his veedubs said clean them out or replace but dont remove entirely. I had them off this morning and made sure they werent blocked etc, after taking the best part of two hours to get hot water going into and out of the matrix i dont really wanna have to repeat the process.

 

Thatll have to wait for wed eve as il go and get new pipes from vw, had to do some serious bodging to the coolant pipes when the neck snapped off the matrix, cut pipes here, joined them there, just to make sure there were no kinks in the pipes etc. Moh, the saga continues.

[Valerian 0]

Well...sorted my heating problem yesterday.

The bypass valve was almost completely shut and only allowing a very small flow of coolant through.

I managed to get hold of another bypass valve of a non running 16 valve Golf which had the same part number.

Turns out i was right and the expansion tank cap valve had given up the ghost.

Engine runs much cooler and the heater is absolutely roasting on full heat.

[bigray 0]

Hmm, il give both a go i think, worth a shot. Currently driving around with my dash in pieces. Cant see it being the valves on mine as after goin to/from gym (15mile trip) both hoses are red hot which suggests to me that oolant is circulating thru the heater matrix. Il get a new cap and whip the valves out and see if that cures it, if not, someone at work mentioned sumthing called an "air lift" none of the mechanics had heard of it (good start) then i asked a "technical expert" (clever fucker) and he knew ot it was tec, meant to be used on cars with air in the intercooler or sumthing.

 

Cheers

[jimmyvwjunkie 0]

i have the same problemo. it sux

[Valerian 0]

Hmm, il give both a go i think, worth a shot. Currently driving around with my dash in pieces. Cant see it being the valves on mine as after goin to/from gym (15mile trip) both hoses are red hot which suggests to me that oolant is circulating thru the heater matrix. Il get a new cap and whip the valves out and see if that cures it, if not, someone at work mentioned sumthing called an "air lift" none of the mechanics had heard of it (good start) then i asked a "technical expert" (clever ****) and he knew ot it was tec, meant to be used on cars with air in the intercooler or sumthing.

 

Cheers

 

An airlift is basically a tool that can be used on the cooling system to check for leaks and to erradicate air locks.

Not many garages/mechanics in the UK seem to use this tool or even know it exists.

 

[bigray 0]

Is it just me or does that look and sound like a compression tester? :?

 

Gunna try and get rid of valves first and see if that cures it, if not im gunna do a basil fawlty on it, with a pick axe

 

:salute:

[Valerian 0]

Is it just me or does that look and sound like a compression tester? :?

:salute:

 

From what i can gather you connect it to a compressed air line and use to either push or suck the air out of the cooling system.

It can also be used to pressure test the cooling system.

 

Are there any mechanics here that can verify how this tool is used?

[bigray 0]

Got one off the snap on man today, woo hoo, Empty the system, push valve bit into expansion tank, connect air line to airline bit, put other pipe into coolant ur replacing, press switch, the air is pumped out of system till its at certain no. vacum, make sure it has no leaks by leaving for 20 secs, slowly turn the valve on coolant pipe, the coolant is drawn into the system and theoretically there is no air and the oolant should fill to the cold level mark............ Well everything else has gone wrong with the job so far, i can only laugh.

 

If that doesnt work im gunna get new pipes and get rid of valves as the matrix shud b man enough to take it if its new?

 

:salute:

[Valerian 0]

Let me know how this goes....i was rather wondering at what pressure these VW heater matrix bypass valves actually close, or start to close, at.

Thing i'm getting at is....When pressurising the system with this airlift tool, could there be a risk of the bypass valve closing due to the excess pressure

from using the airlift. :shrug:

 

Have you actually taken your bypass valve off to see if it is closed.

You can tell just by looking down the barrel of the valve if it is closed.

The other method i used to test it was to hold the valve under a running tap to test the water flow.

I'll take a photo of my valve tomorrow but i'm not sure that the camera will be able to see down the mouth of the barrel as well as the eye can.