Heater problems

[turnerjr]

Good evening all, I have a strange heater issue that I’m hoping someone can shed some light on.

I apologise for the length of this but I think its important I list every detail as Ive been very methodical with this and still failed miserably! lol.

 

Its a 1995 uk spec which Ive owned for about 15 years. Its been maintained regardless of cost, and has had regular coolant changes. Cam belt service is up to date and I always ask for the water pump to be changed at the same time. Ive only ever used toyota red long life coolant in it.

 

I noticed a few months ago that the heaters were not getting hot, unless I went for a really hard drive, and when I backed off and took it steady, they went back to being cold. The heaters always used to get red hot.

 

I checked the bottom rad hose which was cold, top hose was hot, one of the heater matrix hoses was hot, the other cold. There was no loss of coolant and no overheating, temp gauge was always at half way. I did some research with the search function and decided to follow a members guide of flushing the heater matrix. I couldnt remember when the thermostat was last changed so I ordered a new one.

 

I striped the car down and drained the coolant. I disconnected the pipework for the matrix by the rear of the cam cover and connected up two pieces of garden hose to the matrix. I put the heaters on hot with the ignition on, and flushed it backwards and forwards several times with a hosepipe. The water was pretty clean both ways, and I had a good flow of water in both directions, similar to the flow the hosepipe produces.

 

I removed the thermostat, but fitted the housing and bottom hose back on, (not connected to the rad) and flushed water through both flexi hoses at the back of the engine that I had disconnected from the matrix. The water that came out the bottom hose was also pretty clean. I took the top hose off and flushed this through aswell, and the radiator. Again, these were pretty clean.

 

I connected everything back up, filled with water, and put some wynns coolant flush in, then jacked the car up as high as I could, started it up, let it run for 10 minutes with the heaters on hot, gave all the pipes a good squeeze, and put the rad cap on. I left the car idling for about 30 minutes, I couldnt drive it as its not taxed and I had the front end stripped to replace the bonnet catches.

The heaters werent red hot, but were an improvement and I hadnt fitted a thermostat so thought this might have had something to do with it. I turned the car off and drained the system down again, (which was pretty clean) and flushed everything through with the hose to get all the rad flush out.

 

I dropped the car to the floor and parked it facing downhill to make sure everything had drained out.

While the coolant was draining I decided to check the thermostat with some boiling water. The old thermostat looked like it had some rubber or something stuck in it, and when I added it to boiling water, it only opened about 1mm. I tried the new one, and it opened much more. Excellent, I was hopeful a dodgy thermostat was the cause of my heater problems!!!!

 

I connected everything back up, fitted the new thermostat and gasket, and filled with fresh coolant. I started the car, jacked it up and ran for 10 minutes with the heaters on hot. I topped the overflow tank up, gave all the pipes a good squeeze, then put the rad cap back on. The heaters were still cold, but the temp gauge was on half way which it normally is, so I dropped the car down, shut the bonnet and took it for a quick spin.

 

The heaters are an improvement but dont feel like they’d melt your face like they used to.

The heater matrix hose closest to the bulkhead is red hot, the other is quite hot. Top rad hose is red hot, bottom one is quite warm.

Ive checked the arm in the passenger footwell and disconnected it so I can move it manually. I can feel a difference in the temperature when this is moved forwards or backwards, so I guess whatever the rod is connected to is working.

Does anyone have any ideas what the problem could be please, before I loose my marbles?

[Scooter]

Geez as I read through I was thinking oh it could be 'x' and then you tried what I was thinking every time!

 

The key I think is the reason the matrix pipe out isn't as hot, I'm not sure what drop is normal (there must be some) but I suspect both in and out pipes would feel pretty hot (unnoticeable difference ie too hot to hold for anytime? Perhaps someone could check their car with the heater on full heat).

 

All I might suggest is does the heat vary if diverted to the screen or feet etc? Perhaps the plastic ducting has come away at a joint so air is escaping? But I spose this would have to be between the matrix and the fan, ie the fan isn't just pulling in air through the matrix but from the cabin air behind the dash? I have replaced an air con expansion valve in my time but I can remember the exact layout behind that.

 

As you had good matrix flow perhaps you have an airlock in it now? If you didn't before perhaps disconnect the two pipes and fill that separately with coolant?

Edited April 16, 2020 by Scooter (see edit history)

[Scooter]

The statement re the temps going up with revs effectively fitted with my old car that had partially blocked matrix.

 

If it's still like that, it has to be a flow rate issue through the matrix? the system allows diversion of coolant so if the matrix is blocked completely the engine still gets the coolant it needs but as designed the matrix should see the required flow.

 

Also if you started a couple of months ago perhaps the heater is the same but didn't feel like it given the rise in ambient temps? A possible 'reach' just throwing out ideas....

[SupraLEDrears]

Disconnect all heater matrix hoses near the head where the pice of metal is then run a hosepipe through the heater matrix both ways for 5 mins. You can add some fairy liquid before you start, the foam lifts out some bits too. I do this twice a year when mine starts blowing cold. You'll need a jubilee clip to keep the hosepipe in. Don't open it full force, just gradually build up the flow until it's fully flowing.

[turnerjr]

Hi scooter, thanks for the input. You have thrown some good ideas in there. I will check the air diversion in the morning. I still feel like the matrix is blocked somehow. I never thought of the idea that coolant could still flow even if the matrix was blocked. It just seems odd to me that the heater has always worked fine, and the system has been ran on the proper coolant for so long, why has it suddenly become blocked now when the rest of the system looks so clean. If there was an air lock, would I get hotter air at higher revs and cooler air at low revs?

 

Thanks for the reply harry. I have tried the seperate matrix flush and have good flow in both directions. I will give your method of using washing up liquid a try though and see if that shifts anything

[Scooter]

The matrix water ways are very fine and it can collect debris.

 

It's a balance of trying to clear it but definitely not perforate it! Hence washing up liquid, the milder holts stuff.

 

If you rig up some garden hose with funnels you can test the through flow just under gravity rather than hose pressure which might highlight a lack of free flow.

[Scooter]

http://www.mkivsupra.net/vbb/showthread.php?338647-heater-matrix-flushing-feedback&highlight=Matrix

[Swampy442]

Are the flaps that control the air moving OK?

[turnerjr]

hanks scooter. I checked out your thread on cleaning the matrix originally which gave me the inspiration to have a go at flushing mine. As I seemed to have good flow through the matrix I didnt bother flushing it like you did, but just did the whole system as I was sure the thermostat was the main issue. I will now follow your guidance with the holts stuff (think wynns is the same as its non acidic) and gravity and refill the matrix first and see what effect that has.

 

Yes swampy, the heater control flap seems to work as I can feel a difference between the hot and cold setting when it is turned. The directional flaps also work so I can divert air to the demister, feet etc

[turnerjr]

After failing miserably to flush my matrix, I decided to use scooters method to do it properly.

I disconnected both pipes at the back of the head and flushed the system through with cold water to remove any coolant. I then connected a piece of clear pipe to each matrix outlet. I put a funnel on the out hose (which was only warmish with the engine running) and poured cold water into it to see if gravity would work instead of forcing water through. Water came out the other hose and into a bucket so I decided it couldnt be that blocked.

I then poured some hot water into the outlet (not far off boiling so probably about 70degree centigrade) to make sure my set up and hose would take the heat before adding the holts speedflush. It worked fine with no leaks.

I added half a bottle of speedflush to a 2 litre bottle of very hot water, and with the ignition on and heaters on max heat, I poured the solution in until it was gone. Water by this point was trickling into the bucket.

I left this for 10 minutes then turned the ignition off so I wouldnt kill my battery.

I then left this for an hour with the solution in the matrix.

I then connected the hose pipe up to the outlet and flushed the system. I left the hosepipe running for about 10 minutes with the ignition on. some crude came out, almost looked like bits of sand, there was probably only about a table spoons full in the bottom of the bucket. I was expecting more to be honest.

I decided to do the same again, but in reverse, so boiled the kettle and added the remaining half a bottle of speedflush to the boiling water and poured into the inlet for the matrix instead of the outlet which I did originally.

Again I left this for 10 minutes with the heater on, then left it to sit for an hour with the heater off.

Instead of flushing through with cold water, I decided to run a kettle full of boiling water down the outlet pipe in the hope that I could push any crude back out in the opposite direction. I did this with 2 full kettles of pure boiled water.

I probably got about the same amount of crud out again.

I then flushed the matrix for 10 minutes in both directions with the hose pipe connected.

I then ran coolant into the outlet pipe until coolant ran out of the inlet pipe to force out any trapped air. I disconnected the clear hose and connected the normal pipes back up, topped up with coolant at the radiator and jacked it in the air. After idling for 10 minutes both the inlet and outlet pipes were very hot and the heaters were very hot! success!!!

I took it for a spin and the heaters were ridiculously hot, like they used to be. I was very happy!

One final test, put the aircon on and turn the temp down. This also worked fine.

When I turned it back up however, the heaters only made it to luke warm at best. I was very unimpressed!!!

I got back home, checked the outlet pipe, which was warm again. I turned the heaters off all together and then put my hand on the outlet pipe. I could feel the temperature rise to the point I couldnt touch it anymore.

I turned the heaters back on, which produced warm air, and the outlet pipe returned to being warm.

With the engine off I can hear the mechanism working when you adjust the temperature. I disconnected the rod again and you can move it backwards and forwards freely.

I really dont know what to do now!!!

[Mr2kyle]

Did anyone get to the bottom of this as I’m also having issues with my own heating, fuses checked, matrix replaced with a new Toyota one, coolant system bled and metal rod for actuator checked and working correctly. Could it possibly be the shape of the pipes going into the matrix have too many bends on them as the more bends the harder it is for coolant to flow easily down it? Total long shot but I’m pulling at straws now really...

[m12aak]

5 hours ago, Mr2kyle said:

Did anyone get to the bottom of this as I’m also having issues with my own heating, fuses checked, matrix replaced with a new Toyota one, coolant system bled and metal rod for actuator checked and working correctly. Could it possibly be the shape of the pipes going into the matrix have too many bends on them as the more bends the harder it is for coolant to flow easily down it? Total long shot but I’m pulling at straws now really...

Sounds like you're having a nightmare with yours 

The shape of the pipes shouldn't be an issue as the coolant system is pressurised at 1.1/1.3 bar so there should be plenty of flow. If both pipes leading to your new matrix are piping hot, I would have thought that it have to be something wrong with the HVAC system. I did notice that I had to go for a hard drive to get mine to bleed out fully (I flushed mine using Scooter's guide and it fixed it for a while, it's blocked again), so maybe take it to redline a few times and see? Hopefully it's now something quick and easy for you to sort. 

I'm contemplating just replacing my matrix, but I'm going to give a flush one more go as it's a lot quicker and cheaper to do.

[Scooter]

Did you attempt to fill the matrix before attaching the pipework or did you attached all pipework dry and then fill the rad and expansion tank etc?

It could be a bleeding/air lock issue. In this weather you could probably get close to boiling water disconnect the in and out matrix pipes by the cam covers poor it in and there ignition and blowers on and check you get some warmth, if you do then you know it's a (lack of) flow issue? 

 

[mwilkinson]

Alas Toyota no longer supply a heater matrix and the only aftermarket one is quite frankly rubbish.

Chris Wilson was looking into the possibility of having a high quality one made but this never got any traction.  I think he was concerned the cost would be prohibitive to getting enough orders to make this viable.

[turnerjr]

Unfortunately I never got to the bottom of this, its still very temperamental. I found the harder I drove my car, the hotter the heaters would get, but this now doesnt always seems to work. The generally just blow cold air, warm at best. I’m pretty convinced its the water valve that is faulty. I’m guessing it’s some sort of gate that closes when the temp is turned down to stop hot water flowing through the matrix and opens when you increase the temperature to allow the hot water to flow into the matrix.

I was going to contact chris wilson about the possibility of getting new matrix’s made, but as toyota have discontinued the water valve and you need to strip the dash out to change both items, I decided I couldn’t be bothered.

Ideally I’d need to get hold of a second hand water valve so I can look at its operation and see if my theory is a possibility, and if so could a faulty unit be successfully repaired.

Unfortunately they are hard to come by and the only one I could find was some joker on ebay asking £1000+postage for the complete heater assembly!

[Scooter]

I fitted a bleed screw into the pipe work by the bulkhead, the in or out pipe just so I could be sure it wasn't air locked. It should all self bleed and I'm not sure this really helped much but it was a reassurance at the time as unscrewing it and having coolant come out, just like home radiator bleeding, helped me eliminate that.

I still think sometimes it can be more debris. The internal pathways are tiny, if the matrix ever got partially blocked then it will have been from rust. The system will be contaminated and so there is a chance of reblocking. If you feel it was better initially and got worse again then it could be this. 

Years ago I replaced the top and bottom rad hoses on one of my cars and the old hose was lined in rust residue. With the iron block etc poor coolant changes or even running on just water for a time and you could get excess particles. The block drain under the turbos is hard to access and often neglected, so even a coolant flush and renew when you change a matrix might still mean another batch of crud is there to recirculate back to start the blocking off again? 

Got to be worth a flow test/reverse flush on those bulk head pipe, if you attach a funnel and hose pipe to extend these then you flush into a clean bucket and 'pan for particles'. If you get lots of crud out, then go all out on a complete coolant flush ie undo that block drain, remove both rad pipes (inspect inner bores) flush the rad and block thoroughly clean the expansion tank etc. If you get good flow then I'd be tempted to carefully flow near boiling kettle water through it while inside you have the blower on. If you get better heat than normal then you know the inner workings of the dash and controls are ok and it's a water flow/matrix heat exchange issue?