Heater!

1252 Views 23 Replies 8 Participants Last post by deepfat, 2 mo ago

davidwheeler

Discussion Starter · 3 mo ago

Since the first time I took out the engine the heater has not worked despite bleeding freely. After the second time, the same problem, both heater and radiator bleeding easily.
Today I got stuck in a traffic jam and found hot air coming out of the vents despite the engine temperature remaining perfect. As soon as I got going again the air from the vent went cold again. Even when the fan was turned to low.
???

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deepfat

· #2 · 3 mo ago

I will presume you have bled the one in the engine compartment? did the bulkhead bleed have a good flow as these tend to block up with crud, lastly did you have the heater on hot when bleeding.
On the hot/cold vent as a complete and utter guess maybe at tick over (in traffic) the air lock is in a position to allow the heater to work but increased revs/flow moves it to block the flow. This could be tested by repeating what happened if you can't find a jam just let it tick over. If it does happen again it points to an air lock, unless!!!! something I just thought of there is a restrictor in the 4 way connector maybe this was disturbed/lost in the engine work. I know very little about this but I think it affects the heater, I have attached a thread and others are available.
MGF & MG TF Owners Forum - Plastic part in coolant rail - (the-t-bar.com)

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davidwheeler

Discussion Starter · #3 · 3 mo ago

Yes, both bled freely. I cannot find a 4 way connector and am not aware of any foreign bodies but it is certainly a thought and would possibly explain the intermittency. I will try bleeding hot and with the engine running. I am not that bothered with spring coming on, just curious.

D4KGP

· #4 · 3 mo ago

davidwheeler said:
Yes, both bled freely. I cannot find a 4 way connector and am not aware of any foreign bodies but it is certainly a thought and would possibly explain the intermittency. I will try bleeding hot and with the engine running. I am not that bothered with spring coming on, just curious.

I was under the impression that the engine needs to be running to do the bleed otherwise the water pump is not circulating the coolant and any air that is present, so the bleeds that you have done were pointless. Regards D4KGP.

IanMc

· #5 · 3 mo ago

D4KGP said:
I was under the impression that the engine needs to be running to do the bleed otherwise the water pump is not circulating the coolant and any air that is present, so the bleeds that you have done were pointless. Regards D4KGP.

That is correct.

Chris T

· #6 · 3 mo ago

I can’t help thinking that both this and the poor running question are linked.

Man in the Car

· #7 · 3 mo ago

davidwheeler said:
...... both heater and radiator bleeding easily.

deepfat said:
I will presume you have bled the one in the engine compartment?

davidwheeler said:
Yes, both bled freely.

As you originally only referred to bleeding the at the radiator and heater bleed points, and deepfat then asked about the bulkhead bleed point and you replied by referring again to "both", I am prompted to ask for clarification that you have indeed bled from all three bleed points?

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deepfat

· #8 · 3 mo ago

Thanks #7 I presumed when he said heater bleed he was referring to the front bulkhead bleed, rad is obvious but he did not mention the engine compartment perhaps we will get confirmation of what bleeds?
I've only had mine 21 months and last year was dreading doing this after a cam/WP change having read tales of woe on here and elsewhere.
I put the heater on hot and did an initial fill and bleed with the engine off, started it up and went round at intervals checking all 3 bleeds and topping up. Once warm I revved it now and again, hopefully to move any stubborn air locks, still checking all 3 bleeds. Once fully up to temp one final check and that was it, perhaps I was lucky but it wont worry me in the future (fingers crossed)

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davidwheeler

Discussion Starter · #9 · 3 mo ago

I have bled all three but not while the engine is running so I shall try that and report back!

D4KGP

· #10 · 3 mo ago

davidwheeler said:
I have bled all three but not while the engine is running so I shall try that and report back!

Hi yes that's what I would do. I have just replaced the heater's water valve on my F and naturally bled the system, but on further inspection noticed a pipe that may split in a short while. So now I have to drain down replace the pipe and bleed again. Make sure you have the heater set to hot when you do the bleed. Good luck regards. D4KGP.

davidwheeler

Discussion Starter · #11 · 2 mo ago

Bled all 3 with engine running set to hot- no air came out. Now the heater works but only when running slowly or on tickover - but it did that before the last bleed too.. At speed, no joy. Weird. I cannot see that there are still airlocks!
At least Sumer is icumin in.

deepfat

· #12 · 2 mo ago

David I'm getting confused you say "no air came out" if you had the blower on you should have air hot or otherwise! Does the car warm up to normal and then stay there as would normally happen? if it does I think I would concentrate on the heater blower combo. Does air (hot or cold) blow out of the vents according to what is selected ie screen, face vents, footwell, does the air volume out of the respective vents increase with blower speed? If this checks out then you need to check the bowden cable from the temp control is connected to and moving the heater matrix valve. If the valve/cable system works then when the temp control is on hot the pipes either side of the valve should be hot if they are not then I suspect the valve is blocked or NFG.
I confess to only seeing this valve once (in passing) so I'm unsure how much space is available to check the pipes out so hopefully D4KGP who has recently changed this valve (well done) will chime in.

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EllisoJo

· #13 · 2 mo ago

David, you mentioned "

davidwheeler said:
Now the heater works but only when running slowly or on tickover - but it did that before the last bleed too.. At speed, no joy.

Logically, this means that there MUST be water flowing through the heater matrix at low engine speeds, but this stops when engine revs rise above some critical point. It sounds to me as if EITHER something (Perhaps a lump of crud in the heater pipework??) is moving when flow-rate and/or pressure rises, OR too much flow is going to the main, radiator circuit when the engine is fully hot. I believe that if you have a PRT thermostat, an orifice (PEL000040A) should be fitted where the normal thermostat used to be.
On other posts way back in 2015, you mentioned that your car was a "2003 TF135". Is this still he case? I believe that around September 2003 was when PRT thermostats were fitted. Rimmers says "from VIN 4D". They also say that the PRT System can be retro fitted, but "hose runs differ significantly" and you are "required to correctly carry out the necessary modifications to the engine bay pipework - unfortunately not a job for the average DIYer"

My other thought is: can a faulty or incorrectly plumbed PRT cause these symptoms, or a reverse plumbed heater system?. I note that back in 2014, you removed and re-built the engine. I would have thought that if incorrect plumbing (at engine re-installation time) is at fault, you would have found the problem well before now, but perhaps summer driving a very little use of the heater MIGHT have concealed the problem?
If you are confident that the pipework is all correct, then crud in the system might be the problem. I will agree that draining the system again, knowing that you will have to start the whole re-fill and bleed sequence all over again, but I think that in your shoes I would be doing a system drain, then connect a garden hose to each of the heater feed & return pipes, and check that a substantial flow in BOTH directions is possible. Running the outflow into a large container where you can look for lumps of dislodged crud might be informative & reassuring.

Good luck with the investigation. If you find what was causing this weird problem, let us know the cause and the remedy!

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D4KGP

· #14 · 2 mo ago

deepfat said:
David I'm getting confused you say "no air came out" if you had the blower on you should have air hot or otherwise! Does the car warm up to normal and then stay there as would normally happen? if it does I think I would concentrate on the heater blower combo. Does air (hot or cold) blow out of the vents according to what is selected ie screen, face vents, footwell, does the air volume out of the respective vents increase with blower speed? If this checks out then you need to check the bowden cable from the temp control is connected to and moving the heater matrix valve. If the valve/cable system works then when the temp control is on hot the pipes either side of the valve should be hot if they are not then I suspect the valve is blocked or NFG.
I confess to only seeing this valve once (in passing) so I'm unsure how much space is available to check the pipes out so hopefully D4KGP who has recently changed this valve (well done) will chime in.

By what I read in his last post was that he had bled the system with the heater set at hot but no air came out as a result of the bleeding. Not that there wasn't air blowing from the heater when that was turned on. With regard to touching the 3 heater pipes, this could be done if the side panel is removed. I'm beginning to think that his heater valve is not working or only partially open restricting the flow. It's a weird one and I would be inclined to do as Ellisojo has suggested and drain it down again and give it a good flush.

D4KGP

· #15 · 2 mo ago

davidwheeler said:
Bled all 3 with engine running set to hot- no air came out. Now the heater works but only when running slowly or on tickover - but it did that before the last bleed too.. At speed, no joy. Weird. I cannot see that there are still airlocks!
At least Sumer is icumin in.

This is really weird as you say, when you bled the under bonnet point did any air or water come out, if it was water was it scalding hot? Because it should be, get a piece of wire and push it into the bleed point and screw it about a few times this sometimes dislodges crud that might be in the matrix. Is your heater valve working? Remove the driver side panel and check that the cable is connected and that the valve is working, whilst you are in there check that the pipes attached to the valve are hot (2 attached to the valve,1 bypass attached to the matrix) good luck with it all and keep us posted. Regards. D4KGP. ( P.S. if none of this helps the situation do as Ellisojo suggests)

deepfat

· #16 · 2 mo ago

I think Ellisojo with his Sherlock Holmes investigation into previous posts may have hit the nail on the head, from what I've read the restrictor should be fitted in place of the OE thermostat but the PRT also apparently has an unfixed restrictor in it which can be dislodged or lost when work is undertaken in this area. The comment on engine speed affecting the heater baffled me but Ellisojo has jogged my memory and I'm sure I've seen previous posts on these restrictors causing similar problems. The OP needs to check if his car has a PRT, either original or later mod and if so have a look in these areas to check both the restrictors are present.
My car doesn't have a PRT and my initial "new owner enthusiasm" for this upgrade? is seriously waning.

trevtherevs

· #17 · 2 mo ago

deepfat said:
I think Ellisojo with his Sherlock Holmes investigation into previous posts may have hit the nail on the head, from what I've read the restrictor should be fitted in place of the OE thermostat but the PRT also apparently has an unfixed restrictor in it which can be dislodged or lost when work is undertaken in this area. The comment on engine speed affecting the heater baffled me but Ellisojo has jogged my memory and I'm sure I've seen previous posts on these restrictors causing similar problems. The OP needs to check if his car has a PRT, either original or later mod and if so have a look in these areas to check both the restrictors are present.
My car doesn't have a PRT and my initial "new owner enthusiasm" for this upgrade? is seriously waning.

Deepfat:Just a side note, with your newly acquired compressor you can get a vacuum bleed kit and take so much worry from the refilling process, Of all the toys I've bought for mine this one thing gives unrestricted joy each time I use it.(sorry to hi Jack the op post)

D4KGP

· #18 · 2 mo ago

deepfat said:
I think Ellisojo with his Sherlock Holmes investigation into previous posts may have hit the nail on the head, from what I've read the restrictor should be fitted in place of the OE thermostat but the PRT also apparently has an unfixed restrictor in it which can be dislodged or lost when work is undertaken in this area. The comment on engine speed affecting the heater baffled me but Ellisojo has jogged my memory and I'm sure I've seen previous posts on these restrictors causing similar problems. The OP needs to check if his car has a PRT, either original or later mod and if so have a look in these areas to check both the restrictors are present.
My car doesn't have a PRT and my initial "new owner enthusiasm" for this upgrade? is seriously waning.

Well I've read that PRT's are not necessarily a cure or a aid in reducing the risk of HG failing, if that's the reason you were thinking of fitting one. I know that I wouldn't, but each to their own. Regards D4KGP.

davidwheeler

Discussion Starter · #19 · 2 mo ago

I meant that no air came out of the bleed nipple - nor water. But previously with the radiator cap off water came out tso the nipple is patent. I should try again with the system hot and pressurised.
I fitted a new PRThermostat a few years ago so I guess I have the later type. I have just looked on the spares and see there was a thermostst fitted ?in the head? I cannot really see from the pictures where it is. It had a PRT fitted when I bought it. I do not know about any restrictors that may be fitted - where should I look for them?

D4KGP

· #20 · 2 mo ago

davidwheeler said:
I meant that no air came out of the bleed nipple - nor water. But previously with the radiator cap off water came out tso the nipple is patent. I should try again with the system hot and pressurised.
I fitted a new PRThermostat a few years ago so I guess I have the later type. I have just looked on the spares and see there was a thermostst fitted ?in the head? I cannot really see from the pictures where it is. It had a PRT fitted when I bought it. I do not know about any restrictors that may be fitted - where should I look for them?

Have a look at #15 when I replied to this problem you are experiencing. Remove the under bonnet nipple and push wire into the hole and screw it about, also clean the nipple to make sure it's not blocked. There isn't a thermostat in the head.

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