318IS overheating .........
Moderator: martauto
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mark_biddle
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I have seen a few posts about overheating and heater matrix, but not sure it applies to M42 engine. Basically I have changed rad, waterpump seems OK, the watervalve in the heatermatrix was shot, so new one of those (Ԛ£105 !) but still same. The two hoses that go through the bulkhead seem OK, but only the bottom one is getting warm, which kind of suggests the heater watervalve is not opening, but I can hear it clicking, and as I say it is brand new ! Getting the right hump now ......... I have seen things about rad cap needs to be yellow and bleeding the cooling system, neither of these I know much about. Any help would be great ! Thanks in advance.
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Martinaston
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The heater matrix will not warm up if it's full of crud.
You said you flushed the rad but did you do the matrix ?
From within the engine bay take the two hoses off it and attach a hose pipe.
If it's not bunged up it may be just an air lock and the only way to move it is to rev the nuts out of the engine.
Put the car facing uphill if you can every little helps.
You said you flushed the rad but did you do the matrix ?
From within the engine bay take the two hoses off it and attach a hose pipe.
If it's not bunged up it may be just an air lock and the only way to move it is to rev the nuts out of the engine.
Put the car facing uphill if you can every little helps.
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Martinaston
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When you say the waterpump seems ok does that mean you took it out and had a look ?
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mark_biddle
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I have not flushed the heater matrix. The water is really clean, so assumed that all was fine on that front and the rad was clear as well..... maybe I assumed too much ! The water pump seems fine as when the engine is running and the rad cap is off you can see water being pumped into the rad. I might try and get the matrix out and have a flush of that.
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Martinaston
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It's a big job to get the matrix out, you have to take the dashboard and the heater box out.
It took me about 7 hours to change mine.
It took me about 7 hours to change mine.
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mark_biddle
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Yes, put new genuine BMW thermostat in at a cost of Ԛ£25 !!!!!
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Martinaston
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The yellow disc on the radiator cap (140 on the underside) was a cheap fix by BMW to release pressure at a lower setting to stop the matrix valve splitting (newer plastic ones) and burning the driver or passengers legs, Ending in expensive court cases that they could not win when the car was checked.
Unfortunatly the yellow cap is just a fail safe but does nothing to help find the original overheating problem.
As a few people have mentioned on other threads, just put a piece of pipe in to bypass the matrix and try running the engine to see if it still overheats.
If it bleeds and runs ok then its time to pull the dash and heater box out.
If you get a new matrix get the one with the metal pipes and leave yourself lots of time to do it.
Unfortunatly the yellow cap is just a fail safe but does nothing to help find the original overheating problem.
As a few people have mentioned on other threads, just put a piece of pipe in to bypass the matrix and try running the engine to see if it still overheats.
If it bleeds and runs ok then its time to pull the dash and heater box out.
If you get a new matrix get the one with the metal pipes and leave yourself lots of time to do it.
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mark_biddle
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Well it is getting desperate now ..... I have bypassed the heater, but it still overheats. I will be changing the waterpump, as that is only part left that I have not changed. Stupid question, but how do I bleed the system ?
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elliot
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theres a bleed screw on top of the thermostat housing, run your engine at about 1200 rpm and undo it every couple of mins. you want to put your heaters on full and on hot aswel. this should all take about 15 mins
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Geeman
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Elliot... the bleed screw ain't on the thermostat housing on an M42 dude... it's on top of the radiator housing...
My heater matrix is now leaking into my footwell. Just bloody re-filled the coolant with new anti-freeze too... so it's all nice and pink - lucky I've got no carpets in then!
Is there a 'how-to' guide for changing heater matrix's...?
Giles.
My heater matrix is now leaking into my footwell. Just bloody re-filled the coolant with new anti-freeze too... so it's all nice and pink - lucky I've got no carpets in then!
Is there a 'how-to' guide for changing heater matrix's...?
Giles.
Last edited by Geeman on Tue Jul 05, 2005 12:32 pm, edited 1 time in total.
sorry dude, your right.-
mark_biddle
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Ahhh, that makes sense, the little blue jobbie at the top. I will have a go tonight. Many thanks.
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E30Mark
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The early water pumps had plastic impellers mounted on a steel shaft, these have known to fall off....
See if you can get a new water pump with metal impellers, my local dealer didn't have a clue what i was on about when i asked for a metal bladed pump.... in the end i used one with a plastic blade, no probs with it at all....
Where abouts are you? maybe someone here could take a look at it for you...
See if you can get a new water pump with metal impellers, my local dealer didn't have a clue what i was on about when i asked for a metal bladed pump.... in the end i used one with a plastic blade, no probs with it at all....
Where abouts are you? maybe someone here could take a look at it for you...
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martinclan
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Just seen this thread.
Sorry to be a bringer of bad news but the heater matrix can have little or nothing to do with the overheating as the water doesn't even pass through it when the heater is off.
When does it overheat - is it when you thrash the nuts off it or all the time - winter or summer? Have you checked the viscous fan coupling? If this is stuffed it will cause overheating when idling in traffic or driving hard.
Could also be the radiator - just because you have flushed it doesn't mean that it isn't partially blocked somewhere.
Cheers
Robin
Sorry to be a bringer of bad news but the heater matrix can have little or nothing to do with the overheating as the water doesn't even pass through it when the heater is off.
When does it overheat - is it when you thrash the nuts off it or all the time - winter or summer? Have you checked the viscous fan coupling? If this is stuffed it will cause overheating when idling in traffic or driving hard.
Could also be the radiator - just because you have flushed it doesn't mean that it isn't partially blocked somewhere.
Cheers
Robin
It's an E30 Jim but not as we know it...
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pacerpete
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More M42 wrongness !!! thankfully the only liquid my 325 uses is petrol!. As rightly pointed out a blocked (i've never seen 1) heater matrix will NOT cause a car to overheat,it will just give you a crap heater.
To change a matrix on an e30 , while not the nicest job in the world isn't too sad you only need to take the console out. There are two types and don't waste your time fitting a used one because it will start leaking in a months time !.
To change a matrix on an e30 , while not the nicest job in the world isn't too sad you only need to take the console out. There are two types and don't waste your time fitting a used one because it will start leaking in a months time !.
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Martinaston
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My god
I've just re-read this thread and after all that (and all your money Mark)
your saying you didn't even know where the bleed screw was.
I think that might have been the problem all along.
Do you own a haynes book ?
I've just re-read this thread and after all that (and all your money Mark)
your saying you didn't even know where the bleed screw was.
I think that might have been the problem all along.
Do you own a haynes book ?
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mark_biddle
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I am at my wits end with this thing now. Bought a new alloy rad, tried that, still overheating, now I have a new water pump. When tring to get old one off, the fillister bolt was rounded off and somebody had been at it with the mole grips ............ I got the dremmel out and have ground the head off and got the rest off the stud out. All four bolts are now out, but do you think the pump will come off .......... Any bright ideas on how to get it off ? I can see the two threaded bits in the water pump and they are same size as the nuts that hold the pump on, I have tried putting these two bolts in and tightening to see if they will lever it off, but it has all got a bit tight, and I dont want to strip the threads. I am racing this car in 2 weeks, so really need to get it sorted ! Any ideas welcome now.
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mark_biddle
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Well after much blood,sweat and tears (not to mention WD40 !) I have managed to get the water pump off. It did not seem too bad, but after replacing it and bleeding as mentioned all seems OK now at long last. Many thanks for peoples help, but I get all I deserve for buying a car with 130k and no service history !