help please - overheating 3000m
Discussion
hi there
any advice or help appreciated. overheating probs with my m.- at present running without a thermostat(not too keen on this) this runs at about 90 degrees on gauge but still creeps up in traffic. it has the 2 fan mod on radiator but does not seem to come on till the temp on the gauge is over 125 deg. and only stays on for a short while and not constant enough to bring temp. down and if car is left to run at standstill will go up all the way to 140 deg.not good. any advice - could it be faulty otter switch? or faulty sender unit? - what replacement would be best?
- are 74 deg. thermostats available? poss. bypass otter switch for manual control? anything i am missing?
any info appreciated - newish owner - learning all the time!!!!
cheers all
ian
any advice or help appreciated. overheating probs with my m.- at present running without a thermostat(not too keen on this) this runs at about 90 degrees on gauge but still creeps up in traffic. it has the 2 fan mod on radiator but does not seem to come on till the temp on the gauge is over 125 deg. and only stays on for a short while and not constant enough to bring temp. down and if car is left to run at standstill will go up all the way to 140 deg.not good. any advice - could it be faulty otter switch? or faulty sender unit? - what replacement would be best?
- are 74 deg. thermostats available? poss. bypass otter switch for manual control? anything i am missing?
any info appreciated - newish owner - learning all the time!!!!
cheers all
ian
Hi Ian,
74deg thermostats are available but I'd be surprised if you needed one of those. I used to have all sorts of overheating scares with my 1600 (Ok, it's a smaller engine but it's reasonably tweaked) but they've completely disappeared since I had the system flushed and the radiator recored. I run a standard radiator and fan setup but I do, however, switch between an 88 and an 82 winter/summer.
You might also want to check that you actually have the correct radiator fitted - I recall reading about some cars having a single core unit fitted instead of the twin-core (or something like that), with the result that cooling was inadequate.
The otter switch just turns the fan(s) on and off doesn't it? Are the fans coming on at all?
I think it's probably just going to be a case of working your way through everything methodically.....
Best of luck.
Kris..
'75 1600M
74deg thermostats are available but I'd be surprised if you needed one of those. I used to have all sorts of overheating scares with my 1600 (Ok, it's a smaller engine but it's reasonably tweaked) but they've completely disappeared since I had the system flushed and the radiator recored. I run a standard radiator and fan setup but I do, however, switch between an 88 and an 82 winter/summer.
You might also want to check that you actually have the correct radiator fitted - I recall reading about some cars having a single core unit fitted instead of the twin-core (or something like that), with the result that cooling was inadequate.
The otter switch just turns the fan(s) on and off doesn't it? Are the fans coming on at all?
I think it's probably just going to be a case of working your way through everything methodically.....
Best of luck.
Kris..
'75 1600M
-Check the timing with a timing strobe. If it is out it will run hot
-Check your water level- if it is more than 1 or inches below the swirl pot then top it up. If it goes down again then look for leaks- espially behind the water pump where the pipe for the heater runs.
-Also, check the torque on your inlet manifold, should be about 20 lb ft, if it is loose then might be worth replacing the gasket with a good quality item, the reinforcements around the water channels wander and block the flow. This happened on both my, and a friends, Essex within about 3 months of each other.
-Apparently you should not run without a thermostat. I got a 84 oC one from partco that works well. Drill a small hole in it as that can help avoid airlocks.
- On the subject of airlocks, run the car with the swirl pot cap open(this should be blank with 13/14 psi cap on the expansion tank BTW- buy new ones as a matter of course). You need a thermostat in, when it opens keep it running, the water will rise and may suddenly drop. if this happens that is the airlock going. Do this when you refill the system a couple of times and as a matter of course too
-Backflush the system inc. the rad (take it off), Adrian Venn told me there is a plug beneath cylinder no. 4 exhaust branch where you should backflush from, and from the thermo housing
-Make sure you have got a water pump with a cast impellor, not a pressed steel one.
The above are all things I have done which have pretty much, touch wood, cured my overheating probs. As you can see I am well read on the subject!
There may be some more stuff to do, but that lot should keep you busy- best to do it all in one go to save messing about!
-Check your water level- if it is more than 1 or inches below the swirl pot then top it up. If it goes down again then look for leaks- espially behind the water pump where the pipe for the heater runs.
-Also, check the torque on your inlet manifold, should be about 20 lb ft, if it is loose then might be worth replacing the gasket with a good quality item, the reinforcements around the water channels wander and block the flow. This happened on both my, and a friends, Essex within about 3 months of each other.
-Apparently you should not run without a thermostat. I got a 84 oC one from partco that works well. Drill a small hole in it as that can help avoid airlocks.
- On the subject of airlocks, run the car with the swirl pot cap open(this should be blank with 13/14 psi cap on the expansion tank BTW- buy new ones as a matter of course). You need a thermostat in, when it opens keep it running, the water will rise and may suddenly drop. if this happens that is the airlock going. Do this when you refill the system a couple of times and as a matter of course too
-Backflush the system inc. the rad (take it off), Adrian Venn told me there is a plug beneath cylinder no. 4 exhaust branch where you should backflush from, and from the thermo housing
-Make sure you have got a water pump with a cast impellor, not a pressed steel one.
The above are all things I have done which have pretty much, touch wood, cured my overheating probs. As you can see I am well read on the subject!
There may be some more stuff to do, but that lot should keep you busy- best to do it all in one go to save messing about!
Is it really over heating, you mention that the fans cut in at 125. check the voltage stabilzer earth, as this is a common cause of "over heating" The fuel and temp gauges run via the stabilzer and it needs to be earthed correctly....it should be on the rear of the dash, afixed along with the earthing wire by a wood screw!!!!!
>> Edited by Adrian@ on Tuesday 15th June 20:55
>> Edited by Adrian@ on Tuesday 15th June 20:55
As Adrian says have you really got an overheating problem? Spent lots of time and money chasing a similar one on my 1600M,turned out to be a Ford sender unit fitted when engine rebuilt by local tuning firm,total mismatch with the Smiths clocks.A simple test-can you put your hand on the top hose when the gauge says youre making steam if you can it ain't boiling yet
Hi,
Obverheating is a common problem on M cars, but there are some simple measures that can improve the situation.
1. clean the radiator or have it recored, this make a big difference and even simple cleaning by backflushing can improve cooling quite a lot.
2. Install a racing thermostat for instance from Stewart, these thermostats have much bigger flow area and therefore improve cooling.
3. Remove the bypass flow, this increase the flow trough the radiator and make all cooling liquid go trough the radiator.
4. install 2 8" electric fans behind the radiator, NOTE not in front where they will hinder airflow.
5. Use redline water-wetter and plain water for summer, only add antifreeze if needed in winter.
I have applied all of these measures in my car that is tuned to >200BHP and I have no cooling problems any longer using the standard radiator, the cost of these modifications is less than the cost of a new improved radiator which is not really necessary. An additional benefit is that the car look completely original.
http://www2.gol.com/users/tube/coolingsystemmodifications.html
Regards Hans
>> Edited by valve on Friday 18th June 15:06
Obverheating is a common problem on M cars, but there are some simple measures that can improve the situation.
1. clean the radiator or have it recored, this make a big difference and even simple cleaning by backflushing can improve cooling quite a lot.
2. Install a racing thermostat for instance from Stewart, these thermostats have much bigger flow area and therefore improve cooling.
3. Remove the bypass flow, this increase the flow trough the radiator and make all cooling liquid go trough the radiator.
4. install 2 8" electric fans behind the radiator, NOTE not in front where they will hinder airflow.
5. Use redline water-wetter and plain water for summer, only add antifreeze if needed in winter.
I have applied all of these measures in my car that is tuned to >200BHP and I have no cooling problems any longer using the standard radiator, the cost of these modifications is less than the cost of a new improved radiator which is not really necessary. An additional benefit is that the car look completely original.
http://www2.gol.com/users/tube/coolingsystemmodifications.html
Regards Hans
>> Edited by valve on Friday 18th June 15:06
Hi
I can't add a great deal excepting that mysterious overheating problems have often been tracked to lean mixtures and this can still happen on Injection..and that includes dud fuel.Thermostats are there to keep engine at best operating temperature and should only be out of faulty..they usually give adequate flow if not faulty and so are either in or out of the equation. Remember the basics..can get confused with circular problems! ..motor overheats because, getting too hot, not getting rid of heat, being heated through ancillaries not functioning properly.
The clever chaps before me have covered the rest however:
Did you buy this car NEW?
If not it may have had a problem someone dudded..including silicon abuse or rust choked cores in rad./block. Some motors have even been found with casting sand blockages in water galleries.
Use only coolent mixes in the radiator..if s/hand someone might have used tapwater and corroded head..is water disappearing?..could be between cyls..? could be hot spots in head causing local overheat.
Be confident of this first up..BMW turn out a car usually pretty pretty pretty good, they are no fools, and I have owned a few BMW...radiator sizes etc SHOULD be ok but of course they block..is rad. core face equally hot all around after short run? Are hoses able to suck in and block when motor racing (have a look)
You must check the actual temp although we all know what steam means. Cars also need good oil flow to stay cool, turbos if fitted need adequate cooling.
Are the fans actually blowing air through the fins of the core ..you can check that. Can you see through core fins..are THEY blocked. Fans are essentially for idle speeds,in traffic and coming down from a fast run.. therefor if the car is overheating at speed the fans are the least likely problem unless added to a car and are blocking rad.air flow at speed.
Valve timing,lean mixture, ign advance(a function of the ECU usually today)all need initial checks...valve drive belt/chain stretch can alter timing.
Fan belt stretch at speed can allow pump to be inefficient..check static belt tenion ok.
Is oil flow adequate..high pressure doesn't gurantee adequate flow.
Is it manual or auto..? as a matter of interest
The water pump advice was good from one chap there (saves blades corroding) and is the pump working..simple check..and BMW seems to, like fiat, need to have the cooling system bled through the proper "valve" someone noted earlier.
The main thing is fix it before it cracks. Ring/Email BMW in Germany if no use in UK!
Cheers
I can't add a great deal excepting that mysterious overheating problems have often been tracked to lean mixtures and this can still happen on Injection..and that includes dud fuel.Thermostats are there to keep engine at best operating temperature and should only be out of faulty..they usually give adequate flow if not faulty and so are either in or out of the equation. Remember the basics..can get confused with circular problems! ..motor overheats because, getting too hot, not getting rid of heat, being heated through ancillaries not functioning properly.
The clever chaps before me have covered the rest however:
Did you buy this car NEW?
If not it may have had a problem someone dudded..including silicon abuse or rust choked cores in rad./block. Some motors have even been found with casting sand blockages in water galleries.
Use only coolent mixes in the radiator..if s/hand someone might have used tapwater and corroded head..is water disappearing?..could be between cyls..? could be hot spots in head causing local overheat.
Be confident of this first up..BMW turn out a car usually pretty pretty pretty good, they are no fools, and I have owned a few BMW...radiator sizes etc SHOULD be ok but of course they block..is rad. core face equally hot all around after short run? Are hoses able to suck in and block when motor racing (have a look)
You must check the actual temp although we all know what steam means. Cars also need good oil flow to stay cool, turbos if fitted need adequate cooling.
Are the fans actually blowing air through the fins of the core ..you can check that. Can you see through core fins..are THEY blocked. Fans are essentially for idle speeds,in traffic and coming down from a fast run.. therefor if the car is overheating at speed the fans are the least likely problem unless added to a car and are blocking rad.air flow at speed.
Valve timing,lean mixture, ign advance(a function of the ECU usually today)all need initial checks...valve drive belt/chain stretch can alter timing.
Fan belt stretch at speed can allow pump to be inefficient..check static belt tenion ok.
Is oil flow adequate..high pressure doesn't gurantee adequate flow.
Is it manual or auto..? as a matter of interest
The water pump advice was good from one chap there (saves blades corroding) and is the pump working..simple check..and BMW seems to, like fiat, need to have the cooling system bled through the proper "valve" someone noted earlier.
The main thing is fix it before it cracks. Ring/Email BMW in Germany if no use in UK!
Cheers
Hi thanks for that...same thing applies whtever the car ..however my quick glance through the original letter saw "my m" and to me, preconditoned, that means "my M series BMW"...I'm not embarassed by the error , but thanks anyway for waking me up...perhaps something helped nevertheless.
If its not a PI one cause of lean mixture overheating is leaking inlet manifolds, usually though accompanied by some rough running or stoppages at lower speeds.Another is mistuned sidedrafts.
The other question "are you worrying unecessarily"?, usual running temperature of a motor is about 180 degs. Thermostats may open at 70degs but that is simply because the thermostat has one job..get the temperature of the engine up fast and then get out of the way.
For the rest, I bow out, first principles are first principles whether a Fordson Tractor or a Ferrari. Hope all is ok.
Cheers
If its not a PI one cause of lean mixture overheating is leaking inlet manifolds, usually though accompanied by some rough running or stoppages at lower speeds.Another is mistuned sidedrafts.
The other question "are you worrying unecessarily"?, usual running temperature of a motor is about 180 degs. Thermostats may open at 70degs but that is simply because the thermostat has one job..get the temperature of the engine up fast and then get out of the way.
For the rest, I bow out, first principles are first principles whether a Fordson Tractor or a Ferrari. Hope all is ok.
Cheers
Hi all,
Mine's overheating at the moment as well. In fact I'm working on today it between the showers.
If you want to run without a thermostat, then take an old one, and remove all the centre parts, and replace like this. This will give enough restriction in the flow so that the water will get to the rear of the engine.
I've also moded the water flow, so that there is a take-off at the rear of the inlet manifold. The Scimitar boy do this, and a special pipe is available from specialist Scimitar dealers.
I've also put a fibre-glass plate in front of the rad. But this will only apply for rear upright rads.
I run a 72 degree thermostat (recomended by Ian Bannister).
The car is tuned and timed correctly (courtsey of John at JW Engineering). John is also sending me a new water pump, as mine is just starting to make a whining noise when hot. I'm at present using a laser temp. guage to check the rad to see if there is a cold spot. The rad. should be OK as it's only 3 years old.
However even with all this, the faster I go the hotter it gets...so I'm restricted to 50mph at the moment!
Good luck, and please let me know if you cure it, as it might help me.
Pietro
Mine's overheating at the moment as well. In fact I'm working on today it between the showers.
If you want to run without a thermostat, then take an old one, and remove all the centre parts, and replace like this. This will give enough restriction in the flow so that the water will get to the rear of the engine.
I've also moded the water flow, so that there is a take-off at the rear of the inlet manifold. The Scimitar boy do this, and a special pipe is available from specialist Scimitar dealers.
I've also put a fibre-glass plate in front of the rad. But this will only apply for rear upright rads.
I run a 72 degree thermostat (recomended by Ian Bannister).
The car is tuned and timed correctly (courtsey of John at JW Engineering). John is also sending me a new water pump, as mine is just starting to make a whining noise when hot. I'm at present using a laser temp. guage to check the rad to see if there is a cold spot. The rad. should be OK as it's only 3 years old.
However even with all this, the faster I go the hotter it gets...so I'm restricted to 50mph at the moment!
Good luck, and please let me know if you cure it, as it might help me.
Pietro
Pietro
No rain in Mid-Wales!
There must be something very amiss with your car, it really isn't that hot at present. I would flush the whole system out, it sounds like you have a flow problem, this could very well be the waterpump, this could have broken up inside restricting the flow, hence less flow at higher rpm. (could be related to the whining noise?!?)
My car ran a trick engine as you know and never overheated (except when I holed the rad at Aintree) in 12 years. But I did have several heating system mods and a big vent at the back of the bonnet.
The trick with M's is make sure that you get plenty of air in and out!
davidy
No rain in Mid-Wales!
There must be something very amiss with your car, it really isn't that hot at present. I would flush the whole system out, it sounds like you have a flow problem, this could very well be the waterpump, this could have broken up inside restricting the flow, hence less flow at higher rpm. (could be related to the whining noise?!?)
My car ran a trick engine as you know and never overheated (except when I holed the rad at Aintree) in 12 years. But I did have several heating system mods and a big vent at the back of the bonnet.
The trick with M's is make sure that you get plenty of air in and out!
davidy
Hi David,
Just taken some readings. The result is that with the fan off, the temperature at the inlet at the top is 88 and at the outlet 87. With the fan running it's almost the same. However with the fan running, the temperature where the fan is, is about 20 degs lower.
I agree that it seems to be a flow problem. The core is only about 3 years old, and although the car was standing for about 18 months, I did flush it before putting it back on the road.
I've just spoken to John, and he is going to call a friend, and see what he thinks.
I should receive a new (Ford) water pump on Monday. I think that I'll also take the rad to a specialist and get it cleaned properly.
If that does not fix it...I'll just go and sulk!
Pietro
Just taken some readings. The result is that with the fan off, the temperature at the inlet at the top is 88 and at the outlet 87. With the fan running it's almost the same. However with the fan running, the temperature where the fan is, is about 20 degs lower.
I agree that it seems to be a flow problem. The core is only about 3 years old, and although the car was standing for about 18 months, I did flush it before putting it back on the road.
I've just spoken to John, and he is going to call a friend, and see what he thinks.
I should receive a new (Ford) water pump on Monday. I think that I'll also take the rad to a specialist and get it cleaned properly.
If that does not fix it...I'll just go and sulk!
Pietro
I agree, except that I use an electric fan, and that is showing a 20 degree drop with in it's bounderies.
Anyway, radiator is out, and going to be looked at on Monday. Having problems removing captive nut on the water-pump, so have sprayed with WD40. Will do this over the weekend and try again on Monday.
Oh M's are fun.
Pietro
Anyway, radiator is out, and going to be looked at on Monday. Having problems removing captive nut on the water-pump, so have sprayed with WD40. Will do this over the weekend and try again on Monday.
Oh M's are fun.
Pietro
PATMAN
Be careful here, you don't want to make everything run too cool. Remember oil takes a lot longer to get up to temperature than water.
I had the following system which worked well in the car for many years including track days, fast road driving and sprints/hillclimbs.
1) Big Fat Radiator courtesy of Exactly TVR.
2) Twin Kenlowe fans on rear of radiator with Kenlowe sensor and fan override switch.
3) 74 degree stat with a couple of holes drilled in it, so there was some flow through all the time (car took slightly longer to warm up
4) Two expansion tanks in series, the extra volume in the radiator meant that when hot the system expanded beyond the first tank!
5) Vent in rear of bonnet, an SE modification. I believe that one of the problems is that the hot air has nowhere to escape at the bulkhead. You could really feel the warm air on a hot day when stationary after a long run.
6) Remote Oil Filter but not cooler.
My car ran at Stat temperature always on the road, it would rise maybe up to 90 when arriving at a long queue after some spirited driving. In fact it ran cooler than our Griff 500 when we were caught in the same traffic jam on a hot day on the M25!
My engine was non-standard and put out somewhere between 185 and 205bhp, and even after giving it 'death' on a trackday the temperature would only rise to 100 or so.
My header tank would always be about 3/4 full when cold. If I topped it up it would always return to 3/4 full. My car never overheated.
(BTW I had the low front radiator, not the later upright model)
Hope that helps
davidy
Be careful here, you don't want to make everything run too cool. Remember oil takes a lot longer to get up to temperature than water.
I had the following system which worked well in the car for many years including track days, fast road driving and sprints/hillclimbs.
1) Big Fat Radiator courtesy of Exactly TVR.
2) Twin Kenlowe fans on rear of radiator with Kenlowe sensor and fan override switch.
3) 74 degree stat with a couple of holes drilled in it, so there was some flow through all the time (car took slightly longer to warm up
4) Two expansion tanks in series, the extra volume in the radiator meant that when hot the system expanded beyond the first tank!
5) Vent in rear of bonnet, an SE modification. I believe that one of the problems is that the hot air has nowhere to escape at the bulkhead. You could really feel the warm air on a hot day when stationary after a long run.
6) Remote Oil Filter but not cooler.
My car ran at Stat temperature always on the road, it would rise maybe up to 90 when arriving at a long queue after some spirited driving. In fact it ran cooler than our Griff 500 when we were caught in the same traffic jam on a hot day on the M25!
My engine was non-standard and put out somewhere between 185 and 205bhp, and even after giving it 'death' on a trackday the temperature would only rise to 100 or so.
My header tank would always be about 3/4 full when cold. If I topped it up it would always return to 3/4 full. My car never overheated.
(BTW I had the low front radiator, not the later upright model)
Hope that helps
davidy
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