635csi Overheating?

[bedumon]

Hi all.

So finally bought a new car. 1982 635csi A. Noticed it was overheating in traffic so changed waterpump, thermo, fan and new fluids. However it still seems to be overheating. I'm getting hot air in the cabin but the temp gauge is still reading red. When the car is left idling for a while it overheats, but with a punch a gas it starts coming down.

Any help from the M30 gurus would be much appreciated.

Cheers. P.S pics will soon be added.

[Blitz]

Viscous fan coupling?

[MJJ_ZX6RR]

Poor condition main engine earth strap on my M30'd E30 made my temp gauge read much higher than the engine temperature actually was. It would be up near the red zone, but measuring the coolant temp using an IR thermometer proved the coolant temp was at its normal 92-ish deg C.

The fact that you say increasing the revs brings the temp gauge down suggests you may have the same issue.

If it is actually overheating, air in the coolant or not working viscous fan (as above).

Martin.

[bedumon]

Thanks for the help guys.

I've already had the viscous fan changed so the next step is the sensors. I'm going to change the temp sensor and then re-bleed. Going to also have a look at adding another earth from the engine and see if it helps.

Any other info would be much appreciated.

[bedumon]

Forgot to ask if anyone could also clarify which sensors are for what.... There are 4 above the thermostat and I want to know which would be best to change.

http://realoem.com/bmw/showparts.do?mod ... g=35&hl=29

Number 6,7,8 & 9 are all sensors, but which might be responsible for overheating?

Thanks.

[leeparkes]

Does the needle go down quickly when holding the revs on or does it stay in the red for a moment then creep down? Is the bottom rad hose as hot as the top one when the engine overheats?

The viscous maybe new but have you tested it? rolled up newspaper will tell you if its locking up or not, you should hear it though as they roar when they lock.

If its not overheating when cruising at 30mph the only reason its overheating at idle is no cold air to the front of the car, or a bad earth.

[cecotto479]

Or a faulty thermostat or a partially blocked radiator or a faulty water pump or a slightly loose drive belt or a air lock.

The fact that it clears when you rev it makes me wonder if it's coolant flow related. Pump, belt, blockages or air.

[bedumon]

Is the bottom rad hose as hot as the top one when the engine overheats?

Bottom hose does not get as hot as the top.... Is my radiator the culprit?

[leeparkes]

If the bottom hose is cooler the engine shouldnt be overheating.
To test the rad remove it from the car and flush it out with a hosepipe in the top stub then vise versa, empty the rad and block the bottom stub, now fill it with hot water and feel around for 'cold spots'.
I suppose you could do this with the rad still in the car just depends how much room you have.

If it comes back good id then check the stat, probably easier to check the stat first.

[bedumon]

Does anyone know what temp the thermostat should open up?

[leeparkes]

Depends on the stat, should be stamped somewhere on it. M30 stats are normally 80 degree.

[e30kev]

this could be a long shot but does it have the same type temp dial as on the e30 instrument cluster?
if so then check the nut on the back isnt slack as i had a 325i that did the same as yours is doing and i changed nearly everything cooling wise trying to fix it before my mate found this out.
after tightening this it was fine, hth

[leeparkes]

Does the needle go down quickly when holding the revs on or does it stay in the red for a moment then creep down?

[bedumon]

It doesn't really go down rapidly. But when the cars parked and overheating a little punch of gas makes he needle shift left.

Going to test he rad next. Thermo seems to be fine and opens up at 80 degrees.

[Andyboy]

Try drilling a small (2-3mm) hole in the stat outer ring and refitting it with the hole at the top. It cured a similar issue with an E28 525i that nothing else would fix.

[pacerpete]

Try drilling a small (2-3mm) hole in the stat outer ring and refitting it with the hole at the top. It cured a similar issue with an E28 525i that nothing else would fix.

There I was having a nice peaceful afternoon and you reminded me of your Ex mates turd, the Rhodesmeister !

It was the 'cured' sump plug that really impressed me !

[Andyboy]

Try drilling a small (2-3mm) hole in the stat outer ring and refitting it with the hole at the top. It cured a similar issue with an E28 525i that nothing else would fix.

There I was having a nice peaceful afternoon and you reminded me of your Ex mates turd, the Rhodesmeister !

It was the 'cured' sump plug that really impressed me !

Just to really cheer you up:


The enquiry is complete.The vehicle details for B794 COB are:
Date of Liability 01 04 2012
Date of First Registration 30 01 1985
Year of Manufacture 1985
Cylinder Capacity (cc) 2494cc
CO2 Emissions Not Available
Fuel Type PETROL
Export Marker N
Vehicle Status Licence Not Due
Vehicle Colour BLACK
Vehicle Type Approval Not Available
Vehicle Identity Check (VIC) Marker.
VIC required.
A Vehicle Identity Check (VIC) marker has been set against this vehicle record. For more information on the VIC marker please visit Vehicle Identity Check
Vehicle Excise Duty rate for vehicle
6 Months Rate £118.25
12 Months Rate £215.00
Please be aware that if the vehicle has recently been relicensed or a SORN declared, these details may not yet be updated on the vehicle record.


This fukcker just will not die!!

Note the colour change, VIC marker and the fresh half dozen in the screen!

[leeparkes]

Did you sort this out?

[bedumon]

Still as confused as ever....

So now I've changed the water pump, thermo (twice), coupling (twice) and blade, rad and still overheating.

Ran the car without the thermo and did not overheat....

I've had the head tested and come back fine. So now has anyone got a proper way of bleeding these things because I don't think my mechanic is doing it right.

Also is it essential to use BMW coolant, or will regualr blue stuff do?

[pacerpete]

Still as confused as ever....

So now I've changed the water pump, thermo (twice), coupling (twice) and blade, rad and still overheating.

Ran the car without the thermo and did not overheat....

I've had the head tested and come back fine. So now has anyone got a proper way of bleeding these things because I don't think my mechanic is doing it right.

Also is it essential to use BMW coolant, or will regualr blue stuff do?

Regular blue is fine.

Check the thin bore hose that goes between the radiator and the coolant reservoir, if this gets blocked, it will causes all sorts of dramas. Be very careful removing it from the radiator as the plastic stub on the radiator doesn't need much grief to snap

Check with a small screwdriver/nail etc that the stub is not blocked with crud and then blow through the radiator end of the hose and check for crud coming out of the other end of the hose, ideally with it removed from the coolant reservoir.
Finally make sure the stub on the coolant reservoir is not blocked, Obviously an airline is your freind if you have access to one.

These cars are generally straight forward to bleed, though often years of beasting will leave the 8mm bleed screw a mangled stump which will only respond to a pair of vise grips.

Once the heater blows hot AND STAYS hot when left idling for 5 mins or so you should be done.

[Andyboy]

Try drilling a small (2-3mm) hole in the stat outer ring and refitting it with the hole at the top. It cured a similar issue with an E28 525i that nothing else would fix.

Also, try listening to the advice of those who have had this problem.

[bedumon]

Try drilling a small (2-3mm) hole in the stat outer ring and refitting it with the hole at the top. It cured a similar issue with an E28 525i that nothing else would fix.

Also, try listening to the advice of those who have had this problem.

Thanks for the advice but that looks to me like a very short-sighted botch job. I reckon it would probably do more damage tot he car in the long run.

So still no better off......

Think its time to visit the BM specialist.

[pacerpete]

Try drilling a small (2-3mm) hole in the stat outer ring and refitting it with the hole at the top. It cured a similar issue with an E28 525i that nothing else would fix.

Also, try listening to the advice of those who have had this problem.

Thanks for the advice but that looks to me like a very short-sighted botch job. I reckon it would probably do more damage tot he car in the long run.

So still no better off......

Think its time to visit the BM specialist.

So did you check the radiator to coolant reservoir bleed off hose etc ?

[Tom_Maverick]

Try drilling a small (2-3mm) hole in the stat outer ring and refitting it with the hole at the top. It cured a similar issue with an E28 525i that nothing else would fix.

Also, try listening to the advice of those who have had this problem.

Thanks for the advice but that looks to me like a very short-sighted botch job. I reckon it would probably do more damage tot he car in the long run.

So still no better off......

Think its time to visit the BM specialist.

it's only going to be a pinhole and it's the advice I got from a local BMW specialist! it just means the trapped air can be released with the thermostat shut!

[Andyboy]

Try drilling a small (2-3mm) hole in the stat outer ring and refitting it with the hole at the top. It cured a similar issue with an E28 525i that nothing else would fix.

Also, try listening to the advice of those who have had this problem.

Thanks for the advice but that looks to me like a very short-sighted botch job. I reckon it would probably do more damage tot he car in the long run.

So still no better off......

Think its time to visit the BM specialist.

No problem mate. Spend a couple of hundred quid at a 'specialist' who knows no more than us. We've being doing all this for a long time. Advice is free, but please feel free to ignore it - no skin off my nose!

By the way, many thermostats have a bleed hole. How exactly will it cause damage?

[MJJ_ZX6RR]

As I found out to my cost yesterday (in my defence, it was a very long day changing a sump gasket on an M30), fitting the thermostat the wrong way round means the thermostat housing is not quite sealed and thus you will never succeessfully bleed the system.

This 'ere realoem link (http://www.realoem.com/bmw/showparts.do ... g=11&fg=35) shows the right way round.

Muppetry is everywhere, despite good intentions.

Martin.

[AndyG]

I'd go with Andy's suggestion.

It's either that or pay some bigger bills.
Chances are its something like this or a small blockage in the small bore pipe that runs from the header tank into the radiator. They tend to block leading to overheating problems.

[Dezzy]

Andy you can only dream of one day being a BMW specialist.


I would love to see what qualifies most of these specialist's, A sign above the door 9/10 times i would bet!

[Andyboy]

Andy you can only dream of one day being a BMW specialist.


I would love to see what qualifies most of these specialist's, A sign above the door 9/10 times i would bet!

I could have a sign over the door and be under an X reg Mondeo scratching my arse. E30 M3 turns up. "Fackin 'ell, thats one of them M Tech motors innit?"

[Dezzy]

Andy you can only dream of one day being a BMW specialist.


I would love to see what qualifies most of these specialist's, A sign above the door 9/10 times i would bet!

I could have a sign over the door and be under an X reg Mondeo scratching my arse. E30 M3 turns up. "Fackin 'ell, thats one of them M Tech motors innit?"

"Fook me guv, Avent seen one of them before!"

[DanThe]

Everybody knows real M3's have grill badges

[Dezzy]

Everybody knows real M3's have grill badges

And 17" wheels

[DanThe]

Those are Alpine M3's Dez for fooks sake

[Dezzy]

They must be the fibergash ones then? I've heard a bit about them!

[DanThe]

The ones with V6 engines