HELP WITH COOLING SYSTEM

[Mnbrennan]

I'm opening this up to the wider knowledge, as I'm about at the end of my tether.

When I bought the smurf (2.8, M52 engine) the coolant was never really getting up to temperature (hanging around the blue mark) so I installed a new thermostat and viscous clutch (which was sticking on). Whilst I was doing that, the thermostat housing got a crack in it, so I purchased another. I had a right job bleeding the system, with the temperature heading upwards, a stab of the throttle bringing down and heat to the vents. No heat to the vents, temperature heading up, stab of the throttle, heat to the vents, temperature down (to mid way). I finally managed to get it to stop this behaviour, and it stopped over heating.

The only issue at this point was a lack of heat to the vents at idle, but warm air coming back when above c.1500 RPM. Again this didn't seem right, but I lived with it for a while.

My theory was that there may have been an issue with either slipping belts or with the water pump. So last week I replaced both (which required the cooling system to be drained). To refill the system, I filled through the top hose, squeezing pipes as I went. I put everything back together and started the car. And the behaviour started again . No heat to the vents, temperature heading up, stab of the throttle, heat to the vents, temperature down (to mid way). It seemed to stabilise this evening on my trip back from the train station, but was still getting odd behaviour with no heat to the vents at idle.

I asked @BMBabe to help me to bleed the system again. I asked her to hold the revs at c.2500 RPM while I opened the bleed valve. At first there was a bit of air came out, but then nothing but water. Still no heat to the vents at idle

I've just taken the car out and it seems to have done more harm than good. Again, no heat to the vents, temperature heading up, stab of the throttle, heat to the vents, temperature down (to mid way).

The only other concern is the white smoke from the exhaust - it's never lost coolant as such, so assume (hope, pray) that this isn't all being caused by a head gasket issue. I should say that the temp never got above 3/4 at any point in the above narrative.

Sorry for the long post. Can anyone offer any guidance?

 

[andyglym]

I'm opening this up to the wider knowledge, as I'm about at the end of my tether.

When I bought the smurf (2.8, M52 engine) the coolant was never really getting up to temperature (hanging around the blue mark) so I installed a new thermostat and viscous clutch (which was sticking on). Whilst I was doing that, the thermostat housing got a crack in it, so I purchased another. I had a right job bleeding the system, with the temperature heading upwards, a stab of the throttle bringing down and heat to the vents. No heat to the vents, temperature heading up, stab of the throttle, heat to the vents, temperature down (to mid way). I finally managed to get it to stop this behaviour, and it stopped over heating.

The only issue at this point was a lack of heat to the vents at idle, but warm air coming back when above c.1500 RPM. Again this didn't seem right, but I lived with it for a while.

My theory was that there may have been an issue with either slipping belts or with the water pump. So last week I replaced both (which required the cooling system to be drained). To refill the system, I filled through the top hose, squeezing pipes as I went. I put everything back together and started the car. And the behaviour started again . No heat to the vents, temperature heading up, stab of the throttle, heat to the vents, temperature down (to mid way). It seemed to stabilise this evening on my trip back from the train station, but was still getting odd behaviour with no heat to the vents at idle.

I asked @BMBabe to help me to bleed the system again. I asked her to hold the revs at c.2500 RPM while I opened the bleed valve. At first there was a bit of air came out, but then nothing but water. Still no heat to the vents at idle

I've just taken the car out and it seems to have done more harm than good. Again, no heat to the vents, temperature heading up, stab of the throttle, heat to the vents, temperature down (to mid way).

The only other concern is the white smoke from the exhaust - it's never lost coolant as such, so assume (hope, pray) that this isn't all being caused by a head gasket issue. I should say that the temp never got above 3/4 at any point in the above narrative.

Sorry for the long post. Can anyone offer any guidance?

I had exactly the same Martin, blead it to death and the only thing that cured it was;

New radiator
New water pump
Serpentine belt and pulleys
Thermostat

Still not perfect but 100% better than it was.

 

[Mnbrennan]

The history says in July 2014 (c. 15,000 miles ago) it had the following:

• New radiator
• New viscous fan coupling
• New fan
• New belt tensioner
• New belt
• New top, bottom and bypass hoses

 

[colb]

White smoke from the exhaust would have me thinking head gasket, are you loosing coolant after running it, has the level dropped?
If you try bleeding it get the front of the car as high as possible maybe run it up on ramps if you have any then make sure heater is set to hot in the car and bleed it with the engine running. Any air trapped in there should with patience work its way out with the engine running.

 

[Jack Ratt]

My head gasket went without warning during the Euro trip last summer. The temp gauge was no where near the red at any time. It is a particular weakness of the M50/M52 engine.

http://www.motorreviewer.com/engine.php?engine_id=67

http://mywikimotors.com/m52b28/#Problems

Have a look at these articles for a better insight.

 

[Mnbrennan]

White smoke from the exhaust would have me thinking head gasket, are you loosing coolant after running it, has the level dropped?
If you try bleeding it get the front of the car as high as possible maybe run it up on ramps if you have any then make sure heater is set to hot in the car and bleed it with the engine running. Any air trapped in there should with patience work its way out with the engine running.

It's never lost a drop. Should mention when I filled it ( a number of times ) I had the front jacked up

 

[Andy-M]

Mines the exactly the same Martin. Took mine into work and vacuumed the cooling system to pull the coolant back in. Made no difference. Its got to something with the flow. On mine if hold it at 1200 rpm you can burn your hand with air coming out the vents. Let it tickover and slowly goes cold. Dab of revs comes back warm.

 

[Mnbrennan]

Mines the exactly the same Martin. Took mine into work and vacuumed the cooling system to pull the coolant back in. Made no difference. Its got to something with the flow. On mine if hold it at 1200 rpm you can burn your hand with air coming out the vents. Let it tickover and slowly goes cold. Dab of revs comes back warm.

Exactly this!

 

[Andy-M]

Its got to be something restricting the flow to the heater matrix or the waterpump not man enought on tick over. I don't think its block matrix because the heater get to hot when over tickover.

 

[Jack Ratt]

Mine never lost any coolant, and I checked it before we set off from home for the Euro trip. When I first got the car I had similar experiences with regards to the heating system blowing hot and cold and I really thought I sorted mine to a degree by just massaging the hoses when I refilled the system. The temp gauge needle was always in the middle of the gauge.

 

[NZ00Z3]

Still sounds like air in the system somewhere.

A couple of notes that may help:
- You didn't mention if you had the heat turned on to hot or not. Setting it to hot helps clear the air out of the core
- Raise the front of the car (hill or axle stands etc). This raises the header tank to help push out any trapped air.
-Check out the "Engine coolant system" in the below link
https://www.bimmerforums.com/forum/showthread.php?2189681-Z3-FAQ-(Frequently-Asked-Questions)

 

[Mnbrennan]

Still sounds like air in the system somewhere.

A couple of notes that may help:
- You didn't mention if you had the heat turned on to hot or not. Setting it to hot helps clear the air out of the core
- Raise the front of the car (hill or axle stands etc). This raises the header tank to help push out any trapped air.
-Check out the "Engine coolant system" in the below link
https://www.bimmerforums.com/forum/showthread.php?2189681-Z3-FAQ-(Frequently-Asked-Questions)

Thanks, I did the above points, I'll have a rad of the link.

Paul sent me this link (https://zroadster.org/threads/brrrrrrrr-its-cold-in-here.5667/) which concluded a blocked heater matrix. The OP sold up before anyone found out if it solved the problem!

 

[BMBabe]

He is now outside again tinkering with the Zed

 

[Stevo7682]

I may be able to help a bit lynne's zed had similar issues no heat unless at motorway speeds while i was trying to dry it out i had all the interior carpets out i thought I'd look into it further.
Discovered entry hose heating up but little to exit hose so off came both the rubber hoses tried to clear with a hose with little to no effect so after looking at it to get matrix out needs heater box out so decided a plan b was needed so cut both the aluminium pipe on the straight section before entering the matrix this allowed me to remove it after a bit of messing around with various things got it a lot better ( was full of a solid rust like sediment )
After fabricating a repair to allow me to put all back together warm heat ( but not hot ) at idle much hotter driving but still not as hot as my dakar
So my next step probably over this weekend is to run a chemical descaler through the cooling system then water flusb and refill see if that gets things to where i would like .
Stephen.

 

[Mnbrennan]

Thanks I had suspected this was the case Steve. The water pump that came off was just fine

Have just taken it out again and seem to have got the water temp stable at least

 

[MRH1966]

Had the same problem with mine. Done the same as you. Just kept bleeding and running it. It blew the bottom rad hose off while at the MOT station. It must have pushed the air block out as since it has been filled again, everything works great!!
Maybe try back washing the heater with water from a hose to clean it a bit?

 

[t-tony]

My best guess is heater matrix partially blocked., these are usually a square flat shape with the in and out pipes both at one end. The matrix silts up allowing water to flow across the end of the matrix but not actually passing through the whole of the matrix.

Tony.

 

[Stevo7682]

Thanks I had suspected this was the case Steve. The water pump that came off was just fine

Have just taken it out again and seem to have got the water temp stable at least

If you'r happy its bled properly then fire it up from cold before the thermostat opens the coolant only circulates through the engine and heater matrix the 4 and 6 should be the same matrix wise so top inlet bottom outlet after 2 to 5 mins the top rubber matrix hose at bulkhead should be heating up ( even at idle from cold ) if the heaters are on face vents speed 2 should be getting warmth at vent and bottom rubber hose should be also heating up ( less than top as some heat removed by blowers on ) top rad hose should be also heating a bit ( lower cold till thermostat opens) .
If you continue to warm up thermostat will open all pipes and radiator should get hot .
If everything heating up ok bar the bottom matrix hose then its blocked or partially blocked then comes the fun bit depending on how bad it is will depend on how heavy handed you need to be to sort it.
Stephen.

 

[t-tony]

That's true Steve, but if the Matrix is partially blocked the hot water will still short circuit the main Matrix meaning you only get a percentage of the heat transfer available. The issue here is not overheating of the engine is it just the lack of heat transfer into the cabin through the heater, and this can only be down to the Matrix being blocked.

Tony.

 

[Mnbrennan]

If you'r happy its bled properly then fire it up from cold before the thermostat opens the coolant only circulates through the engine and heater matrix the 4 and 6 should be the same matrix wise so top inlet bottom outlet after 2 to 5 mins the top rubber matrix hose at bulkhead should be heating up ( even at idle from cold ) if the heaters are on face vents speed 2 should be getting warmth at vent and bottom rubber hose should be also heating up ( less than top as some heat removed by blowers on ) top rad hose should be also heating a bit ( lower cold till thermostat opens) .
If you continue to warm up thermostat will open all pipes and radiator should get hot .
If everything heating up ok bar the bottom matrix hose then its blocked or partially blocked then comes the fun bit depending on how bad it is will depend on how heavy handed you need to be to sort it.
Stephen.

One pipe is definitely colder than the other

That's true Steve, but if the Matrix is partially blocked the hot water will still short circuit the main Matrix meaning you only get a percentage of the heat transfer available. The issue here is not overheating of the engine is it just the lack of heat transfer into the cabin through the heater, and this can only be down to the Matrix being blocked.

Tony.

Exactly that, I had stopped the overheating issue but still had issue with cold vents at idle. I changed the water pump as I though that there may not be enough flow at idle to get water into the matrix, with it just circulating the engine.

It appears this isn't the problem, so therefore it must be the heater matrix.

I need to have the dash out at some point to swap to the extended leather so will have a more in depth look then