Car running slightly hot

[chippy]

During normal forward motion and at idle my car runs as expected with the water temp needle bang in the middle(even in the recent hot weather!!). When i have to slow for traffic and am running at a slow crawl, the temp needle sometimes creeps up toward three quarters on the gauge and then returns to normal. I'm sure even with the hot weather it shouldn't move at all.

So far i've tried;

Replacing
-Viscous coupling on fan(old one was a bit weak)
-Thermostat(in case it was running wrong temp range)
-Fluids

Checking
-radiator for damage/blockage
-aux electric fan
-fluid circulation

I've checked for the normal signs of head gasket failure and all seems ok, just running out of ideas now :?

Anyone had a similar problem before or got any other ideas :?: :idea:

[c_w]

How easy was it to replace the thermostat? do you need any other items (like seals etc) to replace apart from the thermostat itself?

I bought the thermostat as mine didn't seem to warm up fully half way in winter but never got round to changing it, and it seemed that the top and bottom hose stayed cold until the engine reaches nearly halfway so assume that its probably OK anyway.

I drove mine over the weekend when it was hot, the gauge stayed central all the time. I did notice the viscous fan being on when setting off from lights though after being stationary for about a minute, but the gauge never moved off central that I noticed.

[chippy]

The thermostat is fairly simple to do but involves removing the viscous fan & shroud, throttle sensors and under tray(for draining coolant. While i was doing the thermostat i also changed the water pump & air con belts as they were a bit cracked and the whole job took about 2 hours max.

There are 2 o-rings that should be replaced when refitting the thermostat housing.

With my car, apparently up to around year 2000 the water pump had a plastic impellor which can loose its effectivness over time in circulating the coolant :roll:. Well its either that or the aux. fan temp sensor is not reading correctly :?:

Will post up when i've tracked it down :wink:

[Ivo]

With my car, apparently up to around year 2000 the water pump had a plastic impellor which can loose its effectivness over time in circulating the coolant :roll:.

This is a well known problem with "normal" Z3's, did not know same pump was used on MC's :shock: Are you sure the impellor was plastic :?

[c_w]

The pump is different to other Z3s but not sure if its metal or plastic impellar.

[chippy]

With my car, apparently up to around year 2000 the water pump had a plastic impellor which can loose its effectivness over time in circulating the coolant :roll:.

This is a well known problem with "normal" Z3's, did not know same pump was used on MC's :shock: Are you sure the impellor was plastic :?

Was told this by an ex bmw mechanic, but have not been able to confirm this yet!!

[chippy]

With my car, apparently up to around year 2000 the water pump had a plastic impellor which can loose its effectivness over time in circulating the coolant :roll:.

This is a well known problem with "normal" Z3's, did not know same pump was used on MC's :shock: Are you sure the impellor was plastic :?

Was told this by an ex bmw mechanic, but have not been able to confirm this yet!!

[chippy]

Well, i've now replaced the water pump, pump belt and double temp sensor and still the car goes up to 3/4 on the water temp gauge when creeping (10-20mph) in traffic :evil: :roll:

This is starting to bug me now!! (hate being beaten by things like this)

Any other thoughts :?: :idea:

[KIDDLE]

Is it a faulty gauge? ... never known one to go wrong but if all else has been tried??
Other than that can you get hold of a thermal scanner to see what the real temp of the engine is?
We had some really smart kit for temp readings on bearings where I worked last, did not need to touch anything and gave really good readings showing temps.

Not got access to the kit now as moved jobs, but anyone on here may be able to help.

[chippy]

Kiddle

Thought about the gauge but seeing as it reads as you would expect, ie on warm up etc, and also when it shows the temp approaching 3/4 you can hear the viscous fan 'roaring' on acceleration which would indicate the water temps being high, i'm assuming its ok :?:

[spunkym]

Radiator is probably stuffed.

[chippy]

Radiator is probably stuffed.

Had all the surrounds off the radiator to have a good inspection of it and there is no sign of any damage, corrosion, build up of crap in fins or leaks!!

Going to try a special radiator chemical flush on Friday to see if it has a partial blockage :roll:

[Lee]

Radiator is probably stuffed.

Had all the surrounds off the radiator to have a good inspection of it and there is no sign of any damage, corrosion, build up of crap in fins or leaks!!

Going to try a special radiator chemical flush on Friday to see if it has a partial blockage :roll:

Tony

I know you have been working hard to get this sorted and I know you wont be beaten by it :D

No luck with a differnet battery and a possible spike or erratic current?

Lee

[chippy]

I know you have been working hard to get this sorted and I know you wont be beaten by it :D

No luck with a differnet battery and a possible spike or erratic current?

Lee

Hi Lee

The gauges read consistantly, ie showing higher reading only under same driving conditions, so doesn't point to voltage spike, irregularity etc. I have a spare good battery in the garage, so might try it anyway :roll:

[paulzeee]

Tony,

How did this work out for you after ? I have noticed recently that mine has started doing the same, just climbs up a bit more than half way in traffic and then when out on the mototway drops a bit. Seems to operate between 1/3 and 2/3.
Its really annoying! Havent replaced anything yet only all the coolant has been flushed out of it recently. I'm thinking viscous fan??

Paul

[paulzeee]

Sorry just seen this thread is three years old...!

From the archives :thumbsup:

[Mpower06]

has anyone sorted this out???

Iv changed the Waterpump, Thermostat, all belts, pulley's and hoses but still no change.

BMW mechanic sugessted the Vicous fan???