OverCooling Problem

[BeemaBoy]

Hi All

Got a bit of a strange problem with my 87 320I that I have been living with for a while, but want to now get sorted out

The car seems to overcool badly! It NEVER gets up to centre guage and usually stays just above the 1/4 mark when I have been driving for a while. Lately though, when cruising, the temp now drops as far as going to the other side of the 1/4 mark and almost on to the cold blue mark...

I replaced the timing belt about a year ago and replaced the following items at the same time, with BMW parts...

Radiator, WaterPump, Thermostat, ECU temp sensor and did a coolant flush aswell as add all new coolant...

Can anyone suggest what is causing this. It only seems to overcool when driving and gets between the 1/4 mark and 1/2 mark when stationary...

Thanks so much
Rawdon

[E30Mark]

Sounds like a duff thermostat, next time you start the engine from cold check the radiator hoses for heat. The coolant shouldn't be pushed through the radiator until the engine block is up to temperature. If the hoses / rad both get warm straight away then it sounds like the thermostat is jammed open.

[BeemaBoy]

Hi E30Mark

I have replaced the thermostat with a BMW one of the same type that came out of the car. I will try that test and let you know

Thanks
Rawdon

[Morat]

It could just be an instrumentation fault, the brown temp sensor feeds the gauge on the dash. Brianmooore will know what to short where to get full deflection on the gauge for a test too.

[Brianmoooore]

First point is that needle on about the quarter mark is perfectly acceptable. E30s seem to run with the needle just past the quarter mark, or dead on the centre mark, which, I pressume, is a reflection of the rating of the thermostat fitted. The gauge is not linear and the whole centre section of the gauge only covers a few degrees.
The best indicator of a failed thermostat is a temperature gauge that moves around - generally running cool, but increasing when working the car hard, and dropping again when the engine is lightly loaded. Once a temperature gauge reaches its normal operating point, it should not move,except for a slight increase when stopped in traffic, or a larger increase if you stop the engine and turn the ignition back on a short while after.

[BeemaBoy]

Thanks for the replies guys

Firstly, the thermostat is an 80C or 176F one. This is the one that was given to me by BMW, suited to the climate in South Africa...

The needle does wander a bit. If I am cruising, the temp drops onto or below the 1/4 mark. If I really push the car, the same thing happens except that it wanders around the 1/4 mark a lot more. When sitting stationary or crawling in traffic, the temp climbes fairly rapidly (1-2 minutes) towards the centre of the guage...but will never go any further. As soon as the car is back at cruising, the temp drops back to around the 1/4 mark within 3-4 minutes...
Problem is that when I open the bonnet, the engine does not feel cool...it feels as hot as my M50 525I E34 BMW...

I have tested the temp sensor and it was within tolerances. I also jumped the wire on the guage connector to a ground and the guage went straight to the other side of the red...so I assume that is working?

Could this be an over-active viscous fan at all?

Thanks
Rawdon

[DHFiS]

In my experience the viscous fan works perfectly until the fluid leaks out and then it doesnt work at all.

[Brianmoooore]

In my experience the viscous fan works perfectly until the fluid leaks out and then it doesnt work at all.

This is what they usually do, but there is also a bearing between the two parts, and bearings can fail and seize.
If this had happened though, you would certainly know about it because of the noise.
Even if the viscous was driving the fan continuously, it still shouldn't affect the engine running temperature.

[fowler]

an 80C africa and australia thermostat will get to about 1/4 thats it no more no need to panic as the correct ones for this country are 86c i think
just means your cooling system is extra efficient

[BeemaBoy]

Hi Guys

Was just throwing the viscous fan out there as another possible cause, but I guess not...

I remember one of my friends telling me that the cooling system is very efficient...but isnt that bad for the car and fuel consumption? I know my 525I and 740I race to get up to that centre point on the guage ASAP!

I will in the near future, be selling the E30 and I would really like to make sure that this will not be a problem for the next owner...as I want this car to live on for quite a few more years

Just out of interest...does anyone else have a L-Jetronic E30 that they can compare the temp to mine?

Thanks so much
Rawdon

[DanThe]

If you have an 80° thermostat fitted the gauge will show 1/4 when the engine is up to temperature, this is the norm, in traffic it will raise to just under 1/2

[BeemaBoy]

Thanks for the reply DanThe...

So, this is okay for the engine then or should I ask BMW for a higher rated Thermostat?

Thanks
Rawdon

[kulvinder]

If you have an 80° thermostat fitted the gauge will show 1/4 when the engine is up to temperature, this is the norm, in traffic it will raise to just under 1/2

This is exactly what happens to mine. Its normal.

[DanThe]

Leave it alone

[jermyns]

Mine is a L-Jetronic E30 as well, and I live in Sydney Australia, so its hot!

The temp guage has never moved above the quarter mark in the 10 years that I've owned the car. Hope this eases your concerns.

[town325i]

it will be fine my old 325 was the same never bothered me one bit only when stuck in bad traffic on the motorway would it creap up and then the fan would cut in and keep it all under control

[BeemaBoy]

Great...thanks so much to you all

Had put my mind at ease. Just so use to my other cars racing and staying at centre, I guess I forgot that the E30 does not do this...

Keep well and happy motoring...

Cheers
Rawdon