E39 530 Sport - Duff Thermostat??

[griff430]

During the summer, my car used to run with the engine temperature gauge at
approximately the half-way mark, and it does this around town in the winter
too, but when I'm on the motorway, or other open roads when the car's speed
is generally higher, the temperature drops to much nearer the 'cold'
indication (just above the blue marker).

Is this normal on a 530 Sport? The reason I'm concerned is because I'm
taking the car to the Alps in March, so I want to make sure the cooling
system is in performing properly, to avoid any engine freezing problems,
when the air temperature is bound to be much colder than it is in this
country.

It sounds like the thermostat could be a bit duff to me. If that's the case, is it difficult to diagnose/fix? I'm fairly handy with a spanner and screw driver, and have changed thermostats before, but on a different league of car (Ford Fiesta!!), so I just want to check out the possibility of doing it myself first, before I get ripped off at the BMW garage. If it's a job that could go horribly wrong (bearing in mind it's got the complicated climate control and auxiliary ventilation pack fitted), then I think I'll bite the bullet and pay BMW.

Any comments/suggestions would be much appreciated.

Thanks,

Dan.

[HarryW]

Let me know the answer as my 528 does this . I'm assuming it is the thremostat stuck open too.
Apparently the normal failure mode for the thermostat is stuck closed and a cooked engine .

[Egbert Nobacon]

No its not normal.

In my current 530 Sport, and the 528 I had before that, the temp gauge never moved/moves from the middle. Even in South of France in high summer / alps in winter.

Probably be one of three things.

Thermostat failed.

Impellor in water pump broken (some have plastic components that break)

Air lock in cooling system.

I had a thermostat fail on my 528 and thought about changing it myself but one look at the lack of space at the front of the engine put me off. My Specialist changed thermo, pump and coolant reasonably quickly from memory and the bill was not excessive.

Other forums and my specialist advised to change the water pump at the same time - Some have plastic impellors which can break off.

The E39 cooling system is prone to airlocks if not filled correctly which can lead to erratic temperature fluctuations. I had to follow a certain method including setting the heater controls to a certain position to ensure the heater matrix was pumped full.

I can't remember the precise order of things now but pm blackspider if you need it as he is a tech

Edited by Egbert Nobacon on Tuesday 23 January 17:07

[sparkythecat]

I have an E39 530i and as others have said the needle never strays from the centre.

There is a fair bit more dismantling involved in changing the thermostat on this beast than there was on a Fiesta. You have to remove the fan and shroud to get your tools near the thermostat housing. I think the thermostat housing is an intergral part of the thermostat on this engine so a replacement is likely to be upwards of £30


You'll be paying for an hour to an hour and a half garage time if you're going to the stealers. Also factor in new coolant as they'll probably replace it as a matter of course.


Why not spend £15 on a Haynes manual and see if you're up to the job?

Edited by sparkythecat on Tuesday 23 January 23:28

[griff430]

Thanks for the info/advice. Sounds like a job for the garage to me. Might be worth paying the bill up front, instead of attempting the job myself, and then ending up with a bigger bill

[CommanderJameson]

I had something similar. Turned out to be engine thermostat overreading and causing the engine to run cool.

[noor]

i had the same thing on my 528. The first thig i noticed was that it didnt thow out hot are on the motorway and hence saw the low temp reading on the gauge. Its definately the thermostat - 30 quid ish.

[B'stard Child]

HarryW said:

Let me know the answer as my 528 does this . I'm assuming it is the thremostat stuck open too.
Apparently the normal failure mode for the thermostat is stuck closed and a cooked engine .

That used to be the case but technology has moved on somewhat and most modern thermostats get lazy ie fail open rather than closed

[blackspider]

9/10 its the thermostat...

The needle always stays in the centre-if it moves away theres a problem.As its dropping to the blue then it sounds like the thermstat supports have broken off=not a problem,just a new stat and about 20 mins to fit.

[HarryW]

blackspider said:

9/10 its the thermostat...

The needle always stays in the centre-if it moves away theres a problem.As its dropping to the blue then it sounds like the thermstat supports have broken off=not a problem,just a new stat and about 20 mins to fit.

Would a main stealer charge 0.3 of a unit, what I mean is that the book hours for the job. If so, I wouldn't get my hand dirty myself, parts must be no more than £30 too

[blackspider]

No,thats the time I take to do the job(taking my time).I dont know off hand the book time,but by the time you've added replacement of the stat and topping up and bleeding the cooling system a stealer is going to be charging at least an hours labour.

The stat depending on the type you have starts at about £30-if you have a mapped thermostat then it will require the whole housing which is a bit more.

Sorry I cant give definate costs.Its because we dont get involved in pricing on the technical side-this is to save technicians dropping themselves in it by telling the customer its going to cost £50 when it turns out to be £150-its happened before.

[sparkythecat]

blackspider, I can see you doing that on a 4 cylinder engine, but HTF do you get at the thermostat on the 6 without removing the shroud, fan and/or radiator?

Is this you?

[blackspider]

The cowl can be moved up 30mm which gives direct access to the bolts,even then it takes seconds to get the fan and cowl off.After 6 years of doing them you tend to find large short cuts.
What also helps is 6 years working with TVR's,you soon find that your fingers can work it the tightest of spaces.


P/s Nice one

Edited by blackspider on Monday 29th January 21:05