TWO failed thermostats in 2 months ??

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UPDATE:

Pulled the stat and ripped out the internals and refitted....

Also took the expansion tank/rad overflow hose off and blow it through and cleaned out the weep hole to the tank to try and see if there was a blockage.

Run her up to temp and fingers crossed no issues! will report back later once we have been out to see the in-laws.

Mine acts in the same manner as GullH's videos at the different temps and revs....
 

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GullH said:
I don't understand.

What does this do?

How does this fix the car?
Click to expand...

Its not a fix, it is a temp solution to what I think is the issue....

The rad top hose was hot and firm, the expansion tank was boiling over....the bottom rad hose was cool the rad surface was cool-ish, this would normally indicate the stat isn't opening to allow flow through the rad and permit correct cooling operation.

By ripping out the stat internals means that coolant is always circulating the rad and being cooled (admittedly over-cooled) so should stop the overheat and over pressure I am having.

It is only a temp solution while I get a replacement stat...and even then I will be replacing with a non-standard stat that runs at 88degC rather than the 105degC, this will give me more 'head room' between a hot engine (105) to an overheated engine (considered to be over 110) BMW just ran the engine so close to the limit to try and help reduce emissions and get a large V8 Engine through the emission regulations in force at the time.
 
Saint.V8 said:
Its not a fix, it is a temp solution to what I think is the issue....

The rad top hose was hot and firm, the expansion tank was boiling over....the bottom rad hose was cool the rad surface was cool-ish, this would normally indicate the stat isn't opening to allow flow through the rad and permit correct cooling operation.

By ripping out the stat internals means that coolant is always circulating the rad and being cooled (admittedly over-cooled) so should stop the overheat and over pressure I am having.

It is only a temp solution while I get a replacement stat...and even then I will be replacing with a non-standard stat that runs at 88degC rather than the 105degC, this will give me more 'head room' between a hot engine (105) to an overheated engine (considered to be over 110) BMW just ran the engine so close to the limit to try and help reduce emissions and get a large V8 Engine through the emission regulations in force at the time.
Click to expand...

Right...that makes sense now...

Will you keep us posted as to the non-standard stat, in terms of availability and effectiveness?

That would be helpful if Anyone has a similar problem in the future.
 
From my research, the required stat is from a 7 series BMW 740d. Havent found anyone yet that can supply as yet over in the UK as this seems to be a left hand drive only motor.
Ive mailed a couple more guys this weekend. If anyone wants to have a dig around this thread may be of help.
Will report as and when I get any info.
 
rewmer said:
From my research, the required stat is from a 7 series BMW 740d. Havent found anyone yet that can supply as yet over in the UK as this seems to be a left hand drive only motor.
Ive mailed a couple more guys this weekend. If anyone wants to have a dig around this thread may be of help.
Will report as and when I get any info.
Click to expand...

I have a link to a stat that is compatible on computer at home, when I get back I will post links to it.
 
I'm interested in cooler running! I've had 3 rads, 2 overheats and a head gasket go because of one. I know the system is meant to run pressured and thus hotter but I'd prefer to have less 'issues'...

Charlie
 
Saint.V8 said:
fullfatrr.com - View topic - 4.4 Thermostats - could it be this easy for a lower temp ?[/url]
Click to expand...

Also

Replaced thermostat with 180 degree - Page 2

Which directs to the abbes kit which means cheap auto store thermostats can be used....

80°C Thermostat kit for BMW E39 540i E38 740i X5 M62 - Reduce engine temperature - Abbes-Performance.com


I'm definitely changing mine - I have a spare body so will buy the abbes kit... Anything over boiling point in a cooling system I just think is bad....

Charlie
 
charliedurrant said:
Also

Replaced thermostat with 180 degree - Page 2

Which directs to the abbes kit which means cheap auto store thermostats can be used....

80°C Thermostat kit for BMW E39 540i E38 740i X5 M62 - Reduce engine temperature - Abbes-Performance.com


I'm definitely changing mine - I have a spare body so will buy the abbes kit... Anything over boiling point in a cooling system I just think is bad....

Charlie
Click to expand...
Not sure on the Abbes thing....the M62 stat body outlet to the rad bottom hose is angled and the one they show is straight...it may not fit!
 
charliedurrant said:
Also

Replaced thermostat with 180 degree - Page 2

Which directs to the abbes kit which means cheap auto store thermostats can be used....

80°C Thermostat kit for BMW E39 540i E38 740i X5 M62 - Reduce engine temperature - Abbes-Performance.com


I'm definitely changing mine - I have a spare body so will buy the abbes kit... Anything over boiling point in a cooling system I just think is bad....

Charlie
Click to expand...
Boiling point is pressure dependant. Lowering the running temperature lowers efficiency, 95C is quite normal.
 
Quite right, Boyles law etc. Still I'm so bored of all the cooling issues I've had and if this helps keep things cooler I'll be happy...I'll happily loose an MPG v a head gasket replacement, also LPG causes my engine to run hotter than on petrol (that is what I understand anyway) - the vehicle is also used to tow 2.5t.

Charlie
 
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