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-   -   Diesel thermostat definative answer (https://www.the75andztclub.co.uk/forum/showthread.php?t=68468)

rossocorsa 12th December 2010 23:00

looking at this diagram

http://i724.photobucket.com/albums/w...g?t=1287527634
can anyone expalin how coolant expansion is accommodated when both stats are closed? that does look worrying for that reason I feel that the stat should be in the outlet not inlet(????)

BigRuss 12th December 2010 23:21

It's not an ideal thing to have two thermostats, it would be far better to remove the old one then fit the remote housing, however the old stat being weaker should open very quickly after the new stat opened.

I don't see any issues with thermal expansion from what I can see it should be unaffected.

Jules 13th December 2010 00:20

So long as the additional Stat has the bleed hole drilled, I don't see a problem as the OEM Stat is fitted with a ball valve anyway. (This allows fluid to expand or contract either way)

But Guys, don't expect the remote stat to run as hot as a correctly functioning OEM type.

88 deg on the cool return coolant through the OEM Stat is bound to give hotter results than 88 deg in the outlet from the cylinder head area.

Don't get me wrong, the Remote stat is a good economical mod but I fear will never work as well as the BMW design.
For that reason I am still offering a fitting service for both types!

Two BMW Stat install jobs have just come in for the New Year ..............for my sins :xmas-smiley-010:

t_i_m 13th December 2010 08:18

Quote:

Originally Posted by BigRuss (Post 634039)
It's not an ideal thing to have two thermostats, it would be far better to remove the old one then fit the remote housing, however the old stat being weaker should open very quickly after the new stat opened.

I don't see any issues with thermal expansion from what I can see it should be unaffected.

I would be very wary removing the old stat completely I imagine it will also be acting a flow restrictor to create the correct pressure in the block which is why the thermostat is positioned where it is.

On mine coolant was returning to the header tank immediately (with the in-line stat in place).

I had 82-84deg on a 20 mile dual carriageway run this morning, it went upto 88deg up a hill when the stat clearly opened and dropped to 86deg (load was increasing at the time). After reaching 'full' temperature and everything fully warmed up I saw 87 deg a few times even at slower speeds.

Overall its an improvement for me but like Jules says its not as effective as replacing the OEM stat.

Mintee 13th December 2010 08:44

Quote:

Originally Posted by t_i_m (Post 634104)
I would be very wary removing the old stat completely I imagine it will also be acting a flow restrictor to create the correct pressure in the block which is why the thermostat is positioned where it is.

If you are going to remove the old 'stat completely then you might as well fit an OEM on as a replacement. The effort involved would be the same and they even cost a little less than the in-line version!
Quote:

Originally Posted by t_i_m (Post 634104)
I had 82-84deg on a 20 mile dual carriageway run this morning, it went upto 88deg up a hill when the stat clearly opened and dropped to 86deg (load was increasing at the time). After reaching 'full' temperature and everything fully warmed up I saw 87 deg a few times even at slower speeds.

Overall its an improvement for me but like Jules says its not as effective as replacing the OEM stat.

It sounds as if you are running a few degrees cooler than the Chevy 'stat as I know that mine opens (using the dash OBD) when it hits 92C and but more often it sits @87C. I really recommend that someone with these 88C 'stats trys fitting one that is designed to open a little later if they want to run a few degrees hotter all the time.

wuzerk 13th December 2010 08:46

Update
 
I did some testing on the British In line thermostat system today and compared it with the Chevy 'stat.
The problem with the British one is that he has drilled a quite large bleed hole in the thermostat when it does not need a bleed hole as there is one built in on the edge of the opening plate! The Chevy 'stat has the same built in hole so does not need an additional hole either which I found out the hard way! This means of course that too much water is bleeding through to the rad lowering the available temperature. The problem is how to block up the unnecessary hole?
not enough room for a pop rivet so I suspect soldering is the only way to block it.


There are no problems caused by leaving the original early opening stat in position. The whole point of my experiments was how to attain a good running temperature without having to remove the original.

Mintee 13th December 2010 08:54

Quote:

Originally Posted by wuzerk (Post 634110)
The problem is how to block up the unnecessary hole?
not enough room for a pop rivet so I suspect soldering is the only way to block it.

Wouldn't it be easier and quicker to just fit another 'stat? :confused:

wuzerk 13th December 2010 09:04

Holy stat
 
I have e mailed the British supplier re the hole but it is probably too late for everybody now.
I tried standing the housing on end with the 1 1/2" uppermost and pouring water into it. It drained through in less than 10 seconds which is too fast.
Unless somebody comes up with a simple hole blocking idea (like epoxy putty) then a new stat will be the answer. My spare Chevy stat physically fits but will need some gasket goo around the recess where it sits.

I am not very impressed by the quality of the 'British' stat.

rossocorsa 13th December 2010 09:04

did no one tell him not to drill an extra hole? I think we already concluded that the heater acts as a by pass anyway if it fits I think I will try the vauxhall opel 92 degree stat that someone mentioned maybe not a lot of extra help in winter but might improve efficiency in summer

any idea what car the stat in it came from?

Mintee 13th December 2010 10:08

Quote:

Originally Posted by rossocorsa (Post 634115)
did no one tell him not to drill an extra hole?

Who told them to drill an extra hole? :confused:


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