Engine: D52447: Thermostat replacement - Guide

[Ron_XC90]

I like that interface!!!

[bobdabuilda]

Originally Posted by BestGear

Hi Chaps



perhaps the marked temperature is when its fully open, NOT when it starts to open?

Sounds like a little physics experiment is in order with a new thermostat, a bain marie and a thermometer. I did this once with an audi a4 thermostat that was also marked 90 degrees but was only fully open at that temp and began opening at around 85.

[BestGear]

Originally Posted by Ron_XC90

I like that interface!!!

Yeh, its nice and clear.... although you are limited to viewing data from 4 sensors at a time really.

You can step through the data and see chronologically what each sensor is doing... and also if any DTC appear, you see what each sensor was up to exactly when the DTC was triggered - handy for diagnostics.

David

[BestGear]

Originally Posted by bobdabuilda

Sounds like a little physics experiment is in order with a new thermostat, a bain marie and a thermometer. I did this once with an audi a4 thermostat that was also marked 90 degrees but was only fully open at that temp and began opening at around 85.

Hi

Yes, think it must have started to open around 80-85 degrees... The flutter on the graph will be the stat opening and closing making the water temp fluctuates.... its just doing what a stat is meant to do - many folks think a stat is shut when cold, and open once hot..period. You dont really think about it opening and closing by varying degrees all the time the engine is in use.

The journey was a mix of heavy stop start trafiic and also 60mph on the bypass so a stable cruise.

At least my heater works now... we will see next winter when its really cold. I just got so fed up of never being able to sclear the screen with the heater if left to idle!

David

[BestGear]

Originally Posted by bobdabuilda

Sounds like a little physics experiment is in order with a new thermostat, a bain marie and a thermometer. I did this once with an audi a4 thermostat that was also marked 90 degrees but was only fully open at that temp and began opening at around 85.

Hi

I had a wee search around the web and it seems that the stamped temperature on a themostat is the temperature that its fully open, NOT the temperature that it starts to open.

Having replaced the engine and EGR (yes, EGR - its water cooled) thermostats on my BMW E60 - the economy of the car has increased considerably (8-12MPG)! Seems that modern diesels are not fuel efficient unless circa 82-92 degrees.

David

[markh1]

Gents,

This evening I have been trying (and failing) to remove the thermostat housing.

I can't for the life of me see a way of removing the lower torx bolt that holds the housing to the block. There are two holes there but neither of them are big enough to fit a torx driver through.

Please can someone tell me what tool they used?

Many thanks!

[SwissXC90]

Originally Posted by BestGear

Seems that modern diesels are not fuel efficient unless circa 82-92 degrees.

Would make sense.
As a reference: my XC90 runs at 87° to 89°C, very steady.
Mainly at 89°C on the motorway
Never seen it over 90°C

As we come into winter I will be interested in the warmup cycle when it gets under 9° and the auxilliary diesel heater kicks in (I got the car in March 2016 and it was already too warm to have the auxilliary heater run)

PS: here's a good page on testing thermostats:
http://www.davidboettcher.uk/thermostat.php

[JohnL]

Best Gear,
What interface are you using please? Will it work on 2003 model year?


Markh1
Could you not open the hole out a bit more to take your torx?

John

[markh1]

John,

The thought did cross my mind but I am loathed to start drilling holes if other people have successfully managed to change the thermostat without drilling.

it would also not look very good to any prospective buyer as and when I sell the car on.

I have ordered a haynes manual so maybe that might help. If not the local volvo main dealers has quoted £170 labour to change it and will happily use the part I already have.

[cheshired5]

Originally Posted by markh1

I am loathed to start drilling holes if other people have successfully managed to change the thermostat without drilling.

Could you not measure the hole diameter using a drill bit that just passes through then buy a torx driver with the same or smaller diameter?

The alternative is just to disassemble some components in the area to facilitate access.