2.5 DSE (BMW) Removing Thermostat

Hi, I am a DIY mechanic, I want to check / replace my thermostat on my 2.5 DSE BMW engine P38.

Just want some advice on what i need to take off to get to it / in what order.

Thanks in advance.

i was told that the viscous fan needs to come off to do mine i have a p38 2.5 dhse but my mate across the road has a v8 one and managed to do it from underneath the car without moving anything hopefully the diesel is the same as gonna do mine over the xmas.

Its pretty straight forward if you can get a socket to it - its on the front of the head. Not sure what its like on p38, but I have that engine in my Classic and there's just room to get fingers/spanners/socket on the 3 bolts through and round the viscous fan a bit fiddly, took me about an hour just 2 days ago.

made a huge difference - engines up to temp within a mile or so AND my mpg has come back to a sensible figure.

you can get to it from underneath but it is worth investing in hose clamp removal pliers ,the ones with about 2ft cable ,about £40,should be a drain bung on the bottom of rad

I have just done the job and I had no end of problems. I have a 2000 DSE auto.
Rave said remove the top half of the fan cowl. First problem - the fan cowl is in one piece - I then found the viscous fan is a lefthand thread on the DSE. Must have tightened it more and couldn't get the bugger off.
I ended up unbolting the water pump pulley bolts to get the fan and water pump off in one piece. Got the fan off eventually in a vice in the workshop. God it was tight! I also had to remove the radiator and side brackets. Gave me chance to flush the radiator out at least. Replacing the thermostat was easy.
When I put it all back as well as using copperslip on all threads. Hammeriting all brackets and using stainless bolts, I cut the fan cowl so the top part unclips easily. Overall it took me about 2 full days.

The stat is on the front of the head. It's only held on by three 10mm bolts but . . .

The fan is in the way as is a pipe. I'm told that you can lift out the rad with the one piece cowl (don't believe what you read in Rave the 2000 has a one piece cowl) and the fan. I couldn't see how to do it so, as I already had the air conditioning condensor out, I removed the intercooler, swung the oil cooler out the way, lifted out the rad and cowl and then unscrewed the fan. You'll need a fan spanner and remember that it's reversed thread.

So, in answer to your question, replacing the stat is chilfd's play - getting to the stat is a different story.

Merry Christmas to all.

Thanks for the advice, actually very helpful for once

I will try getting to it this week and let you know how I get on.

I have small tools and fingers so hopefully wont have to take the rad off!

Merry Christmas!

What sort of MPG do you get off this engine?

The viscous fan nut is always a pain, plenty of copperslip when you put it back together should make it marginally easier next time. Once it's off (and the rad hoses) you can withdraw the fan and cowl together. Protect the rad with a piece of hardboard and you should be able to get the stat with some stubby tools. Also pay attention to the torque values, guessing and going too tight knackers the seal and it will leak.

My insurance renewal is in a month and they want 4 grand to carry on insuring my 4.6 v8 so I want something either cheaper to insure or better MPG. May just have to go for a 2.5 diesel instead but I love my V8

I use it as a daily driver and the 4.6 is costing me a bomb so I'm looking for any option to get better mpg really.

Poppers said:

My insurance renewal is in a month and they want 4 grand to carry on insuring my 4.6 v8 so I want something either cheaper to insure or better MPG. May just have to go for a 2.5 diesel instead but I love my V8

I use it as a daily driver and the 4.6 is costing me a bomb so I'm looking for any option to get better mpg really.

Click to expand...

If you gwt the dse (diesel) fit a tuning box and it makes it a whole heap better, mine keeps up with the V8s easily now and im gettin even better fuel figures,

hi been reading all these posts on thermostats. my 2.5 dse warms up ok but i have noticed in this cold weather the gauge barely goes above the blue. on the motorway it drops below the blue.i dont think i have a stat in. does this affect fuel consumption at all or can i do engine damage? a lot of people have said with the 2.5 diesel this is done to prevent over heats. my heater is still warm even at minus 5 not red hot but at least warm. your comments are welcomed.

Poppers said:

My insurance renewal is in a month and they want 4 grand to carry on insuring my 4.6 v8 so I want something either cheaper to insure or better MPG. May just have to go for a 2.5 diesel instead but I love my V8

I use it as a daily driver and the 4.6 is costing me a bomb so I'm looking for any option to get better mpg really.

Click to expand...

What? You pay 4k insurance? Are you pulling my plonker?

Poppers ... I had a 4.6 HSE insured by Peter Best Ins services..TOTALT for the year.................................£168 .94 (BTW ..I'm 55 with full NCD)

Range Rover Boy ...

I have small tools and fingers

Click to expand...

You wanna consider re-wording that a bit .....!!!

I am 18 mate, so it's still ridiculously high for me even though I've gotta be the worlds slowest driver haha.

anorakmark said:

hi been reading all these posts on thermostats. my 2.5 dse warms up ok but i have noticed in this cold weather the gauge barely goes above the blue. on the motorway it drops below the blue.i dont think i have a stat in. does this affect fuel consumption at all or can i do engine damage? a lot of people have said with the 2.5 diesel this is done to prevent over heats. my heater is still warm even at minus 5 not red hot but at least warm. your comments are welcomed.

Click to expand...

Running the engine cold will certainly affect your fuel consumption and it's not good for engine life either. It could be the sat or the viscous coupling on the fan seized.

anorakmark said:

hi been reading all these posts on thermostats. my 2.5 dse warms up ok but i have noticed in this cold weather the gauge barely goes above the blue. on the motorway it drops below the blue.i dont think i have a stat in. does this affect fuel consumption at all or can i do engine damage? a lot of people have said with the 2.5 diesel this is done to prevent over heats. my heater is still warm even at minus 5 not red hot but at least warm. your comments are welcomed.

Click to expand...

That was exactly the same problem I had, replaced thermostat (£9 and 30 mins) it gets straight up to temp and stays there.

I would recommend replacing the thermostat then if that does not fix it look at the fan.

I replaced the thermostat yesterday, it was pretty easy and only took 30 mins - plus time making sure everything was working property.


Tools:

5mm allen key for engine cover
13mm spanner for wiring bracket
10mm spanner for wring bracket and thermostat housing
Screwdriver for hose clips.


Method:

Take the small plastic front cover off the top of the engine.
Remove the 2 bolts under the wiring bracket.
Remove the radiator top hose to thermostat. (also drains off water)

Then there are two bolts on top of the thermostat housing and one beneath - which i got too from the side, leaning over the batter cover.

Then there is space to remove the housing and thermostat, watch out for the seal.

Replace and rebuild.

If you want to replace all the coolant you need to remove the bung in the bottom of the radiator to drain it.

The coolant capacity is 11L but remember there will still be some in the system - and remember to add anti-freeze!!!

It look a bit of messing about and a run around the block before my heaters came back to full temp (prob an air lock)

Now its all sorted and working perfectly, the temp gauge is getting to the exact centre within a couple of minutes and is staying there.

Also its helped with the hot starting problem I had as its keeping the engine hotter.

Hope that helps.

anorakmark said:

hi been reading all these posts on thermostats. my 2.5 dse warms up ok but i have noticed in this cold weather the gauge barely goes above the blue. on the motorway it drops below the blue.i dont think i have a stat in. does this affect fuel consumption at all or can i do engine damage? a lot of people have said with the 2.5 diesel this is done to prevent over heats. my heater is still warm even at minus 5 not red hot but at least warm. your comments are welcomed.

Click to expand...

That was exactly the same problem I had, replaced thermostat (£9 and 30 mins) it gets straight up to temp and stays there.

I would recommend replacing the thermostat then if that does not fix it look at the fan.