88C direct fit thermostat for M62TU

[Kris G]

Hello,

figured i would share this info.

new member here. but been lurking for 6 years.
i have been wanting to operate at a lower temp than 105-110C for years.
I dont agree with running that hot for a multitude of reasons.

finally found out about a direct fit 88C thermostat to replace our 105C units.

it was used on the e38 740d and the e65 745d.

just picked one up from ECS.

part number 11512248542.

the e39 & e38 guys have been been running them, which is where i discovered it. plenty of discussions about it on those forums.

excited to finally run cooler. especially considering i deleted the mechanical Fan on both my 4.6.

[Kris G]

Update:

After installing yesterday car runs 90-1c on the highway.
Peaking at 92-3c occasionally.

Cycles between 93-5c while idling at operating temp.
Car has no mechanical fan/clutch. Or fan shroud.

This is greatly improved from the factory operating temps of 104-5 hitting 108c on the highway. Hanging at 108c-110c sitting as the aux fan cycles.

Funny thing is the aux fan still cycles with the 88c thermostat. Its definitely cycling at 94-5c while sitting. Have to investigate this more to see exactly whats going on.

Going to add a 25 or 100 watt 12ohm resistor to simulate a load for the MAP cooling circuit.

Havent gone in with BMW specific software to check for a MAP code yet.

[EODguy]

Interesting, I run about the same over here but my X has the "Gulf" package so it may be the same thermostat because the radiator looks like a standard one not some extra beefy one.

Sent from my SM-A730F using Tapatalk

[Kris G]

does your car have an electrical connection at the thermostat?
would love to know this.

The 88c thermostat does not have an electrical connection. it has the opening for the connection blanked off with a engraved plate that says 88c.

[Purplecty]

I installed the Behr 88c tstat in my Dinan 4.6 as well and for some odd reason, it is running 96c-103c. I mainly see 99-102c while driving. I have the same tstat in my e38 and it runs 90-95c all the time. I am pretty sure I bled the X5 pretty well and did not see any bubbles. Any ideas?

[Kris G]

After 16k miles w/ the 88c:

The car runs from 90-95. It may briefly touch 96c when idling before aux fan cycles on. (AC off) I think there were 2 or 3 times it hit 97-99c as I entered a warm damp tunnel.

It usually runs cooler with the AC on at hot idle.
Typically 93-94c. Due to the aux fan always running.

I also have a constant P0128 code for below regulating temp.
Sometimes the SES light will go off, but the code is still there.
The good news is after a reset, I can get all the emissions monitors ready to pass inspection, before the code is triggered.

I have still not added the resistor.

Purple city, It sounds like you may have an out spec unit. I would contact the vendor. 90-95c is where these run mostly, as does your e38. It's not trapped air in the cooling system causing your issues. These engines are easy to bleed.

[Purplecty]

Originally Posted by Kris G

After 16k miles w/ the 88c:



The car runs from 90-95. It may briefly touch 96c when idling before aux fan cycles on. (AC off) I think there were 2 or 3 times it hit 97-99c as I entered a warm damp tunnel.



It usually runs cooler with the AC on at hot idle.

Typically 93-94c. Due to the aux fan always running.



I also have a constant P0128 code for below regulating temp.

Sometimes the SES light will go off, but the code is still there.

The good news is after a reset, I can get all the emissions monitors ready to pass inspection, before the code is triggered.



I have still not added the resistor.



Purple city, It sounds like you may have an out spec unit. I would contact the vendor. 90-95c is where these run mostly, as does your e38. It's not trapped air in the cooling system causing your issues. These engines are easy to bleed.

Thanks for the reply Kris! I may try and reach out to the vendor I purchased it from but it was purchased August of 2018 and was sitting on a shelf as a spare. I decided to use it on the x5 when I purchased it as it needed a tstat. If the vendor wont replace it, I will just go with an OE style unit and have the DME programmed to open it at 88c similar to the mechanical one and I should obtain the same KTEMP results! I do prefer the mechanical one for piece of mind with the common issue of coolant running into the DME from the tstat connector but they have tripled in price since 2018...

[Clavurion]

Originally Posted by Purplecty

I do prefer the mechanical one for piece of mind with the common issue of coolant running into the DME from the tstat connector but they have tripled in price since 2018...

So how much does it cost there?

Here is price for original part.

https://www.bmwautoparts.net/en/sear...11512248542%09

[Purplecty]

Originally Posted by Clavurion

So how much does it cost there?



Here is price for original part.



https://www.bmwautoparts.net/en/sear...11512248542%09

That's the best recent price I have seen! That is around the same price I paid in 2018. I was looking on amazon UK and eBay. Wonder if they'll ship to the US? Doubfult? I found one vendor dropped it to $102USD... The OE tstat is now $65 on FCP and I now found out the DME can also be adjusted to open it at 88c...

With shipping prices this one may be the best option of I dont go the OE route...
https://www.ecstuning.com/b-vemo-par...512248542~vmo/

These Vemo are just repackaged BEHR MAHLE 88C Tstats...

[Kris G]

Im not sure it's as simple as reprogramming the DME.

That circuit isn't designed to run all the time. I find it very hard to actually meet the parameters for it to engage, when it does, it's only until while under WOT loads.

There is a complicated way to do it, by modifying the circuit and adding power and controlling the switching ground via PWM or something similar I think.

https://xoutpost.com/bmw-sav-forums/...long-post.html

I'd love to see some links on just a reprogram if you know of any.

I am probably going to add another 88c to my 2nd 4.6.
Was contemplating trying to figure out programming the p0128 code off.