E38 735i Engine thermostat

[Dimitris]

Hello all.

I am trying to find a 88C or lower engine thermostat for my E38 735i to replace the 105C thermostat without much luck. I do know that there are lower temperature replacment outther, see it in other forums, but I ca not locate one .Can anyone help please.

Many thanks a new member

D

[Greydog]

Morning Dimitris

Welcome to the Forum

With the E53 4.6is I fitted an Electric Engine fan from a later 4.4 model controlled by aan 88deg thermostat inserted in the top hose, that combined with a Febi engine thermostat rated the same kept things cool even when towing our Horse trailer

Hope this helps

Dave

[Dimitris]

Hello.

Thank you for the responce. I have decided to change just the engine thermostat for now to an 88C MAHLE from an E38 740D engine. It doe not have the electric resistor but i have read that this will not cause any issue.

I am interestead on the lectric option. How did you integrate that and from which vehile does it come from?

 

Thanks

[Greydog]

Hi Dimitriis

I used a Thermal Fan Switch 38mm for the top hose on a V8 Defender/Discovery. The actual Electric fan came from a later model 4.4 V8 X5 and after removing the engine driven fan and shroud was a straight replacement just needed a little thought wiring it in so it looked OEM

Good Luck

Dave

[Dimitris]

Thank you Dave. Mine is a 735i, is this what you have ? I will def do that in the near future.

[Greydog]

Morning 

The car i did the upgrade on was a BMW X5 4.6is 2003 not a 7 series however the engine in your car should be an M62 V8 my 4.6is was also M62, just a larger version of your engine

Dave

[Dimitris]

Hello Dave.

I finnaly managed to find a solution to the thermostat. I removed it for the summer. I am sill in search for a 88C unit. The X5 thermostat has a clip on hose and mine is with jubilee clips, so it does not fit. 

I have another question regarding VIN number. My VIN is an 18 character and not 17. Is there a free site that I can use to find when the car was made? 

Thanks

[Greydog]

Hi Dimitris

There are BMW Vin decoder sites that should supply the full Build sheet date of Manufacture etc

Or put the last 7 digits of the Vin into the search box of www.realoem.com It will call up your model and you will have the Year and Month of manufacture

As for the 88c Thermostat I fitted remember I changed the engine driven fan for an Electric fan from a later model the thermostatic switch was from a Landrover defender, I cut the top hose and fitted the thermostatic switch

There are Fan control thermostats that fit into the top of the radiator, just take the hose off slide it in replace the hose and tighten the clamp. Most are temp adjustable so you should be able to get where you want to be. See attached image

Dave

 

[Dimitris]

The best site ever !!!

 

Many thanks

As for the electric thermostat, I am aware of this one as I am using it on my 69 MGB for the electric fan conversion.

The engine thermostat of this car is at 105C, which is too high in my opinion. I just want it to open lower to save the engine and all the low-quality plastics that they used.

The X5 thermostat is an 88C but the hose fittings are not the same. I am planning to take the 88X thermostat from an X5 body and fit it to an 105C body. This way I can keep the engine temperature low. Will let you know once its done.

Dimitris

 

[Dimitris]

Hello I am back in this post with a new question

I have removed the 105C Thermostat and fitted a 88C thermostat. The engine worked well all summer. I parked it and did not used it until now.

Last week I started the car and I almost immediately got the temperature dial on the cluster going from blue to red and back again.

Once the car is warm this the water temperature dial is stabilized. I initially thought that I have a faulty temperature sensor, failed sensor giving infinity across the resistance load.

I have been looking for a water temperature sensor without any luck, my car is a 1996 model and can not find it on the spare parts list.

I’m suspecting that the problem may be a result of the electric resistance on the water thermostat being removed. Does anyone having similar problems?