BMW M5 Forum and M6 Forums banner

1 - 20 of 27 Posts

·
Registered
Joined
·
130 Posts
Discussion Starter · #1 ·
I display the coolant temp from IC function 7, I drive in city for about 7km, normal city condition, not heavy traffic, outside temp is approx 25 C, I found the temp max up to 76 C only!

Is it correct? If not, what part will be the problem? thermostat?
 

·
Registered
Joined
·
3,184 Posts
Most likely thermostat. Possible, but unlikely, are an instrument cluster fault and/or temperature sensor on the thermostat housing.
 

·
Registered
Joined
·
3,184 Posts
There is a very small chance that the temperature display is not correct due to a faulty sensor or cluster, but 99% of the time it's the thermostat, in which case the reading of 76 C will be accurate. If everything is running normally the temperature should never go lower than 79 C when warmed up.
 

·
Registered
Joined
·
69 Posts
When i was seeing temps of 72-73 deg i opted for the thermostat replacement straight way. This did fix the issue and temps are now stable at 79 deg. Richard's right though, it could be the other things but they are less likely.

Depends whether you do the work yourself?

If you use a mechanic (and have to consequently pay for labour), i'd be inclined to replace the cheap temp sensor on the thermostat cover yourself and see if that is the problem or not. If the temps are good, then :biggrinbounce: otherwise at least you know the thermostat replacement won't be a waste of money.
 

·
Registered
Joined
·
130 Posts
Discussion Starter · #6 ·
When i was seeing temps of 72-73 deg i opted for the thermostat replacement straight way. This did fix the issue and temps are now stable at 79 deg. Richard's right though, it could be the other things but they are less likely.

Depends whether you do the work yourself?

If you use a mechanic (and have to consequently pay for labour), i'd be inclined to replace the cheap temp sensor on the thermostat cover yourself and see if that is the problem or not. If the temps are good, then :biggrinbounce: otherwise at least you know the thermostat replacement won't be a waste of money.

I check the ETK, the sensor on the thermostat housing is a double temp switch, so it seem not the source of the display of IC for coolant temp? Maybe the control switch for aux fan?

And my memory, in WDS, it stated the M5 coolant temp is not direct from temp sensor, it was calculated by another things?

Also, the original thermostat for M5 is 79 C, seem lower than another BMW model, M50 88, M52/M54 seem high with 92!
 

·
Registered
Joined
·
205 Posts
So the temp is not correct!
My money is on a bad T-stat as well. I bet you have a good bit of soot on the exhausts, right? When my engine temp returned to normal and the car stopped running rich, the soot accumulation on my exhausts dropped by at least half.
 

·
Registered
Joined
·
3,276 Posts
I check the ETK, the sensor on the thermostat housing is a double temp switch, so it seem not the source of the display of IC for coolant temp? Maybe the control switch for aux fan?

And my memory, in WDS, it stated the M5 coolant temp is not direct from temp sensor, it was calculated by another things?

Also, the original thermostat for M5 is 79 C, seem lower than another BMW model, M50 88, M52/M54 seem high with 92!
The sensor on the thermo housing has two circuits. One feeds the DME...the other feeds the cluster. Small chance its gone bad, but almost certainly a defective thermostat.
 

·
Registered
Joined
·
622 Posts
I was in the 70's and no codes. Then it moved to high 60's and low 70's It started throwing temp codes. New Thermostat fixed it. the car should run just at or a little above 79 as a Normal temp
 

·
Registered
Joined
·
3,553 Posts
The sensor on the thermo housing has two circuits. One feeds the DME...the other feeds the cluster. Small chance its gone bad, but almost certainly a defective thermostat.
+1 to what TMc has stated. If your dash gauge is reading leftof center by much, then the temp. sensor would be my 1st choice. Go with a new thermostat and truct us......79C is a good number.

Now, depending on how many miles you have on the car, I would spend the $25US and replace the temp. sensor while you are there regardless.
 

·
Registered
Joined
·
991 Posts
Having the same issue. Ordered a new t-stat, both temp sensors and 2 gallons of BMW blue for the flush. Will report back.
 

·
Registered
Joined
·
130 Posts
Discussion Starter · #12 ·
I was in the 70's and no codes. Then it moved to high 60's and low 70's It started throwing temp codes. New Thermostat fixed it. the car should run just at or a little above 79 as a Normal temp
Yes, It still no code now!
 

·
Registered
Joined
·
130 Posts
Discussion Starter · #13 ·
My money is on a bad T-stat as well. I bet you have a good bit of soot on the exhausts, right? When my engine temp returned to normal and the car stopped running rich, the soot accumulation on my exhausts dropped by at least half.
Yes, 4 exhaust pipe have some soot inside and gas mile is low 4km/L in city drive!
 

·
Registered
Joined
·
130 Posts
Discussion Starter · #14 ·
+1 to what TMc has stated. If your dash gauge is reading leftof center by much, then the temp. sensor would be my 1st choice. Go with a new thermostat and truct us......79C is a good number.

Now, depending on how many miles you have on the car, I would spend the $25US and replace the temp. sensor while you are there regardless.
The needle of coolant gauge is stay at a little above 10 clock.
 

·
Registered
Joined
·
968 Posts
Had the same issue with the temperature running at the 10 oclock position and eventually got an SES light. Local dealer had a 15% off fall labor and parts special, so I replaced the thermostat, radiator hoses and fuel filter. No SES light and the temperature runs at the 1130 position and engine runs stronger. Because the engine was running cool it also threw a catalytic converter code on my Peake reader, but the mechanic told me it was a result of running cold. The mechanic said about 7 years is the norm for the S62 thermostat regardless of mileage. Side benefit is that the heater gets warmer much faster now as the weather is cooling here.
 

·
Registered
Joined
·
906 Posts
Good choices here on renewal parts

Having the same issue. Ordered a new t-stat, both temp sensors and 2 gallons of BMW blue for the flush. Will report back.
Best approach here, in my opinion, as it gives a fresh "set of eyes" for the DME. Not only for fuel
scheduling, but also for the DME's regulation of the auxiliary (pusher) fan.

Regards,
Alan
 

·
Registered
Joined
·
906 Posts
Thermo and sensor replacements

Yes, 4 exhaust pipe have some soot inside and gas mile is low 4km/L in city drive!
The needle of coolant gauge is stay at a little above 10 clock.
Replace your thermostat, it's defective. Suggest you also replace both sensors (on thermostat housing and
in lower radiator hose) as well. Both are relatively inexpensive and they play major roles in the control that
the DME exercises on engine management.

As previously mentioned, the sensor on the thermostat housing is dual-element. One is used for the analog
gauge in the instrument cluster, while the other is for the DME. When you are looking at "KTEMP" in test #7,
the digital display value is the one being seen and used by the DME. So, if you seeing less than 78-79 degrees
while at freeway speed, with outside air temps of 50-60 degrees F (13-15 degrees C), fuel scheduling will
be biased toward rich, reducing power output, wasting fuel and contributing to long-term degrading of the
catalytic converters.

Regards,
Alan
 

·
Registered
Joined
·
111 Posts
Had a quick question as I was searching for some answers. How long does usually take for the engine to reach normal operating temp? It was a cold day here in Chicago today. It took almost 15 min for the car to warm up. 10 min was idling in the driveway and a little over 5 just cruising very slowly down the street. I started thinking to myself, "what if the t-stat is stuck open" About 10 min later my "service engine soon" light comes on. Im going to run to Autozone soon for a reading. Havent bought a Peake yet so got to go there. This is the first time I drive my car after buying 2 months ago as well. Just wanted to know how long your cars usually take to warm up. Mine took about as long as my diesels usually do today.
 
1 - 20 of 27 Posts
Top