BMW M5 Forum and M6 Forums banner

1 - 8 of 8 Posts

·
Registered
Joined
·
13 Posts
Discussion Starter · #1 ·
Car was running cold and threw off p0128 code.

Just wanted to say thanks for all the info on this forum, it sure made a heck of a difference.

With that in mind I have a couple of suggestions that make this task easier (some of them were already mentioned in this forum, but this will hopefully make for a useful summary):

-> There is no need to drain the entire coolant (unless you plan on replacing it, of course), use a transfer pump to drain around 2.5-3L from the expansion tank.

-> As you will undoubtedly discover, removing the thermostat housing will be a PITA. Spray some Kroil on the 3 back pipes and let it set for 15 min or so. When removing wiggle left-and-right and it should come out much easier. Btw if you don't know Kroil do yourself a BIG favor and get a couple of cans from Amazon or whatever. This stuff is nothing short of amazing and always leaves me in awe. I've yet to see a nut that I couldn't remove with this thing, even 15 yr old exhaust bolts with epic rust.

-> If the thermostat is really stuck to the housing (mine was) spray some Kroil around the seal. Use some visegrips on the thermostat spring column and wriggle it left-right to allow the oil to penetrate. Even if you don't see the seal moving at all when you wriggle do it anyway, trust me the kroil is getting in there and will make removing a breeze after 10 min (I'm telling you this stuff is amazing)

-> If you need to remove the inner thermostat seal, use a regular pulley with arms inverted (this has been mentioned before by vantaam I believe). To easily insert the new seal, just put it in the freezer for a few hours beforehand and it will slide effortlessly in the housing.

-> After replacing the o-rings, cleaning all mating surfaces, installing thermostat, etc it is time to put back the housing. To make it a lot easier, use a very slight dab of clean engine oil and coat the o-rings. Like really almost nothing, a good way to do it is flip over an engine oil bottle then open the bottle cap and touch with your finger tip in the oil layer in the inside of the cap and then rub that in the o-rings.

-> Add the coolant back (or use new one) and remember to turn on full heat, full blast for several minutes for coolant system air bleeding.

Hope this helps if you decide to tackle this job in the future. :cheers:

Best regards
 

·
Registered
Joined
·
933 Posts
Thanks. Peake code 69 (engine coolant temp plausibility) is starting to triggering my CEL after being a soft code for a couple of months. Looks like a new thermostat is needed.


Sent from AutoGuide.com Free App
 

·
Registered
Joined
·
220 Posts
I'm going to have to tackle this job soon so this is very helpful. And you are right about Kroil. It puts all other penetrating oils to shame. It's used heavily in the aviation industry.

Pat Arnold
 

·
Registered
Joined
·
765 Posts
The seal ring-in-the-freezer trick is a good one and one I forgot when I did mine. Something else that can be done in addition to putting the ring in the freezer is to also place the thermostat housing in the oven at a couple hundred degrees, or place in boiling water (not too hot). The combined effort would definitely make for a smooth fit.
 

·
Registered
Joined
·
328 Posts
Nice write up. I recommend having extra o-rings on hand. They have a habit of getting cut by the pipe making them less than useless. I went through a couple of extra when I did mine. YMMV.
 

·
Registered
Joined
·
1,061 Posts
Thanks. Peake code 69 (engine coolant temp plausibility) is starting to triggering my CEL after being a soft code for a couple of months. Looks like a new thermostat is needed.


Sent from AutoGuide.com Free App
If you let the car sit for long periods to warm up in cold weather you will get a code 69. I've accidentally triggered it twice myself. Check OBD test 7 (Ktemp) should be running between 80-86°C this time of year. (30-50°F ambient) during normal driving. A little closer to 85-88°C in the summer (Texas). If you're not getting above 80°C ever then yeah the t-stat may need to be looked .
 

·
Registered
Joined
·
933 Posts
If you let the car sit for long periods to warm up in cold weather you will get a code 69. I've accidentally triggered it twice myself. Check OBD test 7 (Ktemp) should be running between 80-86°C this time of year. (30-50°F ambient) during normal driving. A little closer to 85-88°C in the summer (Texas). If you're not getting above 80°C ever then yeah the t-stat may need to be looked .
Thanks. It has been sitting for 7-10 days at a time over the last three weeks due to sub-freezing temps and snow. It was 55F yesterday, so I took it out for about 30 mins. Oil got up to temp, but coolant topped out around 74C. Got code 69 while it was warming up, reset, and it did not come back. Same thing happened last week. Will run it longer to see what coolant temp does.


Sent from AutoGuide.com Free App
 

·
Registered
Joined
·
1,061 Posts
Oh so what I meant by sitting for long periods was sitting idling (motor running) to warm up before driving. That's how I triggered my code 69. But if you're topping out at 74°C ktemp you maybe looking at a t-stat job.<!-- google_ad_section_end --><!-- / message -->
 
1 - 8 of 8 Posts
Top