new thermostat: is it me, or is it really happening?

s328 · 11th April 2009, 17:49

Hi, I know that t-stat replacing is pretty common so I wanted to share an observation and ask for your opinion on it. I changed my t-stat 2 days ago (thanking M5board for very detailed description of how to do it and what can go wrong with O-ring) and almost instantly felt that car has changed. Before that my car was running pretty "cool": 76-78C with 3,000-3,500 rpm on 45 - 55 mph (not exceeding the speed limit

) Now, after I have changed the t-stat, my car under the same conditions shows 84 - 88C and according to my "butt-o-meter", it FEELS more powerful in terms of responsiveness, acceleration and "speed happiness". I know that S62 engine has several "limp modes", so my question is this: do you think that feeling "cool", DME was putting the engine in one of those modes, perventing it from unleashing more power? Thank you and happy motoring

TMcNasty · 12th April 2009, 21:09

Quote:

Originally Posted by s328

do you think that feeling "cool", DME was putting the engine in one of those modes, perventing it from unleashing more power?

No. But at some point the S62 (and any engine really) that sees a "cool" motor will richen the mixture to try and warm the motor up to operating temperature. A rich (or lean) mixture is not as efficient as the proper mix so you lose power.

You may gain power if you go just a bit lean, but a real lean mix is very bad. Best to get the mix right.

DouglasABaker · 13th April 2009, 03:12

84-88C seems awfully high for a 79C thermostat - are you sure you weren't reading the Oil temp?

d-

s328 · 13th April 2009, 16:17

Quote:

Originally Posted by DouglasABaker

84-88C seems awfully high for a 79C thermostat - are you sure you weren't reading the Oil temp?

d-

I got 88 when it was pretty hot and I was stuck in traffic. During the weekend I continued monitoring my temp and it was 79 - 81 (82 in several occasions) under normal driving conditions ~3,000 - 3,500 rpm @ 50 - 60 mph. Thank you for pointing this out.

s328 · 13th April 2009, 16:20

Quote:

Originally Posted by TMcNasty

No. But at some point the S62 (and any engine really) that sees a "cool" motor will richen the mixture to try and warm the motor up to operating temperature. A rich (or lean) mixture is not as efficient as the proper mix so you lose power.

You may gain power if you go just a bit lean, but a real lean mix is very bad. Best to get the mix right.

Thank you. Yes, I was noticing that in the morning during a quick warm-up the exhaust smelled richer than it should and now it smells not that rich.

avlnch · 13th April 2009, 16:28

Quote:

Originally Posted by s328

Thank you. Yes, I was noticing that in the morning during a quick warm-up the exhaust smelled richer than it should and now it smells not that rich.

Sniffing your exhaust =

and then you'll look like

while everyone else is

so be careful.

Later

s328 · 13th April 2009, 16:31

Quote:

Originally Posted by avlnch

Sniffing your exhaust =

and then you'll look like

while everyone else is

so be careful.

Later

well, all ABC's in the area were closed, so had no other choice

Highly recommended when the timing is the issue

Cheers

DouglasABaker · 13th April 2009, 18:12

Quote:

Originally Posted by s328

I got 88 when it was pretty hot and I was stuck in traffic. During the weekend I continued monitoring my temp and it was 79 - 81 (82 in several occasions) under normal driving conditions ~3,000 - 3,500 rpm @ 50 - 60 mph. Thank you for pointing this out.

that sounds normal...