I recently had the water pump and timing chain on my 1979 450SL replaced. Previously when the car was at operating temperature, it would idle @750 RPM. Now it idles @550 RPM when warm. Is this normal? Should I adjust the idle back to 750 RPM?
450SL Warm RPM
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'80 450SLC Afro RHD Ikonengold, '01 113 W638 'Liz Hurley'
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3,254 Posts
Your car shoud be K-Jetronik (CIS)
Maybe when pump was replaced mistakenly someone turned the idle screw.
Maybe if parts of idle control were removed for w/pump replacement debris fell in and now aperture is smaller = less rpm.
Maybe warmup idle regulator parts were cleaned (on the top of the pump) and now bimetal operation is more free. If this is the case, after adjusting idle your warmup rpm's will be lower.
After you adjust idle back to recommended, check CO2 levels. They are somewhat connected.
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It's a good idea to fill in your profile with car details so that it is easier to get answear in the future
Maybe when pump was replaced mistakenly someone turned the idle screw.
Maybe if parts of idle control were removed for w/pump replacement debris fell in and now aperture is smaller = less rpm.
Maybe warmup idle regulator parts were cleaned (on the top of the pump) and now bimetal operation is more free. If this is the case, after adjusting idle your warmup rpm's will be lower.
After you adjust idle back to recommended, check CO2 levels. They are somewhat connected.
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It's a good idea to fill in your profile with car details so that it is easier to get answear in the future
Very possible.Djenka018 said:
That could happen.Djenka018}Maybe if parts of idle control were removed for w/pump replacement debris fell in and now aperture is smaller = less rpm.[/quote said:
Check everthing.Djenka018 said:
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Cause we won't remember that the first question included your car details.Djenka018 said:
'80 450SLC Afro RHD Ikonengold, '01 113 W638 'Liz Hurley'
Joined
·
3,254 Posts
idle at low will depend on many factors.
My SLC had shaved camshaft (cam lube rail cloged) and years-of-no-drive cloged injectors when I purchased her.
She could hardly idle at 700-800rpm in D. Idle in N was ~900-1000 or she stalls, jerks and jumps.
Nearly new camshafts (original 01/02, no visible marks of wear) and new set of injectors produced purring at 750rpm in N and smooth enough idle of 600-650 in D. After closing/replacing all vacuum leaks and replacing all hoses where fuel mixture passes, she can idle at ~400rpm and she copes with ease (just for test purpose).
And it feels much more powerfull. Way much more.
I believe my problems were most common (power killer) problems.
My SLC had shaved camshaft (cam lube rail cloged) and years-of-no-drive cloged injectors when I purchased her.
She could hardly idle at 700-800rpm in D. Idle in N was ~900-1000 or she stalls, jerks and jumps.
Nearly new camshafts (original 01/02, no visible marks of wear) and new set of injectors produced purring at 750rpm in N and smooth enough idle of 600-650 in D. After closing/replacing all vacuum leaks and replacing all hoses where fuel mixture passes, she can idle at ~400rpm and she copes with ease (just for test purpose).
And it feels much more powerfull. Way much more.
I believe my problems were most common (power killer) problems.
Thats funny, but another little thing about the idle in gear I found with everything fine tuned I still and a little problem in D. What cured it was taking out about a 1/3 qt. of over fill from the transmission fl. Cured on first start afterwards.
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