And it's mad as heck

On cold starts the 450SEL has a fairly loud buzz from the center front of the engine. Goes away after 3-4 minutes. Looks like the warm up regulator is in that area. I haven't had time to use a stethoscope but am wondering if anybody has run across this and has a quick answer.

I don't think it's the cold start injector cause I think that comes into play only during cranking and the first few seconds of run time.


Michael

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Usta haves '69 250/8, '76 280C, 1971 250C 114.023, 1976 450SEL 116.033
Current have, 1983 300SD 126.120

could be a vacuum leak in the warmup reg or aux air system.what year is the car?

It could be the aux air valve - but it could be a lot of things. Listen around with a stethoscope or, a poor man's stethoscope, a cardboard tube from a paper towel roll.

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Current:
2021 Charger Scat Pack Widebody "Sinabee"
2018 Durango R/T

Previous:
1972 280SE 4.5
2014 Jeep Grand Cherokee Limited "Hefe", 1992 Jeep Cherokee Laredo "Jeepy", 2006 Charger R/T "Hemi"
1999 Chrysler 300M - RIP @ 221k

It's a 1976 450SEL with the CIS mechanical injection. I'm going to attack it with a rubber hose this weekend if I get a chance. Atually, I'll stick the hose in my ear and listen.

Michael

__________________
Usta haves '69 250/8, '76 280C, 1971 250C 114.023, 1976 450SEL 116.033
Current have, 1983 300SD 126.120