Author Topic: Engine sounds like a diesel when warm...  (Read 9195 times)

Ulf

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Engine sounds like a diesel when warm...
« on: February 11, 2009, 09:56:14 »
My otherwise lovely 230 SL has a quite a bit of what sounds like valve clatter when it gets warm. When started from cold there is very little noise, but as the engine temperature rises the sound becomes more audible and slightly intrusive. The valve clearance have been set, same with the throttle linkage, there is no smoke and a compression test showed perfect compression on all cylinders.
Any ideas on what might cause this?

Thanks in advance

Ulf
1965 230 SL in silver (DB180)
1982 Land Rover Series III SWB
2008 Jaguar XF 3.0
2005 Mini Cooper

Naj ✝︎

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Re: Engine sounds like a diesel when warm...
« Reply #1 on: February 11, 2009, 17:38:34 »
In my view, the engines run a lot quieter when the valve clearances are set at 0.003 inch inlet and 0.007 inch exhaust rather than the metric gaps (0.1 and 0.2 I think) recommended.

naj
68 280SL

waqas

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Re: Engine sounds like a diesel when warm...
« Reply #2 on: February 11, 2009, 22:41:03 »
In my view, the engines run a lot quieter when the valve clearances are set at 0.003 inch inlet and 0.007 inch exhaust rather than the metric gaps (0.1 and 0.2 I think) recommended.

The recommended is actually 0.08mm and 0.18mm, which come to 0.00315" and 0.00708". I can't imagine differences of 0.00015" and 0.00008" would noticeably change the sound of the engine, and these differences should lie well below typical valve clearance measurement error.
« Last Edit: February 11, 2009, 22:45:33 by waqas »
Waqas (Wa-kaas) in Austin, Texas

230slhouston

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Re: Engine sounds like a diesel when warm...
« Reply #3 on: February 12, 2009, 03:38:06 »
Ulf,
Could the clatter be the timing chain perhaps?

Maistran

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Re: Engine sounds like a diesel when warm...
« Reply #4 on: February 12, 2009, 04:17:28 »
Hello,

Check to see if the valve cover hold down straps are up against the cam shaft. This will cause all kinds of valve clatter.  See the details in the"valve adjustment tour".  Flat wear areas on rocker arms will also cause noise.  If you run across any valves that are way way out of adjustment remove their rocker arm and inspect the surfaces for wear.

Badly worn ball studs get a  "crown". This wear can make valve adjustment inaccurate and difficult. The crown can be ground off flat or the ball stud can be replaced to improve valve adjustment accuracy.
Joe Alexander
Blacklick, Ohio
1969 Dark Olive 280SL
2002 ML55 AMG (tow vehicle)
2002 SLK32 AMG (350 hp)
1982 300TD Wagon turbo 4spd.
1963 404 Mercedes Unimog (Swedish Army)
1989 flu419 Mercedes Unimog (US Army)
1998 E430
1974 450SLC Rally
1965 220SE Finback

upside2k

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Re: Engine sounds like a diesel when warm...
« Reply #5 on: February 12, 2009, 21:38:00 »
I would agree with one of the previous replys: ::)

CHECK YOUR DRIVE CHAIN FIRST! If you lose the chain it will be very costly. That eliminated, move on to the valve train components.

glenn

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Re: Engine sounds like a diesel when warm...
« Reply #6 on: February 12, 2009, 21:44:30 »
Flatbed it to The PUB Hospital in July.  Recovery rate is extremely high!!

Ulf

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Re: Engine sounds like a diesel when warm...
« Reply #7 on: February 13, 2009, 09:21:05 »
Flatbedding it to PUB is unfortunately not an option as I live in Denmark  ;), but I'll have my mechanic check the timing chain, tensioners etc. and set the valves once again. But if the timing chain is indeed the issue, wouldn't the sound also be present with a cold engine?

Ulf
1965 230 SL in silver (DB180)
1982 Land Rover Series III SWB
2008 Jaguar XF 3.0
2005 Mini Cooper

230slhouston

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Re: Engine sounds like a diesel when warm...
« Reply #8 on: February 13, 2009, 14:59:39 »
Ulf,
My experience with timing chain clatter was; the oil is a little thicker when cold, as it warms and thins a little the clatter increases. Replaced the chain and tensioner and solved my problem.

Maistran

Benz Dr.

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Re: Engine sounds like a diesel when warm...
« Reply #9 on: February 13, 2009, 16:50:16 »
That sounds more like bottom end problems. Look for a bad pin bushing or rod bearing.

You can test for this by pulling each plug wire off one at a time. The problem area will go quiet when you take that cylinder out.
1966 230SL 5 speed, LSD, header pipes, 300SE distributor, ported, polished and balanced, AKA  ''The Red Rocket ''
Dan Caron's SL Barn

1970  3.5 Coupe
1961  190SL
1985   300CD  Turbo Coupe
1981  300SD
2013  GMC  Sierra
1965  230SL
1967 250SL
1970 280SL
1988 560SEC

dseretakis

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Re: Engine sounds like a diesel when warm...
« Reply #10 on: February 13, 2009, 17:16:01 »
I know this sounds really obvious but did you check the engine oil level?  This happened to my parents on a 450SEL.  They failed to check oil level for very long time.  One morning they started it up and heard this awful metal on metal clattering sound.  They took it to their mechanic who told them that it needed a new timing chain and that it may have suffered expensive damage.  They then took it to the MB dealer who discovered that it had no more than a quart of oil.  They topped it off, the noise went away and the car was fine for another 200,000 miles.

Ulf

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Re: Engine sounds like a diesel when warm...
« Reply #11 on: February 16, 2009, 08:31:51 »
I've tried pulling off the cables one by one, but it doesn't change anything. The oil level i correct as well, think I'll go for the timing chain replacement once the snow melts away.
1965 230 SL in silver (DB180)
1982 Land Rover Series III SWB
2008 Jaguar XF 3.0
2005 Mini Cooper

Benz Dr.

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Re: Engine sounds like a diesel when warm...
« Reply #12 on: February 16, 2009, 22:00:30 »
When the engine is cold so is the oil and it's at a higher viscosity. As the engine warms the oil thins out and the thick cushion it once provided is gone. If there's any excess play between parts it will show up AFTER the engine warms.
In my experience it usually goes in this order:
valve rocker noise
rod knock
piston slap

Valve rocker noise is the easier to fix than the other two. Setting the valves may be all it needs.
Rod knock is serious and you aren't going much further for very long.
Piston slap is caused by a collapsed piston skirt. It only takes about .005'' or less to make noise. It can bang away in there for quite a while and still run OK. In either case keeping the engine speed down is a good idea. Both require pulling the engine apart and rebuilding.
1966 230SL 5 speed, LSD, header pipes, 300SE distributor, ported, polished and balanced, AKA  ''The Red Rocket ''
Dan Caron's SL Barn

1970  3.5 Coupe
1961  190SL
1985   300CD  Turbo Coupe
1981  300SD
2013  GMC  Sierra
1965  230SL
1967 250SL
1970 280SL
1988 560SEC