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450 Auto Box Oil Level Check

Started by Serpico, 10 June 2004, 03:06 PM


This question is from a smart arse who has been clever enough to build motor cycle G.P racing bikes and engines that have won and broken lap records in the Isle of Man T.T. The toughest longest, road race in the world.

This same smart arse can't even check the oil on his 50K mile mint show winning 1979 450SE.

I am meticulous about checking levels and tyres etc every week and pride myself on the detailing of my 450.

A month ago I lost reverse drive on the Auto box, first thing I did was check the oil level, everything looked fine spot on, exactly correct on the dipstick. Got the car lifted by an Auto box specialist recommended by the U.K M.B Owners Club. When checking back with the guy he shows me a plastic bucket with less than a egg cup full of fluid that came out when the box needs 2 gallons.

He told me there was no fluid in the box  :?  and I had been getting a false reading, as he he had when he checked the level before starting work on it, this apparently is because the box dipstick shows correct level when in 'P' hot or cold.

That was the most expensive 2 gallon of Auto Transmission fluid in the world at G.B £950 to get the box rebuilt. :(

Anyone know the the exact correct procedure for accurately checking the Auto Box fluid level on a 450SE? I have had this car almost since new and never really spent a penny on it except for meticulous routine servicing and cosumables and loving care.

Where did the two gallon of fluid go?  :?




Here's what the Mercedes Benz owners manual states:

    At regular intervals, check the fluid level of the automatic transmission together with engine oil prior to every long trip, at the latest, however, after every 6,000 miles (10,000 km).

    Check transmission fluid level with the engine idling, parking brake engaged and selector lever in position "P". The vehicle must be parked on level ground. Prior to check, allow engine to idle approx. 1 to 2 minutes.

    Measure oil level with the dipstick completely inserted and locking lever released (1).

    Painstaking cleanliness must be observed!

    To wipe the dipstick, use a clean, lint-free cloth (preferably leather).

    To fill the transmission with fluid, only pour it through a fine-mesh filter into the dipstick opening. Even the slightest impurity may cause operational troubles.

    The oil level in the transmission is dependent upon the oil temperature. The maximum and minimum oil level marks are applicable references only if the transmission fluid has reached its normal operating temperature of 176 degrees F (80 degrees C). -- If, however, the transmission fluid cools down to 68-86 degrees F (20-30 degrees C), which is the normal shop temperature range, then the maximum oil level will be approximately 1.20 in (30 mm) below the minimum mark on the dipstick. We stress this point because an oil change is normally performed when the transmission oil has cooled down to shop temperature.

    The fluid level must not exceed the dipstick maximum mark with the fluid at operating temperature. Drain or siphon off excess fluid, if required.

    Then push dipstick all the way in and swing lock lever downwards (2).
    This is how I do it personally:

    - Warm car up to normal operating temperature (based on gauge on instrument panel or flow of coolant).

    - Slowly cycle through all gears (about 5 seconds in each gear) and place in "P".

    - Take out dipstick, clean it with a shop rag, insert dipstick, count to 10 and check level.

    Other than checking where the fluid level is between the marks, I also check the color of the fluid. It should be a clear, ruby red color with no impurities.

    I would recommend you schedule a transmission flush every once in a while. When this is performed, a machine is hooked up to the transmission lines that replaces the old fluid with new. It does wonders for the transmission!

    As to what happened with your transmission, I'm reserved about the notion of how little fluid you had left inside the transmission. I guess you could verify their honesty quite simply by asking them: "I was told the reaction valve and seal often goes bad on these transmissions. Did you get a chance to check that when you were working on my transmission?". If they say "No", ask why they haven't...

    -- Mike G.


    Many thanks for the reply Mike, I have obviously not used the correct procedure. I have checked when up to temp but never run through the sequence you describe.

    I have also relied on the Mercedes 'Stealerhip' to do routine checks and fluid and filter changes during regular sevicing. Unfortunately they they are across the Irish sea in England where I lived until I retired to Ireland a year ago.

    Will be seeing the employee who actually did the strip and rebuild tommorow at a classic show and I see him once a month at vintage club meetings so will have plenty of opportunity discuss it with him.

    I would have helped myself if I had bothered to read the manual myself instead of relying on the Mercedes shop.

    Tom Loughridge


    I know this isn't directly related to your initial post, but didn't you race Eddie Crooks' Suzuki's at the TT? You've got quite a fame!


    That's me I raced Crooks Suzuki T250 abd T500 Production bikes and a TR250 and TR500 before I switched to Yamaha's. then Maxton Yamaha's

    An interesting classic motor cycle site on the Crooks Suzuki's was set up by a guy called Murray Burnard from Perth W.A. Not sure of the www but if you use Google search engine and search 'Tom Loughridge' you will go straight to it.


    I was going to post a similar topic except I was wondering should the level be checked whilst the motor is running or should the engine be turned off.  I always thought the later was correct procedure following a warm up period however my owner's manual which covers 280's 350's and 450' se and sel's (excl 6.9) says to check whilst engine is running.

    Doing this method there's barely a drop shows up on the dipstick's tip.  Using the warm up period and turning the engine off shows a level just under the top mark.  Otherwise fluid is clear reddish colour.

    If I do as the manual states then my statement in other threads regarding modulator valve and not losing any fluid may be wrong.

    Has anyone got any thoughts to this matter, how do you check your AT oil?
    1973 350SE, my first & fave