Valve Adjustment

[tobybul]

How would I know if my 300D's need valve adjusting?

[Hit Man X]

Ever done it on your car before? If not, I'd go ahead and do it.

You'll notice a drop in performance. Harder starting. Etc.

[barry123400]

The only way you can know unless the situation is pretty well out of hand is to check them every fifteen thousand miles. They may or may not but thats about the only way to know. You should get faster everytime you do it for the first few times. If you do not check them on the early mercedes gas cars every 10K you get to pull the head and replace the burnt exhaust valve. After a couple of times I never missed a 10k check on the ones I owned. Less likely on the 1970s cars and up as they increased the interference fit on the adjusters a lot. Too many diesels are owned by past owners that felt if it runs it's a diesel so do nothing. A valve check is worthwhile on most all piurchases. As mentioned in the last post they can cause problems if left too long a time.

[SD Blue]

Originally Posted by tobybul

How would I know if my 300D's need valve adjusting?

With a feeler guage.

(As Hitman said, if you haven't done it and don't know the last time it was done, it would be best to go ahead and check them.)

Every 15,000miles or once a year.

[pawoSD]

I've been cheating, I did it twice around 15-16k and they said that they weren't much out of adjustment....so I am going to have it done around 250-251k, which is just over 20k since the last adjustment. It runs flawlessly and starts on the first crank even when its 25F outside....so they are probably pretty close.

[tobybul]

My 84 & 85 start at first crank all the time... I was wondering more about sounds from the engine to listen to besides the diesel sound....

Is the DieselGiant valve adjustment guide a good one to follow?

[Shorebilly]

Howdy,

I like the once a year approach....

When I was working on the Big diesels, I would walk the valve covers every morning.....one would be surprised what one can "feel" thru the feet....

SB

[Ken300D]

I think the safest recommendation is to adjust the valves whenever you get a new-to-you vehicle that requires this procedure, and from that point on follow the 15k miles maintenance interval. This will keep the valves and their seats in optimal condition - that's why MB specifies the maintenance cycle.

Ken300D

[tscorda]

615, 616, 617 manual says every 15K. Just did my 1979 240D after having not done in in 20,000 miles only one valve was a little tight. If you drive alot, once a year is probally the dab that'll do ya

Takes about an hour and hour and 1/2. For meputting the valve/cam cover on is always the hardest step for some reason.

Clean your feeler gauges good after use. Always replace the rubber gasket with a new one. Check your timing while your are in there.

Regards Tom

[Diesel Giant]

Here is how to do it. It will make a very NICE difference in how the car starts and runs.

http://dieselgiant.com/valveadjustment.htm

Just did one on a 300d and it idles like a kitten sleeping.

I'm ashamed to admit this, but my second 240D, an '84 Euro model, went several hundred thousand miles without every pulling the valve cover. When I finally got a wild hair one day and decided to check them, they were not far off at all.

Unless you are not changing oil very often or have some reason to believe that the valves are not staying set as well as they should, I think 15,000 miles is overkill.

I have been criticized and even TORMENTED for my frequent, hot overnight drain oil change regimen, but I think that it was at least partially responsible for my lack of valve train wear.

[SD Blue]

Welcome back Larry! Have things slowed down a bit...... enough to catch your breath?

Probably the important thing is to at least check them, especially if the vehicle is new to you. (Mine were all set, intake and exhaust, to 0.1mm from the PO.)