Last night I got my valve cover gasket in the mail, so decided to do my 300TD's (OM 617) valve adjustment right then and there. I thought I'd relay my experience to help those who follow... It was my first time, so I probably made a lot of little mistakes that someone else would like to be warned of.

First off: I removed all the linkages from the top of the valve cover, because I wanted to polish up the cover a little bit. The four 13mm bolts on top, and the two 5mm allen bolts on the side were a pain to remove. When I reassembled, I used some anti-sieze compound, like the previous assembler neglected to do! Whenever bolting steel to aluminum, you should really use a little slather of anti-sieze to prevent chemical welding.

I marked the linkages with a system of sharpie marks. One slash to one slash, two slashes to two slashes, three slashes to three slashes, etc. Reassembly was a breeze.

Here was my big problem:

My valves were mostly tight. One or two of my intake valves were in spec, but everything else was between a little, and a lot tight (it had been about 20,000 miles since the last valve adjustment). The car had been running pretty well, but was a little stumbly on cold starts, and mileage had dropped a bit.

I adjusted all the valves with homemade wrenches by immobilizing the bottom nut, and loosening the top nut by turning it counterclockwise. Then, I tweaked the bottom nut, turning clockwise to loosen the valve, and counterclockwise to tighten the valve, until the clearance was right. Then I tightened the top nut, and moved on. That was BAD. I restarted the car after reassembly, and it ran like crap! stumbling, misfiring, etc. Very bad!

I disassembled, checked my valves, and they were all WAY too loose!

Thats when I made a revelation: The bottom nut is the valve adjustment nut, but the position of the top nut still affects the position of the valve. You have to adjust the bottom nut, tighten the top nut, and THEN check your clearance! So loosen the top, make your adjustment on the bottom, then retighten the top, and check your status.

After going through and readjusting every single valve, I reassembled, and everything sounded great! Whew!

Another tip: I made my own wrenches by bending approximately in the same places as the Hazet wrenches, by looking at a picture. I had to grind the lower wrench down quite a bit so it would fit the thin nut, and I had to widen the mouth on my two wrenches, because those 14mm nuts are really 14mm! My wrenches barely fit at first.

I had some trouble with a few of the valves not adjusting properly. The bottom spring and large flat nut on the spring would rotate along with the adjustment nut... I was able to solve the problem by lightly grabbing the large flat nut with a crescent wrench, while adjusting the bottom nut. However, it was a little tricky. I guess thats what the third Hazet wrench is for.

Anyway, after polishing the valve cover (half assedly, because it was now very late at night), reassembling, lubing up all the linkages, and bolting it all back together (this time with antiseize compound), and torquing the valve cover to 11ft/pounds (lighter than you think you should do...), everything works great! Thanks for the advice I've gotten on the board, couldn't have done it without you.

peace,
sam

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"That f***in' biodiesel is makin' me hungry."

1982 300TD Astral Silver w/ 250k (BIO BNZ)
2001 Aprilia SR50 Corsa Red w/ 5.5k (>100 MPG)