I've had my '84 300D for about a year and have run into a clanking noise coming from somewhere underneath the car, but only after long drives (about 2 hours or so). Other than that it runs great. It seems to clank at a faster rate when I am accelerating.
Does anyone have any thoughts on what the problem is? I know I haven't given much to go on. This is a great site, by the way, it's answered many nagging questions for me (usually i can find my answer using a search). Thanks.

My best guess would be something with the exhaust. I noticed that my car after a long drive sometimes when idling will make a clanking sound too but it's the exhaust hitting the suspension in one place, it's badly welded but it dosn't bother me. On the other hand, my dads acclaim clunks like no tomorrow because the honey comb in the catalyctic converter is loose, the hotter the exhaust gets the stranger noises it makes. It's all I can think of, I would not say it can be engien related cause engine you will hear from the beginning to the end, so it is most likely something that changes shape a bit once heated up, like exhaust.

xp

Thanks XP. I plan on taking the car to have a few things looked at soon (A/C mainly) and i will have them take a better look at the exhaust. It looks to me like the rear portion of the exhaust is fairly new but the front portion is a little rusted. thanks for the advice....

davetrif-another new englander !! - could suggest besides the exhaust which could be a likely culprit they / you also check diff oil -excessive play in the diff, and 1/2 shafts.

btw,watch the diesel forum for the next n.england gtg!

__________________
1984 300D Turbo - 231k....totalled 11/30/07 RIP

Thanks. Now i have a new problem. On my way home today my brakes were very sluggish and the engine won't shut down right away. From what i've been reading here it must be some type of vacuum problem. Any suggestions?

make sure there is no leak or blockage in the brake booster line leading from the vaccuum pump on the front of the engine and also the 'tee' fittings in the line are open/clear. do a search on the diesel forum.. you will find a wealth of info on those subjects there.

__________________
1984 300D Turbo - 231k....totalled 11/30/07 RIP

The vacuum pump is pretty sturdy on the 82-85 300D cars. However, the check valves can gum up and stick, and there is one check valve on the output of the pump (that is, vacuum side) that is known for breaking or dislodging.

You can take the front cover off the vacuum pump once you pull off the fan. The fan comes off with four bolts. Inside, there are three round check valves about the size of a nickel that you can pop out and clean. On the output pipe, you might find pieces of the output check valve, like a spring and a plastic piece.

On my car, the plastic piece on the output check valve managed to get exactly lodged against one of the other check valves and blocked it off. It is now functioning fine without that output check valve.

Of course, before you tear into the vacuum pump, you really should take a vacuum reading with a gauge, and look for a broken or cracked vacuum line running from the vacuum pump to the brake vacuum assist unit.

Ken300D

__________________
--------------------------
1982 300D at 351K miles
1984 300SD at 217K miles
1987 300D at 370K miles

Thanks for all the info. I will be following up on it in the next couple of days. Funny after parking my car about an hour away when i had the brake problem, i went back to retrieve it and drive it as is. Not far into the return trip the brakes were normal again and when i shut it off it turned right off. But i will be checking the vacuum pump. thanks again