300SD transmission acting up, need advise.

[John Winn]

Good morning.
Over the weekend my 84 300SD transmission started acting up. 1-2 shift is fine, 2-3 shift is fine, 3-4, no 4!! I checked the fluid level and it was about 3/4 quart low and I added fluid, and after a bit of driving it finally started shifting fine again. Sunday morning, same thing, but straightened out pretty quick. Yesterday morning, I couldn't get fourth at all..I know that 1-2 and 2-3 problems are usually adjustments, but what is likely when the 4th gear quits?? Is this the "B2 piston failure? When it is doing it, it goes straight into neutral...Acts almost like something is sticking because when it straightens out (if it does) it is back to normal and shifts great...What should I look for? She has 191,000 miles...I know a trans is in my future anyway because the front seal leaks, and I don't want to put 600+ into a high mileage trans but if I can prevent spending 2500+ right now that would be great..The local dealer quoted me a lower price for a rebuilt installed (22-2400)(correction, see comments below)than my local benz shop who said about 2600. Any recommendations would be really great..I live in Austin TX by the way...John
PS, I posted this message in the tech help section yesterday and thought I would post here too..The problem comes and goes..Today it has been shifting perfect..Sure seems like something is sticking intermittantly..I went to the dealer yesterday and they want $2150. for the trans and 700. to install..Someone had mentioned ordering from someplace but I am concerned what would happen warranty-wise on one shipped in...Any thoughts on this phantom problem anyone?? Thanks a billion!!! John

[william rogers]

I had my trasmission on my 81 sd back flushed at a local lube shop it cost 80 dollars ,the fluid looked fine on the dip stick but when it came out of tranny during the back flushing it was very dirty , it shifts better now, might be worth an 80 dollar gamble..
William Rogers.......

[can-do]

Greetings John,

I wish I had an answer to your problem but feel that we both may share the same problem. I have a 300TD that if I let it shift by itself, I feel 1st to 2nd, and 2nd to 3rd, but no shift feeling from 3rd to 4th, like it happens without notice or not at all. I tried manually shifting it, and all seems well, except I don't think it downshifts under a load going up hill unless I punch it to the floor to engage the downshift switch. Shouldn't it down a gear with the tranny linkage from 4th to 3rd, and the switch on the floor from 3rd to 2nd? You would think as you are losing RPM's going up hill that it would downshift to keep your rate of speed. Any info you can provide would be great. If your's operated fine before this problem, I would suggest draning the tranny fluid and replacing the filter to get perhaps the gummed up valves loosened by some new fluid flowing through it. I personally think I need to get my linkage fixed first. Maybe you can shed some light on my problem, as I haven't owned this oil burner long enough to know how it should respond.

Thanks,


Charles

[longston]

Normal automatic transmissions in gasoline engines shift via the vacuum produced by the gasoline engine, but the automatics on diesel engines need to have vacuum produced by a separate vacuum pump.

After that having been said, it isn't unusual to have to manually shift one of these transmissions, or to have them need to be kicked down on hills by "flooring it".

Y'all ain't the Lone Rangers heah, it's just the nature of the beast! And john, I'd take that transmission problem to a reputable Independent garage, or even to AAMCO before I had the dealer gouge my wallet out of my pants. After all, transmissions are transmissions, even in a mystical Mercedes...

Perhaps all your problems are vacuum related, and not transmission problems, but I would still suggest a fluid and filter change before you see varnish or discoloration in the fluid... And consider Redline http://www.redlineoil.com, or another synthetic fluid when you do change the fluid.