300SD Trans Question
 

I'm getting ready to buy an old '81 300SD tomorrow in good shape. Everything works good and drives nice except when the trans shifts into high it slips for a second. No slips after it's in high gear or in any other gear . Only as it shifts to high. It has close to 300K on it I think. Engine was replaced and has only 150K. Any idea what I might be looking at? Trans rebuild?

Thanks for the help.

RE: 300SD Trans Question
 

manual or auto?

RE: 300SD Trans Question
 

Sorry, it's an automatic. I didn't know they made manuals for this model.

RE: 300SD Trans Question
 

Yeah, i have an 81 300 SD that kinda sux at shifting gears. Dont worry about it too much unless you really think its a problem. AIM me at erfaniman if u have any questions about it.

RE: 300SD Trans Question
 

Thanks for the reply. I am not familiar with these 300's but any time a trans is slipping it sounds like a prob to me. I guess i'm just wondering if it's a matter of filters or some other part needing replacement or what. If it's something that doesn't get worse too soon I can live with it. Was this a common prob or just, in this case, 300K of normal wear.

Thanks

RE: 300SD Trans Question
 

My 87 300 D has the same issue. There is an adjustment (modulator valve) for slipping, or better known as flaring. I have tried to adjust the modulator valve to correct this but I haven't been able to. If I adjust the MV for harsher shifts in high gear, it makes the first 3 gear shifts bang too hard.

As these transmissions get high in the mileage, the disc's within the tranny (similar in function to a clutch) get worn and burned. I think the first stages of this wearing show up in upon the shifting point into 4th, or high gear, with flaring a bit until the disc's fully engage. Also, there is the possibility that an internal valve is getting sticky. There is available (AutoZone) a transmission additive that cleans the sticky varnish off all internal parts. I tried it, but it did nothing for me, but I have heard others say it worked like a miracle cure!

I just ease off the pedal a little bit until it's fully engaged into high and hope things wont change too much for another year or more. Rebuilt tranny's go anywhere from $1400 up.

RE: 300SD Trans Question
 

Hey ben, could you specify on the engine cleaner you mentioned? thanks

ALi,
81 300SD 86 320 SDL 91 420 SEL all under 200k each

RE: 300SD Trans Question
 

Thanks for the info. I think I better look for something else or get alot better deal on this one!

RE: 300SD Trans Question
 

Here is a link to an article that may stir you in the right direction for your slipping (flaring) transmission question

http://transmission.articles.mbz.org/k1/


Phil

RE: 300SD Trans Question
 

Thanks for the link on the trans prob. Looks interesting and will give it a try if I get the car tomorrow. Trans probs are good for negotiating car price if nothing else!