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Hello All,

This regards my 1989 300SE with 233k miles. With my transmission issues (the car first downshifts from 4th to 3rd, then won't go past 3rd, then downshifts from 3rd to 2nd, then won't go out of 2nd), the feedback is that the problem is most likely an issue in my valve body. Before pulling my valve body and working on it myself, I was looking into purchasing a rebuilt one.

In my search, I came across a thread elsewhere that said the valve body can be adapted to allow for first gear start at all times. I would LOVE this feature. Is this true? Is this easily done? And are there instructions anywhere on how to do it? Because if that's the case, I'll be rebuilding and adapting my valve body myself.

Thanks,
Bill
 

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Did you check that o-rings on kick down solenoid valve or the valve itself are not leaking?
 

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Did you check that o-rings on kick down solenoid valve or the valve itself are not leaking?
I have. Good idea, though.

I have checked and looked at everything external. The car did this transmission thing when I bought it and drove it to our warehouse. I changed the fluid and filter, and it worked for a couple days. Then it started downshifting and refusing to upshift again. I looked at the entire kick down system, including the relay. I looked at the bowden cable. I looked at everything that was an external possibility. Eventually I added some Tans-X and the transmission ran perfect for about 800 miles. Then I took it on the interstate (for the 2nd time ever) and its been down hill ever since. The thought now is that something was sticking in the valve body, and the Trans-X loosened it. But it's sticking again.

My ATF looks cherry red on my dipstick. But when I syphon some out through the fill tube, it's almost brown. It may be another filer and fluid change may do it. But I'd just as soon rebuild/replace the valve body when I'm down there again.
 

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Did you check that o-rings on kick down solenoid valve or the valve itself are not leaking?

I understand that module only works on the 8-cylinder engines. Thanks though.
 

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Hello All,

This regards my 1989 300SE ...

In my search, I came across a thread elsewhere that said the valve body can be adapted to allow for first gear start at all times.
I believe the 300 has 1st gear start even if it is a North America model.

Maybe the lack of 1st gear start is related to your other transmission issue.
 

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To check solenoid valve seals you have to unscrew the valve. Threshold of being internal...
Hmmmm... I disconnected and reconnected the solenoid. I have not removed the solenoid. I thought I could see any leaks externally. I'll look into this. Thanks.
 

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Discussion Starter #8
I believe the 300 has 1st gear start even if it is a North America model.

Maybe the lack of 1st gear start is related to your other transmission issue.
I appreciate the suggestion, and I'd love for that to be accurate. I don't think so, but I'll keep digging.

Right now it will start in 2nd, and kick down into first with the gas pedal fully depressed. Also, I can do the thing where if I'm stopped, I place the transmission in 2 and then back to D it will start in 1st. But I want to always start in first.

I was told I can adjust the bowden cable to where it will do that, but I haven't been able to find that adjustment. The best I get is that kickdown.
 
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