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Transmission flaring, sometimes

Started by ColMustard, 14 May 2011, 11:06 AM

Squiggle Dog

Quote from: BWalker82 on 19 May 2011, 07:47 PM
I seem to have no first gear at all.  When I select L it starts in second.  And when I use the kickdown switch, it blows the fuse. 

I think that if you replace the kickdown switch all will be well. If the kickdown solenoid were bad I think that it would blow the #4 fuse immediately when the key was turned.
Stop paying for animal cruelty and slaughter. Go vegan! [url="https://challenge22.com/"]https://challenge22.com/[/url]

1967 W110 Universal Wagon, Euro, Turbo Diesel, Tail Fins, 4 Speed Manual Column Shift, A/C
1980 W116 300SD Turbo Diesel, DB479 Walnut Brown, Sunroof, Heated Seats, 350,000+

ColMustard

Hey all, thanks again for the wealth of information. Been really busy recently, picked up a tach amp, window trim for the rear, and replaced the driver side regulator. The windshield seal came in yesterday from mbklassik :D yeah, havent had much time to fool around with the transmission. Im going to refer to that link and see what can or cant be done. For the time being, ive beem manipulating it so it doesnt flare. yes the car was sitting for a time before I got it. Then I drove it around for a summer and then put it away for quite some time, and now have been driving it everywhere. I will get back with further information as I get time to diagnose. Sounds like a vacuum gauge purchase is in order:)

BWalker82

Quote from: Squiggle Dog on 19 May 2011, 09:30 PM
Quote from: BWalker82 on 19 May 2011, 07:47 PM
I seem to have no first gear at all.  When I select L it starts in second.  And when I use the kickdown switch, it blows the fuse. 

I think that if you replace the kickdown switch all will be well. If the kickdown solenoid were bad I think that it would blow the #4 fuse immediately when the key was turned.

Thanks, Squiggle, I will try that! 

Big_Richard

i dont know about that - doesn't the switch just sent +12v to the kick down solenoid ?

if so the short is going to be in the wiring from the kick down switch to the solenoid or the solenoid coil itself.

Squiggle Dog

Quote from: Major Tom 6.9 on 20 May 2011, 05:12 PM
i dont know about that - doesn't the switch just sent +12v to the kick down solenoid ?

if so the short is going to be in the wiring from the kick down switch to the solenoid or the solenoid coil itself.

I think that if the switch is shorted out it will pop fuses when used. I'm not sure about it not allowing first gear to function, though.
Stop paying for animal cruelty and slaughter. Go vegan! [url="https://challenge22.com/"]https://challenge22.com/[/url]

1967 W110 Universal Wagon, Euro, Turbo Diesel, Tail Fins, 4 Speed Manual Column Shift, A/C
1980 W116 300SD Turbo Diesel, DB479 Walnut Brown, Sunroof, Heated Seats, 350,000+

BWalker82

Thanks for the guidance.  I'm gonna try to swap that switch in the near future and see if that helps any.

Is the transmission discussed anywhere in the online maintenance manual? 

Squiggle Dog

Quote from: BWalker82 on 21 May 2011, 08:17 AM
Thanks for the guidance.  I'm gonna try to swap that switch in the near future and see if that helps any.

Is the transmission discussed anywhere in the online maintenance manual? 

Not that I know of, and it seems unavailable online. I really wish that I had a transmission manual when I replaced mine.
Stop paying for animal cruelty and slaughter. Go vegan! [url="https://challenge22.com/"]https://challenge22.com/[/url]

1967 W110 Universal Wagon, Euro, Turbo Diesel, Tail Fins, 4 Speed Manual Column Shift, A/C
1980 W116 300SD Turbo Diesel, DB479 Walnut Brown, Sunroof, Heated Seats, 350,000+

TJ 450

The transmission manual is a separate publication unfortunately. There was a PDF version floating around somewhere though... As to its whereabouts, my memory fails me. 8)

I will say however, that the special "bolt" (for lack of a better term), needs to be tightened to a specific torque, as it is the actual valve and is sealed with o rings. The box around it is simply the solenoid coil itself and that's all.

Beware though, as I have a sneaking suspicion that access to the valve will be somewhat difficult with the transmission in situ. I might suggest you should test that coil with a multimeter before jumping to conclusions about its failure.

Indeed, the kickdown switch sends +12v down to the coil, which grounds out through the transmission casing. I suspect a likely cause of the issue is that the wire could have suffered chaffing on the body and shorted.

As a test, I would remove the terminal from the solenoid, tape it off and try and operate the kickdown switch. If the fuse blows, you have an issue upstream of the solenoid, if not you have isolated it to the solenoid.

It is always a good idea when troubleshooting these sorts of problems to use a systematic approach and definitively eliminate elements of the system starting from one end and work in a linear fashion rather than jumping around all over the place in a fragmented fashion... This is what I have found anyway.

Tim
1976 450SEL 6.9 1432
1969 300SEL 6.3 1394
2003 ML500