Kevin in Atlanta

Mercedessource is discounting their Modulator Pressure Gauge testing kit 15% for Halloween here: 61x Diesel Automatic Transmission Modulator Pressure Test Kit

I ordered one.

MjRocket

Kevin I'll just borrow yours. ; )

Kevin in Atlanta

No problem. You pay shipping both ways and we have a deal

careful1

Got that one...fellow rennlister ihoe informed me about it. Payed full price because that seems to be the way "I roll".

MjRocket

Just ordered one...Thanks for the heads up Kevin.

MainePorsche

That kit is nice for checking the modulator pressure.
This kit has two gauges with ranges to cover modulator and operating pressures. Also has multiple adapters in metric and standard, and comes in a nice case. Operating pressure is beyond the range, or close to the extreme on the Mercedssource gauge.
Good for other vehicles, uses too.

fonetico

This is a rather timely thread for me as I'm about to embark on a modulator valve replacement. I'm a complete amateur as far as the transmission is concerned and I'd like some advice as to whether I should leave it to an expert.

To some degree the gear box has always been covered in fluid. I had the mod valve changed when I first bought the car but I can't remember whether the fluid leak was apparent then or whether it started subsequently. It lasts about six months before I notice erratic gear changes and on four occasions my friendly Porsche expert has serviced the gear box with replacement filters, gaskets and most recently with a new oil pan. With the correct fluid level the gear changes are perfect.

But it still leaks!

Last week I decided to risk it and see whether I could find the leak myself. My strategy was to thoroughly clean the underside and make a number of short runs followed by thorough inspections.

I didn't take long to discover the modulator valve was slowly being immersed in fluid with it even appearing in the vacuum line.

So, am I biting off more than I can chew? Can I assume pressure readings are already ok and all I need is a straight swap and everything should work as expected? Is the adjustment for hard/soft changes straightforward and won't need other complicated adjustments?

Kevin in Atlanta

Good point. In my case I already have an oil pressure gauge for that purpose that will connect to the lines provided in the kit.

MainePorsche

If you can get the car up, level, have basic tools and willingness, it is an easy job. A ratchet, socket (10mm I think), small extender or deep socket, torque wrench, rags. Simply remove and replace. Be sure you'd have the thrust pin/plunger in place. The modulator should come pre-set from the factory. Fits in with the vacuum stub at about 10 0'clock. You might want to drain a fluid to minimize egress. Adjustment is very simple if needed. While under, I would give a good hand wipe down and inspect for other leak points - there are multiple possibilities. See the links I posted for the OP previously for the 722 transmission.

MainePorsche

Another reparative, or preventative maintenance, item would be the O-ring for the control pressure control (Bowden cable) coupler to the transmission. The Bowden cable goes into the transmission on the Right side of the unit. It is a white conical shaped piece of plastic with the cable entering at the apex. If I recall, I first detached the Bowden cable up top at the manifold to give me more slack (it is a ball/cup attachment on the labeled cable in the image). Then detach the white conical piece. I believe at its base there was a pinch tab and then you turned CCW. This will allow you to lift the 'cone' up to see the linkage which must be detached to get the O-ring off/on. The cable attaches to a thin flat piece of metal with a hole at the end. The transmission end is a thin rod with a right angle bend at the end which sits through that hole for its linkage (#3 in the image). Just slip it out of the hole - remove old O-ring and slip over - replace new one the same way - re-attach the rod through the hole - then re-attach in reverse step. This is a known leak point on the Right side. It is a trifle tedious for visibility is not the best, and your third hand always seems to be absent. Thin long needle nose pliers are needed here.

fonetico

Eternally grateful.

careful1

fonetico, on the modulator ,It really helps to take the bolts out of the heat shield and move it as far out of the way as possible. Also pop off the shift cable making sure not to lose the small wire keeper . I used a socket Allen with a short extension to get the Allen bolts out. I also used an Allen wrench on the most forward bolt because when it is loosened out it runs out of room.

Craig (MainPorsche),I've got everything buttoned up so I'm ready to fine tune the shifting. What do you suggest? Thanks,Doug.

SMTCapeCod

Well now if the WYAIT train is leaving the station, see the B2 servo threads by Landseer.

And the shift flare correction kit for the valve body.

Both above are factory updates.

MjRocket

Craig

What is the shift flare correction kit? Please elaborate.

Thx

SMTCapeCod

See/search MB Valve Body Kit: 126 270 44 77 for the stock type.

http://www.peachparts.com/shopforum/...it-piston.html