On the way to school today my car decided not to shift up from 1-2.But if I put it in N and dropped it to D it would shift up and continue on.

I called my mechanic and he said to go out to my car with it running and remove the black plastic line coming off the blue "UFO" looking device and see if its sucking(by putting it on my tongue.. heh). The modulator diaphram could be leaking and or has shrunk because of the cold and is beginging to fail from cracks.

anyways... I just want to verify that it is not a B2 piston failure since if the B2 failed I would loose any form of shifting up and or down.As soon as I get home I'll pop out my mityvac and test to see if it holds vacuum as well as if it "sucks"


My car has been shutting down slower. Last week when it was mid 70's in the morning and high 80's it would shut down without an issue. Now it "diesels" for a second as it winds down.. typical of a vacuum leak and I have isolated my already known leak, the passenger front door lock.


"My car runs on suck"


**update** hooked the mity vac up to the line going to the modulator and... it does not hold vacuum.. Now I just need to get my transmission code and order one... I bet its been leaking for a while since my shifts sucked, which I attributed to an old transmission -crosses fingers-

Before you order one, check to make sure the little bit of rubber vacuum line down at the modulator that conencts the hard line to the modulator isn't leaking. On my car the modulator itself held vacuum but leaked like a sieve when sucking on the hardline from the engine bay. That piece of rubber vacuum line had hardened and started leaking. FYI, you'll need metric rubber vacuum line as the nearest SAE stuff is just a tad too large to connect to the hard line without leaking.

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'83 300DTurbo http://badges.fuelly.com/images/smallsig-us/318559.png

Broadband: more lies faster.

Silicone vacuum hose has the ability to stretch a lot more than rubber vacuum hose and might be an option if you cannot find metric vacuum hose.

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84 300D, 82 Volvo 244Gl Diesel

I'll give that a look tomorrow since I have to go to work soon. I did go under earlier and take a look and made note that the connection could be leaking.

I also noticed that its very dirty under there(which made it hard for me to find the modulator... green what green.. its all black!).. darn my leaky engine...

I'll remove the fitting tomorrow and test the modulator directly then cap of the line and see if that holds vacuum

what inner diameter of silicone hose would I need if I cannot find the metric stuff

There are three weak points on the modulator before the modulator itself:

1.) the vacuum tubing attachment as previously mentioned
2.) the little black cap that covers the 'T' handle. that thing actually needs to hold vacuum!
3.) the o-ring behind the modulator (you have to take it out for this, so you might as well replace it, unless cash is tight)

check these before ordering a new one. they all could contribute to a leak without the modulator itself being bad.

I also believe the 1985 units have black modulators.

Good luck,
dd

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'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car

if you end up ordering a modulator, make sure you order the pin behind it as well. It does not come with the modulator as I thought it would.

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1982 300CD Turbo (Otis, "ups & downs") parts for sale
2003 TJ with Hemi (to go anywhere, quickly) sold
2001 Excursion Powerstroke (to go dependably)
1970 Mustang 428SCJ (to go fast)
1962 Corvette LS1 (to go in style)
2001 Schwinn Grape Krate 10spd (if all else fails)

I too have hard shifts and was tuning the pin on the modulator today to soften the shifts, no change though in either direction. I noticed the black cap had a crack in it. I did not know this was designed to hold in the vacuum as stated in an earlier reply. I was going to oder a new modulator. Can anyone provide pics and links or a description in what is involved in removing/reinstalling a new modulator? Is it relatively easy to remove? Seems tight under there. Does a new cap come with a new modulator?

Thanks,
Todd

Just unplug the black line to the modulator and run without vacuum to the tranny, it'll shift hard and have very harsh down shifts but if it still won't shift properly then it's an internal issue (ie. B2 piston). The modulator is just there to make the shifting more civilized, and the bowden controls the point at which the shift occurs.

My new modulator came with a new cap. Do a search on the forum. You need to remove the trans. cross brace and drop the rear of the trans down a few inches to gain access. Pull it straight out or you'll break the plastic pin behind it. Clean all the crud around the modulator with brake cleaner before you take anything apart. Cleanliness is a must. Its not that bad of a job , do the research and dive in.

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'83 240D 264k on 100% biodiesel/ 31mpg
83 300D 217K the $800 gem
'82 300D 267K the new WVO project car finished and driving for free
International tractor B275 on B100
Ford 555 backhoe on B100
Sargent 25 ton Rough Terrain crane on B50

As I am waiting for my MityVac to do more troubleshooting on my harsh shifts from 1-2 and 2-3, as I stated earlier, I turned the vacuum modulator pin on the tranny 1 full turn counter clockwise. My question is, can this do any harm to the tranny? I read somewhere not to turn the modulator until all other vacuum components have been tested. Of course, I did not wait. I believe the shifts softened a bit and suspect I could use a new modulator. I just want to make sure by turning the key a full turn CC, that I have not done something wrong that could damage the tranny. Another symptom I have is an early shift to 2-3. As soon as it shifts from 1-2, it immediately shifts to 3rd. Are both of these symptoms vacuum related? Possibly pointing to the modulator?

Thanks again.