vacuum pressure tester for transmission
10-10-2012, 04:36 PM
#1
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vacuum pressure tester for transmission
Hello. Does anyone know which vacuum pressure tool I should buy to test the transmission modulator? I am unsure what fittings I need to test it. So I basically disconnect the line from the modulator then plug it into a test port? Thanks
10-10-2012, 05:36 PM
#2
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Any hand operated vacuum pump will test the modulating control. Disconnect the vacuum line to the modulator and connect the hose from the hand pump. Draw vacuum using the hand pump and verify the modulating valve holds vacuum. If it doesn't, check the rubber cap covering the adjustment pin. If it is cracked or doesn't seal the unit won't hold vacuum. If you can't get the modulator to hold vacuum it must be replaced. If the modulator is good, re-attach the vacuum hose. Go to the engine bay and find the vacuum line under the air cleaner housing that goes down the back of the engine headed to the back. Attach your hand held vacuum pump to that line and draw a vacuum. If the vacuum won't hold then the flexible parts of that vacuum line need replaced.
Mike
Mike
10-11-2012, 12:17 AM
#5
Nordschleife Master
This is a popular choice on the MB forums. I am pretty sure this will work on a 928's version of the 722.xxx trans, but since I own a manual.... It worked flawlessly on my friend's C Class MB as well as mine once I borrowed his gauge set-up. Obviously, check the specific pressure values of the 928 Rogerbox. They are all different. Also, I am not sure if the test port is in a similar place next to the modulator valve.
http://www.benzworld.org/forums/w202...urching-2.html
and another thread: http://www.benzworld.org/forums/w201...l-replace.html
The pictures below show the story. This is my interpretation of a post on Wikipedea except this shows a 722.423 Tranny instead of an '82 Diesel. The first picture show the Gauge I bought at Harbor Freight for $5.99 (had a coupon) and the Banjo Bolt set-up that came from a local M/B wrecking yard $20.00 Oddly enough the Banjo Bolt dealy hooks to something called an ALDA on Turbo Diesel M/B's. It's odd because that is what we call our C, since it was first owned by a woman who's first name was ALDA.
The Banjo Bolt/Wet Washer set-up gets cut in half and assembled with a hose long enough to reach the Driver's window.
The next pictures show the Modulator and the Pressure Port where the Modulator pressure is taken. There are two other ports like this one for other readings. The bolt takes a 12mm wrench. The Banjo Bolt and Wet Washer are installed in place of the bolt next pic.
Next you unhook the Vacuum to the Modulator and plug the Vacuum porton the Manifold.
Start the car and read the pressure and take note, also check for leaks. If all is OK, go for a drive and hang the Gauge through the Drivers window. Drive 30mph in 4th and take another pressure reading.
Mine idled at 70lbs. and drove at 68lbs. Supposed to be at 53.66lbs.
I made a 90 degree small screwdriver to fit in the Modulator and that is what you see in the picture protruding from the Modulator. Start the car and turn the screw adjustment on the Modulator Clockwise for up and Counterclockwise for down. I dialed mine down as you see in the picture adjusting the pressure down below 53.66 slightly to make up for the 2lb. drive/idle differential. You could also drive the car with the Gauge hooked up again if you are really picky. From what I have read, most M/B Mechanics do not need to drive the car. I put her back together and she drove better than ever, with no more flash shifting!
I haven't talked to him in a bit, but would be happy to ask to borrow the set-up if you had trouble sourcing any of the parts required.
His pics.
http://www.benzworld.org/forums/w202...urching-2.html
and another thread: http://www.benzworld.org/forums/w201...l-replace.html
The pictures below show the story. This is my interpretation of a post on Wikipedea except this shows a 722.423 Tranny instead of an '82 Diesel. The first picture show the Gauge I bought at Harbor Freight for $5.99 (had a coupon) and the Banjo Bolt set-up that came from a local M/B wrecking yard $20.00 Oddly enough the Banjo Bolt dealy hooks to something called an ALDA on Turbo Diesel M/B's. It's odd because that is what we call our C, since it was first owned by a woman who's first name was ALDA.
The Banjo Bolt/Wet Washer set-up gets cut in half and assembled with a hose long enough to reach the Driver's window.
The next pictures show the Modulator and the Pressure Port where the Modulator pressure is taken. There are two other ports like this one for other readings. The bolt takes a 12mm wrench. The Banjo Bolt and Wet Washer are installed in place of the bolt next pic.
Next you unhook the Vacuum to the Modulator and plug the Vacuum porton the Manifold.
Start the car and read the pressure and take note, also check for leaks. If all is OK, go for a drive and hang the Gauge through the Drivers window. Drive 30mph in 4th and take another pressure reading.
Mine idled at 70lbs. and drove at 68lbs. Supposed to be at 53.66lbs.
I made a 90 degree small screwdriver to fit in the Modulator and that is what you see in the picture protruding from the Modulator. Start the car and turn the screw adjustment on the Modulator Clockwise for up and Counterclockwise for down. I dialed mine down as you see in the picture adjusting the pressure down below 53.66 slightly to make up for the 2lb. drive/idle differential. You could also drive the car with the Gauge hooked up again if you are really picky. From what I have read, most M/B Mechanics do not need to drive the car. I put her back together and she drove better than ever, with no more flash shifting!
I haven't talked to him in a bit, but would be happy to ask to borrow the set-up if you had trouble sourcing any of the parts required.
His pics.
10-11-2012, 12:19 AM
#6
Nordschleife Master
or just listen to Tails.
10-15-2012, 05:31 PM
#7
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Sorry for the late replies the vehicle will not up shift from second. their is no slack in the bowden cable. Also how loud is the kick down solenoid sound? Is their an electrical way of testing it? I bought a might vac vacuum tester from autozone and disconnected the vacuum line from inside the engine back and it help pressure. when it decides to stop raining i will raise the car up and check to see if the modulator will hold pressure then try and adjust it. Alright this is slightly confusing. Now do I unplug the vacuum cable from the transmission modulator and plug the tester into the spot where I unplugged the cable from (to see if it will hold pressure)? Now adjusting the modulator, is the vacuum line that comes from the engine bay plugged in when I do the adjusting?
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10-15-2012, 05:58 PM
#9
Rennlist Member
This is a popular choice on the MB forums. I am pretty sure this will work on a 928's version of the 722.xxx trans, but since I own a manual.... It worked flawlessly on my friend's C Class MB as well as mine once I borrowed his gauge set-up. Obviously, check the specific pressure values of the 928 Rogerbox. They are all different. Also, I am not sure if the test port is in a similar place next to the modulator valve.
http://www.benzworld.org/forums/w202...urching-2.html
and another thread: http://www.benzworld.org/forums/w201...l-replace.html
The pictures below show the story. This is my interpretation of a post on Wikipedea except this shows a 722.423 Tranny instead of an '82 Diesel. The first picture show the Gauge I bought at Harbor Freight for $5.99 (had a coupon) and the Banjo Bolt set-up that came from a local M/B wrecking yard $20.00 Oddly enough the Banjo Bolt dealy hooks to something called an ALDA on Turbo Diesel M/B's. It's odd because that is what we call our C, since it was first owned by a woman who's first name was ALDA.
The Banjo Bolt/Wet Washer set-up gets cut in half and assembled with a hose long enough to reach the Driver's window.
The next pictures show the Modulator and the Pressure Port where the Modulator pressure is taken. There are two other ports like this one for other readings. The bolt takes a 12mm wrench. The Banjo Bolt and Wet Washer are installed in place of the bolt next pic.
Next you unhook the Vacuum to the Modulator and plug the Vacuum porton the Manifold.
Start the car and read the pressure and take note, also check for leaks. If all is OK, go for a drive and hang the Gauge through the Drivers window. Drive 30mph in 4th and take another pressure reading.
Mine idled at 70lbs. and drove at 68lbs. Supposed to be at 53.66lbs.
I made a 90 degree small screwdriver to fit in the Modulator and that is what you see in the picture protruding from the Modulator. Start the car and turn the screw adjustment on the Modulator Clockwise for up and Counterclockwise for down. I dialed mine down as you see in the picture adjusting the pressure down below 53.66 slightly to make up for the 2lb. drive/idle differential. You could also drive the car with the Gauge hooked up again if you are really picky. From what I have read, most M/B Mechanics do not need to drive the car. I put her back together and she drove better than ever, with no more flash shifting!
I haven't talked to him in a bit, but would be happy to ask to borrow the set-up if you had trouble sourcing any of the parts required.
His pics.
http://www.benzworld.org/forums/w202...urching-2.html
and another thread: http://www.benzworld.org/forums/w201...l-replace.html
The pictures below show the story. This is my interpretation of a post on Wikipedea except this shows a 722.423 Tranny instead of an '82 Diesel. The first picture show the Gauge I bought at Harbor Freight for $5.99 (had a coupon) and the Banjo Bolt set-up that came from a local M/B wrecking yard $20.00 Oddly enough the Banjo Bolt dealy hooks to something called an ALDA on Turbo Diesel M/B's. It's odd because that is what we call our C, since it was first owned by a woman who's first name was ALDA.
The Banjo Bolt/Wet Washer set-up gets cut in half and assembled with a hose long enough to reach the Driver's window.
The next pictures show the Modulator and the Pressure Port where the Modulator pressure is taken. There are two other ports like this one for other readings. The bolt takes a 12mm wrench. The Banjo Bolt and Wet Washer are installed in place of the bolt next pic.
Next you unhook the Vacuum to the Modulator and plug the Vacuum porton the Manifold.
Start the car and read the pressure and take note, also check for leaks. If all is OK, go for a drive and hang the Gauge through the Drivers window. Drive 30mph in 4th and take another pressure reading.
Mine idled at 70lbs. and drove at 68lbs. Supposed to be at 53.66lbs.
I made a 90 degree small screwdriver to fit in the Modulator and that is what you see in the picture protruding from the Modulator. Start the car and turn the screw adjustment on the Modulator Clockwise for up and Counterclockwise for down. I dialed mine down as you see in the picture adjusting the pressure down below 53.66 slightly to make up for the 2lb. drive/idle differential. You could also drive the car with the Gauge hooked up again if you are really picky. From what I have read, most M/B Mechanics do not need to drive the car. I put her back together and she drove better than ever, with no more flash shifting!
I haven't talked to him in a bit, but would be happy to ask to borrow the set-up if you had trouble sourcing any of the parts required.
His pics.
Great post!
I have to admit..our modulator/etc are muuuch easier to get to.
10-15-2012, 07:08 PM
#13
Chronic Tool Dropper
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Need to get the right sized one, but there are two sizes on the steering rack that, along with a used/leaking steering hose as a banjo fitting donor, might be the core of a similar DIY pressure gauge kit for our cars.
When looping the hose from the side of the trans to go up to where you can see it while driving, the hose WILL be in close proximity to the exhaust system. Choose hoses, routing and insulation carefully so you don't cause a fire.
When looping the hose from the side of the trans to go up to where you can see it while driving, the hose WILL be in close proximity to the exhaust system. Choose hoses, routing and insulation carefully so you don't cause a fire.
10-15-2012, 07:32 PM
#14
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When I set the modulating pressure on my '90 I was able to route the hose over the top of the DS primary muffler heat shield and between the rear lower control arm link pin mount and the body. It was kind of a limbo to get into the driver seat without dropping the gauge or closing the hose in the door but it is do-able. I was able to drive and see the gauge at the same time to read off the modulator pressure.
Mike
Mike
10-15-2012, 08:54 PM
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Still have not had time to lift up the car (still raining outside), but what I did was turn the key into the on position and press down on the kick down switch underneath the pedal. I did not hear anything from the transmission. I am starting to think this transmission needs the modulator pressure adjusted, a new kick down solenoid and those $10 springs to make it up shift.
