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240D potential transmission failure
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I suspect that what I have is a auto trans failure and I'm looking for wisdom from this collective group of guru's. The car is an 83 240D. So here is the story.
About 4 months ago this trans problem first appeared. I went to the store, put the car in park and left the engine running. After returning I put the shifter into drive and the car would not move at all. I cycled through the all gears which didn't produce any movement in the car. I turned the engine off and let the car sit for about 5 minutes. Once I re-started the engine, I was able to drive home without a problem. Checking out the VCV it was discovered to be bad, so I replaced it. I installed both a vacuum and pressure gauge to assist in both knowlege of what the trans was doing but also hopefully if this problem re-occured I could trap something. This was back in september of 2013. Fast forward to 1/18/2014. I was headed home and sitting at a stoplight. When the light turned green, I pressed the GO pedal and as the rpm's increased, the car stay motionless. Looking over at the pressure gauge, the reading was 0. It should normally be around 20 psi at idle. I tried the same trick which had worked 4 months ago and turned the engine off and let it sit for about 2 minutes this time. After re-starting the car, I got pressure and quickly tried get the car moving. It did move but soon started slipping with a fluctuating needle on the pressure gauge and then went to 0. Stepping on the pedal resulted in just the engines rpm's going up. This happened a few other times going home which was about 1/4 mile away, but I got home. Once in the driveway, the pressure again went to 0. I was hopping that the fluid levels where low, but the opposite occured. The fluid was about 1 to 2 inches higher on the stick than it should have been. The fluid looked pink and didn't smell. I didn't give the fluid level another thought until today. More about that in a little bit. Today upon starting the car, the pressure went up to 20 psi and was steady as it has been since installing the guages a few months ago. I was able to shift through all gears and moved the car forward and backward in the driveway. All of a sudden the pressure dropped to 0 resulting in no power to the rear wheel. Before the pressure dropped to 0 and was holding steady at 20 psi I checked the fluid level at idle and in drive. It was right on the mark between full and add. I have my suspicions and I have one more pressure check to do and that is the working pressure. I'll get a connector and a gauge to do this today, but as I've mentioned I'm looking for the collective wisdom of the forum. Here are pic's of what I've found so far: Pic3G1 shows vacuum to the VCV and pressure at idle Pic5G2 shows vacuum going down and pressure starting to rise as rpm's are increased to around 1k. Pic6G3 shows vacuum on acceleration but pressure needle started fluctuating and dropping towards 0. After the pic was taken the needle moved back to 20 psi. Thanks you in advance |
Hmm
Isolate the modulator
Use your hand pump to verify the modulator holds vacuum. I don't recall if you replaced the filter, could it have fallen off? The symptom sounds suspiciously like several recent units that had a broken spring in the valve body. Serious varnish on the valves in the body can mimic this issue. Failing gaskets between the valve body and transmission case can mimic this issue. Loose bolts holding the valve body to transmission case can mimic this issue. . |
Very interesting. Can the valve body be rebuilt or should a new one be used ?
As for the modulator, I installed a new one back in October after the first episode of the car not moving when shifted into drive. The original was bad. I have changed the tranny fluid but not the filter. Once I get the car in the garage, I'll drop the pan and let you know what I find. |
You mentioned the fluid was 1- 2 inches higher on the stick, and was pink.
Should be red. Maybe the Transmission Cooler in the bottom of the Radiator is leaking Coolant into the Transmission. What does the Coolant look like in the Radiator? Charlie |
Radiator fluid is still green. I suspected fluid leaking from the radiator in to the trans also. Didn't see any traces of red dots floating around in the fluid.
As for the color of the tranny fluid, charmalu your correct in it is red, just depends on how the sun light hits the dip-stick. :D |
FYI
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The fluid level is random high, then comes back down to normal level = common symptom of internal AIR on the suction side = making FOAM. . |
If there is air on the suction side, wouldn't that indicate a clogged filter ?
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Possible
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Change it, while you are in there. Minimal cost fix. . |
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Roy, can the broken springs you mention be replaced ? Can a solvent be used to clean varnish on and within the valve body, or is this a bad idea because it might introduce other problems ? |
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Ok, I've got a gauge mounted to the working pressure port. The car was run for about 5 minutes. The ambient temperature was 10 degrees so I guess that constitutes as cold. Also checked vacuum at the VCV and it was holding Hg, as per WHunters request.
The following are initial findings: Pic1 - shows the vacuum test on the VCV Pic2 - shows the working pressure port in the upper right corner of the frame. pic3 - shows the vacuum, modulating and working pressure at idle. pic5 - shows the vacuum, modulating and working pressure as the GO Pedal is being depressed. I could not get this to fail, meaning getting the modulator pressure to drop to 0. I moved the car out of the garage and up & down the driveway a few times and still it did not fail. I'll do some more testing tomorrow before I drop the pan. |
Finally, someone using logic and pressure gauges to diagnose a trans problem.
Just so we are using the same terminology, Working Pressure = Line Pressure? ( the highest pressure in the trans, it comes directly from the front pump. ) Random high fluid levels that don't have obvious foaming are caused by the torque converter not being charged. ( filled with fluid under pressure ) This one of the reasons for no drive and can cause poor acceleration until it fills. Given you have a drop in modulating pressure and seemingly loss of torque converter charging, I'd lean towards a line pressure regulator issue. Loss of line pressure will result in loss of pressure to apply clutches / bands, it takes a while for the converter to empty so the fluid rise might not be immediately apparent. Shutting the engine off allows the pressure regulator to move towards full pressure. Does this trans still have a rear pump installed? There are a few check valves in the system to prevent front pump pressure from spinning the rear pump when it is disengaged. However I'm not sure there would be a large enough internal leak to cause the symptoms you are having. As for fluid color, if you can see through it you don't have much or any water mix. Water will cause the fluid to become opaque and more towards white. Sometimes in early stages of water mix, you will have bubbles that won't pop. ( water droplets floating in the oil) |
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Picture three - engine at idle
Where was the gear selector? http://www.peachparts.com/shopforum/...ure-026_s4.jpg The data for the test is => http://i185.photobucket.com/albums/x...18pressure.jpg If it was in "D" the working pressure is possibly good - I need to check the exclusions on the original document though The modulating pressure is too low. |
Sorry I forgot to say.
The data needed is for the .117 listed above the highlighted .118 data in the borrowed from someone else picture You need to drive the car for quite a bit to get the transmission oil warmed up before you start making these measurements - needs to be at the operating temperature (I'll look that up as well) You need to tell us more about the gear selected - pictures show the position when pressing the "GO" pedal are nice but not relevant to the data in the FSM. If you do the stationary tests in "D" and in reverse as described above and the data is good it is then worthwhile doing the tests at 65 kph. (The main point of making measurements is to compare with FSM data - if however you loose all pressure at some point then you know what that is!) |
I am always amazed at what a simple trans fluid change will cure. I had a similar issue to yours with my 240D trans slipping and not staying in gear and I changed the fluid and filter and it seems to be operating better now. Still not right but better anyway. My transmission is one of the old non vacuum units so there are many more variables involved with yours.
Stretch is correct about the transmission needing to be at operating temperature to get the correct readings with the gauges. Hopefully it will be warmer this weekend so it should be easier to get the car warmed up. |
Thanks Stretch. The above pics where taken with the car in park. I will get some long hose and route the line pressure gauge thougth the firewall and in to the car as the other two gauges are. I'll also pic up a device to measure temps.
The forecast for the weekend calls for much more tolerable temps. Stretch, documentation which the modulating pressure was set to was at 2.8 bar with the modulator disconnected from the vacuum line. What's shown in the pic is with the Vacuum modulator connected to the VCV. |
FYI
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In the OE climate chambers, it is called a slush box, where they test transmissions to -80° F.. :eek: If the engine is at 80° C, the transmission should be at operating temperature. They share the radiator. On a cold start, Running for 5 minutes will not reach anything near transmission operating temperature. . |
Some data...
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...I've suffered...
...I had to boot up Windows to find this data - dreadful experience! Looking through the German FSM the data for USA models is given in a separate section. Use the headings from this table => http://i185.photobucket.com/albums/x...18pressure.jpg But the data from here => http://www.peachparts.com/shopforum/...1&d=1391108340 As Roy mentioned above the transmission operating temperature is 80 degrees C - this is in the owners handbook. I reckon the best way is to use a IR thermometer reading off of the transmission oil pan. (Or thermocouple and multimeter) |
Stretch, a thought accord to me. When I set the modulating pressure, the document stated to disconnect the modulator valve from the VCV. 2.8 bar was the obtained setting.
For these modulating and working pressure settings documented above, do I also disconnect the modulator valve ? Currently the VCV is connected to the modulator. |
First things first - the transmission needs to be at the right temperature and you need to have it at stand still in drive - then the measurements will start to have some meaning. (The test for in reverse at stand still is also there)
Ignore the vacuum measurements at the moment; concentrate on the hydraulic pressures in the table posted above. |
Greg
Be sure to convert the pressure between BAR and PSI.
Here is a great utility for doing conversions. Convert.exe . |
^^^
Hee hee "old money" : "new money" = "aaaaarrrrrggggggggg"! |
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Getting ready to change trans fluid and filter, but just for giggles I wanted to see what pressure readings I'd get before and after fluid and filter are changed.
Reason for this test was because the modulating press would go to 0 within a minute of running the car. When I jacked the car up to connect a gauge to read working pressure, I couldn't get the modulating press to drop even after 5 minutes. After warming the car to operating temps, that's 80C I still couldn't get it to fail, so I took it for a road test in my community. If the car broke down, I wouldn't have far to walk. The attached file has the finding. Currently the car is cooling and I'll drop the pan shortly. . |
Screen shot!
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If you do a screen shot of your spreadsheet it might help with the more lazy of us about here who don't want to upload PDFs!
http://www.peachparts.com/shopforum/...1&d=1391288457 I assume the values are bar Your working pressure is way too low - 3.2 bar is way down on the 7.2 bar it should be - the reverse should be more than 16 bar and you only have 6.6 This looks like a weak front pump problem - but - we should see how a new filter and oil behaves before we read it the last rites |
I agree
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Best of luck Greg. . |
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Ok Gent's, the pan is drained and off the car, also the filter has been removed. I didn't see it when taking these but in reviewing the images I saw something that was quite interesting along with the crap in the pan. Which was expected. Taking pic with ambient light didn't show the problem, but using a flash did. Notice the discoloration of oil in the pan, this is also on the filter and the bottom of the valve body.
Roy's as per your request, I will cut this filter open and get some pic's of it. Let me know what you think, before I button it back up with a new filter. |
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Rest of Pic's. I did a double-take on this and went back and checked the pan again. That discoloration was only visible in using the flash.
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Have you got a magnet Greg?
Is this stuff magnetic? http://www.peachparts.com/shopforum/...re-050_11s.jpg It looks a little like brake band / clutch lining to me - which is paper based... ...dry it out and see what you think. This still doesn't explain the low working pressure but it could indicate more trouble to come. |
In person, it looks like separation of oil and not a pile of material correct?
Seen it before, not cause for alarm, likely graphite from friction plates maybe some graphite from cast iron. |
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OK
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If this is the first time that pan has been off. This is normal wear and tear trash. Here are pictures of plugged transmission filters and serious sludge. . http://i2.photobucket.com/albums/y13...4/IMG_3523.jpg http://www.clublexus.com/gallery/dat...73_Medium_.JPG http://i2.photobucket.com/albums/y13...4/IMG_3520.jpg http://www.agcoauto.com/content/imag.../Too-much2.JPG http://i.imgur.com/8ZzZG.jpg http://fixeuro.com/Transparency/Pan_...Pan-Sludge.jpg http://www.binderplanet.com/photopos...2/photo_21.JPG . |
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Graphite is a form of carbon. |
That may be true, but per a suggestion from Stretch, I used a relatively strong flat bar magnet and moved it around the bottom of the pan. What ever is in there is non magnetic for nothing stuck to the bottom of the magnet. The pan has been cleaned out and a new filter installed. The pan has been put back on the tranny.
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I''ve got a spare .1 transmission... not sure the exact number, but if you need it, I'll clean it, and get you exact info.
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Thank John, I may have to take you up on that. A test drive will tell !
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Here are pictures of the front pump http://www.peachparts.com/shopforum/...ront-pump3.jpg http://www.peachparts.com/shopforum/...ront-pump2.jpg http://www.peachparts.com/shopforum/...-pump-bits.jpg http://www.peachparts.com/shopforum/...llow-shaft.jpg Here's a picture of a clutch plate http://www.peachparts.com/shopforum/...n-disc-new.jpg Used brake bands http://www.peachparts.com/shopforum/...ke-band-b2.jpg http://www.peachparts.com/shopforum/...ke-band-b3.jpg All pictures in this thread http://www.peachparts.com/shopforum/diesel-discussion/304903-722-118-automatic-transmission-rebuild-monster-diy.html |
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Due to frustration and cold weather, this job has taken a little longer than expected. The frustration was from tranny oil leaking on the floor between the pan and the transmission casing. I discovered that this is a normal occurrence for the pan with the new gasket doesn't seal correctly and takes some playing around to get it right.
When looking at the torque specifications for the filter pan bolts, their not very tight. I remembered that they where held securely and where somewhat difficult to remove. It was like someone used locktite on the threads. So I treated this as something which needed the threads cleaned so the bolts would go in smoothly and without binding. I first started with cleaning the bolts. Die required was 1.25 * 8mm. Next was to clean the threads with a tap. What was discovered was I not only removed the old thread material but also so aluminum buried in the hole and caked with oil. The bolts screwed into the holes without a problem. |
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Ok folks I've got some good news. Results are in attached file. Don't know how to insert the image into post.
Summary is that trans, although may not be at factory spec, and I didn't expect it to be, it shift in and out of gear flawlessly, minimum shifting delay's between Neutral, drive and reverse. Still has good pickup especially in regards to transmission pressure readings. All in all I'm pleased with the results from changing the filter and fluid. Although I may have a trans which will fail in the future, at the moment I cannot tell but it seems to be responding better than when I bought the car. Attached pic's are at pressure reading in idle in park. Note: Shift delay from "N" to Rev = approx 1 sec Shift delay from "N" to Drv = approx less than 1/2 sec Car was at operating temp of 80C as shown From dead stop and pressing the pedal to the floor, pressure pegs above 10 bar, then drops to above 50 psi then to 70 as it shifts into 2nd. Same results in Reverse. With pressing pedal to floor in reverse pegged gauge above 10 bar dropping to 8.2 as speed leveled off. No notice of trans failing to shift or turn rear wheels as in test prior to changing filter. Trans fluid level on stick is at top level mark on dip stick after test was completed. |
Screen shot of results
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Here's a screen shot of the results in your word document Greg
http://www.peachparts.com/shopforum/...1&d=1395039450 I love the use of two units of pressure! The idea, however, is to reproduce the situations in the FSM so you can compare your measurements with this data http://www.peachparts.com/shopforum/...mation-usa.jpg |
Stretch, I was trying to reproduce the FSM and thought I did. Please advice if I didn't! The transmission according to the VIN is a 722.117. Using your chart for reference, the modulating pressure should be 2.8 at 40. Mine is 2.6. Wrking pressure should be 5.2, mine at 4.8 bar. The results in my chart where at driving at 40 mph which according to the FSM reading should be done at that speed. If I'm not mistaken, I still have some life left in this transmission, but there are signs of wear as expected.
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Tests are With "D" selected 1) Measure modulation pressure => at stand still 2) Measure working pressure => at stand still 3) Measure modulation pressure => at 65km/h 4) Measure working pressure => at 65km/h With "R" selected 5) Measure working pressure => at stand still If the working pressure at a standstill is too low then it might be worthwhile considering a new front pump (as discussed before) Note temperature readings are probably best made on the bottom of the transmission oil pan. |
I agree with the pump replacement. Converting to FSM display of data as follows:
With "D" selected 1) Measure modulation pressure => at stand still ------ 1.3 2) Measure working pressure => at stand still ---------6.7 3) Measure modulation pressure => at 65km/h ---------2.6 4) Measure working pressure => at 65km/h ------------4.8 With "R" selected 5) Measure working pressure => at stand still ---------- 8.2 units are in bar |
Well Greg the only really big difference is the working pressure with reverse selected. That's my biggest concern.
With "D" selected 1) Measure modulation pressure => at stand still ------ 1.3 => should be 4.4 +/- 0.2 2) Measure working pressure => at stand still ---------6.7 => should be 7.2 +/- 0.4 (used value from 1979) 3) Measure modulation pressure => at 65km/h ---------2.6 => should be 2.8 4) Measure working pressure => at 65km/h ------------4.8 => should be 5.2 +/- 0.2 (alternatively 4.9 +/- 0.2 for 1979) With "R" selected 5) Measure working pressure => at stand still ---------- 8.2 => should be higher than 18 (or 16 for 1979) The modulation pressure is a bit low at standstill. But the working pressure is kind of OK. I reckon it is worthwhile driving the car for a bit and after a while perhaps doing another oil and filter change to see if you get any improvement. I wouldn't mess with the modulation pressure just yet. The improvement in the measurements after a fluid and filter change are really promising. Drive the car - but don't let the transmission slam into gear. Check your fluid level again |
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