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Car Forum / Driving, Maintenance, Tuning / Maintenance and Repair / November 2005No Drive at All Ranges (zero line pressure)
Hi I have a 4L60E of a 94 Chevy with no drive at all ranges. Before this happened, there seem to be some problem with downshifting, and I had to manually shift it to lower gears in order to get a good acceleration from a stop. This had been going on for about a month or two. Then one day, while accelerating through about 20mph, I heard a little clicking sound, very light but clear, and suddenly there was no drive at any range. Now, I checked the fluid level which seem to be normal. Oil was not burned, but I changed the fluid and filter anyway. The pan was actually quite clean with no debries. The next thing I checked is the line pressure, which, not surprisingly, is zero. I have worked on trannies before, but I'd like to get some more opinions from the experts here before I start to take out the tranny. Thanks in advance, Jizhong Obviously it internal, major pressure loss somewhere, the internal gears in the pump are bad, engagement lugs on the convertor broke( unusual). You'll see when it's apart. > Hi I have a 4L60E of a 94 Chevy with no drive at all ranges. > [quoted text clipped - 18 lines] > > Jizhong Hate to ask but you have checked to make sure the converter is turning with the engine? Possibly the bolts have come out or the flex plate broke.  SignatureSteve Williams > Obviously it internal, major pressure loss somewhere, the internal gears in > the pump are bad, engagement lugs on the convertor broke( unusual). You'll [quoted text clipped - 25 lines] > http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups > ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- Good question Steve, I skipped right over that. > Hate to ask but you have checked to make sure the converter is turning > with the engine? Possibly the bolts have come out or the flex plate [quoted text clipped - 44 lines] > ----= East and West-Coast Server Farms - Total Privacy via Encryption > =---- Yes, I checked and verified the bolts did not come loose on the flex plate. I did one more check today on the pressure. I wanted to find out if there is any pressure at all. The gage I used before is a 400psi unit. I took out the gage so the port was open to the air. Guess what, after I started the engine. no fluid came out. So this is absolutely zero pressure. Now what? Jizhong >Good question Steve, I skipped right over that. >> [quoted text clipped - 50 lines] >http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups >----= East and West-Coast Server Farms - Total Privacy via Encryption =---- Sounds like maybe the pressure regulator has jammed shut. Professor www.telstar-electronics.com From my shop manual it looks like there should be some pressure if the pressure regulator is jammed. Now I don't see any pressure. Even if I leave the main line port to the air and with engine running, nothing came out, as if the TC is disconnected to the flex plate. Of course, I checked they connected. Jizhong >Sounds like maybe the pressure regulator has jammed shut. > >Professor >www.telstar-electronics.com Didn't the front pump disintegrating used to be one of the classic failure modes of the TH700R4 (a direct predecessor of the 4L60E, if I remember right)? I've had a couple of friends to whom that happened, and I think the symptoms were pretty much identical. I *thought* they had most of the really crummy aspects of the 700R4 ironed out before it went electronic, but....?? > Hi I have a 4L60E of a 94 Chevy with no drive at all ranges. > [quoted text clipped - 18 lines] > > Jizhong If it disintegrated, I'd had least see some debris when I opened up the pan. Anyway, I'm going to over fill the tranny and see if any fluid comes out when started. Jizhong >Didn't the front pump disintegrating used to be one of the classic >failure modes of the TH700R4 (a direct predecessor of the 4L60E, if I [quoted text clipped - 25 lines] >> >> Jizhong > If it disintegrated, I'd had least see some debris when I opened up > the pan. not necessarily. When the pump fails two things tend to happen: 1) fluid quits flowing pretty quickly, so the parts don't necessarily go far 2) any parts would promptly get jammed in all the other parts of the tranny (convertor, valve body, actuators, clutch packs) because the pump SUPPLIES pressure to all of those areas and the last place the fluid goes after the pump is back to the pan.... What you said is reasonable, but I don't know if it is based on actual experience or conjectures. I'd think there would be something prior to the breakdown. Jizhong >> If it disintegrated, I'd had least see some debris when I opened up >> the pan. [quoted text clipped - 7 lines] >SUPPLIES pressure to all of those areas and the last place the fluid >goes after the pump is back to the pan.... |
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