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#1
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does the pressure also depend on vacuum?? if so check your vac lines first!!
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1979 300D 220 K miles 1995 C280 109 K miles 1992 Cadillac Eldorado Touring Coupe 57K miles SOLD ******************** 1979 240D 140Kmiles (bought for parents) ![]() SAN FRANCISCO/(*San Diego) 1989 300SE 148 K miles *SOLD |
#2
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Quote:
I did discover a new idea, however: I may need to look at my "working pressure control valve" in the valve body. Does anyone know, if an issue with that valve would cause my symptoms? |
#3
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There are, in fact, four different valves in the valve body that are involved in the control of the basic/working pressure. It very well may be that one or more of them is stuck or that a spring is broken. And yes, your symptoms can arise from that. Much easier to remove and inspect the valve body than the whole box. |
#4
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Quote:
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#5
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Folks, very interesting development!
I pulled the valve body, split it, and found a potential issue with the "Basic Pressure Control Valve". Here's a photo of the valve after I removed the spring: https://ibb.co/PtwBjSc Here's the location on a diagram: https://ibb.co/B263VfZ Ok stupid question... this thing is supposed to move right?! I assumed so, because it's a valve, but it's not moving AT ALL. I have gently pushed the "rim" visible in my first photo, as well as further inside and I cannot get any movement whatsoever. Assuming I haven't thought of anything, is this my smoking gun? If this was jammed in such a way that it was venting working pressure, that would certainly do it.. I just want to make sure I'm thinking of everything here. If it is indeed stuck, I'm not sure how I would get it unstuck without marring anything. TIA! |
#6
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Thanks Bill, I certainly feel like a Gomer sometimes at 32. I only really picked up a wrench in my late 20s so I am still learning a lot.
I just happened to replace the carrier bearing on my other w123, because it was shot. The symptoms were certainly different than what I’m experiencing on this car. Further, when I had the driveshaft out I inspected the bearing closely and it looked very good. Mercedes part too, so I didn’t want to replace it. I don’t think the transmission is the cause, because those guys are seasoned professionals and they tested the transmission before shipping to me. I am thinking driveshaft. One question: if one of the flex discs isn’t completely seated into the yoke of the transmission, would that cause vibration? I recall seeing that one of my new discs didn’t seat completely flush, there was a slight gap. I didn’t think anything of it, because that gap is front/back and I didn’t think it would cause a driveshaft imbalance. Bill, you said that 2 cycles per second is typical driveshaft frequency, how can that be? It’s certainly spinning much faster than that. Just curious what makes you say that. Thanks! |
#7
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Hello all,
I wanted to update this thread for the common knowlege. I also have a new issue unfortuntely.. I ended up taking the valve body apart in my old transmission, cleaned it very well, found a few sticky valves, put it back together and.... no change. Total pressure still very low, I'm assuming the pump had failed but cannot confirm. I then decided to replace the transmission, and do it right with a rebuilt unit from Sun Valley. A friend of mine graciously offered his help and use of his lift. Took us 2 hours to get the old unit out, and 3 hours to get the new rebuilt unit in. "While I was in there" I did the flex discs, and the rear centering bushing on the drivshaft that was damaged. So now today: Took it for a long drive and got the fluid level dialed in to perfection. It shifts well, but now I have one new issue: At 55mph+ I feel a subtle pulsing vibration, about twice per second. It's more pronounced the more throttle I give it. It's pretty mild, I doubt my wife will notice it, but it bothers me for sure. Perhaps I did something wrong with the driveshaft? I marked the halves and put them back together properly. I also torqued everything down to proper spec. Any ideas what would cause this vibration? TIA! |
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