Hey all,

A new day, a new issue =)

I've had this 85 300D CA car for only a little bit, been doing some minor stuff here and there but overall no major issues.

The car has always had a few minor shifting bugs (hard 1/2 shift when cold, etc) but nothing that has demanded my attention. No flare to speak of. the PO also had a recent receipt for a AT filter kit so it appeared he had changed the fluid out within the last year.

Then a couple days ago the 3/4 shift appeared to be flaring and then almost immediately as soon as it shifted into 4th it would slip - RPMs climb fast but car didn't go anywhere. If I dropped it into "S" I could get the car home as it seems to keep the transmission in 3rd.

So I started researching and diving into the world of AT diagnostics. I got Kent's manual and have started going through the motions. The car seems to be making decent vacuum and the modulator line holds vacuum OK. This is an 85 cali car with the blue saucer, I haven't tried bypassing it yet.

So then I remembered a situation with my old 740T volvo where it slipped really bad and found out I had little or no ATF. So today I checked and it was WAY overfull. Using the "10mm under the low mark when cold" method I started pulling out fluid to try to get there... and pulled out almost a full liter of fluid. I'm still more like 5-6mm below the low mark, but went to test drive since it was now in the ballpark. Car actually did shift smoother than it had before, but the 4th gear slip remains. Any words of advice would be greatly appreciated, I'm beginning to worry something is toast =( Also worth noting the car takes a second or so to go from park to reverse, and I've read that can be indicative of other issues..

Any and all comments greatly appreciated.

Sean
85 300D CA "Sonny"
Ukiah, CA

K2 clutch slipping...not good. What you need is a transmission gauge...measure the modulator pressure, working pressure, and governor pressure. My bet is that you're going to find low pressures. Caused by low fluid level, a worn valve body, a bad governor, leaky clutch seals or worn friction material. Transmissions begin to die from 4th gear because 4th places the greatest demands on the hydraulic system. Here's an article you may find helpful:

http://www.atraonline.com/gears/2008/2008-07/2008_7_38.pdf

How long has it been running on overfilled transmission fluid?

__________________
Only diesels in this driveway.
2005 E320 CDI 243k Black/Black
2008 Chevy 3500HD Duramax 340k
2004 Chevy 2500HD Duramax 220k

Mxfrank,

Thanks for the info! I'm going to get a pressure gauge and see if I can get those figures. If the working and modulator pressures are low, is that indicative of a bad valve body? That's what I'm gathering from the article, but as you said sounds like it could be many things...

Hard to tell. We bought the car a couple months ago, I don't know exactly when the PO did the ATF/filter change. It could have been running this way for over 6mo...

Sean
85 300D CA "Sonny"
Ukiah, CA

I thought the main symptom of overfilling was foaming. Are you testing with the motor running, at 80deg?

The thing to know is that it takes a lot of fluid and pressure to engage fourth, because both clutch packs have to be filled and pressurized. So if you have low pressure anywhere, fourth gear won't engage. Where this usually ends up is a leaky clutch pack and a rebuild, but go through the motions.

Sean, have you had any luck figuring out the slipping? I'm having the same issue. My 300td was overfilled as well, fourth gear slipping. I drained fluid to the proper level, but still slips in fourth. All other gears are ok, and if Im careful in fourth I can feather the throttle lightly and can drive. But...if I encounter a hill, and have to push the pedal down, it slips and I have to put it in "S"