1986 300 SDL 246,000 miles Transmission vs. OVP problem? Could someone weigh in? (HEL

[ron59b]

I purchased a 1986 300 SDL from a friends and it had a few problems, but I got it for a great price. The main issue was the injection pump had a problem with the #4 delivery valve not pumping properly. Also the car had an issue when taking off cold. When starting out cold, it would take an unusual amount of time to reach an appropriate cursing speed. It seemed that the turbo wasn’t really kicking in and the car would not run properly until reaching 40 – 50 miles per hour. This was all about 1.5 years ago.

What I’ve done or had done since that time:

• Purchased a used pump off of the forum and had it installed.
  • The guys that installed the pump didn’t do something correctly and the car ran rough at idle.
  • Vacuum lines seemed to not be hooked up correctly. The turbo wasn’t kicking in at all.
  • I used several diagrams off this forum and attempted to correct the vacuum line issue.
• I took the car to a mechanic and had the pump issues corrected.
  • I was told the timing for the fuel delivery was off. And thus corrected and reinstalled.
  • He also told me that the transmission wasn’t shifting at the proper times and he changed the fluid, filter, module, and kick down switch.
  • The mechanic also cleaned the intake manifold and turbo.
• The car is now running much better, but the shifting problem is still not corrected. (I have not gotten the car back, only been to visit it and learn more.)
  • The car seems to be starting out in 3rd gear and that is causing it to be sluggish in picking up speed.
  • Once the car reaches about 50-60 mph, it runs more smoothly.
  • He also stated that the car still isn’t downshifting as expected.
  • The mechanic drained some of the fluid put in some additives to improve shifting. ( He has not driven the car to see if this helps)

Now for my main group of questions:

• I know that the OVP Relay appears bad (researched myself on the forum)
  • Symptoms – Tachometer not working.
  • Clock not working. Anti lock light on the dash is on
    
  • Dash light for switches not working.
  • Changed the relay with a used one and no change. ( This was done before putting it in for repairs)
• Could the OVP Relay problem effect shifting of the transmission?
• If not the OVP Relay, what else could it be?
• If the fluid change doesn’t work, the mechanic wants to pull the servos on the transmission and clean them.
  • He stated that the fluid and filter was very dirty when he changed it.

I know this is lengthy, but I wanted to give you the full story, in hope of finally resolving this issue. I am rather tired and completely out of ideas. I had the question about the OVP Relay and needed to weight in on it.

Thanks,

Ron

[WINGAS]

No idea, but you deserve a bump sir.

[ron59b]

Thanks my brother for your vote of confidence....Have a great day....Hopefully, someone will be able to advise me soon..

[mbdoc]

On the side of the injection pump the vacuum control valve for the trans resides.

Correct adjustment in critical.

OVPR does power up computers that can affect kick-down on the trans, other than that the trans is purely mechanical.

[ron59b]

Do you think it would make sense to replace the OVP Relay before proceeding any further? I know that my mechanic did make several adjustments prior to today. He is an old fashion mechanic with over 28 years experience on these cars. Thus far he has brought about better results than those previously.

[sixto]

The electrical symptoms strike me as a lack of voltage or poor ground. It could be a bad OVP relay but it could also be worn brushes in the voltage regulator.

Check that the car has the right transmission. The numbers 722.321 (and lots of others) should appear on the passenger side of the transmission just above the pan mating surface. If you see 722., someone might have installed a transmission from another model.

There are 4 aspects to shifting: throttle position and movement influence shift timing, simulated manifold vacuum influences shift firmness, a kickdown switch at the far end of throttle pedal travel induces a downshift and max rpm shifts, and transmission internals manage everything else.

For the throttle position and movement piece there is a cable from the passenger side of the transmission to the throttle linkage ahead of the oil filter. There should be just the right amount of slack in that cable. Too much and you'll be in cruising gear too soon, not enough and it'll downshift with the slightest throttle input.

As M.B.DOC said, there's a vacuum controller on the side of the IP. The controller should get vacuum from the engine vacuum pump and route the output through a vacuum amplifier then to the transmission. The controller see at least 18"Hg from the pump, and at idle not much less should be available to the transmission. Make sure it holds sufficient vacuum before bothering to adjust it.

The clock and dash lights are unrelated to the OVP. The clock might need new capacitors. The dash lights might need a new rheostat (dimmer switch) or new bulbs.

Sixto
87 300D

[tinypanzer]

Originally Posted by ron59b

Now for my main group of questions:

• I know that the OVP Relay appears bad (researched myself on the forum)
  • Symptoms – Tachometer not working. Not ovp symptom
  • Clock not working. Anti lock light on the dash is on That's probably the electrolytic caps in the clock istelf. The ABS light is a possible OVP symptom
    
  • Dash light for switches not working. Not ovp symptom
  • Changed the relay with a used one and no change. ( This was done before putting it in for repairs)
• Could the OVP Relay problem effect shifting of the transmission?
• If not the OVP Relay, what else could it be?
• If the fluid change doesn’t work, the mechanic wants to pull the servos on the transmission and clean them.
  • He stated that the fluid and filter was very dirty when he changed it.

I know this is lengthy, but I wanted to give you the full story, in hope of finally resolving this issue. I am rather tired and completely out of ideas. I had the question about the OVP Relay and needed to weight in on it.

Thanks,

Ron

Just to put you at ease with the OVP thing.....