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

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