C4 4+3 overdrive problem
Thread Starter
Heel & Toe
Joined: Sep 2007
Posts: 17
Likes: 0
C4 4+3 overdrive problem
I have an 87 C4. The car has 93000 orig. miles and a problem has cropped up with the overdrive shifting. We only drive it during the summer and store it the rest of the year with a short drive once or so a month when the weather is good. When I took it out the other day it would not stay in overdrive unless driven at light throttle, as soon as I step on the gas --lightly-- it shifts out and stays out unless I press the switch several times. It will go back in and stay as long as I don't put any more pressure on the throttle. What and where is the kick down switch and how does it work--does it read off the TPS or vacuum or??? Suggestions please, Thanks
Safety Car
Joined: Jan 2004
Posts: 3,556
Likes: 13
Checked the fluid level in the O/d recently?
The O/d fluid and filter should be changed at 12,000 mile intervals
Low fluid is one common cause of problems ;there is a switch in the O/d that monitors pressure ; if too low ( low fluid ) it will prevent the O/d from staying engaged
O/d operation in your year is totally from the computer relating to inputs it is programmed to receive ; engine temp , road speed , TPS volts , etc
This chart
http://www.5speeds.com/43table.htm
shows what yours "should" do under certain operating conditions
The O/d fluid and filter should be changed at 12,000 mile intervals
Low fluid is one common cause of problems ;there is a switch in the O/d that monitors pressure ; if too low ( low fluid ) it will prevent the O/d from staying engaged
This chart
http://www.5speeds.com/43table.htm
shows what yours "should" do under certain operating conditions
Le Mans Master
Joined: Sep 2006
Posts: 6,050
Likes: 147
From: Phoenix AZ
2021 C4 of the Year - Modified Finalist
The problem you describe is worn clutches or hard seals...
1.
Your overdrive clutches could be worn to the point that a large power effort makes the clutches spin instead of holding.
2.
There are various seals inside the overdrive. When the seals can no longer hold the pressure, the fluid bypasses.
When you lightly give it gas, they can hold some pressure, but any more power, they just let the fluid bypass to the point that enough fluid gets by the seals that there is not enough pressure to hold the clutches together and they spin against each other.
It's time for a seal kit and some clutches.
1.
Your overdrive clutches could be worn to the point that a large power effort makes the clutches spin instead of holding.
2.
There are various seals inside the overdrive. When the seals can no longer hold the pressure, the fluid bypasses.
When you lightly give it gas, they can hold some pressure, but any more power, they just let the fluid bypass to the point that enough fluid gets by the seals that there is not enough pressure to hold the clutches together and they spin against each other.
It's time for a seal kit and some clutches.
