4 + 3 overdrive
Thread Starter
Intermediate
Joined: Jul 2004
Posts: 33
Likes: 0
4 + 3 overdrive
Hi Gang
Long time not being in contact with the forum.
I have a 1986 C4 with the 4 +3 overdrive unit. Was overhauled about a year ago, since than the guy has gone out of business. Any way I am having trouble with it staying in the overdrive. The car is in good condition and has only 88,000 on it actual miles.
Is there any way I can get parts for the overdrive unit.? And here is what is does in a brief...As soon as the temps come up, and I start driving it down the freeway about 65/70 MPH I can go like 12 to 15 miles and it drops out of overdrive, almost like clock work.
Now does this sound like a solenoid or the pressure switch acting up, or temp related. It goes into overdrive just fine then I start the drive on the freeway that distance and it drops out of the overdrive. And there is no getting it back into it again. The thing that gets me is the almost exact distance every time. I have done this several times, so it is not my imagination.
Thanx....Gunny
Long time not being in contact with the forum.
I have a 1986 C4 with the 4 +3 overdrive unit. Was overhauled about a year ago, since than the guy has gone out of business. Any way I am having trouble with it staying in the overdrive. The car is in good condition and has only 88,000 on it actual miles.
Is there any way I can get parts for the overdrive unit.? And here is what is does in a brief...As soon as the temps come up, and I start driving it down the freeway about 65/70 MPH I can go like 12 to 15 miles and it drops out of overdrive, almost like clock work.
Now does this sound like a solenoid or the pressure switch acting up, or temp related. It goes into overdrive just fine then I start the drive on the freeway that distance and it drops out of the overdrive. And there is no getting it back into it again. The thing that gets me is the almost exact distance every time. I have done this several times, so it is not my imagination.
Thanx....Gunny
Drifting
Joined: May 2006
Posts: 1,428
Likes: 7
From: Chewelah Wa
Mine does this when the fluid level is not all the way full. I have a small leak, and after awhile it will lose just a few ounces. I will pull the plug and top it off, I am good to go for another season. I am unsure if they all act this way.
Thread Starter
Intermediate
Joined: Jul 2004
Posts: 33
Likes: 0
4 + 3
Hi Powerpig
Ya I am real good about keeping the fluid changed and up to the mark. It does not really hold that much so I figure it is best to keep it full.
Do you have any info on getting parts for these overdrives.?
Thanx...Gunny
Ya I am real good about keeping the fluid changed and up to the mark. It does not really hold that much so I figure it is best to keep it full.
Do you have any info on getting parts for these overdrives.?
Thanx...Gunny
Le Mans Master
Joined: Sep 2006
Posts: 6,050
Likes: 147
From: Phoenix AZ
2021 C4 of the Year - Modified Finalist
I would first rig up a switch to turn it on without the computer aided engage to find out if it is the trans or the ecm.
I have a 4+3 in my 57 chevy truck, no computer. But it's manual. never drops off line, even when low.
I have a 4+3 in my 57 chevy truck, no computer. But it's manual. never drops off line, even when low.
Thread Starter
Intermediate
Joined: Jul 2004
Posts: 33
Likes: 0
Hi Coupe
Hey thanx for the tip, I have read some place about bypassing the 2nd shift relay on the side of the transmission that will do this I think.
If it would drop out at diff speeds or distance might make more sense in figuring out what is causing it, but the same distance and I am really thinking temp too as far as the trans lube.
I will give it a try, thanx....
Thanx....Gunny
Hey thanx for the tip, I have read some place about bypassing the 2nd shift relay on the side of the transmission that will do this I think.
If it would drop out at diff speeds or distance might make more sense in figuring out what is causing it, but the same distance and I am really thinking temp too as far as the trans lube.
I will give it a try, thanx....
Thanx....Gunny
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Thread Starter
Intermediate
Joined: Jul 2004
Posts: 33
Likes: 0
Hi four speed
As much as I wish you was right, I really don't think that is it. I have checked it several times and it does have a new filter and new fluid, and after it is warmed up I check the level and it is right on the mark. And sitting on a very level place too.
Just thinking about the fluid level and how this starts acting up after driving that distance, my thinking is if it was the fluid level it would do it right away, why would a low fluid level take that long to give me the problem.?
Thanx....Gunny
As much as I wish you was right, I really don't think that is it. I have checked it several times and it does have a new filter and new fluid, and after it is warmed up I check the level and it is right on the mark. And sitting on a very level place too.
Just thinking about the fluid level and how this starts acting up after driving that distance, my thinking is if it was the fluid level it would do it right away, why would a low fluid level take that long to give me the problem.?
Thanx....Gunny
Safety Car
Joined: Jan 2004
Posts: 3,556
Likes: 13
temp wire a switched power supply direct to the O/d terminal and use that to engage the O/d manually.
That way you bypass the ECM and relay so if the O/d still drops out again you have confirmed it is a O/d ( mech ) problem
and not a electrical ( ECM , relay , wiring ,etc ) problem
Well used elec parts can work fine when cold but fail when warmed up