I wanted to run an issue by all the experts on here – with my ’86 Iroc-Z, I have noticed that after the car has been parked for a day or two, then I fire it up to back it out of the garage, I put it in reverse and nothing happens. If I keep my foot on the brake and wait for 10, 15, maybe 20 seconds, it will start to “bump” a little like it is trying to engage (lightly), and gradually it will become stronger and eventually will be enough to make the car move and back out of the garage under its own power. If I rev the engine slightly (maybe up to around 2k) during this time when it is not fully engaging, it will turn the “bump” into more of a “slam”, so I don’t do that anymore in case it is harming something. Once I get it backed out, putting it in drive seems fine and it shifts through the gears as it should when I get out on the road. Also, after driving it for a few miles, reverse seems to work better.

I don’t know whether to suspect the converter or the transmission – I don’t know much about automatic transmissions. I have checked the fluid level and it is to the proper mark on the dipstick and the fluid is nice and red in color. The thing I don’t know is, when the transmission was last serviced (filter and fluid)..

It has been suggested to me by more than one person to try putting some Lucas additive in it (non slip) and see how it responds to that. But it seems there is an obvious issue and I don’t know how I feel about a band aid fix like an additive, unless it will actually remedy an issue.. I do know the car has been parked a lot for at least the last 3 or 4 years without much use. I don’t know if there is anything in the 700R4 that could “dry out” and putting an additive in it might remedy something?

Thanks for any thoughts or ideas.

 

The additive may help, your description is low internal pressure, That can be caused by a dry seal (s). or several other things all of which equal a rebuild. What I would do is service the transmission twice with filters and.with 500-1000 miles in between. If it still has the issue then try the additive. If it is still happening then know you are on borrowed time and baby it. Low pressure first shows up in reverse cold start. Low pressure allow slippage and and internal over heating under load you may not noticed. Oh and stop revving it then it will not engage just let it warm up and maybe give it a few minutes after it engages so the pressures get a little higher before you drive it.

A word of warning. Seal softening additive is a last resort because in the right conditions it can cause complete transmission failure. As a seal aged it will get hard and shrink slightly, not driving the car for long periods can speed up the process. The additive does not "fix" the seal it attacks it and causes it to soften and swell. As you may imagine on a brand new trans this could cause the seal to burst or if an older seal has a small tear softening and swelling it could be bad.

This could be an issue with the internal pump or another internal leak somewhere. It does not sound like a converter.

GL

 

Gorn,

Thank you for your info. I appreciate it, and all of that makes sense. I bought the car in December 2019 and the previous owner was unaware of when the last transmission service was done, so I do think I need to start there. I will hold off on the Lucas for now. I did buy a bottle of it, but I will try doing the service first..