Hey there,

I have an 89' with the 6 speed box. Sometimes, the car will not go into gear when it's running, I will try to put in in first and it will start to creep forward but there is a lot of resistance and I stop due to fear of breaking it. If I try again a moment later it will work. Today, the car died at a light and wouldn't go into any gear once restarted and was exhibiting the same symptoms as above. I read up and saw that I should check the fluid and it was well below the "Add" line. Would this be the cause of this issue? I have attached a picture of where the fluid level is.

Additionally, The car will sometimes start and then die immediately after. It also died today at the stoplight but that was the first time it had died while I was out driving it. Any thought on this? I am more concerned with the clutch issue right now however as I want to ensure the car does not have some horrific trans issue. I also noticed the car makes a lot of noise at idle unless I press the clutch in and it also makes a whining noise while driving that increases with speed but I have read that this gearbox (The black tag) is noisy and has differently cut gears as opposed to the blue tag. Mine seems to make the same noises as described in all the other threads about the ZF6 black tag noise but it still concerns me.

 

Yes low fluid can cause issues. Fill the reservour up to the correct level and bleed your clutch system. You have all the symptoms of having air in the system. Because of that, the clutch is not fully disengaging.

Can't speak to your other questions as I don't have the 6 speed tranny.

 

I would Just add that I would find a Cheap Turkey Baster and suck out that Nasty fluid replace/refill it, and pump pedal a bit and if Fluid goes nasty again repeat. Once the Reservoir is filled let it sit for about a hour or two I have found that the clutch Systems seem to self bleed a bit if not totally air bound.

Also why is the Fluid down? is there a Leak or is the clutch about to reach it's end of life.

 

Thank you both for the responses. I'm not sure why the fluid is low so I will be keeping an extra close eye on it. I am actually going to be out of the country for the next 3 weeks so the car will have to sit but when I return I will be back on here trying to diagnose my no start issue. It does have the ,"Service engine soon" light but I need to grab an OBD1 reader so hopefully that will shed some light.

 

You have the classic symptoms of a clutch not releasing completely (hard to shift into gear from neutral when the engine is running).

For your SERVCE ENGINE SOON (SES) light issue, see these links (you don't need to buy a code reader):

https://www.corvetteforum.com/forums...post1574918379
http://corvettephotographs.com/c4vettes/codes.htm

What the error codes mean:

https://www.corvetteforum.com/forums...post1576116036

 

Thanks very much for that. I am going to read them myself.

I topped up the clutch fluid with DOT 3 brake fluid and drove around a while. It didn't seem to stick but the clutch feels like crap. If I hold the pedal down for more than a couple seconds it doesn't seem to build pressure back immediately so basically half of the clutch travel will just be free play. I'm not really sure how to describe this issue but something is definitely not right. The grab point also felt like it was changing based upon how long I held the clutch in. Any ideas on this?

Edit: I guess I should have re-read the responses above. I will go ahead and get new fluid for it and bleed/refill it to see if that fixes the issue.

 

Try this: pump your clutch several times in quick succession then immediately try putting it into reverse or low. If it goes in now without a problem, you definitely have air in the system based on my experience.

If you've tried bleeding it already and it still exhibits air issues, here's a possible resolution for you. Take the cap off the reservoir and have a little gap between the top of the fluid and the top of the reservoir. With the engine off, pump the clutch pedal about 10-12 times quickly and the last time hold it down for about 5 minutes. At the end of the 5 minutes, let your foot slide off the clutch pedal and allow it to pop up on it's own. If you're good or lucky, any air in the system will have worked it's way back up the line between the slave cylinder to the loop right above the master cylinder. With luck any air in the line will be pushed out to the reservoir by the action of the clutch being released.
I've done it and it worked for me though you might have to do it more than once.

Good luck.

 

Thank you for the info. I took a look at the slave and unfortunately, I don't have the proper leverage or skill to bleed it myself. however, the front of the slave was pretty corroded under the paint which leads me to believe it may be leaking and perhaps this was why the fluid was low in the first place. The cars pedal feel is currently very odd and it's making it difficult to drive. I have made an appointment with the shop to look at this as it seems to be above my skill level.

I read the CEL and it returned code #15, Coolant Sensor Circuit High. Apparently this can be the cause of hard starts or stalling which would make a lot of sense. I will look into how to fix this now!

 

Hello All, A quick update and question.

I was able to solve the CEL code 15 by replacing the engine CTS, it still takes a while to crank sometimes but it starts up every time and has not stalled out once!

Next question, I got a replacement slave and the shop said I also need the hose that goes to it because the threads on the hose stripped off and it was in bad shape. Is this the hose that connects to the slave cylinder: https://www.corvettemods.com/C4-Corv...omItemId=12903

Thanks for the help, If this is the part I will order it up immediatley so I can get the car back! I wish it wasn't so darn expensive though!

 

That looks like it. That loop on the one end seems to be the spot air collects if the system is not bled properly.

 

Thank You! That would make sense about it trapping air there. My slave cylinder was horribly rusted and all the paint was chipping off. It was definitely leaking and due for a replacement.