AX-5 Not Bleeding - Any Troubleshooting Advice?

[aris_garage_builds]

Anybody have tips on bleeding a super stubborn AX-5? I’ve been fighting a losing battle after replacing the clutch on my 86’ MJ (external slave). I bought it non-running and the master and slave cylinders were both bad. I replaced both and the clutch while I was at it (and got it running again in the process), but it won’t go into gear and the clutch is crazy soft. There seems to be air I just can't get out of the system. When I bleed, I get air bubbles coming out but can’t seem to build any kind of clutch pressure.

 

I’ve tried literally everything I can think of - traditional bleeding method, power bleeder, vacuum bleeder, the c-clamp method that the Haynes manual recommends, but nothing seems to be cutting it. Is it worth pulling the whole thing out again and trying to bench bleed it? Willing to try just about anything at this point to get it driving again before the winter, I’ve never had a clutch give me this much trouble. Any other recommendations? Let me know if I can provide any additional info that would be helpful for troubleshooting, appreciate the help!

[eaglescout526]

Does the external slave rod have the extension cone on it?

[aris_garage_builds]

5 hours ago, eaglescout526 said:

Does the external slave rod have the extension cone on it?

Do you mean the rod / boot on the end? If so, yes. The only time I tried without it was when attempting the c-clamp / Haynes method (I removed the boot as directed to fully compress the rod). That seemed to be the most successful at moving air through the system, but I still couldn’t get the pedal to firm up.

 

 

[eaglescout526]

 

This cone. It goes on the end of the rod/boot 
 

If you don’t have this the clutch will barely engage enough to shift. If it’s still getting air into it, it could be the seals are shot and need a rebuild at both the master and slave. Or there’s a pinhole leak in the lines. 

[aris_garage_builds]

11 hours ago, eaglescout526 said:

 

This cone. It goes on the end of the rod/boot 
 

If you don’t have this the clutch will barely engage enough to shift. If it’s still getting air into it, it could be the seals are shot and need a rebuild at both the master and slave. Or there’s a pinhole leak in the lines. 

 

Ah I see, I bet that is exactly what is causing this problem! It looks like it this part: https://www.summitracing.com/parts/cwa-j3217479

I'll probably pull the system out and bench bleed it just to be safe (and ensure air isn't getting in somewhere) but given that the clutch won't fully disengage I think this is exactly what's needed. Thank you so much, I had no idea this little piece even existed!

[eaglescout526]

That looks like it’s it and no problem! I learned the hard way once what it’s like to shift without that cone and it gave a really interesting half disengagement and a audible clunk while forcing the clutch pedal to stop half way through travel. But that cone should give you the extra amount of travel you need to get back up and running. After a while they just disintegrate. 

[aris_garage_builds]

Alright, I’ve got a bit of a delayed update. I ordered the pivot point piece I was missing and hoped that might be the problem, however I still can’t get it to go into gear. I did another round of bleeding using a steering wheel puller to compress the slave (much less sketchy than using a c-clamp hahah). It appears I got all of the air out of the system and when I compressed the slave the pedal would firm up nicely…but when I reinstalled the slave into the transmission the pedal would go soft again and it wouldn’t shift. This has me worried it’s a larger problem with the clutch or trans - any suggestions on what to troubleshoot next? 

[eaglescout526]

Unique compression method…

 

Can you get the trans to shift with the MJ off? If you can it’s not the trans and it’s the clutch. I had one of the tension springs on the clutch break the retainer off the disc and render it useless. 

[aris_garage_builds]

7 minutes ago, eaglescout526 said:

Unique compression method…

 

Can you get the trans to shift with the MJ off? If you can it’s not the trans and it’s the clutch. I had one of the tension springs on the clutch break the retainer off the disc and render it useless. 

Yes it shifts fine when the truck is off. Just won’t go into gear when I start the truck.

[eaglescout526]

Ok transmission is fine. Something probably wrong with the clutch itself. If it was the transmission you wouldn’t be able to go through the gears with it off. 

[aris_garage_builds]

1 hour ago, eaglescout526 said:

Ok transmission is fine. Something probably wrong with the clutch itself. If it was the transmission you wouldn’t be able to go through the gears with it off. 

That was my initial thought as well - this is actually the second clutch disc I've tried during this repair 

When I pulled the transmission the first time, I put in a LUK clutch (part number Luk-01-024) and ran into similar symptoms. I pulled the transmission back out and compared the clutch disc with the original one that I pulled out of the truck - I quickly noticed that they weren't the same depth. So I ordered a second clutch from M-PACT (haven't used this brand before but the specifications seemed correct for the 2.8, so figured it was worth a shot). When the M-PACT arrived, I compared it with the original clutch and it looked identical. So I was hoping that would fix my problem. Now that the M-PACT is in the truck I'm getting the same symptoms as before - Truck shifts fine when turned off, but soggy pedal and won't go into gear when running. Since the pedal was soggy, I replaced the master and slave with no luck and assumed it might be a bleeding issue. And that brings us to the present haha. I'm running out of ideas honestly, so I appreciate the help!
 

 

[eaglescout526]

Definitely boils down to either a hydraulic issue or clutch issue. Were the clutch plate bolts torqued down right? I’ve had one bolt snap on me and give me quite the issue to shift but not impossible to shift. 

 

Was the pressure plate replaced at the same time? How does it look?
 

Pedal should be a little soft but it shouldn’t be incredibly firm like brakes. 

 

How’s the master? Does it leak by chance?

 

[GonzoTheGreat]

3 hours ago, eaglescout526 said:

Was the pressure plate replaced at the same time?

That's what I was thinking too. The symptoms sound more like bad springs on the pressure plate. Its possible the slave is working, but when the throwout bearing pushes into the plate, there's no resistance and the fingers just bend.

[aris_garage_builds]

Confirmed that the master isn’t leaking, it’s freshly replaced along with the slave. Also triple checked that the bolts were all torqued correctly before reinstalling the trans. I stuck a borescope through the starter hole after bleeding the slave and had a buddy press on the pedal  - confirmed I could see the clutch fork moving, yet the clutch wouldn’t fully disengage. 

 

The clutch / pressure plate theory is intriguing. I did replace the pressure plate but it’s possible something is faulty with it or with a spring. I assume confirming this would require pulling the trans back out?

[GonzoTheGreat]

2 hours ago, aris_garage_builds said:

I assume confirming this would require pulling the trans back out?

Actually if you have a bore scope, and you could see the fork, you should probably do that check again but watch how the throwout bearing presses into the finger springs. 

 

Did the new pressure plate come with the LUK friction disc as a kit? If the disc didn't match the original, what are the chances the pressure plate matched the original?

 

If theres nothing wrong with the clutch hydraulics (and they seem to be fine), then there has to be something wrong with the pressure plate or its spacing/thickness that's preventing it from disengaging. The throwout bearing looked ok?