A few weeks back we wanted to take the Mudbug on a back road adventure. I came up with a route to Hico, TX that would take us on unpaved roads. We got up early to prep the Jeep for the adventure. We took the doors off, removed the soft top, and were excited to get started. I hopped in the drivers seat, put the key in the ignition, pushed in the clutch, and it slammed to the floor without resistance. The clutch was gone.
It was a huge disappointment for us. I looked over at Margaret and said "The clutch is gone". At first she smiled thinking I was just playing around. Then after I pumped it a few times I saw the truth of it wash over her face. At this point there was no telling what could be wrong. I began to worry that we would have to tow it to a transmission shop for repairs. That's not what anyone would want to hear. We closed the gate, put everything back on the Jeep and went in the house to figure out our next step.
We have put a lot of repairs into this Jeep since we got it. I've worked on vehicles since the 80's and know my way around a vehicle. I also knew purchasing an older vehicle would have issues, especially a Jeep. You just don't know how hard previous owners drove it. Admittedly a good portion of repairs were actually upgrades that we wanted to install for performance. Most of the other repairs have been pretty simple like the radiator replacement, exhaust headers, valve cover gaskets, etc. A transmission failure is on a completely different level of repairs though.
Diagnosing The Issue
Before taking it to a transmission shop I wanted to troubleshoot a bit first. We had just driven it the week before without issue so I knew it wasn't the clutch plates or anything major. I crawled underneath and noticed a bit of leaking around the area where the clutch slave cylinder attaches to the bell housing. I removed the clutch slave cylinder and found a seal had gone out in it which allowed fluid to escape. When I disconnected the clutch line I had Margaret push the clutch pedal. Nothing came out of the clutch line so the clutch master cylinder wasn't pushing fluid through to the slave cylinder. Looked to me like the clutch hydraulic system had failed.
Replacing The Clutch Hydraulic System
When systems like this fail it's usually beneficial to replace all of it. This is a closed system that only relies on three components to function. A clutch master cylinder, a clutch line, and a clutch slave cylinder. We ordered all three parts on Amazon for just under $150. I had a few days before the parts would arrive so my son came over to help me with uninstalling the clutch master cylinder. That is a two man job and quite difficult to get out. We also noticed a sticky film on the side walls inside the brake cylinder. On the Jeep, the brake cylinder is also the fluid reservoir for the clutch line. The reservoir would need to be cleaned too.
So many times during repairs one problem will often cascade into more problems. It's common because so many systems rely on other systems to function. Upon removal of the brake reservoir we were unable to get it clean. The gunk was stuck to the walls. Even scrubbing didn't work because of different compartments that prevented us from getting a brush inside. I also became concerned with that gunk getting into the brake and clutch lines. The right decision was to replace the part so we could start with clean DOT 3 brake fluid that would not get contaminated from the gunk inside the old reservoir. I couldn't find just the reservoir but Autozone had a replacement brake master cylinder with a reservoir. Another upgrade...
Installing The Parts
The brake cylinder and reservoir went on without issue as did the clutch master cylinder. That was a bit unexpected since the clutch master cylinder was quite difficult to remove. The clutch slave cylinder however was difficult. There isn't much working room in the area where it is installed. Removing the drive shaft would have helped a lot. Once we installed the clutch parts we had to bleed both the brake lines and the clutch line. I watched a couple videos about purging air from the clutch system, none of them followed the instruction manual from the manufacturer. I decided to follow the provided instructions first and even though accessing the bleeder valve on the clutch slave cylinder was difficult, the process worked perfectly. We also completely purged the brake lines of the old fluid which was very dark until fresh clean DOT 3 fluid came out of each line.
The next day we drove the Jeep a couple hundred miles to test the clutch and brakes. Everything worked perfectly and we had a great day. I've been testing the clutch every couple days to make sure it is holding pressure, which it is. I am also grateful that the issue arose while the Jeep was sitting at the house instead of on the road, or even worse, on a trail.