Tuesday, January 31, 2012

DeLorean Clutch Problems

On the last drive of the season, I noticed that the clutch pedal was very very soft, like it wasn't doing anything until at the very end of the pedal depression. It was also hard to get it into first gear. The next day, I couldn't get it into any gear. I thought the clutch was toast.

I checked the clutch fluid reservoir and discovered that it was bone dry. I looked inside at the clutch pedal and discovered that the clutch master cylinder had been leaking brake fluid into the car:
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I was also told that if I replace the clutch master, I should also replace the slave cylinder because it is sure to fail soon after. I bought new parts from DMCH and attempted to complete the job. The clutch master cylinder was pretty straightforward with little to no surprises. I also purchased a new hose that goes from the reservoir to the master cylinder since it looked like it was cracking. The previous owner also had clamps on the ends, probably to extend the hose's life once the cracking began.

The previous owner also had installed a SS braided clutch line, so I didn't need to worry about upgrading the line. The slave cylinder replacement has got to be one of the most annoying repairs on a DeLorean. You can either attempt to do it from above the engine, or below, or a combination of the two. I decided that certain things were easier to do from above the engine, and most of it was easier to do below.

I removed the engine cover for easier access from above, and jacked up the car on jack stands to allow me to work from underneath. The metal clutch pipe that the SS braided line connects to runs along the transmission and connects to the slave cylinder. While attempting to remove the clutch pipe nut from the slave, the clutch pipe snapped in half. The nut had fused to the pipe, twisting the whole pipe instead of just the nut.

To add insult to injury, one of the slave cylinder bolts snapped while trying to loosen it as well. At this point I thought I was screwed and that I would have to remove the transmission. Luckily the slave cylinder bolts only keep the slave in place, but don't have any lateral forces. The new one should be fine with just one bolt and a large washer holding it in place.

As far as the metal clutch pipe was concerned, I was told on www.dmctalk.org that the SS braided line has enough slack in it to connect directly to the slave, bypassing the metal clutch pipe entirely. So I cleverly hooked it directly to the slave, thus eliminating the need to purchase a new clutch pipe. After I hooked it up, I noticed that the line was way close to the exhaust front pipe, as seen here:
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It turns out that the DeLorean owners that told me that this mod could be done had aftermarket exhausts on their cars and this pipe was no longer there to worry about. So after all my hard work of getting this line to work and bleeding the clutch line, I now have to end up ordering a new metal clutch pipe and installing it like it was originally done. If I were to leave it as-is, the exhaust heat would likely boil the clutch fluid, which is a bad thing.

While replacing the slave, I happened to also break a couple of things. First, there is a plastic tube that goes from the corner of the engine bay:
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It looks like the previous owner broke this and tried to repair it with that larger tube on the end. I just happened to discover it when a wrench fell on it. That tube hooks into the heater control valve, which is in the red square below:
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I'll probably just seal it with some sealant to allow the vacuum connection to work again. The other thing that I found is circled in the picture above. Apparently this wire does nothing on a manual DeLorean, and possibly no DeLoreans. It is likely that it is an extra wire for another make of vehicle that used this same PRV motor. Luckily these things are nothing major.