240SX Clutch problems caused by changing manual transmission fluid

[TheLark]

I have 1991 240 SX with about 122,000 miles on it. I am the original owner. A few days ago I took the car into Jiffy Lube for an oil change and decided to have the manual transmission fluid changed at the same time. When they were done with that job the clutch pedal went all the way to the floor and I could not get the car in gear. My car left Jiffy Lube on a tow truck and I won't get it back for week. Thanks Jiffy. I know this sounds strange but those are the facts. It raises a few questions that I hope someone can help with.

I towed the car to the dealership and the mechanic was able to get in gear temporarily. The diagnosis was that I should have the hydraulic master and slave cylinder replaced. That may be true although I don't know what these are or how to tell a bad one. I still come back to the fact that the clutch was working until I had the fluid changed.

How could changing the transmission fluid cause this? It would help if someone could explain the steps required to do this job. For example, is bleeding the system required or would over-filling cause this to blow a seal of some kind?

[KFL]

Here's the thing there is no way for them to foul it up. Basically remove draing plug on bottom of trans,drain, put back. Remove fill plug, use hand pump and fill with gear oil until it starts to slightly drip out.put back plug. Done.

Bad slave-the seal is busted fluid is leaking in around boot, completely busted upon removal the rubber boot spring shoots out(friends autozone did this)

Master cylinder seal around the master is wet dripping some fluid upon inner fender.

Slave and master cylinders do go bad but very odd about that happening.Shady quite possibly..

Parts are cheap for the most part I would only run OEM personally..some have had luck with generic brands autozone/pepboys..but some have failed. IF you want pics of exactly is what I can take some.Installation is straight foward..for slave.. master is straight as well just a tad more work crawling under dash to remove a pin.I would probably inspect both parts if they look good just bleed system. You may or may not want to bypass dampner box..basically gives the pedal a soft feeling..removal a tad more firmer.(Bleeding with dampner box takes a lot more time air gets trapped)P.S.Find a nice reliable mom n pop shop..some places are shady some are not. Or find a fellow nico member in your area to help out.

[nightkid86]

There is no way changing the fluid would damage the clutch operation. The transmission fluid in no way comes in contact with the clutch.

The diagnosis about the slave cylinder is probably correct. They fail, are cheap to replace, and it's easy to tell a bad one.

[TheLark]

I believe that the replies I’ve received are absolutely correct. And I appreciate the response because I was one step away from suing Jiffy Lube. But it is also absolutely correct that I could not get the car in gear after the transmission fluid was changed.

When you drive the same car for 15 years you normally develop a keen sense of perception when something is about to wrong. Yet there was not even a hint of a clutch or transmission problem. The only thing I can conclude is that the transmission just gets used to the same old fluid if it hasn’t been changed on schedule. It sounds weird but I guess the new fluid was too much of a shock.

I’ve decided to let the dealership replace the slave and master cylinders. But I’m wondering… is there a way to tell if something else should be replaced during that job? It still has the original clutch at 122,000 miles.

[ca18datsun510]

the hydraulic system (master cylinder, slave cylinder etc) are completly isolated from the fluid inside the trans.

[nightkid86]

I'm sure the original clutch is getting pretty worn out, but if it still working fine there is no point in spending the money to get a new one put in. If I were you however, I would find a local mechanic to install the master/slave. The dealership with charge you a whole lot more than a local mechanic. And in my experience I would much rather have a mechanic work on my nissan than a nissan dealership.

-Something about 2 dealership technicians telling me I have a skyline, then installing a water pump and not refilling the radiator up. Dealerships are retarded. Also I have done lots of transmission work but I got lazy and got my mechanic to put a clutch in for me, he charged 250$ labour, the dealership would probably charge around $500.

[ftl900]

There is a reason that someone invented the word "coincidence". It had to fail some time, and that was the time it picked to fail. Happens with computers all the time... you add memory or swap out a graphics card, and the hard drive fails, for no particular reason.

It's coincidence. That's what that word means.

[rogoman]

A few days ago I took the car into Jiffy Lube for an oil change and decided to have the manual transmission fluid changed at the same time. When they were done with that job the clutch pedal went all the way to the floor and I could not get the car in gear. My car left Jiffy Lube on a tow truck and I won't get it back for week. Thanks Jiffy.

I'm willing to bet that your friendly Jiffy Lube also changed the fluid in the clutch hydraulic system and didn't know how to bleed the system.

[TheLark]

As long as we are defining words let me throw in two more... possible and probable. It is possible that it was just a coincidence but I would not say probable. The thing is... the clutch was working when I parked it in the service bay and handed them the keys. When I got my keys back I couldn't even pull it out of the service bay. It isn't like it failed on the way home.

What amazes me that these technicians are supposedly trained and certified. And yet three of them were standing around scratching their head trying to figure out why we could not get my car in gear. Not one of them checked my clutch master cylinder. If there is no fluid in the darn thing it isn't going to work.

While waiting for the tow truck I left to get another car. I later discovered that they managed to get in gear by pumping the clutch (so I was told) and they drove it out of the bay. In the end, I was without my car for nearly a week, paid about $500 to have the master and slave cylinder replaced, and all I really needed at the start was some fluid.

I'll never know for certain what Jiffy might have done but I think they were negligent in several areas and at a minimum contributed to the problem. And I will see to it that they contribute to the bill.

[ca18datsun510]

pls do not refer to jiffy lube staff as technicians. they aer not really trained in anything, they are mostly a bunch of highschool kids etc. learn to change your own fluids, you'll be much better off.