Mystery leak! Where is my hydraulic clutch fluid disappearing to?

ranger
clutches

#1

2001 Ranger. 48,000 miles.

One evening I got to a red light a couple blocks from work. When I shifted to neutral there was a noise and it “felt” like a cable had snapped. My clutch pedal gave no resistance and I couldn’t shift out of neutral with the engine on. A mechanic said my clutch is hydraulic and showed me the little plastic reservoir under the hood which was empty. Apparently it’s not supposed to be empty. He poured in some fluid and got it working fine, but I left the vehicle with him anyway to search for a leak. He didn’t find one (said something about master cylinder and slave cylinder okay) and said it’s possible the fluid evaporated out.

I drove around just fine for about two weeks, and then one morning had the same problem. I poured in some brake fluid and drove fine for another few days, when it happened again. Soon it was every morning, and then every few minutes. I went to another mechanic, who who also could find no leak.

There’s no fluid on the floor of the cab near the clutch and (except for what I spill when I add more fluid) no fluid under the hood. No puddle on the driveway… I’m perplexed, and when I get it fixed I’d like to go armed with a good idea of what is wrong. I don’t want to be sold a new clutch. The clutch works fine. It seems to be the hydraulic system that’s spazzing out. Any ideas on what’s going wrong here? Public transit is fine for now, but when school starts again I don’t think the teacher will be happy with my engine woes.


#2

I forgot to mention that when I go to add more fluid, it doesn’t LOOK like any is missing. It’s as if just a few drops makes all the difference… for another couple miles. It’s not as though the resevoir is empty all the time, only that first time. Thanks for your ideas.


#3

You mentioned there is none on the floor of the cab, except where you had spilled some. I believe this is where the leak is, leaking from the front seal of the master cylinder. I recently had a leak in my hydraulic clutch system and could find no leaks. That is, until I had to peel back the carpeting in the foot well, and found it wet. When I removed the master cylinder, the outer seal was wet inside with brake fluid.


#4

I agree. The fluid is absorbed in the insulation under the floor mat. Replace BOTH the master and slave. When one goes, the other is not far behind…


#5

[b]Because you felt a sudden loss of clutch pedal pressure indicates that there’s a failed hydraulic component. And if there’s no indication of leaking in the master cylinder area, then one must assume the problem is in the slave cylinder.

The slave cylinder is located inside the bellhousing of the transmission mounted on the stub boss. So it sits centered to the clutch assembly. If the seal in the slave cylinder has developed a leak, the hydraulic fluid will be flung out to the inside surfaces of the bellhousing. If there’s a buildup of clutch friction material dust inside the bellhousing, this will soak up any hydraulic fluid. And this is why the leak can’t be located.

Tester[/b]


#6

[b]Because you felt a sudden loss of clutch pedal pressure indicates that there’s a failed hydraulic component. And if there’s no indication of leaking in the master cylinder area, then one must assume the problem is in the slave cylinder.

The slave cylinder is located inside the bellhousing of the transmission mounted on the stub boss. So it sits centered to the clutch assembly. If the seal in the slave cylinder has developed a leak, the hydraulic fluid will be flung out to the inside surfaces of the bellhousing. If there’s a buildup of clutch friction material dust inside the bellhousing, this will soak up any hydraulic fluid. And this is why the leak can’t be located.

Tester[/b]


#7

I should have been clearer: there is NO fluid inside the cab. (there’s no carpet and I peeled back the vinyl to be extra sure.) The fluid I spilled was as I was putting the resevoir cap back on, so the fluid got on various engine parts near the resevoir. The mechanic actually washed the engine area so all the crap I spilled all over wouldn’t mask any leaking.
-JM


#8

Okay, so it sounds like you’re saying the mechanics I took 'ol Lucky to did NOT in fact conclusively rule out problems with the master and slave cylinders. They said they had.
So it sounds like I need to find another mechanic?? And if/when it turns out that one of these cylinders is the problem I assume I need to have the cylinders both replaced… What sort of ballpark is the repair I’m looking at? Sixty bucks? Seven hundred bucks?
NOT looking for a quote, of course. But I’m sure several CarTalkers have had this done.
Also, the internet has divided opinions on Aamco. Anyone pro/con Aamco? -Jenn Murphy


#9

[b]All you need to do is locate a shop that has a boroscope, and ask that they look inside the bellhousing to see if the slave cylinder is leaking.

Tester[/b]


#10

The slave cylinder will cost big. This truck uses an hydraulic throwout bearing, and dropping the transmission is the only way to get to it. Count on replacing the clutch as well, since this is a great time to get to it. Count on several hundred.

But, the master cylinder is easy to get to. This truck uses a plastic (yes, sigh, plastic) master cylinder that is really easy to, but uses a nylon hose to connect it to the slave cylinder. I forgot how they fastened the master to the firewall, tho.

And, STAY AWAY FROM AAMCO. Most of these shops are iffy and can only be counted on to lighten your pocket.


#11

Wow, thanks for all the info.

So it sounds like what I need to do is find a shop with a “boroscope” that can conclusively identify one of the cylinders as the source of the leak.

If it turns out the be the master cylinder it MIGHT turn out to be an “inexpensive” fix, but if it turns out to be the slave cylinder, then I’m looking at a clutch replacement “as long as we’re already in there.”
This is because so much of the cost of replacing the clutch is the labor, right?
By the way, when we talk about “the” clutch, what clutch are we talking about?
According to

and

there is more than one clutch. Do they replace them all? What about all the other cog-looking things? It seems like they would wear out, too.

Well, thanks for the info. If anyone has anything else to add, I?m all ears.
JMurphy


#12

Is the master cylinder the plastic resevoir that I’m pouring brake fluid into? I might sound ignorant, but I’d rather sound ignorant here than at the shop with my wallet open.


#13

That is the resevoir. If you follow the line that comes off the bottom it will lead you to the master cylinder.


#14

Well, that definitely makes more sense. For the record, it doesn’t look at all easy to get to where that hose goes, either.
Is there any chance my troubles origniated from having “air in the lines” from the first incident? What would be the symptoms of failing to “bleed the line” if it were indicated?


#15

Having done these you are correct it is not in an easy spot. As far as the loss of fluid I happen to agree with Tester. Chances are the slave cylinder is leaking and it is slinging it all around in the bell-housing. The easy way to check this is to slide under the truck with a flashlight and a scredriver. On the drivers side of the tranny there is a square rubber plug in the bellhousing. This is were the clutch fork used to go in. Pop the rubber plug out with the screwdriver and look inside. If it is wet the slave cylinder is your problem.
~Michael (Dartman69)


#16

My money is on the slave cylinder.


#17

I watched the second mechanic actually do this when Lucky was up on the lift. He used a flashlight and a mirror-on-a-stick to look in there. He wouldn’t let me come under the truck to take a peek myself, (which is understandable) but it’s definitely been looked at. Several of the mechanics came to look, too, trying to be the hero who found the problem. (My being a blonde girl definitely got my truck some attention, but it didn’t get it fixed. At least they didn’t charge me.)
Thanks a ton, anyway! Jennmurphy


#18

Jennifer:
The only other thing I can think of is the line that connects the clutch master and the clutch slave. I had an instance on my dads Ranger where he was leaking hydraulic fluid from the clutch system. It turned out that the line was bad and it only leaked under pressure (when the clutch pedal was pushed down). The fluid dripped to the ground while driving but left no trace on the truck. Hope that helps.
~Michael


#19

Wow, Michael. That seems to fit all the details I’ve collected on my little problem.
So now I’ve got a few trees to go barking up. If I lived in Vegas I’d put a dollar on this one.
I’ll call some mechanics tomorrow.
Thanks!
Murph


#20

Kudos to everyone: the mechanic said it’s the slave cylinder. He’s gonna replace the master and the slave and check out the clutch at the same time and possibly replace that, too.
Thanks for all your help and ideas, Cartalkers.
And in the meantime, public transportation in LA is not so shabby.
JennMurphy