Hi All,

I'm hoping for some help in diagnosing an intermitent clutch problem. I have an 86 740T with hydrolic clutch. The clutch etc. and slave cylinder was replaced approx 1.5 years ago by Volvo dealer. Just recently it started to quit on an itermitent basis. Seems to be most likely to happen if I hold the pedal down a little longer than normal. Then the pedal goes limp and I can't shift. Pedal comes back with double clutching (so far at least!). Problem would seem to be hydrolic. Tried bleeding the line. Got some air out but has not solved the problem. Question: is there a definitive way to isolate the problem to the master or slave cylinder? Since the master is shared with brakes would the brakes show signs of problem if it were the master? Any advise would be appreciated.

Thanks,

Gerry

Check your clutch fork, maybe it is wearing out at the pivot point, or the fork itself is bending. Once the fork breaks you won't be able to shift at all, ask me how I know this. When the main cylinder or the slave cylinder goes you won't be able to shift at all, and may lose fluid.

Let us know what has happened

1987 745Ti, Toronto (bbbbrrrrrrrrrr ... getting colder)

Clutch and brake master cylinders are SEPARATE units. The only thing they have in common is they share the same fluid reservior. Has the brake master cyl been replaced? The new cylinder has a nipple coming off the rear side of the reservior that is sealed for cars with automatic trans. The end of the nipple needs to be cut off for clutch master hose. If not cut off, thge clutch gets no fluid. Also the clutch gets no fluid if the brake fluid gets too low. Check these items 1st. If no problem is found, possible bad clutch master.

/// Examine the Brake Fluid in the clutch master cylinder. Is it black or dark brown and opaque? It should be amber and clear. It does darken with increased moisture content. There is a chemical reaction between American Dot 3 fluid and Girling rubber in hydraulic systems. Girling uses nitril not SBR in seals. Once contaminated the system will fail in 10 to 20K miles.

Jeep truck began to use Girling clutch systems in the early 1980s. At a later point someone in the assembly plant began to put Dot 3 caps on the master cylinders. There was massive failure of these systems as owners followed the cap instructions to use only Dot 3. This information is available in the NHTSC web site under consumer complaints 1985 Jeep Cherokee.

It is possible that you had your oil changed (probably at a Pennzoil shop) and the clutch was topped off with dot 3. If this is the case I am building a data base to complain to the NHTSC. Send me a e-mail if you can confirm this contamination. Raybestos makes test strips that will indicate the grade of the brake fluid. The Dot 3 indicator is dark enough that it can be identified even if both indicators react and appear in the one test pad for grade.

I would expect you to find leaking fluid if it were the slave cylinder. What you're describing sounds like the master. A cold weather snap can finish-off a brake's master cylinder, so I assume the same rules apply with the clutch.

I've not owned a car with a hydraulic clutch. When you say the master is shared with the brakes, what do you mean? A common casting with two cylinders? Two separate castings with a common resevoir??