BJ8 Brake/Clutch Reservoir Fluid Loss

[RAC68]

I am a little concerned that the last 2 times I checked my brake/clutch fluid reservoir, I found the level had dropped to almost ½” below the separator in both the brake and clutch sections. This is a little misleading as the original level was well above the brake/clutch separator so the loss of fluid was even grater. The first check was after a Memorial Day parade during which the clutch was used heavily. The second time was after a 3 mile back road drive with moderate to light clutch usage. Since both brake and clutch sections were down, I can not rule out that only one system is at fault and splash-over is the cause of both being low.

Thinking that since both reservoirs appeared lower and since I refilled with DOT 5 Silicone fluid before letting the level fall further, my thought was to let the system showing the lost-fluid tell me which unit is failing. My first action was to check the brakes and, given the volume of lost fluid, no wheel brake seemed to provide any definitive indication. Although I did not pull the calipers, no fluid was apparent on the outer side of the disks and no fluid appeared on any peripheral components.

As for the clutch system, the cap of the clutch slave appeared oily on the outside (could be engine oil) and did show a light film on the inside, however, no volume of lost fluid was present when the rubber cap was pulled. This may not be a good indicator as any fluid passing the rubber cap would have been deposited directly on the road.

So where does this leave me? Since the brake system seems to be functioning properly with no hesitation or excess force required, I intend to first rebuild the clutch slave cylinder as this would be the simplest and least expensive way to narrow down the source of the failure. If the problem continues, I then am concerned that the fluid could be leaking into the air chamber of the brake booster and I am afraid I would have to pull the unit and disassemble it to make a determination.

I would appreciate getting a consensus on my approach and, most important, if anyone has a way of determining if fluid is being collected in the booster while the booster is in-place?

Thanks,
Ray (64BJ8P1)

 

[BigGreen]

I think the approach is oké.
Try cleaning around the pieces first
I would not dismantle the booster before the other parts

Hans

 

[Randy Forbes]

Is the car emitting "white" smoke at the tailpipe? Not sure what DOT5 (silicone) burns like, but DOT 3-4 burns white.

Historically, losing that much hydraulic fluid was a keen indicator that the vacuum booster was feeding it to the engine.

If you had a borescope, you could look inside cylinders 4-5-6 to see if there were whitish deposits on them.

Edit: whitish deposits on the exhaust valves of the affected cylinders is what I meant to imply.

 

[RAC68]

Thanks Hans/Randy for your responses.

Randy, I see what you mean. If brake fluid is leaking into the chamber it, will be into the vacuum side and eventually be suck it into the intake manifold and aft cylinders.

Yesterday, before noticing the loss of fluid for the second time, I restarted the Healey to pull out of a restaurant parking space and noticed a billow of white smoke. A little surprised at the amount of smoke, I never connected it to my loss of brake fluid and assumed it was from the carburetor adjustment I performed a few days earlier.

A thought, if I am sucking that much fluid into the engine to cause smoke, should I expect fluid residue on the inside wall of the booster vacuum hose … especially near the booster?

Ray (64BJ8P1)

 

[Randy Forbes]

What you can expect, is an increased likelyhood of a burnt exhaust valve in the cylinders ingesting brake fluid. You're not going to want to let this go for too long :wink:

Edit: previous post (#3) edited for clarity.

 

[Keoke]

If I am sucking that much fluid into the engine to cause smoke, should I expect fluid residue on the inside wall of the booster vacuum hose …

Yes However, if the clutch section is also low then the reservoir itself is defective also where the inner seal between the inner and outer cans has f.ailed

 

[RAC68]

Hi all,

The vacuum line between manifold and booster showed no sign of brake fluid. To verify my findings, I used a cotton swap and found the inner surface dry…. Thank God.

Keoke, the level of the fluid in both sections was about ½” below the separator and either is as you suggest or from splash. If they were both further down then I would agree with your suspicion. In some ways I am sorry that I didn’t let the level fall further and am considering taking the car out to do just that.

My plan is to rebuild the clutch and determine if the issue disappears. If not, I will pull the booster and physically check. If the booster is at fault, I will then determine whether to rebuild or replace.

Thanks for the insights,
Ray (64BJ8P1)

 

[tahoe healey]

Since you are using Dot 5, does anyone know if Dot 5 puts out white smoke? I know 3&4 do for sure.

 

[TodE]

This may or may not be your problem, but soon after I got my BJ8 I had this problem. Since the brake booster is attached to the valve cover (Creating a vacuume to make the booster work)If the valve sticks it will suck the brake fluid into the valve cover. In my case I was sitting at a red light and large, I mean large amounts of white smoke coming out of the exhaust. I thought I had blown a head gasket.
It could be a small leak not causing much smoke.

Good Luck!

 

[Keoke]

Since you are using Dot 5, does anyone know if Dot 5 puts out white smoke? I know 3&4 do for sure.

Yep TH it all makes white smoke

 

[Randy Forbes]

This may or may not be your problem, but soon after I got my BJ8 I had this problem. Since the brake booster is attached to the valve cover (Creating a vacuume to make the booster work)If the valve sticks it will suck the brake fluid into the valve cover. In my case I was sitting at a red light and large, I mean large amounts of white smoke coming out of the exhaust. I thought I had blown a head gasket.
It could be a small leak not causing much smoke.

Good Luck!

Brake booster connects to intake manifold for vacuum supply, not the valve cover, where there is positive pressure.

Valve cover "T" port connects to side (tappet) cover and rearmost air filter to relieve Positive Crankcase Ventilation (PCV...).

 

[BoyRacer]

If the level in both reservoirs is gong down at the same rate, then you have a problem with your reservoir. Fix that first and then you can tell which system is actually causing the fluid leak.

 

[RAC68]

Hi All. Thought I’d provide a SUCESS update.

Well, it’s 95 degrees and close to 95% humidity today in NJ so I decided this was a good time to get down on the garage floor and rebuild my clutch slave cylinder. Although jacking up the car to get my gratly-expanding self under turned out to be a major pain, dismantling, rebuilding, and reinstalling the slave cylinder posed no problems and was completed in a little over an hour.

When examining the slave, the rubber had definitely expanded and I expect the slave was leaking intermittently. The Silicone brake fluid, initially installed over 20 years ago, was still purple and preserved the inner cylinder to the point of being very clean and only needing a light honing. Also, since the clutch fluid had drained from its section of the reservoir without affecting the level for the brakes, I expect that my issue of having both fluid levels lowered was the result of splash and not a leaking seal between reservoirs.

I appreciate many have found bleeding the slave to be a difficult task and I was concerned that I had not remembered any issues when last doing this job over 30 years ago. It turns out that, back then, the transmission cover was off and the bleed screw was easily accessed. This was not to be the case this time as I really did not want to dismantle the interior for this job.

In one of his responses, Keoke had posted a bleed method that could be performed under the car and without the necessity of the bleed extender. His approach suggested that the slave be bleed prior to mounting onto the bell housing by pumping the clutch to fill the cylinder and push the piston to its stop. Once filled, the clutch pin is used to press the piston back into the cylinder while simultaneously opening the bleed screw which is positioned in the up position. He suggested following this process a few times (I did it 3 or 4 times for good measure) while observing the expulsion of air and fluid through a clear plastic connecting tube from bleed screw to recovery bottle before fully installing the slave.

As previously mentioned, the full job took a little over an hour and I credit the ease and success of this task to Keoke’s bleed approach….thanks Keoke. Presently, we are experiencing major thunder storms so I will test the clutch when the weather clears tomorrow.

Ray (64BJ8P1)

 

[Randy Forbes]

... Yesterday, before noticing the loss of fluid for the second time, <span style="font-weight: bold">I restarted the Healey </span>to pull out of a restaurant parking space <span style="font-weight: bold">and noticed a billow of white smoke.</span> A little surprised at the amount of smoke...

What about this?

As Richard suggests, verify that the fibre washer separating the brake & clutch reservoirs is intact. Cleaning sediment from the bottom of the can always being a good idea anyway (can't believe you've gotten 30 yrs out of that fluid, but I'm not doubting you for saying it :wink: ).

Yes, this will require a complete system re-bleeding of the brake and clutch circuits, but after thirty (30!) years, look upon it as an opportunity to re-bond with the car, and a good look-see all around.

Take note of the differing thickness of those (steel) washers; the thinner of the two (2) is for the clutch reservoir:

 

[RAC68]

Hi Randy,

Thanks for the documentation on the reservoir. Although I do not think I have a problem as the clutch slave is functioning properly and reservoir levels are constant, it is time to re-address the full brake and clutch systems. Although my silicon brake fluid was installed in 1989 (a little more than 20 years ago and not 30 years as mistakenly stated) and the systems periodically bleed since. You and Rich make a good point and 20 years is long enough. This winter I am planning to renew all rubber in the brake and clutch systems, as preventative maintenance, and replace the fluid. Based upon the condition of my clutch slave, I am thinking I would stick to using Silicon unless I encounter contrary conditions when dismantling other components. As indicated, I will be using your documentation to check out and secure that my reservoir is functioning properly.

Thanks again,

Ray (64BJ8P1)