Hydraulic System Woes

By Frank Plegge

Originally published in the Austin-Healey Magazine, February 1987


I have owned an Austin-Healey Mk II BT7 for 13 years. I have undertaken to restore my Healey myself and in the time I have owned the car I have done about everything except pull the engine and the transmission. I recently had a situation that I had not seen nor read about in over 10 years of reading Healey Highlights. I thought I would pass on my experience for what it may be worth.



I keep my Healey under a large carport. It is covered. I drive it about 400 miles a year mainly because it is too hot and humid in the summer, too cold in the middle of the winter and I refuse to drive it in the rain. This spring I noticed a need to replenish the brake/clutch reservoir on a regular basis. This really wasn't excessive, but any loss is need for concern. I then began a thorough check. After pulling the carpet back from the firewall and forcing my way in to where I could see, I found the source of the leak.


The clutch master cylinder had been leaking for an extended period and left everything on the inside firewall and forward foot well a lovely mess. I then decided to put the Healey on stands and do a proper job on the clutch master cylinder and the brakes as well. This brings me to the point of my writing and how it possibly could affect other Healey owners who are as unaware as I was.


I have three service manuals – Haynes, Bentley plus Clymer and the original owners manual. Also I make copies of maintenance articles in Healey Highlights and in Thoroughbred & Classic Cars. I have noticed, but did not heed, the warning of not using any other brake fluid except that specified for British vehicles. It seems that the rubber seals used in our Healeys is a natural rubber and the seals used here in the U.S. are a synthetic. With U.S. brake fluid, the natural rubber will break down over a period of time as will brake/clutch hoses, dust covers etc. I have used different fluids in the past and thought if approved for disc brakes it would work.


I began a thorough overhaul of the entire hydraulic system. My concern was justified. Although the brakes and clutch were operating, I found the seals in sad shape as well as pieces of rubber and other foreign matter in the fluid when it was drained. Not wanting to be faced with this problem I decided to use the silicone brake fluid. It made sense for me in that I don't drive my Healey that often to heat up the brakes and possibly get rid of any moisture. As regular hydraulic fluid attracts and holds moisture, it seemed the right thing to do.


In the teardown of the calipers, master cylinders and wheel cylinders, I was really surprised at the amount of corrosion of the metal. The clutch master cylinder had to be replaced because of this. I am including a photo of the condition of the caliper pistons to show the damage. I replaced the pistons at $37.00 each. I am wondering how many other Healeys are in the same condition? The brakes can't last forever and need proper attention.


After draining the system I filled the reservoir with rubbing alcohol to flush out the old brake fluid. I then used compressed air from a source which had a water trap to blowout of the lines all the alcohol and the water which the alcohol itself attracts. All brake hoses were replaced along with the clutch slave cylinder hose.


While I had the Healey on the stands it gave me a rare chance to work under the car. I did a great deal of scraping with a wire brush and painting on the frame and other underbelly parts. I then Waxoyled the entire underbelly. The front suspension was repeatedly cleaned and scrubbed till it was oil-and grease-free, and then painted. The front sway bar was also rebushed. This is a great time to drain the transmission, overdrive and rear end and paint the rear springs with old motor oil. I also followed your article on the suggestions for a tune up. Pulling the distributor wasn't all that bad after all, and setting the timing as suggested had made a difference in the way the Healey runs.


I want to thank you and all the others for their contributions to the preservation of the Healeys. I am not a mechanic only a lover of British sports cars. I also have a lovely TR-3. I want to be able to continue to enjoy them and I look forward to each issue of the club magazine.


Not what you were looking for? Don't forget you can check our back issues using the AHCUSA Magazine Index.


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