Thought I'd share this embarassing gem:
I had a reason to change one of the rear suspension cylinders not so long ago. I won't go into the why's and wherefor's here. Anyway I assembled in the usual manner and lastly connected the two plastic fluid return pipes into the rubber boot.
After a couple of weeks I noticed pools of fluid on the ground at the front of each of the rear wheels. Not another leak I thought.
I got the car on the ramps and had a look. No matter what I did I couldn't find the source. I stripped off the inner plastic wheel arch cover to look inside the circular crossmember running across the width of the rear of the car. The tube was full of fluid and was dripping out the ends.
To cut a long (v.long) story short I had connected the two plastic return pipes the wrong way round. One goes back to the tank via a tee piece from the opposite side. The other goes into the crossmember tube and just ends in mid air. I thought the leaking fluid was coming from there.
The pipe connected back to the tank is the one connected to the strut boot into the hole nearest the back of the car. As the strut moves in and out, with the up and down movement of the wheel, the boot acts as bellows pumping the excess fluid back to the tank. The other pipe is connected into the remaining hole in the boot between the two loops if the retaining clip. I can only surmise this is a telltale mechanism to tell you that the first return pipe is blocked and the fluid can't escape back to the tank. The overflow then comes out of the second ending up appearing out of either end of the crossmember tube.
Anyway, I switched them over to the correct orientation hoping that would solve the problem. It didn't.... So now I have to investigate again. I'll keep you posted on progress.
Cheers
noz 8)
Full Version Low pressure return piping
How embarrasing to get it wrong twice.
The leak did not stop as I said and after the third 5 litre can of LHM I decided it would be cheaper to solve the problem rather than keep buying oil.
Most of what I said above was correct with one fatal flaw. The pipes were the wrong way round. The connection on the rubber boot closest to the rear of the car, which is also the one between the two loops of the retaining clip is the one that goes back to the tank. The other one which connects to the bellows part of the boot is the one which vents into the circular crossmember. The bit about the bellows pumping the fluid back to the tank was tosh (too much alcohol rots the brain). Of course the bellows could not have generated enough pressure to overcome the friction losses of such a small return pipe and also the head of fluid to raise it back up to the tank level.
In fact I removed the strut from the car and studied it closely. When you remove the piston from the strut and look into the bore two recesses are visible. The one nearest the bottom of the cylinder has no seal in it. It gathers the fluid which escapes past the piston and the fluid is forced out of a hole in the casting. The fluid is contained by the rubber boot and the hole in the boot is where the return pipe is connected transporting the fluid back to the reservoir. The recess closest to the outside edge of the cylinder (on the inside of the bore) does have a seal in it. This seal traps the fluid which has leaked past the piston preventing it from leaking to the outside world. The very small amount which gets past this seal ends up in the bellows. As the bellows are forced in and out with the movement of the wheel, air is pushed and pulled in and out of the platic pipe connected to the boot. This pipe vents inside the circular crossmember. Assuming the seal in the strut is working OK you should never see fluid coming out of the pipe in the crossmember. If you do, and the pipes are connected the right way round, then it is a sure sign that your strut seals are faulty.
Sorry to have caused any confusion.
Cheers
noz
The leak did not stop as I said and after the third 5 litre can of LHM I decided it would be cheaper to solve the problem rather than keep buying oil.
Most of what I said above was correct with one fatal flaw. The pipes were the wrong way round. The connection on the rubber boot closest to the rear of the car, which is also the one between the two loops of the retaining clip is the one that goes back to the tank. The other one which connects to the bellows part of the boot is the one which vents into the circular crossmember. The bit about the bellows pumping the fluid back to the tank was tosh (too much alcohol rots the brain). Of course the bellows could not have generated enough pressure to overcome the friction losses of such a small return pipe and also the head of fluid to raise it back up to the tank level.
In fact I removed the strut from the car and studied it closely. When you remove the piston from the strut and look into the bore two recesses are visible. The one nearest the bottom of the cylinder has no seal in it. It gathers the fluid which escapes past the piston and the fluid is forced out of a hole in the casting. The fluid is contained by the rubber boot and the hole in the boot is where the return pipe is connected transporting the fluid back to the reservoir. The recess closest to the outside edge of the cylinder (on the inside of the bore) does have a seal in it. This seal traps the fluid which has leaked past the piston preventing it from leaking to the outside world. The very small amount which gets past this seal ends up in the bellows. As the bellows are forced in and out with the movement of the wheel, air is pushed and pulled in and out of the platic pipe connected to the boot. This pipe vents inside the circular crossmember. Assuming the seal in the strut is working OK you should never see fluid coming out of the pipe in the crossmember. If you do, and the pipes are connected the right way round, then it is a sure sign that your strut seals are faulty.
Sorry to have caused any confusion.
Cheers
noz
You wouln't believe it. Still leaking.
I studied the rubber boot for a while and decided the fluid was getting past the first outlet back to the tank and finding its way into the bellows part of the boot. So I tightened the wire clamp. No joy, still leaking. Unfortunately I've come to the conclusion that the o-ring seal on the piston inside the strut is leaking. That's the only place where the fluid can be getting into the belows part of the boot.
I'll order a couple of new seals from Pleaides and see if that does the trick. I'll report back once I've done the deed.
Cheers
Noz
I studied the rubber boot for a while and decided the fluid was getting past the first outlet back to the tank and finding its way into the bellows part of the boot. So I tightened the wire clamp. No joy, still leaking. Unfortunately I've come to the conclusion that the o-ring seal on the piston inside the strut is leaking. That's the only place where the fluid can be getting into the belows part of the boot.
I'll order a couple of new seals from Pleaides and see if that does the trick. I'll report back once I've done the deed.
Cheers
Noz
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