700 mile trip tomorrow

[dn010]

The problem is the car is not okay to drive again when it cools down; the issue persists with the engine cold per post #24.

My money is still on a small leak somewhere. I wouldn't suspect air getting in there all in one big burst. I'd think a bubble is getting in slowly with each press of the clutch pedal. After 300 miles of driving and enough air has built up, he has trouble shifting. He parks it for the night. He then can't get it into any gear upon starting the car the next morning to test it out, until he pumped the pedal 10 times which would compressing the air, and then it shifts as usual. He then decides to bleed it and it's fine. Drives it another 300 miles and it acts up.

Either way, with enough bleeding he'll have new fluid but I'd still be concerned about it happening again if it was my situation.

[dmcman73]

The problem is the car is not okay to drive again when it cools down; the issue persists with the engine cold per post #24.

My money is still on a small leak somewhere. I wouldn't suspect air getting in there all in one big burst. I'd think a bubble is getting in slowly with each press of the clutch pedal. After 300 miles of driving and enough air has built up, he has trouble shifting. He parks it for the night. He then can't get it into any gear upon starting the car the next morning to test it out, until he pumped the pedal 10 times which would compressing the air, and then it shifts as usual. He then decides to bleed it and it's fine. Drives it another 300 miles and it acts up.

Either way, with enough bleeding he'll have new fluid but I'd still be concerned about it happening again if it was my situation.

Ah, I had missed that part in post 24 that you pointed out.

One thing he should look at is the line going from the remote fluid reservoir to the master cylinder, if it's old or it's the original one then they tend to start "sweating" brake fluid and can draw in air microscopically. Easy enough to check once the inspection plate is removed, if the hose looks wet, that could be one source of the issue.

[Helirich]

If it was air, it would not wait 600 miles before showing symptoms each time he drives the car, my guess is that he has a high water content in his fluid from absorption that after driving for a while, the water is reaching a boiling point causing his issues. Once the car cools down, it's OK to drive again until it heats up to the point of boiling the moisture in the fluid again.

This might be the case because the fluid that came out during bleeding is so grungy looking. When I was on the highway, I basically never shifted. It?s just in overdrive for 200 miles. On both trips, I was driving really fast. A guy would pass me and I would just keep him in sight and follow. I figured he would get the ticket. The guy yesterday was really flying and I would say I averaged 92 mph for over a 100 miles. Some times I had to break triple digits to keep up. The engine water temp stayed normal. Do you suppose the clutch housing was getting hot? I wasn?t going as fast on the trip up, but still was over 80 most of the time. Still, I?ve never heard of water in the fluid boiling.

Ah, I had missed that part in post 24 that you pointed out.

One thing he should look at is the line going from the remote fluid reservoir to the master cylinder, if it's old or it's the original one then they tend to start "sweating" brake fluid and can draw in air microscopically. Easy enough to check once the inspection plate is removed, if the hose looks wet, that could be one source of the issue.

I need to look at that line, but I seem to remember checking it before and it was a new style line. I kind of think dn010 is correct because it?s the most likly. It doesn?t seem to leak a drop out, but air going in is hard detect.

[dmcman73]

This might be the case because the fluid that came out during bleeding is so grungy looking. When I was on the highway, I basically never shifted. It?s just in overdrive for 200 miles. On both trips, I was driving really fast. A guy would pass me and I would just keep him in sight and follow. I figured he would get the ticket. The guy yesterday was really flying and I would say I averaged 92 mph for over a 100 miles. Some times I had to break triple digits to keep up. The engine water temp stayed normal. Do you suppose the clutch housing was getting hot? I wasn?t going as fast on the trip up, but still was over 80 most of the time. Still, I?ve never heard of water in the fluid boiling.



I need to look at that line, but I seem to remember checking it before and it was a new style line. I kind of think dn010 is correct because it?s the most likly. It doesn?t seem to leak a drop out, but air going in is hard detect.

Brake fluid is very hydroscopic and can absorb moisture. When enough moisture is absorbed by the brake fluid in a brake system or clutch, the boiling point of the brake fluid drops. As soon as there is enough heat to bring the moisture to boil, it creates vapor bubbles in the line from the water which will cause the loss of brakes or in this case, clutch. There are a lot of components in that area to cause the clutch fluid to heat up, cross over exhaust pipe, the slave cylinder transferring heat to the fluid, etc; it's not based on speed. That fluid gets hot enough that it used to cause the original vinyl line to expand and cause a loss of clutch movement hence the reason all manual owners upgraded the clutch like to a stainless steel braded one.

If your fluid was grungy coming out, flush the system completely, hopefully it hasn't caused any damage to the cylinder walls in either the master, slave or both.

[David T]

Brake fluid is very hydroscopic and can absorb moisture. When enough moisture is absorbed by the brake fluid in a brake system or clutch, the boiling point of the brake fluid drops. As soon as there is enough heat to bring the moisture to boil, it creates vapor bubbles in the line from the water which will cause the loss of brakes or in this case, clutch. There are a lot of components in that area to cause the clutch fluid to heat up, cross over exhaust pipe, the slave cylinder transferring heat to the fluid, etc; it's not based on speed. That fluid gets hot enough that it used to cause the original vinyl line to expand and cause a loss of clutch movement hence the reason all manual owners upgraded the clutch like to a stainless steel braded one.

If your fluid was grungy coming out, flush the system completely, hopefully it hasn't caused any damage to the cylinder walls in either the master, slave or both.

Just to add a bit more to this very good explanation about brake fluid, as the fluid absorbs moisture it also turns acidic and attacks the iron components in the system especially the bores of the cylinders. Once they get corroded and pitted (rough), as the seals pass over the pits and corrosion they get torn and then leak. To prevent this you should flush and bleed the brakes and clutch at least every other year. Especially if you do not use the car often. By using the car often you heat the fluid up and drive out the moisture from the fluid so it will last longer but even so it should be flushed regularly. Some fluid and a little labor is easier and a lot less expensive than replacing parts.

[Helirich]

Brake fluid is very hydroscopic and can absorb moisture. When enough moisture is absorbed by the brake fluid in a brake system or clutch, the boiling point of the brake fluid drops. As soon as there is enough heat to bring the moisture to boil, it creates vapor bubbles in the line from the water which will cause the loss of brakes or in this case, clutch. There are a lot of components in that area to cause the clutch fluid to heat up, cross over exhaust pipe, the slave cylinder transferring heat to the fluid, etc; it's not based on speed. That fluid gets hot enough that it used to cause the original vinyl line to expand and cause a loss of clutch movement hence the reason all manual owners upgraded the clutch like to a stainless steel braded one.

If your fluid was grungy coming out, flush the system completely, hopefully it hasn't caused any damage to the cylinder walls in either the master, slave or both.

Mine doesn?t have the cross over pipe anymore and I?m pretty sure it has the stainless lines, but I still think the housing could get hot.

[Helirich]

I finally got to work on the car. I had some trouble getting the remote bleeder, so I just used a vacuum one I bought last time. I?m not really recommending one, but it?s all I had. The problem with it is air leaks at the threads of the bleed nipple.

Anyways, here is the first jar of fluid that came out.

IMG_1641.jpg

I dumped it in a bottle and sucked out another.

IMG_1640.jpg

You can see how the color is kind of green on the first jar. Not sure if water does that or heat. It sure doesn?t look good. The clutch is working good now. I still feel like the clutch doesn?t completely disengage until the very last of the stroke. Is that the way the rest of you guys find your clutch? I?m thinking of changing the linkage.

[David T]

I don't like vacuum bleeders just because of what you found out, the threads will leak air. One "trick" that can work is to remove the bleeder and put some grease on the threads and put it back in. Try a "One man Bleeder" which is just some tubing and a check valve.

[dmcman73]

I finally got to work on the car. I had some trouble getting the remote bleeder, so I just used a vacuum one I bought last time. I?m not really recommending one, but it?s all I had. The problem with it is air leaks at the threads of the bleed nipple.

Anyways, here is the first jar of fluid that came out.

IMG_1641.jpg

I dumped it in a bottle and sucked out another.

IMG_1640.jpg

You can see how the color is kind of green on the first jar. Not sure if water does that or heat. It sure doesn?t look good. The clutch is working good now. I still feel like the clutch doesn?t completely disengage until the very last of the stroke. Is that the way the rest of you guys find your clutch? I?m thinking of changing the linkage.

Fully disengaged clutch is at the very bottom stroke, but it should start to disengage as you start pressing the clutch pedal.

That fluid color is from the moisture mixing with the fluid and creating an acidic fluid, mixed with heat and you have green to black fluid. Change your brake and clutch fluid every 2 to three years.