Bleeding air question for a 6.5 engine

[6.5L]

I hope this doesn't get moved. I want some people to see it. Two weeks ago my clutch line decided to kick the bucket. So replaced that, the slave, and the master. Bled the system. Drove it around for a day and a half and then the clutch would not dis-engage. I would pump the clutch for a few minutes to try to bleed some air with no luck. Then would bleed the system again. It would work great for a little while then would start its shit again. So we would bleed it again. Work great. And repeat procedure from then until now. Wouldn't dis-engage at all today which left me driving around town and not being able to take it out of third, which did leave some nice clouds at red lights haha so we bled the system. Works great now. Maybe this is the ticket time it works now for good, maybe it won't, who knows. I suspect air may be getting into the system but I dont know from where. I assume if there was a leak in the system, that when put under pressure would leak fluid and there isn't. Has anybody else experienced this or know what is going on?

 

[jrsavoie]

I had similar problems with the 89 once. Maybe you can find my posts on it. The problem was eventually resolved. I do not remember anything about what went on.

 

[Will L.]

If you can't find one of the connections sucking air / leaking, maybe test the fluid and make sure it hasn't absorbed any water -that will give you the same feeling.

 

[6.5L]

I was talking with my dad and he thinks that with as close as it runs to the exhaust, that maybe it is boiling slightly. He is gonna look to see if he cant find some shit with a higher boiling point than the DOT3. For all the symptoms it has, it seems like a sound theory. I dont know though

 

[6.5L]

Just looked. the boiling point for DOT3 dry is 401*F while wet (3% water) is 284*F. I found that DOT3 absorbs water from atmosphere over time. I know the fluid we used was fairly old so maybe it has just degraded the boiling point that far. Who knows. Worst case scenario a change wouldn't hurt anything.

 

[Will L.]

If external heat can boil dot 3, it will boil dot 5. Yes it is rated for 550f instead of 290f but understand that is a pressure variance loaded rating. Dot 5 can eat some materials. Once you have installed dot 3, rubber materials are not going to withstand the dot5. You would have to start out replacing master,line,and slave. Just draining the dot3 and pouring in the dot 5 WILL CAUSE PROBLEMS I have warned many people at the track about it and everyone came back and said "yeah u were right...". My h1 uses it and I have used it on race cars in the past but the application you are doing is not not likely to fix your problem. The routing in factory location is ok in thousands of trucks...
Did it "boil the fluid" before this repair?

 

[6.5L]

No. Everything worked fine up until this point. But what else would explain what is happening. Just doesnt make any sense to me

 

[ak diesel driver]

I'd suspect the master cylinder and or the rod out of adjustment.

 

[6.5L]

Would that explain why it works great right after we bleed the air out of the system? It seems to be air accumulating in the system somehow.

 

[jrsavoie]

What brand of replacement parts did you use?

I've found that switching multiple parts usually leads to having one bad part in the bunch anymore. All these made in China parts suck.

I'd be looking at the parts you installed. Anymore, you just as well run your old parts til they die. It's to much of a pain to install new - bad parts and then start the diagnostic process over.

 

[Will L.]

Start out buying new dot3 fluid. Re do connection points and check adjustments (AK is on the money). When you buy brake fluid buy the small containers if you want to keep some on hand so they havent been opened exposed to moisture in the air.

Living with the humidity you should chuck any open bottle after a few months, at least but the test strips. Bad fluid in a clutch is annoying, bad fluid in the brakes gets deadly.

No problem of heat before tells you it is not the external heat sorce. Please don't try the dot 5
on the already filled system or you'll be swapping components again in a month or two. If you change over you have to start out with it from new. Many a brembo have been rebuilt in the first 6 months of life from this.

 

[jrsavoie]

In the 89 I had a very small leak in the slave cylinder. These systems do not hold much fluid and a small amount of leakage takes a while to show up. Do you still have your old parts?

If so I would re-install either the slave, master or both and see if you problem is corrected. I'm guessing you have a bad new part or a bad connection.

Would that explain why it works great right after we bleed the air out of the system? It seems to be air accumulating in the system somehow.

 

[6.5L]

Well, today we decided to put new fluid in, disconnected all the lines, replaced both seals, and buttoned it back up and bled it. Works good for the most part. If I let it sit for a while it gets loose but after 3 clutch pumps pressure is back in the lines and the clutch works just fine. I will bleed it again in a day or two. If it keeps up after that I will look at the parts and maybe replace them

 

[6.5L]

By the way, found out the problem, it was a throwout bearing. Replaced the throwout bearing, had it in for about 2 hours and it acted like it went out again. Tore the entire clutch out this time and found the clutch disk had ripped completely in half and that the pressure springs had dissenigrated and fallen behind my pressure fingers which was keeping full movement from happening. New clutch and she is happy.

 

[Will L.]

woohoo! Glad to hear you have it resolved.

 

[WarWagon]

:thumbsup: I have a soft spot for handshakers. :mad2: Then I am reminded of how bad the clutch designs are. Esp throw out bearings. I don't know if the aftermarket makes a better clutch...

Did you check the pilot bearing while you were there?