1990 YJ Clutch problems - JeepForum.com
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post #1 of 2 Old 04-10-2020, 07:46 PM Thread Starter
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1990 YJ Clutch problems

I have a 1990 YJ with the 4.2L engine and 5 speed transmission. I have replaced the clutch assembly with a new flywheel, pressure plate,slave cylinder and master cylinder. The problem I am having is the clutch will not disengage after I drive for about 5 minutes. I have replace the new master cylinder with several different brands, bled system and clutch works ok for couple of miles and then will not disengage again. I have bled the system by gravity, vacuum and pressure but still same issue. I called the tech support for the clutch master and slave cylinder and they tell me I don't have it bled correctly and there is air still trapped in the slave cylinder. I have bled the system and have put over 2 quarts of fluid thru it there is no way that there is still air in slave cylinder. I have contacted the tech support for the slave cylinder and now I am told that this internal slave cylinder design on the 1990 is a bad design flaw from Jeep . I have owned this jeep for over 20 years and never had an issue with the hydraulic side of the clutch system. My question is after replacing the master cylinder with 5 different brands and still the same issue I believe the slave cylinder is bad and not working as it should. There is no fluid loss or leaks in,on or under the jeep, I just believe I have a bad slave cylinder but I don't want to have to take the whole thing back apart to replace the slave cylinder, so I am asking for some help from the members of the Jeep Forum.

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post #2 of 2 Old 04-10-2020, 07:53 PM
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If the problem started immediately after the initial clutch and flywheel replacement, at this point I would suspect either the pilot bearing is bad or the clutch disc is sticking on the transmission input shaft splines.
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clutch , clutch issue , master cylinder , slave cylinder , YJ

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