View Full Version : '85 XJ trans. info,please

July 11th, 2006, 16:13
Hi guys,
This is my first posting, hope I'm in the right forum. I already know you guys are pretty sharp from some of the answers I've read for various problems.

Here's mine, hope you can help.

I'm looking at buying another XJ, an '85 2.5L auto,pioneer package161,000 miles, seller says he just replaced the engine (30,000 on replacement), ridiculously low price.I,ll tell you how ridiculous if I decide not to buy it,(mid to upper 3 figure range). The problem is he replaced the engine because there was a knock. Drove the jeep about 30 miles and now it won't start he says that when he pulled the engine there was a lot of play in the trans shaft he thinks it somehow might need a trans.pump bearing?, a crank pos. sensor and a new computer.

Does any of this make any sense to any of you guys? About how much is this going to cost me in repairs before I can even hear it run? Is there any way at all to get this thing started with a screwed up CPS and computer?

I'm not a mechanic, I'm a carpenter by trade,but I can get by with proper guidance and a Haynes manual. Would appreciate a few expert opinions just the same.

I now own Jeep # 7, an '88 XJ 4.0 auto, pioneer package. I've had 3CJ's, M-38, J-20, and 2XJ's.

Thanks for letting me ramble and use up your valuable space.

Mike Eades,

July 11th, 2006, 16:19
#7? I've got to catch up - I've only got five at the moment...

The XJ in that year used, I believe, the Chrysler TF727 gearbox (or was it the 904? Anyone?) since you're talking about the automatic. The front pump usually has some sort of guide bushing on the shaft, but that's about it from what I remember. There is also a separate input shaft bearing (the input shaft runs through the pump drive shaft usually - the pump drive is typically done with a couple "notches" on the torque conveter nose mating to drive tangs on the pump, and the input shaft is driven by mating splines,) and that might need a bearing - I haven't been into a TF727 for a while, but I seem to recall one being there.

The AMC 2.46L used RENIX controls until the end of the 1990 MY (when it was switched over to ChryCo...) and the RENIX setup WILL NOT WORK without the CPS generating a valid signal. Period. End of discussion.

The RENIX computers are otherwise rather hardy - I've only heard of three to have failed so far, and all suffered from failed injector drivers. I've got one of the ones that failed, I missed the other one, and I'm hoping to get the third for "postmortem" analysis.

I don't suppose you'd still have that J-20 and be willing to part with it, would you? I'm looking for a decent pickup, and I'd eventually like to accumulate a Comanche/MJ, a J-series, and an M35A2 multifuel...


July 11th, 2006, 16:22
unless he has the paperwork to PROVE he's rebuilt the motor...I call BS.

mid to upper 3 digits for an 85?...you can do better.