mjED Posted May 7, 2019 Share Posted May 7, 2019 I could sure use some help in my search for a Manual Tranny flywheel that will fit on a 1985 2.5L 4-banger that I got out of an XJ. I want to swap this with the 4-banger in my MJ, but finding a reference to the correct flywheel is challenging. My first thought is that all the 2.5L 4-bangers must have had the same flywheel, all the way back to the first ones AMC used. I can find plenty of flywheels for newer year engines 1990's, but not the 1980's models. If anyone has insight to my flywheel confusion, it would be appreciated. Thanks. Link to comment Share on other sites More sharing options...
Green Mesa XJ Posted May 7, 2019 Share Posted May 7, 2019 Starting 1986 2.5 is a renix engine so it’ll be that era fly wheel. I believe the 2.5 1985 is carbureted.Looks like 87-90 wrangler 2.5 and 86-90 xj/mj are the same flywheel I remember something about the flywheel being a PITA to source. Worse that the 2.8 V6 Sent from my iPhone using Tapatalk Pro Link to comment Share on other sites More sharing options...
mjED Posted May 7, 2019 Author Share Posted May 7, 2019 Yes the 1985 was a carb engine, one of the reasons I went looking for it. My first thought is that the flywheel should be the same for the 1985. What could be different? Link to comment Share on other sites More sharing options...
Green Mesa XJ Posted May 7, 2019 Share Posted May 7, 2019 Biggest difference if the holes/reluctor for the CPS sensor. I think the clutch kit may be the same for aisin transmission Sent from my iPhone using Tapatalk Pro Link to comment Share on other sites More sharing options...
Eagle Posted May 7, 2019 Share Posted May 7, 2019 18 minutes ago, Green Mesa XJ said: Biggest difference if the holes/reluctor for the CPS sensor. I think the clutch kit may be the same for aisin transmission The '85 used a carburetor and a conventional distributor. No CPS to worry about. Link to comment Share on other sites More sharing options...
Jeep Driver Posted May 8, 2019 Share Posted May 8, 2019 Let's back up............ What year is your MJ? MJs 86 through 90 were TBI, do you want to retain TBI? Link to comment Share on other sites More sharing options...
Eagle Posted May 8, 2019 Share Posted May 8, 2019 My apologies. I zeroed in on the '85, without paying attention to the fact it's going into an '86 MJ. Yes, the '86 has a Renix injection/ignition system, so it needs a flywheel out of an '86 - '90 XJ or MJ 2.5L. Link to comment Share on other sites More sharing options...
mjED Posted May 8, 2019 Author Share Posted May 8, 2019 First thanks to all the responders so far. I have an (AMC 150 cu in (2.5 L) engine, One-barrel carburetor (84-85)) out of a wrecked 1985 XJ . When I acquired the engine it did not have a flywheel. I intend to install the rebuilt engine in my 1990 MJ (2WD), which currently has that same engine from Chrysler and is Throttle body injection (TBI) (86-90). The current engine in the MJ has 290,000 mile on it and need some help, or to be replaced which is my intention. I might be able to use the flywheel that is currently on the MJ when I take the motor out, but I would like to have the new engine complete before I remove the MJ engine. I drive the MJ everyday to work and home. Plan for the new engine. It will be carbureted with a vacuum advance distributor and regular old point and condenser, The parts that I got off the 1985 engine. I do not want any computer chips in the MJ. So I am left looking for one part, the flywheel, I have all the other pieces and a rebuild engine that was bored 20 thou over with new pistons and rods. I am temped to just order one of the flywheels that are for sale on Ebay as a gamble to see if it fits. What do I have to lose. My hope was that someone might know if there was a different flywheel for the AMC version of the motor. I hope this helps explain what I am looking for. I attached a picture of the 1985 engine. Link to comment Share on other sites More sharing options...
Jeep Driver Posted May 8, 2019 Share Posted May 8, 2019 Just curious what makes you think the 85 is any better than the one you've got? Link to comment Share on other sites More sharing options...
Jeep Driver Posted May 8, 2019 Share Posted May 8, 2019 To answer your question directly if you're not using the CPS did any flywheel work you can get a 91 up flywheel you'll be fine. That said you can never go back without pulling the trans off and replacing the flywheel. 86 to 91 flywheels are unattainable they don't exist I looked on eBay last night and you can't even get a used one right now. You say you want to get the new one or the old new one ready before you swap it in it's only takes a couple of minutes to transfer the flywheel from one engine to the other ones you have them both out so I don't really understand what your point is. The wise thing to do is to transfer your existing flywheel to the other engine if the points distributor and carb does not work out for you you can always go back to what you had before. If you're thinking you're going to get more performance out of a carburetor well maybe you will but it'll be expensive you're wiser to stick with what you got. Link to comment Share on other sites More sharing options...
mjED Posted May 8, 2019 Author Share Posted May 8, 2019 Good question. I do not think it is better, but close. Only the head bolts are smaller than the later ones. It took me a while to find a good head for the engine that have the 7/16" head bolts. I am not going to be racing this engine so I think it will do fine for my driving style. I want to replace the existing MJ engine, but I also want to keep driving the MJ as long as I can. It is my everyday driver. I chose the older model of the engine from a 1985 XJ that I found since it already had all the manual stuff. Distributor, intake manifold for carb, etc. pre Renix stuff. Someone had already pulled the 5-speed w/ transCase and taken the flywheel with it from the XJ. I looked for a long time to find an older engine, now I just need to flywheel to complete the drivetrain. Link to comment Share on other sites More sharing options...
mjED Posted May 8, 2019 Author Share Posted May 8, 2019 Thanks Jeep Driver. Only one engine is on the shop table, the other one (with the flywheel) is still in the MJ being driven everyday. The existing MJ engine is not in great shape, just hanging on for now. I am hoping to get as many mile out of it as possible while I finish the new engine rebuild. I have been looking at all the online buying places that I can find keep coming up with the response that the found flywheel for the 2.5L engine IS NOT COMPATIBLE WITH THE 1985 ENGINE. So I though I would try asking here to see if anyone knew more than me. Link to comment Share on other sites More sharing options...
dasbulliwagen Posted May 8, 2019 Share Posted May 8, 2019 If youre not using the injection system, I don't see why ANY 2.5 mounted flywheel wouldnt work, assuming the clutches are the same. Even the 91 and up should work as you wouldnt need to use the tone wheel portion of it for anything. I personally wouldnt spend the money on it because you have a perfectly good one in the truck already and it don't take long to swap it over. The compatibility issues youre reading I think have more to do with getting the engine to run with the computer, than they do about it actually bolting up. Link to comment Share on other sites More sharing options...
dasbulliwagen Posted May 8, 2019 Share Posted May 8, 2019 AND.... I really don't understand why you would want to go carbed. In my opinion youre trading one set of problems for another. Link to comment Share on other sites More sharing options...
mjED Posted May 8, 2019 Author Share Posted May 8, 2019 Thanks dasbulliwagen. I am guessing you are right about the tone wheel. I still would like to not have to remove the one I have from the running truck until I have this new engine ready to install. I have ordered a flywheel and will let everyone know if it fits. The wheel was only $12 on Ebay, it will need to the be resurfaced, but that is easy. Carburetor because I'm an old guy who started working on cars that had carbs. I have several in my shop left over from some old BWM 2002s that I use to have. I guess I am trying to get back to what I am comfortable working with for my everyday truck. Link to comment Share on other sites More sharing options...
Big Dan Posted May 9, 2019 Share Posted May 9, 2019 10 hours ago, Jeep Driver said: 86 to 91 flywheels are unattainable they don't exist I looked on eBay last night and you can't even get a used one right now. I have a renix 2.5 flywheel, if anyone is needing it. Link to comment Share on other sites More sharing options...
Pete M Posted May 9, 2019 Share Posted May 9, 2019 what are the compression numbers for the current MJ engine? leakdown numbers? oil pressure? Link to comment Share on other sites More sharing options...
mjED Posted May 9, 2019 Author Share Posted May 9, 2019 Pete M: I must say that I am not sure, nor am I concerned with the current MJ engine. I acquired the truck in a very bad mechanical state, and a new paint job that had turned everything but the windows blue. I guess it was the easiest to spray the entire truck, trim, bumpers and all, to make it look better than take the time to mask off parts. I have pretty much fixed or replaced every moving part on the truck except the engine and tranny. That will be the final big fix. A rebuilt engine and 5-speed trans. to replace the current engine and 4-speed trans. The flywheel is on the way, I ordered it off Ebay from jeepsunlimitedusa for $12 plus shipping. I will post what the outcome of the fit of the flywheel on the 1985 engine. Thanks as always for asking. Link to comment Share on other sites More sharing options...
Jeep Driver Posted May 9, 2019 Share Posted May 9, 2019 53 minutes ago, mjED said: Pete M: I must say that I am not sure, nor am I concerned with the current MJ engine. I acquired the truck in a very bad mechanical state, and a new paint job that had turned everything but the windows blue. I guess it was the easiest to spray the entire truck, trim, bumpers and all, to make it look better than take the time to mask off parts. I have pretty much fixed or replaced every moving part on the truck except the engine and tranny. That will be the final big fix. A rebuilt engine and 5-speed trans. to replace the current engine and 4-speed trans. The flywheel is on the way, I ordered it off Ebay from jeepsunlimitedusa for $12 plus shipping. I will post what the outcome of the fit of the flywheel on the 1985 engine. Thanks as always for asking. So you are rebuilding the 85 is that correct? If so why didn't you just get a 2.5 out of say a 98 Wrangler? Link to comment Share on other sites More sharing options...
mjED Posted May 9, 2019 Author Share Posted May 9, 2019 Yes, Here is the short block. This block also has the connection for the mech fuel pump, since it was originally carbureted. Transmission almost ready to install. I have gotten a different bell housing that has the throwout piston on the outside instead of the donut one that I now have. One of the parts that I have already changed, twice, since the first one I installed only lasted about three month before it started leaking. Link to comment Share on other sites More sharing options...
Jeep Driver Posted May 10, 2019 Share Posted May 10, 2019 10 hours ago, mjED said: Yes, Here is the short block. This block also has the connection for the mech fuel pump, since it was originally carbureted. Transmission almost ready to install. I have gotten a different bell housing that has the throwout piston on the outside instead of the donut one that I now have. One of the parts that I have already changed, twice, since the first one I installed only lasted about three month before it started leaking. Well, guess you've gone all caveman. Same with the ancient bell too. Slave, internal or external slave, or doughnut if you wish. Link to comment Share on other sites More sharing options...
Green Mesa XJ Posted May 10, 2019 Share Posted May 10, 2019 That bell housing has the CPS hole. Still can be set up either way. Sent from my iPhone using Tapatalk Pro Link to comment Share on other sites More sharing options...
mjED Posted May 20, 2019 Author Share Posted May 20, 2019 UPDATE: The flywheel arrived and it fits just fine. Now I need to clean it up, resurface it and get some bolts. Link to comment Share on other sites More sharing options...
Eagle Posted May 21, 2019 Share Posted May 21, 2019 That'll buff right out ... Link to comment Share on other sites More sharing options...
mjED Posted May 21, 2019 Author Share Posted May 21, 2019 It did clean up, but I am still going to turn it. Link to comment Share on other sites More sharing options...
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