¿As preventive measure, will it be a good idea to extract OEM bolts on engine mounts and apply some anti seize, or will it be better to replace them with grade 8 ones?????
My XJ is close to 148k miles so I dont want any casualties with those darn bolts.-
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if your going through the work of getting them out you might as well upgrade them.
only issue i see with putting anti seize is that you could make it shake out more easily. maybe a lighter thread locker since it would keep it from shaking out but should keep it from being able to seize since there will be something inbetween it but im not to sure
With the high torque output of the 4.0/ unibody design of the XJ, road vibrations are transmitted to motor mounts more than older full frame designs.
On stick shift XJ's, you have more vibration and rpm's than with automatic transmissions.
as bolts slightly vibrate, over a period of high miles (i've crawled web and found quite a few of these "sheared 4.0 motor mount bolts") near 140k where this becomes an issue.
as for bolts, the majority of body bolts use SAE Grade 5 bolts. Grade 8 are much stronger and are a huge pain to drill out and remove.
Personnally, I'd use grade 5 and blue threadlocker. Mainly prevents vibration loosening and prevents corrosion.
As the original poster of this thread, I'll update that my single bolt and fully welded factory "mount plate" (part of motor mount that bolts to block) is holding up perfectly to full throttle power. No cracks at any of the block boss/mount plate welds.
Again: I'd advise folks to just simply grab a torque wrench and CHECK you bolts...too damm easy to do, but what a pain when they shear off!!!!
I checked the ones I could actually reach with a socket today, and they appear tight: Yet they appear to have a "spacer" washer behind them (between mount and block). Ill check them ALL tommorrow and let you know what I find. By the way, mine seems to fall into the "suspect" category, being a '96 H.O. motor, with over 200K and stickshift.
grade 8s arnt that hard to drill if you have the right bits, I do alot of them at work, so good drill bits of all sizes are readily available, I guess thats a different story at home for most people though
Ok, so now I'm a little nervous. I just bought my 94 XJ and one of the things that had been done was to replace the motor mounts. Now when I shift I hear a clunk near the passenger right side. Do the replacement mounts need tightening after a break in period? I'm not too mechanical so sorry if this is a dumb question.
The M.O.R.E. site lists the mounts for 91-96. That would explain why 97+ owners havent really commented on the problem. Ive owned 2 TJs prior to this XJ and I have never heard of any TJs having that problem.
98 XJ Sport with 4.5" lift, 31" MTZs, and other goodies.