Hello everyone, I am trying to figure out how to make sure I don't mess up the timing of my 91 XJS. The chain is busted and all of the pulleys are off except for the very bottom most pulley. Any ideas on how to remove? The engine is a 5.3 V12 by the way. I really just need to not turn the darn cams while trying to remove the bolt. Is there an access panel for the torque converter or some way to stabilize the cams from turning? Thanks for the help.

 

You are NEW, so welcome to the real world of motoring, and the fun is about to begin I reckon.

In behind the oil filter hosing is a plastic cover that when removed exposed the flywheel and it torque converter mount bolts. Jamming the engine via here will work.

Being TH400 transmission, remove the tin pan from the underside of said flywheel, and jam a HUGE tyre lever in teh teeth and do what you must with the front bolt.

I use the starter motor, with a LONG breaker bar and socket on the same bolt. Breaker bar wedged on the LH side concrete floor, and "flick" the starter, and undone that bolt will be.

However, when retightening that bolt the engine will need to be jammed by one of the 2 suggestion mentioned above.

Jamming the engine using the camshafts is the BIGGEST no no I can think of.

 

Sorry for the delay, thanks for the help. Sadly, I'm lost on the rest of the steps...never had this problem with my old 96 explorer...can't figure this out on the XJS though.

 

OK.

The huge bolt of the front pulley, 1" A/F, and a long breaker bar are needed.

A steel tube slid over the breaker bar to extend its length may be needed.

Place the socket on the head of the bolt in such a way that the end of the breaker bar is resting on the floor on the LH side of the car.

The engine rotates clockwise, and the bolt loosens in a counter clockwise direction, so by "flicking" the starter via the key switch will undo that bolt. A quick "flick" is all that is needed, and if the end of the breaker bar is on the concrete floor prior to that action, NO odd noises will be heard.

The jamming of the flywheel is really straight forward. Remove the tin cover between the engine and the transmission (under the car obviously), and you will see the ring gear (many toothed wheel that the starter meshes with to rotate the engine). This is the toothed thing that a large bar is used to jam the engine.

 

As Grant says but also ensure you have disconnected the fuel pump relay and depressurized the fuel system before flicking the starter of safety.

 

I was able to get the front bolt off after jamming the flywheel. My issue is that I am lost from there. With my 96 explorer all I had to do was remove the covers of the timing chain and release the tensioner. I just don't know what to do now considering that there is not a cover for the chains. Sorry to be such a pain.

 

OOPS.

The timing cover of the V12 is basically sandwiched between the upper alloy sump pan, and the 2 cylinder heads.

Removal is TIME consumong, seriously, and the studs at the top edge at the cylinder heads need to be removed once the nuts are off.

Then the first 10 or so bolts of the sump alloy pan will need to be released (about 2 full turns), and then that same pan CAREFULLY wedged in a downward motion, so as to release the "grip" on the timing cover.

Then the cover will need to CAREFULLY driven off with a wide blade. It is mounted on 2 dowels. GREAT care here, as it will damage/crack/snap in a heart beat.

This WILL damage the front section of the 2 head gaskets that seal the cylinder head to the timing cover to stop oil leaks, OH NO, so refitting will be tricky, and COPIOUS amounts of Hi-Temp RTV to seal those joints will be mandatory.

Once the cover is off the plastic tensioner will stare you in the face, and it will still be under savage tension, so a carefully placed G clamp will allow compression of it for removal. If its broken, most are, that tension will still be there to a less degree, so please be careful.

When refitting that tensioner leave it compressed until the cover is resecured, then trigger it via the rubber bung on the RH side front face.

This is a HUGE DIY task, and I have done it 3 times, and NOT nice at all.

This engine aint no Exploder, trust me.

I do not go this path unless I am OBSOLUTELY certain that tensioner is at fault. Rotating that engine anticlockwise will do it every time. Lots of banter on that one, but I know what I know.