Hi currently rebuilding the engine, and I can't figure out the timing chain tensioner. As I've read, one should remove bolt, and then use allen key in hole to adjust. On mine, I can turn the bolt both ways, it neither comes out nor gets further in. So on mine, not able to adjust with the allen key. Is it faulty? Can I drill it out, new threads, new generic bolt? And what does the filter gauze do, can't it live in the oil haze environment inside the engine?

And when that is solved, how tight should the lower chain be?

 

The lower timing chain tensioner has no facility for manual adjustment, this is all done by oil pressure from the main oil gallery, (the tensioner sits at the front end of this). The little filter gauze is there to prevent crud from blocking the hole in the tensioner that takes the oil under pressure from the gallery. Internal to the tensioner is a rachet device and spring. New tensioners come with a removeable locking plate that keeps the piston secure when the tensioner is off the engine. On installation of the tensioner, one removes this and the piston will move outwards and initially tension the chain, then, when the engine is started the oil pressure will cause the tensioner piston to move out slightly to complete the tensioning action. As the chain wears, the piston moves out to the next ratchet position The only cure for a slack chain is to replace it if the tensioner can no longer tension it. Most people replace the tensioner and chain together. The upper chain is tensioned manually.
The chain guide below the tensioner is adjustable as one of the holes for the securing bolts is elongated allowing it to swing on the lower bolt. However this is normally only done once when installing the timing chain.

The above is my memory from rebuilding two XK engines in the 80s, one from a bare block. Of course my memory may be failing me, but I think I'm right. Others with more recent experience will hopefully contribute.

Why not take and show us a photo of what your problem is. I hope the threads aren't stripped on the tapped holes or you are in trouble. You'd need to get a Helicoil insert put in if this is the case.

 

Yes, pictures will help, always.

Here's my own theory. Just found a book on the development of the 3.8 in the E, and Jaguar did many updates over those 4 years. To me, even though my OEM service manual talks about adjusting after removing setscrew, it can't be removed now, and it seems to be automatic, you have to set it so there's a little play, and then when it starts, oil pressure will press it out, and if far enough, it'll by itself move a notch? Makes sense? Engine is 1964.
If I'm right, the locking tabs on the setscrew have no value?

 

Now I'm doubly confused. There seems to be no hole in my block for any oil pressure to adjust the tensioner, see picture

???

 

So, just guessing, keeping in mind that this engine has been taken apart and assembled by people apparently not knowing what they're dealing with (and as opposed to me too proud to ask), could I have an oil pressure controlled tensioner in a non-oil pressure controlled block??

 

Well, well ! Nothing surprises me about Jaguar engineering practices. Early XK engines had a spring loaded tensioner, but this was changed to an hydraulic one later. SNG Barratt show this on their pages for the Mark IX saloon, (part EAC3629). The drawing also shows the little gauze filter. The same is shown for the Mark 1 saloon, and the Mark 2.
https://www.sngbarratt.com/English/#.../assembly/2283
Is that lug where I would expect the gauze filter to sit actually part of the casting or can you pull it off ?
A bit of a puzzle. Trouble is the people at Jaguar who could tell you anything are all dead by now.

 

Actually, just got it solved

Tensioner, it is the version before oil pressure, and the bolt is to be removed and then adjusting with allen key. Bolt just turned as I said, and couldn't get out. Now I forced it out patiently, need new threads and a bolt

Thanks

 

Does anybody have a picture (from the web or their own) of the lower front chain area, but with chain tensioner removed? I need to see the area where the tensioner is attached, two threaded holes and a center hole/stud? Picture of mine attached (upside down)