Correct XU10J4 tensioner setup?

[brumster 135 1 Cars]

Can I just sanity check something with you knowledgeable bunch

 

I have two S16/2.0 mi16 (XU10J4) lumps. I came to swap the cam belt on one of them and noticed a minor issue which I just want to check the implications of.

 

Engine 1 has the eccentric manual tensioner along with a fixed lower/front idler

Engine 2 has the eccentric manual tensioner and an adjustable lower/front idler

 

Engine 1 I have noticed the black plastic shroud just behind the top (eccentric) tensioner fouls the tensioner, the round metal backing of the tensioner is pushing the plastic outwards because it doesn't clear the back of the tensioner.

 

I am guessing that the shroud on engine 1 is off an earlier mi16 with the sprung tensioner, and therefore I can simply cut a bit of the plastic shrouding away so it doesn't bend and, essentially, carry on as planned with the eccentric top tensioner and the fixer lower idler. I am assuming there are no other differences to worry about? New cam belt is a QTB341 134 tooth belt.

 

Ta my lovelies

Edited December 31, 2021 by brumster
corrected engine code - apologies, thought these were 'R' engines!

[SRDT 175]

XU10J4 and XU10J4R are not the same, for me engine 1 has a XU10J4R front idler and that's not good on a stock XU10J4 engine.

 

On the XU10J4 you need both manual tensionners to move, much like on the XU9J4.

As the cams are locked you need to tension the belt on both sides so that when unlocked the timing is still right and the average belt tension is good.

Here is a video with the XU9J4, the XU10J4 should be pretty much the same:

 

 

On the XU10J4R they made it simple with only one tensionner and a fixed pulley.

To do that they used two parts cam pulleys. You lock the cams but you free the outer pulleys so they can rotate a bit, this way with one tensionner you can tension the whole belt at once and you can't mess with timing unless you put way too much tension.

[brumster 135 1 Cars]

Ah, perfect, actually I made a little ommission in the first post (corrected); they're both XU10J4 lumps (iron blocks). Engine 1 is on verniers and I'll be checking the timing by valve lift once I've got the new belt on...

 

So actually it's the other way - engine 1 is the correct setup for what it is, engine 2 is a bit odd/wrong as it should have a fixed idler. Thankfully engine 2 is my unused spare one so I can fix/address that when needed.

Edited December 31, 2021 by brumster

[welshpug 1,657]

neither Mi16 used a sprung tensioner,  1.9 used a pair of identical eccentric rollers, 2.0 used an eccentric on the rear and a sliding on the front.

 

 

the Mi/s16 is NOT a J4R, thats the 135 bhp engine.

 

gti6/xsi used a different fixed front idler and eccentric rear tensioner with 136t belt.

 

later replaced by an auto tensioning sprung eccentric tensioner of larger diameter and a longer 137t belt.

Edited December 31, 2021 by welshpug

[brumster 135 1 Cars]

Oh lord, there's me been calling them the wrong model derivatives since day 1  apologies!

 

Ok, so they're XU10J4 engines, *not* R ones, because they've got the mi16-style cam covers on them, not the gti6 type.]

 

So according to Welshpug, engine 2 is the correct setup, engine 1 is running a gti6 setup in terms of tensioners (remember this is a race engine so we're not talking standard cams or pulleys). It's been like this since it rolled out of Longman.... :-/

[petert 586]

This is an inlet side XU10J4 tensioner. Exhaust is the same as XU9J4. It pivots on the 8mm hole and the slot is where the adjustment occurs, locked by the cam belt cover retaining pin.

Edited December 31, 2021 by petert

[brumster 135 1 Cars]

Yup that's what engine 2 has got on it (standard/stock engine). Ok, this is all making sense now ☺️

 

So I'll just trim the plastic down that's getting bent by the tensioner; I'm guessing the shroud is off something else but otherwise everything else makes sense (for a race engine at least)

[welshpug 1,657]

you are turning it anti clockwise to tension right?

 

I think the gti6 tensioner is larger which may explain why it fouls, I don't think you can swap the covers though, as a race engine it may never have had the covers fitted before.

[brumster 135 1 Cars]

2 hours ago, welshpug said:

you are turning it anti clockwise to tension right?

Yup, that's right

2 hours ago, welshpug said:

I think the gti6 tensioner is larger which may explain why it fouls, I don't think you can swap the covers though, as a race engine it may never have had the covers fitted before.

Yes it looks like the moulding of the shroud is a little different in that area, and the gti6 tensioner centre part is quite a large round circular piece of metal, it's just pushing some plastic out that clearly doesn't expect so much tensioner to be there. I'll just dremel it off.

 

Like you say, I think this is a bit of a hybrid setup, my memory is hazy as it's well over 12 years now since Longman built it but I suspect they recommended the gti6 tensioner setup which, on the basis this was never running standard cams and pulleys is not a problem. But I guess the shroud was left off the bare engine that I collected from them and maybe I attached an old 1.9 mi16 one I had kicking about before I put it in the car (I honestly can't remember)...

 

Thanks everyone