Timing advice after tensioner failure

[steve_weegie]

Greetings everyone!

So, it appears I've got a bit of a problem... Bea was driving the car a couple of days ago and complained when she got home that it was "sounding like death". Turns out that when I bought the engine, the last person to change the head gasket did a really bad job of tightening the cam belt tensioner and it's wobbling loose on it's bolt, with no tension on the belt. Fortunately, I believe we've been lucky here and caught it before really bad things happen, as the engine started and sounded ok at idle when I was diagnosing this.

So.... Given I have limited access to tools here and certainly no way to get at the bottom pulley bolt, does anyone know if it's possible to time a VVC K series with the bottom pulley on? Usually I'd be lining up the marks using the cam drive gear, but of course this is hidden behind the pulley. A small bonus however is the engine was delivered without any timing belt covers, so I have pretty much full access to view the belt and pulley once I get the wheel arch liner out.

Any advice on how to do this is welcomed!

[robin]

If the belt hasn't actually slipped, could you not just lock of the crank and cams in current position, then thread over new belt and tensioner? I assume there are no timing covers fitted at all?

That would make it "safe" if not right; you could then wait until you have access to tools to fix that ...

[woody]

Assuming you have no clocks or other measuring device, I would; Take the plugs out, stick a long 1/4" extension in the cylinder nearest the belt. I would then bolt a length of steel (made of 1 or 2" angle) vertically to the head. 1/2" or so below the approx highest point the extension reaches when the engine is turned, this steel would have a hole drilled and through this another length of steel bolted horizontally and relatively firmly to it sitting over the extension so that the extension can act on it.

Give the engine a turn, the horizontal steel will rise to the highest point and shouldn't move with the right tension on the bolt. Give it another turn until the extension touches the steel and you have TDC. That's how I'd do it off the top of my head & without googling; there's probably a better way though.

[robin]

I am not sure the timing marks on the camshafts are to be used at TDC; in fact I believe that they are set at 90BTDC where all four pistons are at the same height.

So ... if you have two identical bars you could remove all four spark plugs and rotate the crank until all four pistons are at the same height (by comparing bar heights of bars dropped down plug holes).

Now lock of crank, rotate cams to align the arrows on the cam sprockets (arrows on both cams should point through the cam shaft centres and also point the same way as one another).

You could easily end up one tooth out this way, but I think on standard cams there is clearance at TDC to allow the cams to be out by one tooth without interference.

Cheers,
Robin

P.S. If, using a mirror, you can spy down behind the crank pulley and see the crank timing sprocket, you should have the sprocket such that the notch on the oil pump housing aligns with a valley on the sprocket (i.e. half way between two teeth). If you don't have the crank at this position then it will be harder to get the belt over whilst the cam sprocket timing marks are aligned.

[steve_weegie]

Hi guys,

Cheers for the help so far. The plot thickens however!! I've borrowed some tools from a neighbour and started to have a good root around. I tried looking at the cam gear with a mirror but either my mirror or my technique isn't up to the job! I did find there's a 90deg timing mark on the inner plastic cover though, and with the yellow line on the pulley aligned with this, i checked the two rear (short belt) timing marks. The good news is they line up perfectly with the horizontal mark on the rear vvc cover, but the bad news is the exhaust cam front side looks in good alignment (as it should being solid) but the front inlet cam gear is out by 1 tooth clockwise.

Now, I'm no expert on VVC timing, but I was under the impression that there was a geared actuator mechanism internal to the head that kind of lined these two inlet cams together. Is that right? If so, I can't just loosen the belt and rotate the front inlet cam round 1 tooth, correct?

I can only assume that the engine was never timed right in the first place, and to be honest, it's been running like a bag of spanners since it was put in the car. The car starts, but doesn't sound right and the idle is really poor like it's always been on this engine. Am I going to have to split the cam carrier to get the inlet cams aligned?

Cheers for the help guys,

Steve

[Shug]

Ah... VVC...

I'd advise reading the engine manual on the VVC timing. I can't remember what it was that was confusing, but from memory, it's not timed in the most obvious way. I don't remember the details on mine, because Rich and Hambo did it while I was doing something else, during the engine swap, but there was a moment of "ah - that's not right" when the belts first went on.

The belt change after that was done at MMC, so didn't even see it.

It's fine if you RTFM, but doing it as logically seems right, doesn't seem to be the way...

Vague post, I know, but I remember the sweat when we first turned it over (by hand), waiting for valve/piston interface.

[robin]

Now, I'm no expert on VVC timing, but I was under the impression that there was a geared actuator mechanism internal to the head that kind of lined these two inlet cams together. Is that right? If so, I can't just loosen the belt and rotate the front inlet cam round 1 tooth, correct?

The two VVC inlet half-cams are independent of one another. That's why the rear (short) belt is there.

There is a long control shaft that spans the whole head on the inlet side but it is there to adjust the eccentric gear that puts the V into VVC - it has nothing to do with the fundamental valve timing.

IMHO you are good to slacken the tensioner, use a spanner to force the sprocket to jump a tooth, retighten the tensioner.

Cheers,
Robin

[robin]

Of course this assumes that the head was assembled correctly in the first place!

[woody]

Know nothing of the vvc side of things, but I have swapped K heads & left the belt on the bottom end before. Think I used a clothes peg to hold the belt to the rear casing on the cabin side and wedged a wooden pencil between the belt & casing at the water pump.

[steve_weegie]

So, things are looking a little better, but not too much...

I popped the tensioner off and rotated the front inlet cam round 1 tooth. Given the facilities here, it looks like the engine is now timed to what I can only assume is correct. Everything is tightened up and locked into place but it still sounds like a bag of spanners, running rough and sounding a bit top-endy. It's certainly down on power and to boot, it also looks like the bottom pulley isn't aligned correctly on the cam drive gear, as it's got a discernible wobble to it... Only got myself to blame here really, as I should have given this engine a good going over before I popped it into the car.

Oh well... Looks like I'll be rebuilding my old block with new pistons and liners and sorting this VVC top end properly, very shortly.

[robin]

Yeah, you've probably allowed the bottom bolt to run loose at some point; the crank timing sprocket will then wear the nose of the crank, chamfering off the leading corner. The result is a wobbly sprocket even when the bolt is tight.

Top end noise could be actual VVC mech fecked - have you had a look at the top end with the cam cover off?