Arse. Death rattle.

My Guzzi V11 was making some very disturbing noises today: the valve
clearances seem to have opened up again despite the fact I did them
last weekend. Worse, the LH rocker-box was making an occasional
godawful banging noise at idle when I got home.

There's slight metallic contamination of the oil with a small head of
fine gritty bits on the sump plug magnet. The rocker box contents look
fine, thought the clearances are definitely open, so not an loose
adjuster nut as I had been hoping. The spark plug on that side looks
fine; mixture maybe a tad rich.

I didn't think to check until the exhaust was pretty cool, but the oil
cooler seemed to be cold, too; I'd expect at least some residual heat
unless the thermostat is sticking, which I will check.

At a guess an oilway's blocked and the camshaft & followers are
borked. Compression is still very good though and there's oil dripping
off the engine internals, so not everything is a write-off.

The oil filter looks very old despite the 'full service, oil and
filter' the previous owner assured me had been done.

Ho hum. Oh well, I've had 2300 fun miles so far.

 

That old line. Along with "regularly serviced", "never seen rain" and
"no expense spared"

Always, always change the oil filter & oil, [1] the rest is fixable,
terminal engine damage is not.

Paul.

[1] On the MT500, as it's dry sump [2], there's a primary oil strainer
backed up by an oil filter further downstream. The filters were manky,
but the oil strainer was blocked completely by what looked like clumps
of horsehair.
[2] Rotax

 

Yeah, I changed the oil when I bought it but figured I'd leave the
filter until the next 'official' service interval which was due a
thousand or so miles later, then put it off another thousand miles. A
shiny new filter arrived a few days ago and is sitting on my workbench
ready to go in next weekend....

 

This is what I'm praying. It looks as though I *might* be able to do
it all without removing the engine. Possibly.

 

What he said. First thing I do on any used bike I buy.

 

Bad form yada,

Well, the engine's out. It went pretty well apart from the clutch push
rod trying to stick to the engine - there was a precarious moment with
the engine balanced on a trolley jack and the clutch push rod, now
extended some three inches from the gearbox, still engaged with the
clutch, but it seems to have survived.

So to the internals.

The LH rocker box seemed to be making some tuly dreadful odd bangs on
that final ride home last week. It reminded me of the noise my old FZR
made when the valve bucket bores got damaged - the valves on that bike
started sticking until hit by the piston, at which point would snap
shut with an almighty 'clack'.

Looking at the LH piston though, no evidence at all of valve-piston
contact. I was quite impressed: the pistons have sort of slipper
skirts. Bore looks fine, as does the piston. The valve clearances were
a bit open but otherwise OK.

So, to the RH head. This had sounded very tappety but no other
untoward noises.

With the rocker box off, the inlet valve clearance appeared to be
several mm, enough for the push rod to get out of line with the
rocker. Sheeit. Yet the adjuster screw was roughly as far in as all
the others. Exhaust clearance: OK-ish by the look of it.

One head nut (yes, one of *those* ones) was a right pig to undo - the
entire stud eventually came out with it. Anyway, all (un)done now.

Piston & bore: apparently OK. Con-rods & small-end bearings: well, I
haven't dismantled them but clearances don't seem excessive.

Now I'm wondering if I can tell my left from my right given that it
seemed to be the LH head that was making the dreadful racket, and yes,
I was looking at the engine the right way round.

I took out three of the cam followers and there is some evidence of
wear on them. They are clearly designed to rotate and the wear marks
are circular.

Why didn't I take the fourth one out? Because it slides so far then
stops dead. I daren't force it for fear of damaging the bore in which
it runs. This stuck follower just happens to be the RH inlet valve
one: I think I see a problem here! I'll have to remove the camshaft
(that's a given anyway) and drop the follower out through the other
end of its bore.

I've tried looking at the camshaft lubrication and so far I've drawn a
blank; there was definitely oil on the camshaft and in the followers.
Perhaps there simply wasn't enough.

The block was obviously designed for oil galleries to the cam
followers; there's one that runs rearwards between the cylinders from
the oil pressure sensor and four that branch off this, one to each of
the cam followers, however, they aren't drilled. I can only assume
that they're an option for models with hydraulic tappets.

So far, the only obvious source of oil for the camshaft lobes is
splash from the crank and whatever runs down from the heads via the
push rod tunnels - the followers are drilled and slotted for this.
There are holes that lead down from above the followers into the
crankcase, but I think these are drain holes.

There was another new erratic rattle from lower near the clutch on
that fateful journey, however, far from being a dying clutch or main
bearing as I had feared, it seems that this is just a baffle that's
broken loose in the exhaust collector box. I can shake the box and it
rattles. Must've just failed too, I don't recall hearing it until the
day the engine went seriously noisy last week. I don't think it's a
bit of engine because it's too big to shake out. Also it could ony
have got into the exhaust via a valve and thus from a cylinder -
highly unlikely given their condition. Bit of an odd coincidence
though.

Investigation will cease for a couple of weeks now; I'm off abroad for
a week and will probably be too tired to do anything useful next
weekend. Gah. Just as it was getting interesting.