Engine advice please

[chris.richard]

further to my post in the "events" section, I need some advice about engine repairs!
At the track test yesterday, I was coming into the pit lane after an hour or so's running, and the engine started misfiring. Realising the fuel gauge was on empty, I filled up, and on restart, the engine fired up and idled fine. after strapping in, when I tried to rev, the engine sounded like the proverbial bag of nails, misfiring and rattling from, I think, the rear head. Put it back on the trailer at that point and went home. I'd hit the raised-from-standard rev limiter several times, but engine was warmed up properly first, and I'd been double de-clutching most down-shifts.
Any suggestions as to what might be wrong, other than mischief from rear cam timing? I know it's the weak spot on this engine (24v). My current thoughts are:- 1)look at top of rear head and see if obvious mischief. 2) If none, re-time cams, compression test. 3) if all is not then well, off with its head and see what that reveals.
Any other things I should be doing?

PS BOLLOX! :mad:

[strat6v]

I can only think of the usual things, fueling, ignition, some carp in there somewhere. seems strange it idles fine but misses when revved. Could you have a coil pack going down perhaps?

I'm sure there must be a mod for the oil pump drive to help with the jumping belt scenario, i'll see what i can find out.

Perhaps it could be time to switch out your 3.0 and swap for a 2.5. Could kill two birds with one stone, right capacity for rallies and better belt arrangement.

[chris.richard]

Unfortunately it's not idling well now - lumpy then stalls. Rattly metallic noises wouldn't be caused by a coil problem, would they?

[strat6v]

OOPS :eek:

It never rains..........

I think the 2.5 has the newer oil pump drive and the timing belt has more wrap on all pulley's.

[Sando]

Have you had a look at the plugs yet? Pain on the rear head but may give you an indication of whats happening to which cylinder or if something has melted - if it had been running weak out on the last lap due to the low fuel?
head Rattles are usually Cam/shim tappet related. Bangs/knocks and clanking get more expensive! I suppose with the cam cover off you could see if the cam timings slipped. Bent valves could give you the symptoms you describe if the buckets and shims are free.
Rob

[Matt No VAT]

Did your noises start after the trip into the kitty litter?

Stones getting in the under belt can be a real problem, it once ended my day out in a very similar fashion to what your describing.

If so, its time to have the head off and see whats left! :(

[chris.richard]

Did your noises start after the trip into the kitty litter?


Technically, yes, but it was over half an hour and many laps later.

thanks for the tips Rob. I'll see what I find, when I can get a chance to look.

[Matt No VAT]

Technically, yes, but it was over half an hour and many laps later.

After clearing out the stones and rebuilding the head on my car I then drove the car from Reading back to my home, for the entire 35 mile journey I could see and hear the stones dropping out and bouncing off the floorpan, so I think its plausable that there can be a few rattling around the engine bay just waiting to wreak havoc on a cam belt. :(

Still, I'll cross my fingers for you that its not major :o

[MikeM]

Are you able to compression or leakdown test it? it might save you pulling it to bits unneccessarily? ...or it might confirm your suspicion that you need to, but at least you might know which pots you need to look at!

[chris.richard]

Plugs out and compression test will be the first bit I think. Can I use my oil pressure test kit for a compression test? What are the pressures generated? I suppose I'd need an adapter from plug thread to gauge.

[MikeM]

I would buy/borrow one if i were you they are nor that dear.

Guy Croft suggests the following for the TC and I guess the alfa engine would not be much different

Crank 10-12 times (throttle fully open) should give a rapid pressure rise to a minimum of roughly 120 lbf/in2, with up to 175-200 depending on what CR your engine is running. The key is that all the readings should be within 10% or so, its the difference you are looking for. If you have one with significant difference try spooning in a small amount of oil and retesting if it rises its likely a cracked piston/ring via detonation otherwise its top end trouble and pull the head off ;-(

[strat6v]

Any volunteers to help Chris 'pull the head off it'? :eek:

Better get my coat, got me runnin shoes on already.