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Discussion Starter · #1 ·
Hi all,

I'm new here but I've been lurking for a while. I've recently become the proud owner of a facelifted Alfa 166 fitted with the venerable 3.2 unit. I bought the car as a laugh as it has over 300 000 miles on it (on its second engine, but original 'box) and zero rust. One of the previous owners used it for extremely long distance commutes, and it's got such a service history that the book has run out of places for stamps - so notes have to be made in the back. Awesome ride, quality, everything really - I love that the switchgear is the same as my old Maserati 4200. Hopefully this'll be less thirsty and cheaper to run though.

Anyhow to the point: I bought it with a lumpy idle and realised on the second day that the guy who sold it to me had put a black sticker over the CEL. How amusing. Although it was nice to know that I wasn't entirely off about the weird idle.

So out comes the ELM 327 and lo and behold: P0300, P0301, P0302, P0303, P1688. Let's ignore that last one for a minute.

The consensus seems to be that if the rear bank is off like this, it's usually timing that's off. Timing or HGF with compression loss due to air movement between cylinders.

The car was serviced by the same workshop throughout its life, but I've read about 'shops sometimes accidentally using the wrong locks on these engines. I figured it's due for a belt change anyway, so I dipped back into the wallet and bought a belt and water pump kit as well as the tools necessary to do the job by the book. No ghetto methods here.

Working on this engine is ace - Alfa really thought about accessibility and serviceability. Now I'm sure someone is rolling their eyes, but earlier this year I did a belt change on an M100 Lotus Elan. If ever anyone wants to visit automotive hell, look no further. But between the Jag XK's, Lotus Esprits, Elans, Maseratis etc that I've wrenched on over the years this thing is the easiest. Hats off to Alfa (We won't speak of the fact it took many days to cut and chisel the old crank nut off cause some idiot had torqued it to 800 Nm.).

Anyhow long story short, my brother and I did the lot, taking great care to do everything carefully, and also cleaning up bits as we went. Now that we are done, the car is still misfiring - no change. Very disappointing given the time and money that went into the maintenance but not surprising since we didn't locate the culprit.

On to my question:
We located TDC at #1 cylinder using a dial indicator, and placed the cam locks on (I have Ricambi locks for the 3.2 - several specialists sell the same part number as suitable for the 3.2 V6, so I hope that they're ok). The locks fit great - nothing like the pictures I've seen on the web where the wrong locks had been used prior.

We checked TDC a few times this way to be sure, whereupon we went ahead and changed the belt.

Now on to what bothers me: at TDC (as we located it), the cam locks fit like a glove. However, the mark on the crank toothed pulley was just left of the corresponding mark on the block. This threw us off - why would the marks be there, if one isn't mean to use them? And surely given the tolerances involved in manufacturing, the TDC crank mark should be dead on.

As we were messing around looking for TDC we gave the marks a go, lining them up; however we found the dial gauge showed movement prior to hitting the mark (i.e we identified TDC before the mark - once we moved the crank to the mark, the dial gauge indicated motion).

In the end, we decided "if this was crucial, the manual would state it" - but maybe we were wrong?

What experience do you guys have with setting the timing? Everyone seems to say its incredibly sensitive. Should one set TDC in the beginning, middle or towards the end of the dwell period? Am I overthinking things?

Or is it just going to be head gasket failure, in which case I am gonna need to gather some strength to go and tear everything apart again (I've been meaning to do a rear suspension rebuild on my Esprit SE but I keep buying clunkers that distract me).

I called the workshop that has looked after the car today and they weren't exactly very helpful or forthcoming, even though I offered to pay them for consulting me. Oh well. You don't ask, you don't get and all that.

Really looking forward to hearing everyones opinions about this, and getting the car working right. It really deserves it. It's such a nice example.
 

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Discussion Starter · #2 ·
Lessons learned: setting TDC with a dial gauge is only going to work if you have a robust setup. I didn't have the intended dial gauge for this job so used a separate one on a stand with the probe inserted into the hole on the TDC indicator. This ultimately gave unreliable readings that weren't easily reproduced. (Side note; ordering the Draper dial gauge and a TDC indicator from some Alfa independents will land you in this kind of trouble - the two are not compatible!)

This weekend I took a step back and did the job again, with a slightly more reliable setup, but also by primarily setting TDC using the mark on the crank pulley and the block. With these marks aligned, we set TDC to within 1/100 of a mm. Note that this method involves deviating from the procedure in the eLearning program - instead of replacing the aux belt crank pulley, you simply wind on the crank nut and washer with the toothed pulley on the crank fully visible and use that to rotate the engine to TDC until the marks align. Cranks and block details are machined to high tolerances, so these are as reliable as it will get.

By setting TDC this way, we discovered that the exhaust cam on bank 2 (cylinders 4,5,6) was out, as well as the intake came on bank 1 (cylinders 1,2,3). Strange that only 1-3 were misfiring.

Anyway, after making these adjustments the car idles evenly and the codes are gone.

I hope this thread helps someone in a similar position. I think setting TDC with a dial gauge is good, but problematic if you don't have the EXACT dial gauge for the TDC indicator that Alfa workshops use - alternative parts and setups result in lateral movement or play within the TDC indicator aperture and give unreliable readings. For the shade-tree mechanic it's probably a better idea to line up the marks on the crank with the mark on the block; in this instance the dial gauge primarily serves to indicate that cylinder 1 is on compression stroke, rather than true TDC.

Further, the Alfa method requires the user to be proficient in the use of a dial gauge and to understand possible issues. Case in point; when we re-timed the engine with the belt on, there's a degree of elasticity when moving the crank; it always springs back a little bit. This makes trying to set it perfectly using just a dial gauge annoying. Aligning the marks (which are finely cut) is far easier.

Happy motoring!
 
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