2.0 Twin Spark Oil Weep

[Citroënbender]

Started timing belt replacement on the well-travelled 147. A "mutt" exchange motor built by ASV out of an engine that experienced cambelt failure, dropped in a 147 Ti to replace a failed cambelt engine; that car was written off in early 2016 and sold to me as a engine donor for my failed cambelt 147 5 door, these belts were done last in 2014/15.

Due by age, not mileage - it's done ~25K in this chassis and not sure how much in the donor vehicle prior. Tensioners and idler in good condition, belts (Optibelt) showing age but not imminent death.

First problem. Oil is passing through the variator solenoid. I've seen this several times before, I believe it's internal seals hardening and failing. I also believe it impedes the "job" of the solenoid by damping its motion. You can see oil has made it right through to the harness connector. I'm yet to hear of a solution to this.

AliExpress lists lookalike solenoids, it would probably cost me most of $800 for a batch of ten or whatever their minimum is - if actually available. Whether they would work and last are two important questions! If it's OK by the vendor to impersonate the Bitron branding, you wonder about the fidelity of any guarantees...



Relief. The balancer shaft oil seals, and front main, appear dry. I don't have a suitable counterhold for the balancer sprockets, so that avoids another headache to resolve.



Problem 2. Apparent oil weep from the front camshaft girdle. The seals are finished, that's a given - but is it "proibito" for me to lightly spray the girdle's contact face with Hylomar or use a smear of Threebond 1211?



As a side note, I put a kit through a spare variator to save money. It was interesting to note, the replacement spring measures shorter than the original by quite a few millimetres.

[Citroënbender]

A related disappointment, variator shells are heavily scored - I'd say swarf rather than grit. Vlade is indicating zero stock but I haven't yet messaged him to confirm. Any other options in Oz?

[Citroënbender]

Last known pair of new shells in Oz, now have my name on them. Vlade is positive he's got a set - somewhere - but in the heat of the moment could not put his fingers on them.

So anyone doing a variator soon, might be well-advised to order ahead.

[Citroënbender]

I'm stepping through the door
And I'm floating in a most peculiar way

Another question. On this particular head the cam girdle has only two dowels. Should it have one per bolt (four total) to mimic the regular caps?

[johnl]

For anyone reading who might be unfamiliar with the architecture of these camshaft bearings and bearing caps;
Note that the frontmost bearing cap is a casting which forms the upper bearing half for both camshafts, so it is a single casting that is like a 'dual' cap serving both camshafts (all other caps are individual castings). The photos show the front bearing of the inlet camshaft, which uses bearing shell inserts. None of the other bearings use shells, the shaft journals run directly in the aluminium of the head and cap castings.

Ignoring the severe scoring around the entire circumference to one side of the bearing, notice the scuff marks where the rotating shaft journal has been in running contact with areas of the bearing shells, and then note the unscuffed areas where the journal has NOT been in contact with the shells. Most of the lower shell has been at least lightly scuffed by the shaft journal, but only a very small area of the upper shell has been similarly scuffed (most of the shell appearing to have never been even touched by the journal).

It seems obvious that the upper bearing shell is laterally misaligned with the lower shell, so the entire dual bearing cap must be laterally offset relative to the head. This means that the camshaft is not running concentrically in the front bearing shells, and the clearance between journal and shells will be very different in different places around the circumference of of the front bearing (and in some places the clearance may well be zero). Due to both camshafts sharing the front bearing cap casting, I suspect there is very probably a similar problem with the exhaust camshaft front bearing (unshelled).

If the (dual) bearing cap were to be fitted to the head (without the camshafts installed), and a finger were to be then run around the ID of each front bearing, I expect it will be possible to feel offset 'ridges' where the upper and lower shells meet, or the unshelled exhaust bearing halves meet.

This ought not to be possible, because the head casting and all of the bearing cap castings (including the front 'dual' cap) have to be simultaneously machined (line bored) while the bare castings are assembled. This is the only way that a correct fit between the upper and lower bearing surfaces can be achieved (whether the journal runs directly in the casting metal or in shells). This is why bearing caps can't ever be interchanged, each one ONLY fitting correctly in a specific location.

So this is a very strange problem...

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What makes it even stranger is that it's not the first time I've seen this with a TS engine. I have a spare TS cylinder head with exactly the same bizzarely unlikely issue...

I dismantled this head some time ago with a view to rebuilding it. What I found was very similar to the bearings in these photos, i.e. the front bearing 'dual' cap is laterally and significantly offset to the head casting (and yes, the dowel tubes were installed, of which there are two). There is similar uneven scuffing of the upper and lower shells as in your photos (but not nearly as bad). None of the smaller individual bearing caps have similar problenms, they all fit together perfectly with zero ridges at the cap / block split lines.

The only theory I have been able to think of that might explain how this anomoly might possibly have occured is that perhaps at some time somebody has fitted the dual cap from a different head...

I just can't think of another explanation. The original dual cap must have been line bored at manufacture while it was bolted to the head casting, so by definition it would have to fit perfectly, but it is a fair way off being a perfect fit. Note that for this sort of thing, there is 'perfect fit', and then there is 'does not fit', there is no 'near enough'...

Not even the vertical machining at the extreme front of the head are a good match (where the cap abuts the head forming two circular holes through which the camshafts protrude), i.e. there are ridges here, where the castings ought to abut with an absolutely flush fit because matching castings would have both been machined at the same time while assembled ....

The upshot is that simply because the dual cap doesn't fit correctly (frustratingly weird...) I consider this head to be scrap metal, unless it is possible to have the dual cap line bored to correct the problem... 

Regards,
John.

[johnl]

I'm stepping through the door
And I'm floating in a most peculiar way

Another question. On this particular head the cam girdle has only two dowels. Should it have one per bolt (four total) to mimic the regular caps?

There are four bolts but only two dowels. 

Regards,
John.

[Citroënbender]

Thank you for confirming the arrangement with respect to that girdle and dowels. I feel relieved.

In terms of the wear, yes I freely acknowledge this motor is - as I called it - a "mutt" and I have no idea if the current piece was originally tunnel bored with the head casting. I did notice the lower shell half is not perfectly seated in the head and the centremost edge up maybe 4-5 thou.

How much better (if at all) it may be practically made without going overboard, will be up for debate in a day or two when I have the new shells.

[johnl]

In terms of the wear, yes I freely acknowledge this motor is - as I called it - a "mutt" and I have no idea if the current piece was originally tunnel bored with the head casting.

The original 'girdle' would definitely have been line bored in situ with the other caps, all bolted to the head. Those specific 'mated' parts will then be the only ones anywhere that will fit that particular head casting.

For it to have ever happened that a non original 'girdle' cap was fitted to the wrong cylinder head leaves me somewhat speechless, the utter incompetence of whomever was responsible is breathtaking. It is such a stupid and almost randomly unlikely cock-up, but it seems the only rational explanation... 

So, in some workshop somewhere, there must have been two disassembled Alfa TS heads sitting on a bench at more or less the same time, and the wrong girdle must have been carelessly picked and installed on the wrong head. This also implies a distinct possibility that there may be another TS head somewhere out there, also fitted with an incorrect non original and ill fitting cap girdle...

Maybe it is the head you own (very unlikely, but stranger things have happened...).

I did notice the lower shell half is not perfectly seated in the head and the centremost edge up maybe 4-5 thou.

I'd have expected that as the girdle bolts are tightened the shells would be 'crushed' until fully seated in the correct position. If not then is some problem...

Regards,
John.