Posted By : Chris Taylor, 05-Nov-2004,
02:16pm
With the engine out and readily accessible, there is a dilemna as to how much to do "in case" and when to leave well alone!
Depending on the mileage and condition of the engine, you could consider fitting a new set of main and big end bearing shells. If the crank is in good
condition, this might stave off an eventual regrind by a good few tens of thousands of miles. (MANY years ago someone in the club used to recommend
changing shells every 50,000 miles if crank was sound, and suggested that with this the crank would last for hundreds of thousands of miles without
needing a regrind. All this assuming good oil, oil pressure, filters etc).
You might also consider fitting new crankshaft oil seals (much easier with the engine out), which would mean taking the timing case off, so why not
change the chain and tensioner as well? Also makes sense to look at the oil pump while the sump is off.
All this is adding up to more and more work, although none of it terribly difficult, time-consuming or expensive. So where do you stop ?!!!!! I suggest
you do NOT take the head off, unless you have reason to believe there's a problem, and that will put a definite limit on the scope of any "just in
case" work.
Bearing (no pun!) in mind the consequences of wearing out and losing the thrust washers, I would DEFINITELY recommend changing them. Yes, it is easy
with the engine out. With the sump off, it's a 10 minute job. As stated elsewhere, make sure they are well oiled, and fitted the right way round. The
bearing material must face the crank face. (Sounds obvious, but fiddling round with the crank in situ, covered in black oil, wheedling the old washer
out etc you can get "disorientated" as to which way the old ones were).
Not sure if it was on this website or on the Yahoo discussion group, but there has been a recent discussion of thrust washers and oversizes. Either
Canley Classics or John Kipping made reference to even thicker alternatives using Mini parts.
Unless it is clear that the washers have been in place for a high mileage, and simply suffered normal wear (although it is the TYPE of use that is
important; how often was the clutch used, as that places the only significant load on the rear washer), I would be slightly worried by excessive end
float. Why have the washers worn? Is there some defect on the crank face? If so, new washers will wear out quickly, so it is worth having a good look
at the crank face, especially the rear one. This IS much easier with the engine out of the car. You will need to turn the crank obviously, so be
careful not to dislodge the upper bearing shell. If you look at the tabs on the shell, it is clear that there is a "right way" to turn the crank to
keep that shell in position.
However, it is also the case that relatively little wear can feel like excessive endfloat. So do measure it if you can to get an accurate
assessment.
Having had a thrust washer fall out, I now make it a rule never to start the engine with the clutch depressed (while it reduces the gearbox drag on the
starter motor, it does place a high load on the thrust washers and there is no oil flowing), and also to avoid sitting in traffic with the clutch
depressed. Use neutral instead!