All,
i've just put new b/e bearings in my vw golf mk 3 1.8 SPi, it's done about 250k, the old ones were worn at the no4 end of the engine, but in good condition at the no1 end, here's a pic:
www.clubgti.com/forum/showthread.php?t=95692
It seems strange that the wear is minimal at one end of the engine, then progressively worse towards the other (no4 cylinder) any ideas what may be causing this, and any predictions for the state of the crank, and hence life left in the block??
TIA Mark
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Job well done at the right time I think. The progessive wear is common on high milers due the several factors. Firstly the weight of the flywheel, secondly the vibration caused by clutch engagement. The other end i.e. No 1 only has the cambelt and the aux belt preload on them so those shells waer more slowly. Check for cam bearing wear and lobe deteriation whilst your in there. Regards Peter
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Fair wear and tear, interesting pictures. There is some evidence of conicity in the crank journal grinding, judging by the wear pattern on the shells, but the increased wear at the flywheel end is not unusual in my experience.
My theory is that this wear pattern is due to the gyroscopic forces acting on the rotating mass of the flywheel as the vehicle is in motion. I have seen this many times before on automotive engines, but never on a stationary engine (all diesels). I have also observed that this problem tends to be worse in transversely mounted engines as the gyroscopic forces are generated as the vehicle rolls. A vehicle with an in-line engine generates no gyroscopic force on roll. Unless driven in a highly enthusiastic manner, forces generated due to vehicle pitch in a longitudinal engine installation are not likely to be very high.
Any comments would be welcome.
659.
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Do you have pictures of the main bearing shells? I would expect to see evidence of similarly increased wear here, towards the flywheel end.
659.
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Do you have pictures of the main bearing shells? I would expect to see evidence of similarly increased wear here, towards the flywheel end. 659.
No, i put some VW quantum sinta gold oil in a few months back and it started knocking (which my limited experience led me to believe was b/e knock) at startup, for 2 - 5 secs, even tho the oil pressure light goes straight out. I then changed the oil for 20w50 and decided to fit new b/e bearings. At 15 quid for OE KS bearings i thought it was worth a throw, although it was really an inspection to see if i need to get another block lined up,hence my question about the likely condition of the crank.
PeterD: It had a new head at 80K, and i'm not too worried about the condition of the current head because i've got a spare lined up. The car runs LPG, so the bearings in the head are the last of my worries...
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If it was gyroscopic forces it matters not if its transverse or not, dont forget thet the gyroscope effect is in *all* directions so should be seen in "right and left" as well as "up and down"
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TourVanMan TM < Ex RF >
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If a vehicle has a longitudinally mounted engine and rolls, there is no gyroscopic effect because the vehcle roll axis is parallel (and not very far from) the crank axis.
Try it with a bike wheel - spin and hold the axle at each end. Rotating the axle has no effect (with acceptable bearings); rotating the axle in any plane perpendicular to its axis generates a considerable force.
659.
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Indeed no effect on roll of car about the axis of the gyroscope BUT there will be effects if you turn the car right or left. Plus there will be anti gyroscopic effects on longitudinal engines when the car pitches up or down on acceleration or braking which wont be "anti gyroscopic" on transverse engine set ups.
So I contend - no difference.
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TourVanMan TM < Ex RF >
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looking at the biggest picture it looks like the bearing may have worn too far and marked the crank?was crank clean on journal with no scoring?
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>> looking at the biggest picture it looks like the bearing mayhave worn too far and marked the crank?
I'm not too sure, it's all back together now.
was crank clean onjournal with no scoring?
YES
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