26 replies to this topic

[bpirie1000]

How deep on the crank does the scoring go?

Just aswell you decided to take out the engine.....

Been on there dry for some time...

[imack]

What is that build up of white powdery material between the bushes in the primary gear? It doesn't look like debris from the crank or bushes. Looks like dried up white grease.
That front bush looks extremely dry, there should be some engine oil in there to lubricant it, which then escapes back to the engine via the drillings between the front and rear bushes.
Not very clear in the photo, but is the primary gear thrust washer fitted the right way round? Looks like the chamber might be facing the primary gear rather than the crank. Also, has the thrust washer got the 4 grooves either side of it?

Edited by imack, 19 December 2024 - 06:20 PM.

[Sharks]

How deep on the crank does the scoring go?
Just aswell you decided to take out the engine.....
Been on there dry for some time...

Not sure yet - the engine isn't out, it's still in the car. I'll stick the Wok and engine mount back on, then pull the body off the subframe this weekend. Will keep you updated once I have the engine upside down and the gearbox off. It's certainly bone-dry. Probably done a good chunk of the last 20,000kms with no oil. The rear bush from the primary gear is pretty solid on the crankshaft.

 

 

What is that build up of white powder...Looks like dried up white grease.
That front bush looks extremely dry, there should be some engine oil in there to lubricant it...
Not very clear in the photo, but is the primary gear thrust washer fitted the right way round? Also, has the thrust washer got the 4 grooves either side of it?

There was no white grease in there, though I did liberally apply engine oil when the primary gear went on. Evidently that's cleared away from the front bush and not been resupplied from the back.

The thrust washer is fitted the right way around, I'm sure of that, though it has no grooves - I noticed that when I bought it. I thought it was odd as it was different to all the old ones I have here, but I didn't think too hard about it. Maybe I should have.

I tried to take it out to get a picture for you, but I can't get my fingers in there with the engine in situ. Will have to wait until I take the flywheel / drop gear housing off.

[imack]

I'd always presumed that the grooves/slots in the primary thrust washer were to aid lubrication to the primary gear bush, but I may be wrong.

[Spider]

I'd always presumed that the grooves/slots in the primary thrust washer were to aid lubrication to the primary gear bush, but I may be wrong.

 

With the crank and gear spinning, any oil that might happen to drip down that way will only centrifuge out through the slots.

[GraemeC]

 

 

The rear bush from the primary gear is pretty solid on the crankshaft.

 

Are you sure - it looks pretty much in the primary gear to me.  Are you confusing the step in the crank for a bush?

[Sharks]

Could be, Graeme - in our devastation we might not have considered that.

 

I have got the subframe out tonight, should have the engine and box split by this time tomorrow. Will put up some photos then.

[Earwax]

Once you have the engine out and continue to dismantle, maybe take some measures/pictures of anything else clutch/ crank related more so for reference - but for instance if the crank end float is a funny number. 

[Sharks]

Donk is in pieces. Pictures as promised:

 

 

The engine looks in good health otherwise, but keen to hear the verdict on the crank. I won't bother to take it out now, I'll wait until next year once the engineering shops are open again.

[bpirie1000]

Need to take some measurements on there to tell properly. How does the primary gear look. Find the reason for oil starvation?

[Spider]

The Front Bush on this one was non-genuine, though I've not had trouble with these particular ones. What I did find as that it was greased on the back, between the bush and the Primary Gear. When supplied loose, they are coated with a preserving grease so that the steel back doesn't rust, I suspect by the feel of the grease, that wasn't washed off before fitting, I suspect this is why it started walking out.

 

The Back (Top Hat) Bush though was of a bronze material

 

 

You can see how bright it is. There's nothing in the material itself that provides any lubrication and running the finger over the swarf, it's course and grippy to the touch. This material needs external lubrication.

With Deva, out of the box it's actually black on the outside (as supplied), it will quickly make a mess and make your hands go black ! The black material I'd say is mostly graphite but it does have other materials mixed in with it.

 

Also, when turned, while it does brighten up, it remains quite dull when compared to bronze based bushings

 

 

Note the size and colour of the swarf on the boring bar. It's also smooth the the touch, almost like powder.

 

 

Finished Primary Gear, ready for Sharks to have his machinist machine the bushes to final size, once his crank is sorted out.

[Sharks]

Unfortunately it appears this engine is going to be off the road for a while.

Over the last two weeks I've stripped the engine further and found quite a bit of carnage. The crankshaft came out in order to take it to be cleaned up to accept the primary gear that Spider kindly rebushed for me, but we didn't get that far. Can you spot the problem?



These bearings don't look so good, and the center main bearing remained on the crank when I took it out, but sits loose in the block and cap.
This engine has done about 50,000kms. The last engine I disassembled had done at least half as many miles again, if not twice as many miles as this one, and I reckon you could have just about used its bearings a second time around. Now admittedly this engine has gone through two idler gear bearings, and is therefore on its third oil pump and gearbox rebuild, and its now apart because the primary gear bearing disintegrated which can't have helped things, but the wear down to the copper on so many bearings can't be explained by contamination from other bits of engine, only some of the scoring.

I've collected a number of theories from people I've shown these photos to so far, including that the people that built this engine for me used bearings that were too tight, or that for one reason or another the pistons aren't going straight up and down, or that there was excessive crank whip / flex, or that the distributor curves caused pre-ignition which lead to bearing damage.

Further tearing down the engine, we arrive at the pistons and bores. They don't look awful my eye, perhaps just a hone and a new set of rings?



Then the cam and followers. The cam bearings are not terrible, though there is some contamination especially on the bearing nearest the oil pump. The followers, which were brand new 5 years / 50,000kms ago have failed. The hardening on at least two of them is disintegrating, and it's damaged the lobes of the cam as a result.




The engine is currently at a machine shop on the other side of town so they can take the cam bearings out and make a decision on the bores. It will be rebuilt - possibly not with this crank as I think its a bit far gone between the primary gear failing and the main bearings, which are already 030 oversize and now need grinding. In the meantime I have acquired a spare engine that should with little effort get the car back on the road for the time being.

Edited by Sharks, 14 January 2025 - 10:48 PM.