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I’m going to pull the sump off to take a look
Technical Big nut too tight?
- Thread starter LiteRye
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Technical Big nut too tight?
Check the conrods are facing the right way.
the hobbler
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Hi Ryan;
As I mentioned earler, with the crank-nut done upto the correct torque, ther should be about 10th clearance between the face of the crank and the adjacent face of the bearing at the TIMING CHAIN end. Some of the 'pattern' bearings are too 'thick' and that clearance is not present. If this is so, the only ways to get round the problem are to (10 get another t/c end bearing OR, (2) remove the t/c end bearing and reduce the thickness of the white-metal that abutts the crank. This can be done on a flat surface (a thick sheet of glass is perfect) and some fine 'wet-'n-dry' emery cloth welllubricated with WD40 (or similar). At the risk of asking a very stupid question, have you got the crank-bearings the right way round---they will fit in either end, but the t/c end has the cut-away for the timing-chain to run in.
Does the crank lock-up if you assemble it, with the crank-nut torqued up, but with the timing-chain cover left off? This can be achieved without having to fit the timing-chain---just the complete pulley assembly
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I finally got around to pulling the sump off on the engine. The clearance between the bearing and crank is about 30thou and can be seen in the photo.
You can see in the attached video the engine moves freely and the crank has some fore aft play.
I took a video of the assembly process. Maybe someone can spot something that looks off. It’s too big to upload here so I will get it Youtubed and post a follow up.
You can see in the attached video the engine moves freely and the crank has some fore aft play.
I took a video of the assembly process. Maybe someone can spot something that looks off. It’s too big to upload here so I will get it Youtubed and post a follow up.
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Trying again for the video.
The crankshaft will do that until you get the front pulley assembled which takes up the end float
Nothing too obvious looking at video, so would double check re spacers and sprockets where tightening crank nut. If you do it a little at a time and recheck as you go hopefully you will see where it is binding.
There does seem to be a general consensus that parts from earlier or later versions can cause binding, so hopefully you can pin point it.
Looking at the large amount of free play / end float of the crank I assume as you nip up the nut it should pull together to give the approved 10 thou. clearance once fully torqued up, providing as others have mentioned there is no issue with incorrect parts.
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I will have to reshoot the assembly video. The end got cut off
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Here’s the Youtoobadoobe
Lovely clear video, thanks.
Any chance you can assemble that area using the old parts, one at a time to identify problem.
Something you may be able to see is any marks in the oil stain darkening to show original position of parts in relation to each other, where they used to sit.
Plus measure with a vernier or micrometer to compare new parts to old, thickness wise.
Unless another Forum member can immediately see problem.
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Only new parts are the lock washer and the sprocket. The rest are reused. I measured the sprocket and both are same size.
If you replaced the main bearing/crank thrust bearing, is there much difference in the thickness when compared with the old one on the thrust area where it runs against the block?
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The bearings and crank were not replaced the only components that are related that were not on the engine when it was running was the lock washer and timing chain sprocket.
I did however just remember that when the bearing was taken off during disassembly that it had a paper gasket between it and the block. From everything that I have read there should not be a gasket on the main bearing
I did however just remember that when the bearing was taken off during disassembly that it had a paper gasket between it and the block. From everything that I have read there should not be a gasket on the main bearing
If the bearing/thrust washer was not changed surely it must point to an issue re the sprockets and spacers etc. used in reassembly.
No chance you took a photo on disassembly?
The only reason I ask and I don't have the specific Fiat 500 knowledge of some other Forum members, just the 50 years as a motor engineer, is it looks a bit crowded with all the spacers and other washer type bits between the pulley and the crank.
Looking at a YouTube rebuild of a Fiat 126 engine () which they say is similar, he does say there is a paper gasket on the flywheel side bearing to engine block. That along with an oil seal in the bearing end is needed to keep it oil tight, at the timing end the oil is needed to lube the timing chain area and relys on the timing cover gasket and oil seal .
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Thanks to Thomas aka the Hobbler we may have figured this out. As it turns out the spacer/washer with the chamfer is not the correct part. It should be flat and mine is “stepped” and about 3mm too thick.
A new part has been sourced and will be on its way to me in a bit. Hopefully this gets me sorted.
A new part has been sourced and will be on its way to me in a bit. Hopefully this gets me sorted.
Well done you for your perseverance and to Tom for solving this, I kept trying to figure out what was wrong but nothing obvious came to mind.
