Hi guys,

What's the difference between main bearings and Big end bearings?

I have to buy some new bearing to my Zetec and on ebay some sells big end bearings and other sells main bearing.

I need all "bottom" bearings (crank and conrods).

Mains are the Crank bearings, Big ends are the bearings in the conrods where they attach to the crank.

HTH

Mark

Thanks,

So will need both sets then.

Be careful tho there are different sized bearings. Best thing to do if your not sure what size they are is take them to ur local engine builder and he will be able to supply you with the correct size. Fitting the wrong size bearings can create all sorts or problems even engine death.

If you require all bottom end bearings then you so need big end and main bearings

big end bearings is the place were the con-rod connects to the crank.

Main bearings are what the crank sits in and turns.

I haven't removed the crank yet, but this is how the pistons and head looks like

[Edited on 5/10/07 by Micael]

[Edited on 5/10/07 by Micael]

sorry, forgot the picture

And the head

Until you get the crank out and check for any signs of wear that may require machining, you wont know what size bearings you will need. The crank may even have been machined previously so requiring oversized (or is that undersized) bearings.

* edited after realising you already stated the crank was still not removed

[Edited on 5/10/07 by Paul TigerB6]

I plan to remove the crank tomorrow.

I suspect that it is a big end bearing failure that has cause the piston hitting the head.

Whilst you are at it check for end float on the crankshaft. That's movement of the crank backwards and forwards along the block. You should be able to check this with feeler guages and find out the acceptable tolerance from either the workshop manual or google it. Don't ignore it if it's too much as it can affect the ability of the crankshaft oil seals to seal as well as wear on connecting components.
You should buy a bottom end gasket set which should include these seals. New shims to control end-float from your dealer or engine component supplier.
Finally make sure you know where they all go when you take the crank out as they are split (like half moons) and should go back in as pairs, in the same position and facing the same way as originally.
Cheers, Pewe

quote:

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Originally posted by Micael
I suspect that it is a big end bearing failure that has cause the piston hitting the head.

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