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Crankshaft End Float


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Err, visited my car in the mech shop recently to be told I've got CSEF and the flywheel moves about 1cm back and forth. What causes this, how is it fixed and is there anything else useful that can be done with this part of the engine in pieces?

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My understanding is that crankshaft end float is something that is measurable on most engines in basic terms it is the movement that you may get on the crankshaft in a front to back orientation. If this is excessive then it is an indication that the thrust washers/bearings could be worn allowing excess movement in the crank.

Afraid that is my limited knowledge of the matter sure someone will spread more light and probably prove me wrong lol

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I was going to add something stupid, like saying that STFC usually fixes the problem. But I just looked in the OH manual and it states the following.

Crankshaft End Float

- Dimension: 0.08 - 0.20 mm

- Service Limit: 0.30 mm

- Controlled by: Selective thrust washers on rear main bearing.

And then it goes on to explain the Main Bearings (number / type / static clearance and configuration bla bla bla).

Oh - STFC - something to do with 'Sell' & 'Car'. :) I'll just go and crawl back into my hole.

Edited by s4simon

Simon  (94 S4)      My Esprit will be for sale in late 2017

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The crankshaft endfloat is purely a measurement of the lateral movement on the crankshaft. It is controlled or set by the thrust washers to ensure that the endfloat tolerance / movement does not exceed a predetermined distance.

Over time this tolerance will increase with wear.

It ensures that the cranckshaft will not hit the Main bearing caps and the block webs, thus preventing damage through contact.

However, this is normaly measured in Thousandths not cms. At 1cm, I am suprised that the engine did not destroy itself. Is this correct?

Any general wear oustide of the manufacturers tolerance is remedied by using thicker thrust washers. These are generally located on either the rear or centre main bearing caps.

If the excessive tolerance cannot be reduced within the manufacturers recommendations, then either a new crank will be required or if there is significant damage to the bottom end, then a new block.

With 1cm of movement. I would be very suprised if there is not any further internal damage.

Hope this helps!!!!!!!!!!!!!!!!

Caught between a rock and a hard place in a catch 22 situation, So its 6 of one and half a dozen of the other. Your damned if you do, but your damned if you don't so shut your cock!!!!!!!!!!!

Lotus Espirt Turbo S3    

Lotus Esprit S4 

Lotus Elise S2 Sport 130


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Fortunately I was there too and wouldn't say it was as much as 1cm but it was most certainly wellllll beyond the 0.3mm service tolerance - I'd have said more like about 5 / 6mm.... Still needs sorting but with any luck will escape any further painful problems? :)

"When I was a kid I used to pray every night for a new bicycle. Then I realised that the Lord doesn't work that way so I stole one and asked him to forgive me."


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