Crankshaft rear main seal

From what I can gather most engines have a 10mm recess and only a handful have a 12mm

 

A lot more than a handful; some are 10mm and some 12mm and most engine builders fit a 10mm seal in a 12mm recess.

The 12mm double lip seal should fit okay but make sure the outer lip doesn’t run up the radius on the flywheel – get your measuring stick out. If it does fit the 10mm single lip seal.

 

If it's fitted flush with the case outside edge would it matter if 10mm or 12mm ?

It'd just leave less gap between case and seal on the inside face

Or should the seal be pushed further in

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The seal should be pushed down to the shoulder to ensure it's perfectly square in the case IMO. A 10mm seal into a 12mm recess could breath new life into a damaged flywheel. Maybe an 8mm seal could do the same for a 10mm case?

 

By shoulder do mean as far in as it'll go?

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Yes. Don't hit it too hard though!

 

So my dilemma is do I fit the 12mm double lip seal or the Elring 10mm seal. If I go with the 10mm do I fit it flush or 2mm further in. My flywheel is good. I did have a 10mm seal fitted flush but this was leaking???????

 

It could have leaked for any number of reasons. Most don’t. Stick the 10mm Elring in

 

...I'll get rid of that gap behind this seal then.. when I go look for that oil leak on the side...



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The seal might leak on the OD, where the casing split is, and a smear of sealant on the split line won’t do any harm. If the bore of the case and the flywheel are in good condition and the seal is fitted properly neither the single nor the double lip seal will leak.

Measure from the end of the crank to the seal outer lip, then measure from the flywheel face to the radius. If the lip runs on the radius, fit the 10mm seal, if it doesn’t, fit the 12mm double lip seal. If you want the (10mm) seal to run on a new bit of flywheel knock it in to the shoulder - but usual practice is to have the seal flush with the outer face of the crankcase.

 

The Elring spring is half the size of the double lip seal

 

But Elring know how to make seals, implying it doesn't matter

 

...or double lip need more spring for the same pressure.

 

...thus wearing faster...

 

wearing the same, the load being split between two lips.

 

I know naff all about seals other than they are supposed to seal, would the second lip not burn up as no oil will get to it ???

 

Exactly my point

 

The second lip is independent and has no spring

 

The outer lip is a dust seal, it doesn’t need a spring, the inner lip seals the oil but if you think the Elring seal is better, fit it. Just a smear of sealant on the split line and knock the seal in to the shoulder. Don’t forget the ‘o’ ring, or the (3) shims when you fit the flywheel.

And don’t ask what sealant to use.

 

...but if it's not Curil T the block might explode

Or Permatex .. Or Curil K2 ... Or hylomar... Or....

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