QUESTION
My mate has just rebuilt the engine in my Ford/Lotus twin cam Escort.
As a part of the rebuild the engine needed a new cylinder head, pistons and con-rods.
In addition to this, the original Lotus crankshaft has been replaced by a secondhand Ford Escort crankshaft with 77.62mm stroke.
The engine has been re-bored and reassembled so I now have an engine capacity of 1700cc.
I have now driven the Escort for 2000kms but I am experiencing excessive crankcase pressure where oil is leaking from the new crankshaft seals.
Can you tell me what might be causing this?
P.N. - Sydney, NSW
ANSWER
An excessive crankcase pressure problem maybe caused by one or a combination of the following items -
1) Excessive piston to bore clearance
2) Incorrect piston ring gaps and orientation
3) Incorrect honing pattern on cylinder walls
4) Insufficient cylinder wall thickness
5) Incorrect or restrictive crankcase venting
Other contributing factors that will promote leaking oil seals are as follows -
1) Worn or badly marked crankshaft journals that the oil seals run in contact with
2) Mis-aligned rear oil seal housing and front timing chest (seals not concentric with the crankshaft journal)
3) Poor quality lip seals (Silicon or Viton double lip seals are highly recommended)
Copyright © 2013 Lotus Marques
My mate has just rebuilt the engine in my Ford/Lotus twin cam Escort.
As a part of the rebuild the engine needed a new cylinder head, pistons and con-rods.
In addition to this, the original Lotus crankshaft has been replaced by a secondhand Ford Escort crankshaft with 77.62mm stroke.
The engine has been re-bored and reassembled so I now have an engine capacity of 1700cc.
I have now driven the Escort for 2000kms but I am experiencing excessive crankcase pressure where oil is leaking from the new crankshaft seals.
Can you tell me what might be causing this?
P.N. - Sydney, NSW
ANSWER
An excessive crankcase pressure problem maybe caused by one or a combination of the following items -
1) Excessive piston to bore clearance
2) Incorrect piston ring gaps and orientation
3) Incorrect honing pattern on cylinder walls
4) Insufficient cylinder wall thickness
5) Incorrect or restrictive crankcase venting
Other contributing factors that will promote leaking oil seals are as follows -
1) Worn or badly marked crankshaft journals that the oil seals run in contact with
2) Mis-aligned rear oil seal housing and front timing chest (seals not concentric with the crankshaft journal)
3) Poor quality lip seals (Silicon or Viton double lip seals are highly recommended)
Copyright © 2013 Lotus Marques