QUESTION
My Lotus 907 engine has just undergone an extensive rebuild at a cost of AU $20,000
The engine has now covered 400Klms and it has excessive crankcase pressure where the oil vapour is saturating the induction air-filter
Can you recommend a suitable crankcase catch can to rectify this problem?
J.H. - Point Cook, Victoria
ANSWER
With such low mileage on an engine that has recently undergone a comprehensive rebuild, then it is not normal for the crankcase to vent so heavily
It would be inappropriate to install at catch can at this point without first investigating what is causing excessive oil vapours
Without being able to see or listen to your engine it is not possible to make a precise diagnosis
However it would be prudent to request the engine builder for the engine build sheet that should contain all the critical dimensions and assembly notes
Excessive crankcase vapours can be caused by the following-
1) Incorrect piston to bore clearance
2) Incorrect piston ring gaps
3) Incorrect piston ring orientation
4) Incorrect cylinder liner hone pattern
5) Incorrectly machined cylinder liners where they maybe slightly tapered or oval
6) Incorrect oil level where it is too high and the crankshaft counter balance weights make contact with the oil in the sump pan
7) Incorrect oil installed - a 20W50 mineral oil with NO friction modifiers/additives should be used for running in purposes
NOTE - If a fully synthetic oil has been installed, then the piston rings will never bed in properly and excessive crankcase pressure will result
Copyright © 2021 Lotus Marques
My Lotus 907 engine has just undergone an extensive rebuild at a cost of AU $20,000
The engine has now covered 400Klms and it has excessive crankcase pressure where the oil vapour is saturating the induction air-filter
Can you recommend a suitable crankcase catch can to rectify this problem?
J.H. - Point Cook, Victoria
ANSWER
With such low mileage on an engine that has recently undergone a comprehensive rebuild, then it is not normal for the crankcase to vent so heavily
It would be inappropriate to install at catch can at this point without first investigating what is causing excessive oil vapours
Without being able to see or listen to your engine it is not possible to make a precise diagnosis
However it would be prudent to request the engine builder for the engine build sheet that should contain all the critical dimensions and assembly notes
Excessive crankcase vapours can be caused by the following-
1) Incorrect piston to bore clearance
2) Incorrect piston ring gaps
3) Incorrect piston ring orientation
4) Incorrect cylinder liner hone pattern
5) Incorrectly machined cylinder liners where they maybe slightly tapered or oval
6) Incorrect oil level where it is too high and the crankshaft counter balance weights make contact with the oil in the sump pan
7) Incorrect oil installed - a 20W50 mineral oil with NO friction modifiers/additives should be used for running in purposes
NOTE - If a fully synthetic oil has been installed, then the piston rings will never bed in properly and excessive crankcase pressure will result
Copyright © 2021 Lotus Marques