QUESTION
Apparently the Cometic sump gaskets are made from something else other than cork and don't require any sealant.
I have been told they don't leak and the bolts only have to be tightened once.
I think they also make cam cover gaskets from the same stuff.
Is this worth investigating and Lotus Marques stocking these gaskets?
D.H. - New South Wales
ANSWER
I can confirm that Cometic sump gaskets are manufactured from a gasket material similar to a coated composite head gasket (has minimal compliance)
For this type of gasket to seal effectively requires a perfectly flat sump pan plus the front and rear alloy housings to be flush with the bottom of the cylinder block.
This type of gasket is very durable and ideally suited for new alloy sump pans that are both flat and rigid.
A quick way to check your sump pan is flat, is to place it on a surface plate or trial fit it on a cylinder block without a gasket.
At this point you may contemplate using a old steel pressed sump pan that does not have perfectly flat sealing surfaces (corrugated sealing lip as standard)
As a matter of interest, Lotus Marques has a simple two step method to ensure sump pans seal when using cork gaskets
With the engine out of the vehicle and mounted on an engine-stand, this provides unprecedented access for inspection purposes.
The first step is to carefully clean the cylinder block faces and half moon recesses at each end with solvent (to remove all traces of oil and debris)
The long cork sump strips should be laid along each side of the cylinder block and the end locating pieces checked for fit (trim if necessary)
With the cork strips in place and with a soft pencil, carefully draw around the cork so as to leave guide lines on the block.
Next, trial fit the cork end pieces and trim as required (ensure these items are a snug fit into the corners where the meet the long cork strips)
Next, remove all the cork pieces and lay out carefully for final installation.
With a quality sealant such as Loctite Grey MAXX, apply a light coating in the gasket area indicated by the pencil marks.
The long cork strips should then be placed in position and aligned with the 1/4" UNC bolt holes.
Light pressure should be applied so the gaskets make contact with the thin film of sealant underneath.
The end corks should then have a light coating of sealant to assist when gently pressing them into their respective grooves.
The clean sump pan should be placed in position without disturbing the gaskets and secured in position with four bolts (just nipped to hold the pan and gaskets in the correct position)
The sealant should be allowed to cure over night and then the sump pan can be removed for inspection purposes.
This two step process allows the gaskets to be secured in place before applying an additional coating of sealant.
It also allows a visual check for misalignment problems prior to the final installation of the sump pan.
Carrying out the procedure with fresh sealant on both sides of the cork gaskets encourages movement and misalignment problems.
This procedure is carefully followed here in the workshop for every twin cam engine rebuild to ensure an oil-tight result.
Copyright © 2015 Lotus Marques
Apparently the Cometic sump gaskets are made from something else other than cork and don't require any sealant.
I have been told they don't leak and the bolts only have to be tightened once.
I think they also make cam cover gaskets from the same stuff.
Is this worth investigating and Lotus Marques stocking these gaskets?
D.H. - New South Wales
ANSWER
I can confirm that Cometic sump gaskets are manufactured from a gasket material similar to a coated composite head gasket (has minimal compliance)
For this type of gasket to seal effectively requires a perfectly flat sump pan plus the front and rear alloy housings to be flush with the bottom of the cylinder block.
This type of gasket is very durable and ideally suited for new alloy sump pans that are both flat and rigid.
A quick way to check your sump pan is flat, is to place it on a surface plate or trial fit it on a cylinder block without a gasket.
At this point you may contemplate using a old steel pressed sump pan that does not have perfectly flat sealing surfaces (corrugated sealing lip as standard)
As a matter of interest, Lotus Marques has a simple two step method to ensure sump pans seal when using cork gaskets
With the engine out of the vehicle and mounted on an engine-stand, this provides unprecedented access for inspection purposes.
The first step is to carefully clean the cylinder block faces and half moon recesses at each end with solvent (to remove all traces of oil and debris)
The long cork sump strips should be laid along each side of the cylinder block and the end locating pieces checked for fit (trim if necessary)
With the cork strips in place and with a soft pencil, carefully draw around the cork so as to leave guide lines on the block.
Next, trial fit the cork end pieces and trim as required (ensure these items are a snug fit into the corners where the meet the long cork strips)
Next, remove all the cork pieces and lay out carefully for final installation.
With a quality sealant such as Loctite Grey MAXX, apply a light coating in the gasket area indicated by the pencil marks.
The long cork strips should then be placed in position and aligned with the 1/4" UNC bolt holes.
Light pressure should be applied so the gaskets make contact with the thin film of sealant underneath.
The end corks should then have a light coating of sealant to assist when gently pressing them into their respective grooves.
The clean sump pan should be placed in position without disturbing the gaskets and secured in position with four bolts (just nipped to hold the pan and gaskets in the correct position)
The sealant should be allowed to cure over night and then the sump pan can be removed for inspection purposes.
This two step process allows the gaskets to be secured in place before applying an additional coating of sealant.
It also allows a visual check for misalignment problems prior to the final installation of the sump pan.
Carrying out the procedure with fresh sealant on both sides of the cork gaskets encourages movement and misalignment problems.
This procedure is carefully followed here in the workshop for every twin cam engine rebuild to ensure an oil-tight result.
Copyright © 2015 Lotus Marques