Front cover oil leaks. Reseal in situ?

[Johnfm]

Pretty sure the bulk of the oil leaks are from the front cover and head gasket area.

I expect if I merely replace the head gasket, the front cover will still leak.

Can it be sealed when I remove the head? Or is it an engine out job?

[billwill]

Pretty sure the bulk of the oil leaks are from the front cover and head gasket area.

I expect if I merely replace the head gasket, the front cover will still leak.

Can it be sealed when I remove the head? Or is it an engine out job?

There is a cork gasket that is placed to the front of the actual head gasket. The cork seals the head-to-Timing-case joint.

[Johnfm]

Sadly, I think there is a lot of leakage coming from the vertical interface between front cover and back plate.

I have cleaned it all up and it is leaking like a sieve at the front - but not just from where that cork gasket lives.

[types26/36]

Lotus used (and supply) a gasket for the backplate to engine but recommend it is fitted without sealer as it can clog up the small oil feed hole that lubricates the timing chain, I always use a sealer but I am careful to use it sparingly.
Lotus never used or supplied gaskets between the front cover and backplate (relying on just a sealer) however most front covers/backplates which are now 40+ years old have had a hard life and have become distorted or gouged from screwdrivers being forced between them. I always make gaskets and use a sealer between the front cover and backplate so unless you have new or excellent covers I recommend making and using gaskets and a sealer.

[rgh0]

Building a twin cam that does not leak is not easy and is an engine out job and then a lot off attention to detail with all the assembly. Not a simple exercise and hard to resist the temptation to do other things once you pull it all apart and start seeing the issues of wear and corrosion on the various components. The dollars / pounds / euros / your currency of choice can quickly mount up

I use a suitable Loctite gasket forming compound for the front cover to back plate join and provided they are flat and the faces in reasonable condition you can assemble without leaks. But you need the head and sump off and its much easier with the engine out of the car.

cheers
REohan

[512BB]

Types 26/36 wrote: I always make gaskets

Make me up a dozen pairs of those gaskets please Brian, next time you are in gasket making frame of mind. I will knock 50p a pair off your new head.

Leslie

[MickG]

Hi John,
I agree with Rohan that the only way is to pull the engine and replace all the seals and gaskets. Careful use of RTV and Wellseal to the jointing surfaces is essential. While the engine is out get all the threads that are directly cut into aluminium drilled out and replaced with helicoils. From memory I think there are six on the front cover, two on the rear oil seal housing and one on the underside of the head. Most will have been over tightened or butchered sometime in their life, will not torque up correctly and will be a cause of further leaks.
If you have not already got I copy I strongly advise that you get Lotus Twin Cam Engine by Miles Wilkins. This has been reprinted at a reasonable cost and is invaluable. Follow exactly his procedures and you will have a leak free engine. at the very least renew all the nyloc nuts. New bolts and washers would be a bonus. A company I use http://www.namrick.co.uk/ have all you require and a good next day service. No affiliation etc etc
As Rohan has pointed out the temptation to do the ?oh while I?m here? jobs can push costs up, so be aware. If as you say tests so far indicate a sound engine then hopefully no major works will be required.

Regards Mick G

[Elan45]

Are you sure the crankshaft seal isn't causing the bulk of your leaks. It'd be at the top of my list and a job that can be done in place.

Roger

[Chris]

Hi Johnfm.

I have been following your plight and I can sympathise with you having suffered the same problem in the past, and I now have a completely leak free engine.
The answer is to remove the head and sump, preferably with the engine out. Thoroughly clean and degrease the engine block face with cellulose thinners or similar, the same applies to the back and front of your back plate and the back plate/front cover mating faces. When satisfied they are all clean, stone all faces using a fine
carburundum stone to remove any raised thread holes etc. which might prevent proper mating. Then, carefully check for flatness by offering the cleaned back plate to the cleaned engine face. If satisfied that there is no rocking, offer up the paper gasket to the block face to ensure it is the correct height, as some are not tall enough, especially if you have a tall or 711m block, the paper gasket must be level with the block top. Apply a thin but uniform coating of wellseal to the block face and locate the paper gasket. apply another thin coat of wellseal to the rear of the back plate and position it locating with the 1/4" screw, but do not tighten at this time.
Next, temporarily fit the front cover making sure the bolt holes line up, and both the front cover and back plate are flush with the block top with the front cover oil seal located over the crankshaft, and the pulley fitted.
If satisfied remove the pulley and front cover without disturbing the back plate alignment, and tighten the 1/4"screw. Lay the timing chain into place and apply a thin but continuous bead of Loctite 274 around the mating face of the front cover and fit to back plate, again temporarily fitting the crankshaft pulley to assist alignment. If still satisfied that the top faces are level with the block top tighten the screws to their correct torque. Using new gasket fit cylinder head, when fitting the cork timing case seal, I fit it dry to minimise extrusion, although a much better material than cork can be found on burtons website, along with fibre type sump gaskets with moulded rubber horseshoe seals, and also a fibre cam gasket all of which are an improvement over the cork.
If you find that your timing case is problematic, fit a Burton cassette type cover they are a quantum leap forward and are essentially fit and forget.
Hope this helps
Chris

[Johnfm]

Thanks all.

Sounds like either do it properly or not at all.

Hardly any point doing a DIY head gasket change if the front cover still leaks loads.

And I really don't have the set up at home to remove the engine.

So, might have to start saving and get an engine hoist etc bought.

[elansprint71]

Hi Johnfm.

I have been following your plight ...........

When satisfied they are all clean, stone all faces using a fine carburundum stone to remove any raised thread holes etc. which might prevent proper mating. .................(sic)

Hope this helps
Chris

Whilst this might help with de-burring any holes (although I'm unsure why there should be any burrs) introducing the possibility of loose abrasive particles is not, in general, a good idea when dealing with an internal/external combustion engine.

Some while ago I suggested a "daft ideas" thread, where non-engineers could post "advice". Unfortunately this did not happen and, as a result, well... you know the rest.

[AHM]

John,

You can do all of this with the engine in. Once you have the head off you have done the difficult bit.

Remove the sump from below. Easier to do if the cross-brace is removable, not difficult to make it removable.

After that the front cover is easy to remove.

The car is your engine stand!

Chris, a nice, detailed, helpful explanation!

Peter, what are you talking about? Suggest you post in your non-engineers thread!

[jono]

Pete,

I'm sure Chris can speak for himself but I think you will find he is a qualified mechanical engineer

Jon (non engineer)

[Chris]

elansprint 71.
I posted Johnfm perfectly sound advice based on established engineering principals, to which you rather ridiculously disagree. However, if you had an engineering background you would have realised that the stoning of machined faces is an essential part of ensuring a reliably flat surface. This does not just apply to I.C. engines, any flat surface which can't be guaranteed will benefit from a light stoning to regain its credibility, and is regular practice throughout the aerospace industry be it axial flow jet turbines, or Rolls Royce RZ 2 rocket engines, all of which I am familiar with. And, you do Johnfm a disservice in implying he would stone a surface yet not re-clean afterwards. I suggest you turn to page 2 of the how to be an engineer manual.
Chris A.M.I. Mech E. H.N.C. Mech. H.N.C. Elect. ex. Flight Trials Engineer De Havilland Dynamics, and Hawker Siddeley Dynamics. With a leak free twin cam engine.

[512BB]

With respect to all, my new years resolution , but probably wont last, I think you will find it bloody difficult to work efficiently, but more importantly, well, leaning over to work on the engine in a +2 engine bay, low down at front cover level, and underneath to remove the sump, et al.......ahhh, horrible.

To do the job properly, as has been suggested, take the engine out, get it on a stand, and crack on. You will be mighty pissed off, if you frig about, do an amateur job, and still have oil leaks when you start her up again.

And for goodness sake, put a new water pump in whilst your at it. They are only 38 quid!

Leslie
Qualified in bullshit