Lotus Elan

Leaking Seal

PostPost by: chicagojeff » Wed Jun 01, 2005 2:38 am

Hello all! Thanks for all the advice on tires, mirrors, prices, etc! My 67 FHC Elan arrived a few days ago. I can't stop driving it! Fantastic. More to report later, but here's a question...how much seal seepage do you all consider "within spec"? I am getting a little drip onto the manifold. Just a drop here and there (but of course that's the one I smell). and a little leakage around the timing chain seal and the head seal towards the back near the oil filler cap. For that matter, I think the oil filler cap is leaking a little too. None of this is all that bad, just trying to see what fellow Elan owners consider "normal".... Also, any advice about replacing the seals when I do it?

thanks again. I will attach pics tomorrow. yours, Jeff
67 S3 FHC
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PostPost by: ElliottN » Wed Jun 01, 2005 4:57 am

I presume you are talking about oil leaks. If you have any petrol leaks – FIX THEM FAST.

Functioning twin cams will leak anything from no oil (pretty rare) to, well, lots…… I have about a quarter of a cup of oil on the trays under my car after a year – from engine gearbox and diff combined. Parts of my engine and chassis are also reasonably well lubricated (well, at least it helps stop rust!). It’s over 30K miles since last rebuild and I drive it 2-3 times a week. The engine leaks are mainly from my front cover and sump but since it’s running strong for street use I’m not planning to rebuild in the short term.

Most of what you have described sounds like the cam cover (including the oil cap). There is a very good discussion here on this topic – use the ref

<a href='http://www.lotuselan.net/forums/index.php?showtopic=767&view=findpost&p=3243' target='_blank'>http://www.lotuselan.net/forums/index.php?...findpost&p=3243</a>

With careful cleaning, new D plugs, good washers for the studs, a good cork gasket, sealant and care installing you can usually get the cam cover pretty leak free.

If you have leaking from the front cover, that’s another issue. Unless it’s a lot I wouldn’t worry until I had a bigger reason to pull the cover (e.g. water pump). There are some products you can apply externally that claim to stop oil leaks but I’ve no experience of them

I’d suggest you look out for the Miles Wilkins book on the Twin Cam Engine (there are usually several copies going at any time on ebay). Even if you never rebuild your engine (I haven’t yet) it’s a great read and very useful for things like understanding how to fix oil leaks.

Good luck and enjoy the grin.
Elliott - 70 S4 dhc
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PostPost by: elans3 » Wed Jun 01, 2005 8:52 am

Sounds like you've got a good one ! Fix the camcover leak and you're pretty much where most of us are, or would like to be from a leak point of view !
Mine is carefully rebuilt, paying a lot of attention to preventing leaks, and it's still not perfect.
One of the major problems is the amount they breathe into the cam cover.
When I was rallying an Escort Twincam, using high of revs most of the time, we used to put a breather elbow on the front of the cover to a catch tank, Vegantune used to make a cast elbow specifically for that purpose, (1970's).
Its a good idea to keep to the standard 40 psi oil pump too.
I also have a Novamotor F3 Camcover, and they made a very similar mod for all their 70's F3 engines.
Without this on a sportily driven roadcar, they do tend to try and find anywhere to leak from.
Enjoy the car, it's the only thing I've ever had that always puts a smile on my face !!!
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PostPost by: chicagojeff » Wed Jun 01, 2005 1:22 pm

Thanks. I have to figure out what to try. sounds like fixing the cam head leak is all I should mess with for now. Has anyone tried Steve's suggestion of skipping the cork seal and just creating your own out of silicon?:

" My way is as follows:-
1) clean both mating surfaces.
2) apply a thin coating of oil to the head.
3) turn the cam-cover upside-down and apply a thin bead of silicon sealant to the mating surface
4) now place the cam-cover on the head held down by its nuts BUT do not tighten them(a gentle pressure just to seat it).
5) leave overnight to cure.
6) there should now be a re-usable silicon gasket attached to the cam-cover which should be a perfect match to the head mating surface."
67 S3 FHC
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PostPost by: type26owner » Wed Jun 01, 2005 1:41 pm

Suggest you use contact cement to glue the cork gasket into place onto the camcover. No adhesive is need between the cork and the head.

The oil cap has a hidden problem which is not easy to fix for the average guy. The spring tangs have to centered on the pins in the camcover exactly or one spring will slip off and the cap will tilt up on that side ever so slighty and spew out the oil. A ring spacer which snaps into the cap to have it center onto the round boss of the camcover is the only way to fix this problem. Dumb design!

For the leaks around the timing chain cover you can apply a fix externally which will work well. Clean those areas so they are oil free and apply a thick bead of silicone RTV. The blue stuff is made to adhere to oily surfaces but works better when the surfaces are really clean.

I've posted tons of stuff here on how to fix all the oil leaks. It can be done because I've done it.
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PostPost by: poiuyt » Thu Jun 02, 2005 12:13 am

Most (all?) of the leaks are from splash, not pressure. Therefore, my fix is as follows (and similar to the method above). It will work for all mating areas, including the fuel pump and any other mating areas.

-----------

Make sure all of the bolts on the front cover are correctly torqued. They can get loose.

Cleaned the seal area with Dimple Green biodegradeable cleaner and hose off.

After the area is dry I used the gray RTP (because it's the one that says oil resistant for foreign cars) and spread it along the outside of the seal seal area with my finger. Did this on all sealing edges.

Leave the RTP to cure for 24 hours. The leaks should be gone.

------------------

Cam Cover technique:

First of all, call Dave bean and get one of those metal shields to install on the cam bolts under the oil cap. This keeps oil from being sprayed directly against the underside of the oil cap and will stop the oil cap leaks.

Clean all of the mating surfaces on both the cam cover and the head. Buy a set of new rubber D-plugs (the old ones get hard).

Run a continuous bead of the gray RTP along all of the mating surfaces where the cam cover rests on the head, including under the D-plugs.

Insert the D-plugs, making sure to press them down and get the pins into the holes.

Lay a bead of gray RTP across the top of the D-plugs so there is once again a continuous bead.

Lay a new cork gasket on top of the RTP and press down slightly all around

Run another bead of RTP on the top of the gasket.

Install the cam cover making sure the cork gasket does not slide out.

Put some RTP on the hold-down pins, in stall new sealock washers, with more RTP on the top of the washers.

Tighten the nuts evenly, pressing the cam cover doan all around to be sure it is seated.

This should take care of the engine oil leaks.

Steve B.
Steve B.<br>1969 Elan S4
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PostPost by: poiuyt » Thu Jun 02, 2005 12:29 am

One more thing - the Miles Wilkinson book, Lotus Twin-Cam Engine, is available new from Classic Motorbooks (motorbooks.com or 1-800-826-6600). That's how I got mine last year.

Steve B.
Steve B.<br>1969 Elan S4
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PostPost by: carrierdave » Thu Jun 02, 2005 10:05 am

Hi Jeff,
I have just finished rebuilding my engine and experienced a number of oil leaks, the first being the oil cap. The way I got round this was to take out the rubber washer in the cap, clean both the rubber washer and cap with cellulose or petrol. Then I ran a bead of RTV in the cap under where the rubber washer sits. I then put the washer back in on top of the RTV and screwed the cap back on.

This has the effect of increasing the thickness of the rubber gasket thus making it a tighter fit as well as sealing up any areas where the oil may have been leaking through. Since I did this I have had no leaks even after removing the cap half a dozen times.

The other area where I found a leak was around the front cover bolts, in particular the one to the left of the water pump – I think it’s the shear volume of oil that cascades down from the head that causes the issue.

Hear I removed the bolt, cleaned it, applied an amount of RTV to the washer surface that makes contact with the front cover and the bolt stem, then replaced it. Again this has cured the problem.

This particular problem was difficult to see with clear oil and had me looking around the engine for the leak for weeks. What happened was the oil would leak out when running, run down to the sump gasket, travel along the sump flange and then drip from any point making it very difficult to pinpoint where the oil was leaking from. At one stage I had 4 separate oil drips from the engine onto the floor – All of which were cured when I found the leak on the front cover.

Apart from the gear box, my engine is now "LEAK FREE!!!!!!!"
Good luck


David
:)
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PostPost by: elans3 » Thu Jun 02, 2005 1:25 pm

Sorry to have to correct poiuyt, but pressure, (both oil and air), is the biggest contributor to leaks in twincams, not splash.
Without pressure, with new gaskets, cleaned & true mating surfaces and correctly torqued fixing bolts, splash will take an age to find its way out, unless incorrect bolts, or bolts with worn shoulders are used.
The design of the engine means that a huge amount of oil is pumped up to the head, and it struggles to get back down.
Coupled with the amount of air that this design creates into the crankcase and cam cover, even with perfect bore / piston clearances and tightly toleranced valve guides, this situation does its best to find gasket weaknesses. Hence the breather elbow on competition engines referred to above.
A high pressure oil pump will only exacerbate the case, particularly as it is not necessary for road use.
This view is echoed by the people who we respect regarding Lotus, and others who, like me have battled all sorts of niggly problems through years of competition with this engine.
Example :-
My first roadgoing Elan, a rather well loved and used, original S3 S/E came to me with a high pressure pump, and leaked like the Torrey Canyon.
Before making the decision to lift the motor and re-seal it, I changed the pump to a standard one, and within a week the leaks all but dried up.
That was almost 3 years ago, and the guy that bought the car still says the leaks are not bad enough to warrant a re-seal.
I have no leaks on my cam cover whatsoever, and, like Keith, all I do is use contact glue on the gasket to cam cover to keep it in the right place, no goo at all on the head, new D plugs and senloc washers each time I lift the cover.
Also I don't over tighten.
On assembly when the engine is cold, I tighten the nuts down progressively with only a 6" long screwdriver type socket wrench, just nipped up by hand, then when the engine has been up to operating temperature and then cooled, you'll find that you can put another quarter to half a turn on the nuts to bring it back to where it was. No ratchet wrenches required, not even 1/4" drive.
I appreciate the fixes with sealant, but having seen too many engines destroyed by wayward pieces of it, I try to use it as little as possible.
Would much prefer a couple of weeps to a damaged crank...
Enough said, as you can see from all the replies above, everyone has different ways and means. Whatever suits you best !
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