Lotus Elan

Oil cap locking pins

PostPost by: benymazz » Tue May 28, 2019 3:45 pm

All,

I have a really nice cam cover for my TC that I would like to use, but it has a problem... it was used for racing in the past and the pins that engaged the tabs on the oil cap to lock it in position were drilled out at some point so that a special cap could be mounted via screws through the top and used in conjunction with a dry sump system (see attached photo).

Any ideas on how this can be corrected? I have a cam cover that has the pins on it that I can reference. I believe that they are original, and they almost look like rivets that were ground flush on the outside. It seems that the two main design constraints here are that 1) it doesn't leak oil and 2) won't break and drop bits inside the valvetrain

I just repainted the one with no pins and it would be nice if all that effort weren't for naught :|
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PostPost by: mbell » Tue May 28, 2019 4:47 pm

Personally I'd fit a threaded oil cap from one of the suppliers. They come with threaded insert that can be epoxied in place.

Two reason for this:
1) avoids need to re fit pins and locate correct locations for pins
2) the standard cap is prone to weeping oil due to crank case pressure if not in top condition. Things like or rubber seal, weak or to strong springs, warn or incorrect positioned pins can lead to leaks.
'73 +2 130/5 RHD, now on the road and very slowly rolling though a "restoration"
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PostPost by: benymazz » Wed May 29, 2019 11:50 am

mbell wrote:Personally I'd fit a threaded oil cap from one of the suppliers. They come with threaded insert that can be epoxied in place.

Two reason for this:
1) avoids need to re fit pins and locate correct locations for pins
2) the standard cap is prone to weeping oil due to crank case pressure if not in top condition. Things like or rubber seal, weak or to strong springs, warn or incorrect positioned pins can lead to leaks.


Probably the best option. The cam cover I'm using right now (the one that is not missing pins) was leaking oil around the cap in the usual place and I fixed it by cutting a piece of 1/16" buna-n rubber sheet and putting it over the existing gasket in the cap. It made the cap a tight fit at first but after a couple weeks has settled in nicely and it no longer leaks oil.
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PostPost by: webbslinger » Wed May 29, 2019 4:06 pm

I did the same fix with a second 1/16" gasket over the old one and it worked for a couple of months until it split. Then it really leaked. That was fixed that with a single 1/8" gasket which is tight and appears like it will last longer. It only has to last until the new threaded "o" ring cap arrives.
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PostPost by: benymazz » Wed May 29, 2019 4:46 pm

webbslinger wrote:I did the same fix with a second 1/16" gasket over the old one and it worked for a couple of months until it split. Then it really leaked. That was fixed that with a single 1/8" gasket which is tight and appears like it will last longer. It only has to last until the new threaded "o" ring cap arrives.


Well I feel like these problems could be mostly avoided if we weren't constantly having to removing the cap to add oil :lol:

Just ordered up the insert/cap thingy from one of the usual suspects. I'm close enough that UPS delivers in one day via normal ground shipping so I will fit it tomorrow when I get home from school and report on the initial results after I drive it to school and back on Friday.
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PostPost by: lotusS2guy » Wed May 29, 2019 10:45 pm

Off topic: I just noticed that my car was only 5 units ahead of yours on the production line. They came from a good batch. :lol:
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PostPost by: webbslinger » Wed May 29, 2019 11:44 pm

Please pass on any wisdom you have installing it. My new cap is a few days away.
You nailed it with your comment about having to add oil all the time. That's exactly the reason I decided to switch caps. My car doesn't use much oil, but I like to keep it topped up and am tired of fighting the old one.
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PostPost by: Davidb » Thu May 30, 2019 8:55 pm

I got tired of oil leaking from the cap-despite two seals and a deflector plate over the cam. So I experimented and have settled on using oil resistant foam - cut to fit snugly inside the oil filler opening. I punched two holes through the foam and threaded a plastic tie threw them that I can use as loop to lift it out when/if oil is needed. The foam sits on top of the deflector plate. Fifteen hundred miles so far and it works fine--and it was free! (the foam MUST be oil resistant)

To correct the oil usage I had the valve guide clearances set as Rohan suggests: 3/4 of a thou" inlet and one point two thou" exhaust. It sounds tight but it cured the oil usage problems on my new engine.
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PostPost by: benymazz » Fri May 31, 2019 12:29 pm

Davidb wrote:I got tired of oil leaking from the cap-despite two seals and a deflector plate over the cam. So I experimented and have settled on using oil resistant foam - cut to fit snugly inside the oil filler opening. I punched two holes through the foam and threaded a plastic tie threw them that I can use as loop to lift it out when/if oil is needed. The foam sits on top of the deflector plate. Fifteen hundred miles so far and it works fine--and it was free! (the foam MUST be oil resistant)

To correct the oil usage I had the valve guide clearances set as Rohan suggests: 3/4 of a thou" inlet and one point two thou" exhaust. It sounds tight but it cured the oil usage problems on my new engine.


Yes, valve guides... the ones in my current engine are in dire need of replacement. If the engine is warm and I come to a stop, even if it only idles for 3-4 seconds I get a little bit of blue smoke. Anything over 10 seconds and the cloud becomes very noticeable. Oil consumption is high - maybe a quart every 400 miles or so, but part of this is burning and part of it is leaking. I'm hoping to have my other rebuilt TC in the Elan within the next month though, so it doesn't need to last much longer. I had not seen that figure for valve guide clearances but I will pass that along to my machinist.

I fitted the oil cap last night. Installation was simple and straightforward. First I cleaned the areas to be epoxied with brake parts cleaner and roughed them up with some 220 grit. Because of the pins being drilled out and being empty holes, I filled them with epoxy and let it harden before I epoxied the insert (so that oil wouldn't leak). The insert also had slots machined into it to engage the pins, but since I had no pins I rotated the insert 90 degrees so that the metal of the insert covered as much of the holes as possible (again, trying to prevent a possible oil leak). I applied epoxy to the insert rather than the cover itself, pushed it into place on the cover and wiped excess away with a paper towel with some acetone on it. While the epoxy was curing I put some aviation gasket maker (following the sound advice of Saint Rohan :D ) on the cam cover and stuck a new cork gasket to it. After the epoxy had cured for about an hour and a half I offered the cover up to the cylinder head and bolted it down. To give the epoxy as much time to cure in the best conditions possible I didn't go for a test drive last night but I will post here after school if I find any leaks once I get home.

-Ben
Attachments
img_8543.jpg and
Cam cover fitted in the car. Cleaned up the plug wires too.
img_8534.jpg and
Holes lightly filled with epoxy. Some more was added later too.
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