Lotus Elan

Proper torque spec for cam cover bolts?

PostPost by: MrBonus » Fri Nov 15, 2019 1:49 pm

I am fighting the good fight against a slow leak from the cam cover gasket and bolts after finally having the car on the road after 1.5 years of non-use.

The cam cover gasket is starting to squeeze out in a few places and know I will be replacing it in the coming months.

That said, it's leaking out of the bolts and a quick microtorque wrench check says they're barely hand tight. I couldn't find a torque spec in the manual but was thinking of going to 5 ft/lbs.

Is there a proper torque spec or is it all just to feel? I know it's not supposed to be particularly tight. Thanks for your help!

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PostPost by: oldelanman » Fri Nov 15, 2019 2:29 pm

The specified torque is 7 lb ft but personally I just use a small ring spanner and tighten them by feel. As you say it's little more than hand tight and overtightening will squeeze out the gasket and may also distort the cam cover. Maybe worth checking that hasn't happened when you next remove it.
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PostPost by: MrBonus » Fri Nov 15, 2019 2:44 pm

oldelanman wrote:The specified torque is 7 lb ft but personally I just use a small ring spanner and tighten them by feel. As you say it's little more than hand tight and overtightening will squeeze out the gasket and may also distort the cam cover. Maybe worth checking that hasn't happened when you next remove it.
IMG_20191115_141444.jpg


Thank you, Roger!

I checked with my microtorque wrench and they're barely tightened to 1 ft/lb. I may push it to 5 just to see if it stops the largest leak which is from the bolts themselves.
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PostPost by: JonB » Fri Nov 15, 2019 4:40 pm

Two approaches might help here

- put O rings on the studs to help an oil seal to form, or
- renew the rubberised SELOC washers

7 LBS/FT seems very low but there it is.
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PostPost by: Mr.Gale » Fri Nov 15, 2019 6:37 pm

I found these at Home Depot I haven't tried them yet, but they look like they might help.

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PostPost by: vincereynard » Fri Nov 15, 2019 7:05 pm

JonB wrote:Two approaches might help here

- put O rings on the studs to help an oil seal to form, or
- renew the rubberised SELOC washers

7 LBS/FT seems very low but there it is.


I have O rings + SELOC + plain washer. (Or 2 plain where the bonnet cable is help.)
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PostPost by: RichardHawkins » Fri Nov 15, 2019 7:48 pm

In my opinion the first thing is to establish whether the head and cam cover surfaces are flat, mine were not. I am using a Viton rubber gasket attached to the head with a Loctite silicon adhesive. I held the gasket in place with the cam cover nuts finger tight until the Loctite had set. I am using Dowty (bonded sealing) washers between the cam cover and the cam cover nuts. The nuts are domed nylon. I could not find an imperial domed nylon, so have used M6. This entailed studs with imperial thread into the head, and M6 for the cam cover.

Just my solution, hope it helps.

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PostPost by: mbell » Fri Nov 15, 2019 9:11 pm

Mr.Gale wrote:I found these at Home Depot I haven't tried them yet, but they look like they might help.


I have used similar but from lowes. I am not sure they have correct temperature/chemical rating for the job.

I've moved to using small pieces of fuel hose on the studs under the cover as suggest on here. These compress and seal from the underside and seem to be working well, better than just copper washers.

I do still use the shown washer on the bolts from through the airbox to seal the bolts holes there.
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PostPost by: Davidb » Fri Nov 15, 2019 9:26 pm

Mr Bonus: Since yours is an early engine, judging by the valve cover, you might want to consider that there is too much oil in the area below #4 exhaust valve-have you read this:
viewtopic.php?f=39&t=45387
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PostPost by: englishmaninwales » Sat Nov 16, 2019 9:29 pm

Cam cover linished with abrasive paper / WD40 on a flat glass surface, until flat.
DIY cam cover gasket, accurately cut from 4mm nitrile sheet. Do not use cork.
Gasket located on the CH with small spots of RTV sealant, allowed to cure 12hrs with light pressure from cam cover.
1/2 moon plugs fitted with small amount of RTV sealant.
Bonded sealing washers with plain washers.
Nylocs at correct torque (as above) and re-torqued after running.

Cured all my gasket extrusion, cam cover leaks, provides easy separation at next cam cover removal and the gasket is re-useable.

Malcolm

Edit to add: eBay link for nitrile sheet
https://www.ebay.co.uk/itm/OIL-RESISTAN ... 3b1525c741
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PostPost by: William2 » Sun Nov 17, 2019 5:16 pm

Whenever I fit a new cam cover gasket I use Well Seal on the cylinder head joint and clear silicon on the cam cover. The Well Seal prevents the cork gasket from sliding about and the silicon means that the cam cover can be removed easily if required. I never like to tighten the cam nuts too much, my reasoning being that the 8 studs are already under a certain amount of stress from the cam cap nuts.
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PostPost by: Davidb » Sun Nov 17, 2019 7:05 pm

Englishmaninwales: This gasket works without any form of sealant?
I will try to find a source in N.America to save on shipping.
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PostPost by: Davidb » Sun Nov 17, 2019 7:27 pm

The ebay listing provided by EMinW does not ship outside the UK. I found this UK supplier that does-plus there are numerous suppliers from the Orient:
https://www.ebay.com/itm/Oil-Resistant- ... A#shpCntId
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PostPost by: Elanman99 » Sun Nov 17, 2019 7:48 pm

Malcolm

How did you cut the nitrile gasket?

I dont currently have a problem with the cambox leaking but I like the idea of never having to buy a cork gasket.

I can see that the cambox could be used as a template and directly guide a very sharp knife but the chances of the sheet creeping whilst being cut makes the likelihood of it getting cocked up quite high. Any tips or guidance would be appreciated.

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PostPost by: englishmaninwales » Sun Nov 17, 2019 8:16 pm

Apologies for the UK eBay link!

The most time consuming bit is cutting out the gasket. I used the cam cover and an existing gasket as templates to mark out the shape. I used a ‘Tipex’ pen as a marker and then cut carefully with a surgical blade with a steel rule. I taped the nitrile sheet down to reduce any movement.

The spots of RTV are just to prevent any movement of the gasket whilst fitting the cam cover, but with care it’ll be fine without any RTV, probably around the 1/2 moon plugs too.

Most importantly, the cam cover must be flat. Mine was mildly distorted and needed quite a bit of linishing to get it flat.

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