Help!! My leaking cam box is making me crazy !!!

[Davy_G]

:banghead:
My 88 esprit has the usual exhaust side cam box oil leak. I've now had it apart three times. It holds for a couple of weeks and then begins to leak again. I'm at my wits end ! Has anybody heard of putting a gasket in here? I know you'd have to shim up the valve clearances to compensate for the gasket thickness, but...
Also, is it really possible for a normal human to work on the timing belt with the engine in the car? Every time I have to @#$%$% with the cam box, I have to haul the engine back out of the car

[dilbert]

Davy_G said:

My 88 esprit has the usual exhaust side cam box oil leak. I've now had it apart three times. It holds for a couple of weeks and then begins to leak again. I'm at my wits end ! Has anybody heard of putting a gasket in here? I know you'd have to shim up the valve clearances to compensate for the gasket thickness, but... Also, is it really possible for a normal human to work on the timing belt with the engine in the car? Every time I have to @#$%$% with the cam box, I have to haul the engine back out of the car

I have absolutely no idea of the arrangement of the components involved, their shape or finish and so-on.

If it's not actually supposed to have a gasket, the surface finish is good and so on, but still leaks anyhow, I was thinking, it might be possible to fit an o-ring.

Obviously it would mean having a groove machined, and I've no idea how practical that might be, but it would mean that you could keep all of the pyhsical dimensions the same, and get a hermetic seal.

Viton O-rings go up to 200deg C, Kalrez 260deg....

[mikelr]

Are you re-torqing you cam box hold downs after a few heat cycles? If not this may be your answer.
It definetly is possible to service the cam boxes with the motor insitue, but of course it is not easy.
Installing a gasket of some sort would work but you would have to be absolutly sure what the compressed thickness would be to accuratly shim the valves. I'm sure if a material was out there that fit the bill it would have been put to use by now.

Good Luck!

Mike R.
94S4 NY/NJ LEO (Lotus Enthusiasts Org.)

[timrdlotus]

What kind of sealant are you using. Your suppose to use Loctite 504 which is a low pressure anaerobic sealer. It's normally not available at in automotive parts stores because most people never use or know of anaerobic sealers. But it's used a lot in aviation, marine and by auto manufactures to seal machined mating surfaces i.e. split cases. I've use permatex aviation liquid gasket with no problems. But what ever you do don't be tempted to use silicon sealers.

Are you sure the surface is absolutely nick free and straight?? you might want to check with metal straight edge.

[deecee]

I tried every product that I could get my hands on and the only thing that worked was "The Right Stuff" Sealant made by Permatex.

Made for Fleet Services, you can immediately drive the vehicle without any down time.

Mine lasted over 2 years without a leak.


Regards,
Dee

[Esprit2]

Davy_G said:

<br/>My 88 esprit has the usual exhaust side cam box oil leak. (Snip)... Has anybody heard of putting a gasket in here? (Snip)... Also, is it really possible for a normal human to work on the timing belt with the engine in the car?

Where does it leak... front, side, back?

Early 907's used a paper gasket, but it would saturate over time and then act as a wick. It was eliminated in favor of using a sealant only.

What sealant are you using? Early manuals called for Loctite 504. 504 is not zero-thickness and you must allow .0015" (one and a half thousandth of an inch) in your valve clearances for the sealant film thickness. Shim .0015" tight dry, and the clearances will open up to spec when you assemble with the sealant in the joint.

Later manuals specify PermaBond A-136. Great if you're in Europe, but not readily available where I live in the USA. Loctite 515 is a competitive cross-ref to A-136, but it's sister product 518 is functionally interchangeable for our purposes and much easier to find at retail. Permatex also sells a private label version of 518 called Permatex Anaerobic Gasket Maker (518__). These anaerobic, thixotropic, sealants are near zero-thickness. Allow .0005" (half a thousandth of an inch) if you're really anal retentive, or just ignore it.

I've also had good results through the years with Permatex Aviation Form-A-Gasket and wouldn't be concerned about using it again. But I've made the move to 518 for my default sealant. Allow .001" for Aviation Form-A-Gasket.

A rubber O-ring goes around the dowel pin/ oil passage at the front-center of the head. If you don't install a fresh one each time you install the cam carrier, a leak will develop near the oil passage fairly quickly. I like to lightly dress the O-ring with Hylomar before putting it in place. But you don't want anything you put on the O-ring to get on the surrounding sealing surface, so use it sparingly.

Apply a thin film of sealant to both sides of the joint (top of the cylinder head and bottom of the cam carriers). Blot lightly with a paper towel Install the carriers and torque the bolts to 16 lb-ft.

Pulling the engine just to do the cams or the timing belt is wa-a-ay over-kill. I'm not so young, not so light and not so flexible, and I do belts/ cams/ clearances in the car all the time. Bosch injected Esprits are have the worst accessibility due to the injector pipes running across the front of the engine bay, but get them out of the way and it's no worse than any other Esprit.

The 4th time is the charm... ;-)

Regards,
Tim Engel
Lotus Owners Oftha North

[davy_g]

Thanks every body! It looks like the consensus is I'm probably using the wrong sealant.

[Esprit2]

davy_g said:

It looks like the consensus is I'm probably using the wrong sealant.

So, which sealant were you using?

Tim Engel
Lotus Owners Oftha North, USA