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Otto Gaskets

Posted: Wed Jun 19, 2019 9:56 am
by simon.holyfield
Next winter, I aim to find the time to address a pushrod tunnel oil leak on my Mk1.

Must I replace the Otto gaskets or are they reusable? I believe they are a fibre gasket with a mesh to stop them moving in the joint, so I am thinking they cannot be reusable?

Re: Otto Gaskets

Posted: Wed Jun 19, 2019 11:12 am
by Gui.dorey
Hi Simes,

I recall reading through a thread here some time ago, that someone had analyzed the Otto gasket and came to the conclusion it was reusable. I'm not sure what the topic was or when it was posted, but likely a search will bring it up. It was thread where someone dissected a gasket to see how they were constructed.

But speaking of replacing them - anybody know where Otto gaskets can be found? or are they now like hen's teeth?

Re: Otto Gaskets

Posted: Wed Jun 19, 2019 11:35 am
by simon.holyfield
The Draganfly website suggests that they are in stock - at least for Mk1s. PN is 75-00 I think - I looked it up a couple of hours ago.

Re: Otto Gaskets

Posted: Wed Jun 19, 2019 12:42 pm
by dave.owen
Simon, Bruce Longman should be stocking them.. It is suggested that they are reusable.


Re: Otto Gaskets

Posted: Wed Jun 19, 2019 8:24 pm
by pkrichardson
Bruce Longman,s are half the price of Drags

Re: Otto Gaskets

Posted: Thu Jun 20, 2019 4:21 am
by paul.ptak
While I have not used the Otto gaskets yet...I have sets for a '50 & '51 SQ4 sitting on the shelf...they look just like the composite head gaskets that are commonly used as upgrades on a Commando engine which I have used plenty of. My belief is that the composite head gasket is not reusable. My belief is based on the fact that composite gaskets do reveal where they have been compressed after heads have been retorqued a couple of times after substantial heat cycles.

Unlike a copper gasket that can be heated upon removal to get it to "swell" and allow it to be compressed again, the composite gaskets stay the same thickness as when they were removed from the engine. I am not suggesting that a copper head gasket is superior because of this fact; my belief is that a composite head gasket is a consumable item that should not be put back into service after being used.

After typing the above statements; I'm looking at the Otto gasket instruction sheet right now; the last note states, "General note: All head gaskets in the automotive industry can only be used once." Also, the Otto instructions call for a re-tighten after 50 miles and again after 600 miles. On a Commando I typically re-tighten or re-torque a head after it has been brought up to operating temperature one time, then allowed to cool to "stone cold", then again after 500 miles after allowing the entire engine to cool down to "stone cold".

Pulling and reinstalling a head takes time and time is money...not worth saving the cost of new gaskets to do it a second time if the reused gaskets don't seal.

Re: Otto Gaskets

Posted: Thu Jun 20, 2019 9:20 pm
by paul.jameson
I have successfully re-used Otto gaskets on iron head Squares starting with the 1936 Cammy. I applied a substance which appears to be no longer available called plastic hermetite to each side of the gasket before re-use. I wouldn't do it on an alloy head Square because of the low amount of torque you can apply to these engines, especially the Mk I.

Re: Otto Gaskets

Posted: Fri Jun 21, 2019 2:43 pm
by john.whiting
My iron head 4 ran without any head gaskets.......I surface ground the barrel and head, lapped ,and blued to check........No iron engine needs a head gasket if the surfaces match exactly......even water cooled engines...........soft head gaskets generally allow the fasteners to pull down bulges in the mating surface......this is clearly seen on sidevalve heads .....Alloy heads and iron barrels do need a gasket to absorb the differential expansion,which will wear away the mating surfaces.