Tech Tip: Installing Triumph Petcock Seals
Installing a new set of replacement Triumph petcock seals should be pretty straightforward and easy right?
I mean, there is only a few washers.. what could possibly go wrong?
If your replacing old Triumph petcock seals with new seals and you incorrectly execute the job you may quickly find that you will have an annoying leak... which means you will have to do the entire job all over again.
Who wants to go through that?
Today I will go over how to install Triumph petcock seals the proper way which will give you a leak proof seal that will last you years to come.
Lets dive in..
What is a Stato / Dowty seal?
A Dowty washer is a synthetic rubber sealing member that is bonded (with pressure and heat) to a steel zinc plated washer.
This form of seal is most commonly used on pipes or fittings with external threads that require a seal to retain liquid or oil internally.
Dowty washers come in various sizes and styles that all work very much the same.
On Triumph's, we see "Dowty" seals used on petcocks and also on unit construction twins that have an external tachometer drive mounted to the end of the exhaust camshaft.
Again, they retain liquid, oil and debris from getting in and / or out.
Installing new seals
Leaks typically arise when the petcock Stato-Seal is damaged during installation or the sequence between the two washers is not correct.
Modern blends of fuel (ethanol) also do not help the longevity of rubber components as it will break-down over time resulting residual leaks.
Lets go over how to install a new set of seals.
The procedure
Using a Triumph 1/4" (BSP) standard petcock and the 70-7351 / 83-0002 washers you will be able to follow along
Take your steel washer and slip it over the petcock threads then take your stato seal and slide it ontop standard steel washer.
Remember - "Steel then seal"
The reason for this order is to allow the seal to "but-up" against the gas tank which in return will give you the best seal.
If one where to install it the other way around, you will get leaks - period.
For me personally, I like to apply a thin layer of teflon pipe tape on the threads as often times the seal is not enough.
Ethanol in today's fuel is very destructive and will not do any justice to the Stato-Seal over time.
Make sure all threads on both inside the tank and petcock are clean and free of any residue.
Since we are dealing with a seal and sharp "edges" on the thread, it is possible for the seal to be damaged upon installation.
If you have P80, chapstick, vasaline or even oil, apply a light film on the rubber so it can glide over the threads preventing the chance of damage..
Similar to installing fork seals!
Once done you can insert your petcock into your tank and finish the job and be confident that you will not have any leaks pesky..
You can also apply the same steps above on some BSA and Norton models that use a stato-seal or a dowty style seal.
Petcock supplies
Should you need any Triumph petcock replacement parts please feel free to view the table below.
Each part within the table will work with most Triumph petcocks (some BSA and Norton) that came standard with the 1/4" BSP petcocks.
Tap on the "click here" in the table to purchase your parts...
| Part Type | Part # | Link |
| Petcock Seal Set | 70-7351 & 83-0001 | Click Here |
| 1/4" BSP Petcock Set (UK) | 83-2800 & 83-2801 | Click Here |
| 1/4" BSP Petcock Set (Taiwan) | 83-2800T & 83-2801T | Click Here |
Thanks for reading today
Thank you to everyone for taking the time to read today's post.
Should you have any questions or would like to join in on the conversation, we encourage you to drop us a comment in the section below.
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Ride safe! - CBS
Alan Garrett
I agree with Richard Beard. I worry about the seal between the steel washer and the petcock. I put some gasket sealer or pipe dope on each side of the washer, if you don’t do that you have a steel to steel joint that will want to leak. With the Dowty seal this is essential, with the Stat-O-Seal it is cheap insurance.
Classic British Spares
@Richard – Agreed to a point. “some” refer to them as the same, one can take it either way. A stato-seal or a Dowty seal.
If you want to get technical that is up to you
However, what we do know that it’s a seal with rubber inside that will stop the tank from leaking
Thanks
Richard Beard
Stat-o-Seals and Dowty seals are not the same and their functions are different.
In your photo the seal at the top left is a Stat-O-Seal—the rest are Dowty seals.
Stat-O-seals are designed to seal a thread with the rubber part being extruded into the threads as the seal is compressed.
Dowty seals were invented by the Dowty company in England during WWII to seal on the hydraulics of aircraft undercarriages. They are designed to seal two faces against each other.
In the pet cock application the correct seal is the Stat-O-Seal as it seals against the thread.
Using a Dowty seal in this application might work but you are relying on the under surface of the gas tank being flat.
HTH