Water Deck Fill O-Ring Size 1 1/2" ??

The O-ring for one of my Water Deck fill caps broke and I was wondering if someone can confirm they are 1 1/2 O ring size?

Its a 2006 Mainship 400 Trawler.......

Thanks,
Jeff in Savannah

Jeff
Suggest you take your fill cap and O ring to a NAPA store where they would have a variety of rings to match your OD and ring cross section. A hydraulic shop could offer same. Get a few extras and change out every few years to forestall water from entering fuel tanks as the rings give out, like your's did.

sunchaser said:

Jeff
Suggest you take your fill cap and O ring to a NAPA store where they would have a variety of rings to match your OD and ring cross section. A hydraulic shop could offer same. Get a few extras and change out every few years to forestall water from entering fuel tanks as the rings give out, like your's did.

Click to expand...

Good advice.

sunchaser said:

Jeff
Suggest you take your fill cap and O ring to a NAPA store where they would have a variety of rings to match your OD and ring cross section. A hydraulic shop could offer same. Get a few extras and change out every few years to forestall water from entering fuel tanks as the rings give out, like your's did.

Click to expand...

Till you get the proper o'rings, tape it over.

If you cannot take the cap to the store because of a keeper chain, you could use a pair of calipers to measure the diameter of the O ring.

I bought on ebay a box of about 1000 "O" rings,claimed to be petroleum resistant, for about $20. Of course they came from that place whose goods must be tariffed out of existence, but I have every size I`m likely to need and a lot I won`t, right to hand.
And, when you replace, smear grease top and bottom of the O ring to ensure a seal, wiping away the excess.

Comodave said:

If you cannot take the cap to the store because of a keeper chain, you could use a pair of calipers to measure the diameter of the O ring.

Click to expand...

I cut my keeper chains off, easier to get the O rings on and insure right fit as you take it to store. I've seen those with Al tanks remove the iron keeper chains for fear of them rusting off and falling into tank.

Benefits both ways to keeper chains. We were way up Lake Powell with another boat along. Pulled into a marina and the dock hand promptly dropped our friends gas cap into 100’ of water. One of our water fills has a broken keeper and there is no way I can see to replace it since it is about 4” down the pipe. Oh well...

My fill cap 'keeper' have a screw holding the keep and cap together. I am not say it is a good idea but, secure the chain with cord or forceps get the proper size o'ring, replace it and put the cap and chain back together. Alas, I am pretty sure I would drop the screw into the tank. SMIRK
Yes, I did replace the o'ring on one fuel tank out of desperation and no, I didn't drop the screw into the tank. Trust me, all the time I was working on it, I was thinking dont drop the screw. LOL I used a long piece of butcher string to secure the chain.

Now, the next multi-billionaire will be the person who can invent a method of protecting the sanitary tank cap from falling overboard. This monumental invention can then be applies to the fuel and water tank caps.

Look at whitecap deck fills 6124B. Mine was fuel yours is water but by they are same MFG, I think?

BruceK said:

And, when you replace, smear grease top and bottom of the O ring to ensure a seal, wiping away the excess.

Click to expand...

If you're using neoprene O-rings, grease, e.g. Vaseline or any petroleum product will soften the O-ring and cause it to swell, ultimately ruining it. Use dielectric silicone grease, it's safe on any O-ring. Never use Vaseline on plumbing parts, it breaks down the rubber.

Maerin said:

If you're using neoprene O-rings, grease, e.g. Vaseline or any petroleum product will soften the O-ring and cause it to swell, ultimately ruining it.

Click to expand...

What material should I look for to replace the O-ring for my diesel fill caps? Obviously diesel is a petroleum product.

I bought replacement O-rings at West Marine, and although I got the right diameter, the rings are too fat (wide cross-section.) When I bring the old ones in to some place like NAPA, I want to be sure I get the right ones this time!

Lots of talk about getting a new one to match the old.
But of course that assumes the old one was/is right.
A considerable amount of crush w enough threads engaged so it will stay down.
I wet mine w diesel oil or apply grease .. sparingly so-as to minimally attract dirt.

I bought the nitrile assortment from HF and they have come in handy on many occasions.
https://www.harborfreight.com/382-piece-o-ring-assortment-67554.html

CaptTom said:

What material should I look for to replace the O-ring for my diesel fill caps? Obviously diesel is a petroleum product.

I bought replacement O-rings at West Marine, and although I got the right diameter, the rings are too fat (wide cross-section.) When I bring the old ones in to some place like NAPA, I want to be sure I get the right ones this time!

Click to expand...

Get nitrile from a hydraulic shop. It's best if you can take the deck fill with to get a good fit. O-rings you obtain from an automotive supplier should be OK with oil, they're typically nitrile or other oil-safe composition. O-rings from the hardware store are likely to be neoprene, and petroleum products will ruin them.

LaBomba said:

I bought the nitrile assortment from HF and they have come in handy on many occasions.
https://www.harborfreight.com/382-piece-o-ring-assortment-67554.html

Click to expand...

Good info, my wife is picking a set up today. Thanks.