Transducer

[Bob&Jilly]

Any advice on reseating a leaking transducer?
Turns out it is the rubber o-ring at the bottom of the cup on my GT15M-1H transducer needs replacement. Needed to remove 6 small screws to see it . Now to find parts and how to replace the rubber o-ring a the bottom
The part number is need 010-12402-00 just don't know where I can find parts?

 

[gswearin]

Lots of posts on this. I sanded the area smooth as I could and used sikaflex.

 

[watson1987]

I used a stupid amount of PC Marine Epoxy and made a donut with it then set the cup right into it. It's worked great for 2.5 years now, I get zero leakage now.

 

[HookedUp]

The boat I had 20 years ago had an in-hull transducer. I was forever working on it and finally replaced it with a thru-hull. When I purchased my R27 I had the dealer install a thru-hull that can see to very deep depths. I need the depth for finding the end of the continental shelf and water temps. Just couldn't go thru an in-hull again.

 

[Bob&Jilly]

Will 3M 4200 work well?

 

[Submariner]

Will 3M 4200 work well?

Yes.

 

[Bob&Jilly]

Yes.

Thanks!

 

[Bob&Jilly]

Turns out it is the rubber o-ring at the bottom of the cup on my GT15M-1H transducer needs replacement. Needed to remove 6 small screws to see it . Now to find parts and how to replace the rubber o-ring a the bottom
The part number is need 010-12402-00 just don't know where I can find it.

 

[Someday*]

I had the same problem. Using Ultrasound Gel instead of a liquid in the cup has solved the problem.

 

[Eager]

I had the same problem. Using Ultrasound Gel instead of a liquid in the cup has solved the problem.

This method is going to be my last resort before fixing mine with a hammer and installing a transom mounted unit. 5 years of this leaks and malfunctions, despite new gaskets…marine tech thought it was fixed (again.) But whenever we get into rough water we lose fluid in it. Recently went to Desolation and lost depth on the way across Georgia Strait and couldn’t get it back. Hammer is looking better and better.

 

[zzr7ky]

I literally took 2 claw hammers to remove my P79 that someone had epoxied to the hull last week!

 

[abastos]

I had the same problem. Using Ultrasound Gel instead of a liquid in the cup has solved the problem.

That's a clever solution! My transducer was leaking since I bought the boat last year. Yesterday I decided to fix it, removing the old sealing and I applied Sikaflex 291. I am waiting 5-7 days to let it dry and cure, then I think I will fill it with ultrasound gel. Any specific brand?

sonar-1.jpeg

• abastos
• Aug 24, 2026

sonar-2.jpeg

• abastos
• Aug 24, 2026

sonar-3.jpeg

• abastos
• Aug 24, 2026

 

[Morelords]

Any advice on reseating a leaking transducer?
Turns out it is the rubber o-ring at the bottom of the cup on my GT15M-1H transducer needs replacement. Needed to remove 6 small screws to see it . Now to find parts and how to replace the rubber o-ring a the bottom
The part number is need 010-12402-00 just don't know where I can find parts?

I thought ours was also leaking out the bottom (cup-to-hull interface). Removed the small six screws this spring and found that the o-ring between the cup and transducer cap was never installed from the factory. Ordered the o-ring directly from Garmin, installed, filled with RV antifreeze, and all has been great for the last 4 months with no visible leakage, like there was before.

 

[abastos]

I thought ours was also leaking out the bottom (cup-to-hull interface). Removed the small six screws this spring and found that the o-ring between the cup and transducer cap was never installed from the factory. Ordered the o-ring directly from Garmin, installed, filled with RV antifreeze, and all has been great for the last 4 months with no visible leakage, like there was before.

do you have the part-number for the oring?

 

[Morelords]

do you have the part-number for the oring?

Here's my order summary with o-ring part #.

 

[DonD]

2014 R31cb ours has been reliable for 4yrs after cleaning fiber glass and reseating but has stoped working . It’s time to examine . Ultrasound gel sounds like a good way to go. Does anyone know of any problems or negatives form using it in lieu of pink stuff?

 

[abastos]

Update 8/31: Yesterday I tried the ultrasound gel, however it did not work. I removed and replaced with pink antifreeze and everything worked fine. I don't know why the gel did no work, but anyway, problem fixed.

transducer-1.jpeg

• abastos
• Aug 31, 2026

transducer-working-again.jpeg

• abastos
• Aug 31, 2026