You don't say what year or type of tachs you have. Since you have gas engines I will tell you to remove the tach and look on the back, on some models there is a very small adjustment screw-type head for setting the tach for 4, 6, or 8 cylinder. For some reason the contacts in the tachs get cruddy. With a very small screwdriver turn the screw back and forth a few times from 4 to 8 and then return to the "8" position for your engines. This usually cures you kind of issues. However, I am assuming you have those types of tachs.

 

Sea Ray uses Teleflex tachometers and gauges. If messing with the settings on the back doesn't clear up the fluctuation, you need to replace the tachs. They aren't horribly expensive and it is an easy job to replace them. To get exact replacements with the SR logo, you will have to go to a Sea Ray dealer and order them (diesel versions were about $175 a few years ago).

 

thank you gents
ill go to my boat tis weekend ad try that
my best

 

My teleflex gauges also did this... I accessed the tach and flicked the switches back and forth and it started reading more true.


Sent from my iPhone using Tapatalk

 

This won't directly answer the question, but I "fixed" mine with Aetna digital tachs. 9 years and still going strong (and accurate).
https://1drv.ms/i/s!AhvlypYhnykglC7O83VRafq-pxtR

 

My tachs have never been right since I've owned my boat but last year the port tach pretty much stopped working altogether. I've read several threads here about pulling the tachs and cycling a cylinder switch in back. Is this the same process for tachs with diesel engines? If not, can this re-calibration be accomplished some other way for tachs with diesels?
I'm tempted to just replace them since they are the original tachs. Are the Aetna digital tachs still the best ones to use? For those that have made this upgrade, which model is better 8905R or 8402?:
http://www.aetnaengineering.com/model-8905r-lcd-tachometer/
http://www.aetnaengineering.com/model-8402-led-tachometer/
Lastly, if I go this route and replace them, is it possible to advance the hour meter to the current number of hours on the engines?

 

When I had my 410 with CAT 3126's I went through the headache of trying to adjust many times, and even replaced the originals with another set of new Teleflex tachs. I still had issues as they just weren't accurate enough. I finally bit the bullet and bought the Aetna digital 8905R-P-H's. They're smaller, so here's some pics of what I ended up doing. I kept the inside of the old tachs for the future if someone wanted to verify hours in addition to writing the hours on them. It was actually quite simple to do, and the digital tachs worked flawlessly.

 

Thanks that looks great. Do the old tachs pop out of that housing somehow so you can just insert the new ones or did you have to get creative by cutting and such? Also what are your thoughts on getting the black bezel instead of the polished if going that route since the inside is all black anyway?

 

Once you remove the old tach from the dash you'll see it basically has a plastic can on the back that holds everything in, and has the clamp mechanism attached to it. I cut the "can" in half on my band saw gently and turned it as I went so as not to harm anything on the inside. Once the "can" was off the guts of the old tach came right out surprisingly. The Aetnas fit perfectly, and I used a little silicone to hold them in place. When the silicone dried I glued the other end of the can back on, and used the original clamp to install it back in the dash. If I were to do it again, I would definitely get the black bezels. When I ordered mine I ordered them in the stainless finish so they'd match the other gages as I thought I end up either making a new dash or making up for the difference in size some other way. Then this idea just kinda hit me so I tried it and it worked out great.

 

I finally put my Aetna tachometers up on the dash this fall but I had a machine shop make a couple of adapters from polished aluminum.

 

The "can" is part of the old tachs. When you remove your dash panel you'll see what I'm referring to. Once you cut the "can" in half, and pull the old tach out it will all make more sense. When you look at the tach from the front, the beveled part and the flat area where the needle is are actually two separate pieces.

I was at the boat today and removed the dash panel and see the "cans" you're referring to. I don't see any way to disconnect these cans from the dash panel. I removed the bracket, disconnected the wires and all I can do is twist it; it nothing will pull off from the back. Did you cut the "can" in half while it was still attached to the dash panel? This doesn't seem right as how would the whole unit be replaced if you just swapped in the same tach as the old one? Perhaps I'm missing the obvious, but I just don't see how the can is detached from the back of the dash panel.

 

You were soooo close, but went the wrong direction. Once you remove the bracket (clamp), tach comes out from the front of the panel.

 

Go Aetna digital tachs and don't look back.

 

When I had my 410 with CAT 3126's I went through the headache of trying to adjust many times, and even replaced the originals with another set of new Teleflex tachs. I still had issues as they just weren't accurate enough. I finally bit the bullet and bought the Aetna digital 8905R-P-H's. They're smaller, so here's some pics of what I ended up doing. I kept the inside of the old tachs for the future if someone wanted to verify hours in addition to writing the hours on them. It was actually quite simple to do, and the digital tachs worked flawlessly.
View attachment 52855 View attachment 52856

I've been meaning to post a pic for awhile. Here is my install with the black bezels. Everything worked out just as you described. Thanks again for all of your help. You're right, it was quite easy but I would've never tried to do it myself without all your guidance.

 

Just saw the pic, and your install looks great! Glad to be able to help, and hope you have a great season!

-Tom

 

Sorry, having issues uploading the pic from my phone. Will try again later.

 

I’d love to upgrade my tachs , much more useful instrument on a diesel boat. Please post boat porn pics!!!

On the list but down behind; move boat home, get head and generator working.

 

Here is the picture of the tachs installed. I opted for the black bezels.

 

View attachment 56368 Here is the picture of the tachs installed. I opted for the black bezels.

Ooooh! Aaaah! Very nice!

 

View attachment 56368 Here is the picture of the tachs installed. I opted for the black bezels.

Very nice. I have a 380 on E row and I need to do this when spring gets here.

 

I'm happy to lend a hand if you need any help. Really not a difficult project and it looks factory. I'm in N54, Tax Holiday. Stop by anytime.

 

In the process of doing mine screws are temporary until 4200 dries. Could you please tell me what type of adhesive you use to glue the two halves back together?

 

View attachment 69121 View attachment 69118 View attachment 69119 View attachment 69120 In the process of doing mine screws are temporary until 4200 dries. Could you please tell me what type of adhesive you use to glue the two halves back together?

You'll laugh, but my first try was 4200 and Gorilla tape. It worked, so I just left the tape. Also, I put a very thin bead of black 4200 around the Aetna to secure it to the inside of the old gage.

-Tom

 

Does anyone know if these tachs are going to work straight out of the box or am going to need to set or adjust anything

 

These work by "counting" the teeth on the flywheel. So you will need to know that number. Once you set that, they are are plug and play.

For Cat 3126's (and 3116's too I think), the flywheels have 126 teeth. I cant see what engines you have, but post it up.

 

Truly a plug and play deal. No wiring needed just mount the tach and connect the wires. Since Aetna uses the Cat tooth counter, there are no adjustments to make, other than setting the dip switches on the back of the Aetnas.......but use the little plastic tool that comes with the tacos because the switches are delicate and easy to damage.

The most opportune time to change to Aetnas is when you replace your dash panels. You can then just have the new panels made with the proper cutout for the Aetnas. My boat came with 5" tach cut-outs which is too large to make a new bezel that looks decent, so I waited a year until I was ready to deal with replacing the dated panels and changing about 100 switches.

For those of you that are trying to mount the Aetnas into the old Sea Ray housing, keep in mind that someday you may need to send thew Aetnas in for service or repair. In 10 years.....about 1000 hours I have had problems that required sending both of my techs in for repair at different times. For me is was a 5 minute job to remove a tach, but if you mount the Aetna inside an old Teleflex case, it could be more of a job to get the tach out and clean up the adhesive on the Aetna case.

 

A little late for me to worry about adhesive,but thank you. I'm a little confused. Aetna uses cat tooth counter but there are dip switches I have to set? Crap, time to read the directions to find the settings.

 

Page 20 for your PPR(126), and page 25 for your dip switch settings which are under the black cap on the back. http://www.aetnaengineering.com/wp-content/uploads/2018/07/18009-8905-8402-Manual-Rev-7.0.pdf

 

What did you guys do with the wiring to the lights at the top of the tach's?

 

Aetna tachs are internally lit. You terminate the Sea Ray tach instrument lights where they are insulated and not touching anything.

 

Excellent, thank you!

 

Ray,

There is one other thing I'll pass on if you are doing your first Aetna tach installation: The dip switches in the back of the Aetnas are very, very delicate. Use no metal tools, nothing sharp and don't let the tool you use on the dip switches slip off. I've had the switches on both of my Aetnas come loose requiring that they be sent back to Aetna to have the dip switch assemblies replaced. The last time, I said to hell with it and just sent Aetna the switch settings back with the tach which has worked extremely well for me. The dip switches were set correctly and they have stayed put.

In the grand scheme of things the repair was minor annoyance given that the Aetna folks are great to work with and very accommodating........and their tachs are far superior to the Teleflex OEM tachs.

 

Thank you for the heads up, I did set them and was very careful to switch them with the provided tool. The folks there at Aetna have been fantastic. I think I have them set correctly according to the provided graph.

 

I believe that I have these set properly according to the graph in the back of the manuals.
Does this look correct for a 126

 

I believe that I have these set properly according to the graph in the back of the manuals.
Does this look correct for a 126 View attachment 96086

Yep, according to the Aetna manual, page 25. Left switch, all zeros: right switch, 01111110