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thank you gents
ill go to my boat tis weekend ad try that
my best
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?
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?
Thanks again for your replies. So the old "can" is part of the dash and not the old tach? If that's th case, you cut the "can" while it was still attached to dash? You describe it as the Aetnas popping in the hole but from the picture it looks like the bezel is on top of the housing...just not sure how you got it to have such a finished look.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.
Thanks again for your replies. So the old "can" is part of the dash and not the old tach? If that's th case, you cut the "can" while it was still attached to dash? You describe it as the Aetnas popping in the hole but from the picture it looks like the bezel is on top of the housing...just not sure how you got it to have such a finished look.
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.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.
I was missing the obvious. So just push on the can toward the front of the panel and it will pop out, front display lens, chrome bezel and all? When I was twisting it, only the tach inside the lens was moving. The bezel/lens on the outside weren't moving at all. That's why I though it had to come out from the back and the lens/bezel were attached to the 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.
I was missing the obvious. So just push on the can toward the front of the panel and it will pop out, front display lens, chrome bezel and all? When I was twisting it, only the tach inside the lens was moving. The bezel/lens on the outside weren't moving at all. That's why I though it had to come out from the back and the lens/bezel were attached to the panel.
Thanks.Yes, the whole tach will come out in one piece. Apparently yours is either stuck from age, or someone removed it previously, and added a little something to secure it in place.
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.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.
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