Older Searay tach issues, any insight out there?

440 Jim

Well-Known Member
Feb 11, 2021
530
Savannah Bend Marina
Boat Info
1989 440 Convertable
Twin 3208T Cats
Engines
Twin 3208T Cats
'89 440CV
3208Ts
Here's the setup


20220408_144611_resized.jpg


My port tach has been all over the place, several issues found and corrected. It got better but still varying alot. I was going to swap the wiring on the tachs and see if it followed to the other side to elimimate the source or tach as the issue. That's when I found the sync "hockey puck" under the helm. I unplugged it and it got better. Tried reversing the two plugs, all it did was disable the sync guage, centered but would not move. Both tachs were steadier though. Any information, schematics, drawings etc. around? I do have the boat wiring diagram but no info on the tachs/sync. TIA
 
The gauge wiring will be from the the engine schematic and not sure they were around in 89. Those older Sea Ray tachs/gauges were Teleflex now Sierra and what you are seeing is very common for those. I would just replace them with a set of Aetna Engineering digital tach's they are great. You can get them in black and also they have a black trim ring that pretty much matches your original tach.

As for the wiring question, they use a common ground and I believe a Grey and/or Black wire for the signals. They come off of the rotary senders on the front of the engine's under the belt guard. Not sure what any previous owner has done so that's just a reference point. The internal windings of those older gauges get tarnished and they start to bounce. Also ground issues can cause that as well, but usually the tarnishing causes this and there done. The other thing you could do is just get all new gauges of the same type, probably a littler less costly but a whole lot more work.
 
On my 2002 310DA I had this issue. On the back of the tach, there is a hole with the numbers 4, 6, 8 standing for the number of cylinders in the engine. If you take a small flat screwdriver and move it back and forth from 4-6-8 several times you will remove the tarnish that forms on the indicator. Be sure to return it to the number of cylinders in your engine. There are other holes in the tach so be certain you are in the one described. You will need a jeweler's type screwdriver, a flashlight and glasses if you were them. Hope this helps!
 
I’d also just go for the Aetna’s if possible. I replaced ours the day we took possession of the boat and they’ve proven invaluable. Spot on accurate and I never have to question the tachs again
 
On my 2002 310DA I had this issue. On the back of the tach, there is a hole with the numbers 4, 6, 8 standing for the number of cylinders in the engine. If you take a small flat screwdriver and move it back and forth from 4-6-8 several times you will remove the tarnish that forms on the indicator. Be sure to return it to the number of cylinders in your engine. There are other holes in the tach so be certain you are in the one described. You will need a jeweler's type screwdriver, a flashlight and glasses if you were them. Hope this helps!
^^ This worked for mine, my port tach was always bouncing around randomly. I popped them out and did this a couple times and now they are rock steady. May be worth a shot before going down the digital replacement route.
 
Thanks guys, I think the end goal will be a completely replaced dash assy. But not for now, just want to keep them going a bit longer. Budget for this year is eroding, 3K on scheduled motor service and a few repairs, new bridge enclosure (should have price soon), new mattresses and custom covers with matching seats being made(crew qrtrs is done), a $1500 interior cleaning ( in proces today), might take a week or two to catch back up.

Understand the sensor feed, just trying to learn all I can about the current setup so I know how to trouble shoot. I am going to try that cylinder selection switch first.

Probably won't be able to do that until weekend after Easter. We'll be down there looking at marina options in Brunswick and north toward Savanna, but not Savannah. I'll certainly give that a shot.

Thanks guys, as always much appreciated.
 
I’d also just go for the Aetna’s if possible. I replaced ours the day we took possession of the boat and they’ve proven invaluable. Spot on accurate and I never have to question the tachs again

+1 on the Aetnas.....Less than $500 for the pair....

Bennett
 
And installation on Cat diesels is plug and play……. takes longer to read the manual than to do the installation. Aetna also sells or you can easily make a black bezel to match your factory gauge bezels.
 
So I cycled the rotary switches several times, on mine it is a ratio, not a cylinder count. Got better, will see long term. About 100rpms off with the sync centered.

While the Aetnas are attractive, I'm thinking of sending the originals off for restoration. Does anyone have a good source for that? Would be most helpful.

Thing is, I like the classic looks. I've been collecting/restoring1968-9 Ford Torinos for over 30 years, GTs and Cobrajets mostly, but wagons, rancheros, all 6 styles of those two years. When I get one ,I try to bring it back as original as possible, preserving the history if you will- just what I like ya know.

Same way with The Office. I have always admired the older sedan bridges having grown up watching them at marinas and along the Indian River where we grew up. Just never thought I would have one...

So we are gonna do thrusters and new nav electronics, but I want to keep the older facade going for a bit longer.

Any help in finding a resource would be much appreciated.

Thanks folks
 
I suggest looking for a local shop that does tachs. I live by Lanier and, when I asked around was given two or three suggestions around North Georgia by some friends that work on high end cars. Here is the one shop a couple people recommended www.hampspeedometer.com
 
^^ This worked for mine, my port tach was always bouncing around randomly. I popped them out and did this a couple times and now they are rock steady. May be worth a shot before going down the digital replacement route.
After winter launch mine was showing idle at 2200rpm, techmitch told me this trick, tach now spot on.
 
I suggest looking for a local shop that does tachs. I live by Lanier and, when I asked around was given two or three suggestions around North Georgia by some friends that work on high end cars. Here is the one shop a couple people recommended www.hampspeedometer.com

I wonder if they could do anything to my 4 in 1 gauges….? Fuel and temp are fine…Oil pressure and charging parts are very erratic…

Bennett
 
It’s not exactly what you’re describing but I used my original housings, gut them, and put the aetnas in. Maybe you could do something similar to keep your oem look?

EB58A0BC-788E-4923-92E8-9463339BE66C.jpeg
 
On my 2002 310DA I had this issue. On the back of the tach, there is a hole with the numbers 4, 6, 8 standing for the number of cylinders in the engine. If you take a small flat screwdriver and move it back and forth from 4-6-8 several times you will remove the tarnish that forms on the indicator. Be sure to return it to the number of cylinders in your engine. There are other holes in the tach so be certain you are in the one described. You will need a jeweler's type screwdriver, a flashlight and glasses if you were them. Hope this helps!

This is the first thing to try for sure. Worked for me and the tachs have been perfect.
 

Forum statistics

Threads
112,946
Messages
1,422,791
Members
60,930
Latest member
Ebrown69
Back
Top