Synch Gauge

N

Nassau Weekender

New Member
Apr 13, 2009
76
Nassau, Bahamas
Boat Info
1988 300 Weekender
Engines
Merc 350 FWC, Borg Warner Velvet Drives, Straight Shafts, Onan 4KW
Can someone tell me where the Sync gauge gets its signal from ?

When the gauge says the engines are synch'd the tachs are different and when the tachs are matched the synch is out ?

Which is correct ?

Cheers
 
Nassau Weekender said:
Can someone tell me where the Sync gauge gets its signal from ?

When the gauge says the engines are synch'd the tachs are different and when the tachs are matched the synch is out ?

Which is correct ?

Cheers
Click to expand...

Use your ears to sync the motors then look at the gauges to answer your question.

When you hear Wuah…..….Wuah………Wuah…...Wuah..... the engines are not in sync by a lot.

When you hear wu, wu, wu, wu, wu you are getting close.

When you hear hummmmmmmmmmmmmmmmmmmmmmmm you are in sync.

So get your motors humming, head out on the coast way, looking for adventure…..or whatever comes your way……..


[youtube]http://www.youtube.com/watch?v=CdiWEmTpwCY[/youtube]
 
Last edited:
The synch gage gets it signal from both tachs. The gage it self has 5 connections. 2 posts are for a grey wire, each going to the respective tach. 3rd post is a purple wire from the ignition (12vdc) and black wire to ground (usually looped in with the other gages). You also have a back light which is blue wire.
 
On all typical Sea Ray systems that I have seen, the input to the sync gauge is from the black hockey-puck looking thing (sync module) behind your dash. The signal comes straight from your motors to the synch module behind the dash. It is then differentiated and the result is sent to your sync gauge. Your tachs are also tapped off of the sync module. Generally speaking, your sync gauge is going to be a better representation of your motors being in sync then your tachs will be. Your tachs are dependant on being accurate and within adjustment. Your sync gauge on the other hand is reading the simple differential between the motors. It is not trying to "interpret" the signal as do the tachs.

Usually in cases like yours, the tach is wrong. To test this, get an external tach and hook it directly to the motor. Also, turn the input selector on the rear of the tach back and forth a few times to clean the contacts. If all else fails, tap on the tach and see if it corrects itself. One of mine does this occasionally and it is irritating.

If it is the sych module, FP has them, or Ebay.....
 
Redhook98 said:
On all typical Sea Ray systems that I have seen, the input to the sync gauge is from the black hockey-puck looking thing (sync module) behind your dash. The signal comes straight from your motors to the synch module behind the dash. It is then differentiated and the result is sent to your sync gauge. Your tachs are also tapped off of the sync module. Generally speaking, your sync gauge is going to be a better representation of your motors being in sync then your tachs will be. Your tachs are dependant on being accurate and within adjustment. Your sync gauge on the other hand is reading the simple differential between the motors. It is not trying to "interpret" the signal as do the tachs.

Usually in cases like yours, the tach is wrong. To test this, get an external tach and hook it directly to the motor. Also, turn the input selector on the rear of the tach back and forth a few times to clean the contacts. If all else fails, tap on the tach and see if it corrects itself. One of mine does this occasionally and it is irritating.

If it is the sych module, FP has them, or Ebay.....
Click to expand...

Are the gages different on a 300? I just rewired my bridge console and the SR wiring schematic shows it as I have described, but that is for a 1986 300 DB.
 
AKBASSKING said:
Are the gages different on a 300? I just rewired my bridge console and the SR wiring schematic shows it as I have described, but that is for a 1986 300 DB.
Click to expand...


My 1983 340 has that module and is wired that way. So was my 2000 290 AJ. ??? Strange......
 
Presentation said:
Use your ears to sync the motors then look at the gauges to answer your question.

When you hear Wuah…..….Wuah………Wuah…...Wuah..... the engines are not in sync by a lot.

When you hear wu, wu, wu, wu, wu you are getting close.

When you hear hummmmmmmmmmmmmmmmmmmmmmmm you are in sync.

So get your motors humming, head out on the coast way, looking for adventure…..or whatever comes your way……
Click to expand...

This a perfect and easy way to sync. i do it like this everytime. :smt038:smt038:smt038

greetings
 
mistercomputerman said:
http://www.clubsearay.com/forum/showthread.php?t=18308

Teleflex sending unit behind the dash. Different ones for gas and diesel, I believe.
Click to expand...


Sometime after 1986, SR must have started to use a differant synch system. The picture below shows my bridge dash. The synch gage is the little one between the two big (tach) gages wired per SR wiring schmatics......

attachment.php
 
I have noticed that my tachs are slightly different when the sync gauge is centered too.

I have taken my "old timer" buddy (he just uses his ear to tell when his motors are sync'ed) out with me a couple times. I tested him & my guages by not letting him see the gauges and running with tachs the same and then sync gauge centered, he picks sync gauge centered every time.

Not very scientific but good enough to make me a believer.
 
AKBASSKING said:
Sometime after 1986, SR must have started to use a differant synch system. The picture below shows my bridge dash. The synch gage is the little one between the two big (tach) gages wired per SR wiring schmatics......

attachment.php
Click to expand...
That wiring looks so nice and clean...... beautiful job.
 
Pack66Dad said:
I have noticed that my tachs are slightly different when the sync gauge is centered too.

I have taken my "old timer" buddy (he just uses his ear to tell when his motors are sync'ed) out with me a couple times. I tested him & my guages by not letting him see the gauges and running with tachs the same and then sync gauge centered, he picks sync gauge centered every time.

Not very scientific but good enough to make me a believer.
Click to expand...

But the Sync gauge won't drink your beer and plug your head like an old timer will. :grin:

Ken
 
My tachs read about 100 - 200 RPM differently when the synch gauge is centered. I go by the synch gauge. Especially since my stbd side tach tends to jump around every once in a while.
 
Thanks guys

Interesting responses. (and the most Ive ever got):smt038

Guess I need to turn the music down then :grin:
 
I replaced the crap tachs these boats came with last year with Faria tachs.now they read even when the sync guage is centered.the teleflex guages these boats had in the 80's are showing their age.
 
"Not only can you hear when they sync, but you can feel it vibrate in your feet if you are barefoot!"

I am assuming you cant feel them vibrate when they are synch'd ? Or does the vibration just change ?
 
I had one tach totally die.I went to my local marine center and bought 2 new tachs.they are Faria tachs.wired up the same as the teleflex but are very accurate.they are dead even when the sync guage reads in the middle.think they were about $50 each.Am probably gonna start replacing the rest of the guages over the winter.Checked them with a digital tach and they were on the money out of the box,no adjustments needed.
 
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