Engine sync lagging

GnrlPatton

Well-Known Member
Jul 12, 2010
708
Maple Valley, WA
Boat Info
Current: 1998 370 Express Cruiser
Sold:1988 230 Weekender
Engines
Twin Cat 3116T
I'm trying to figure out why my port engine lags when throttling up. I have my engine synchronizer on, and as I slowly advance the throttle, my starboard engine spools right up, but port side always lags. It takes a few seconds and then eventually catches up.

Here's a video of it:

The tachs are typically a bit off, watch the sync gauge in the top middle to see it happening.

Anyone know how to adjust that?

Thanks,
Kevin
 
Does it happen when the sync off? Mine did. The port engine took longer to spool up. It was the aftercooler. I removed it cleaned it and it solved my problems. I'm no mechanic but I do get lucky now and then. Also I was told it could be restricted air flow thru the seps. Good luck. I'm sure Frank will have some input. Que Frank in...3..2..1..
 
FWIW, I was schooled not to throttle up with the engines synched. It makes the Glenn-Denning (sp) work too hard. It should only be used to maintain a synched rpm. Again, this is what I was "taught".

Jaybeaux
 
FWIW, I was schooled not to throttle up with the engines synched. It makes the Glenn-Denning (sp) work too hard. It should only be used to maintain a synched rpm. Again, this is what I was "taught".

Jaybeaux

Agreed, I do it on my electronic sync now but not on previous boats with Glendinnings.
 
I have never heard of this... This is in the manual for my boat

Sync 1.png

sync 2.png
 
Does it happen when the sync off? Mine did. The port engine took longer to spool up. It was the aftercooler. I removed it cleaned it and it solved my problems. I'm no mechanic but I do get lucky now and then. Also I was told it could be restricted air flow thru the seps. Good luck. I'm sure Frank will have some input. Que Frank in...3..2..1..
It does it with or without the sync enabled. I've always run it with it on since I've had the boat. I did clean the aftercoolers last year, as part of my troubleshooting efforts to stop the transom sooting. I also cleaned the air seps, but they are probably due for another round of it. Port has always lagged the Starboard engine, but it's gotten noticeably worse over the last few trips I've taken. I'll try looking through the intake systems to see if I have anything to worry about there.
 
Don't know about your sync, I was just worried about you beaching the damn thing in that video :):)
 
The Cat's in my 400DA always lagged one behind the other; my mechanic said if that is my only problem I have none.... He said it is probably minute differences in the injection pump assembly... If you think it's an issue with the synchronizer then there is a procedure to set the clutches in the syncro unit.

Jaybeaux - Where did you understand not to use the throttle when on the synchronizer? Glendinning designed the system to be able to vary the throttle setting.
 
Interesting to hear. I am in the middle of having my injectors replaced (mechanic is having difficulty getting the port motor running correctly afterwards), so that is probably why I've noticed it getting worse. Once he has it dialed in, and I've cleaned and oiled the air seps, I'll see if it improves. I agree that it's not a huge problem, just an annoyance.

Also, I have the Sturdy AccuSync, not the Glendinning. I'm reviewing their info now to see if there's an adjustment possible or not. The manual does say "Synchronizes through a full range of RPM’s from idle to wide-open throttle." so I don't think going from idle to planing speed is an issue with it.

Thanks all.
Kevin
 
Jaybeaux - Where did you understand not to use the throttle when on the synchronizer? Glendinning designed the system to be able to vary the throttle setting.

From my training with Captain. He recommended to get up to where you wanted "manually", then enable the sync, then slide the slave throttle all the way forward. Extra comment: This was a procedure used when going from idle up to cruise speed/2200 rpm. I do make throttle adjustments with the sync on if I have to slow down a bit, or speed up a bit.
 
From my training with Captain. He recommended to get up to where you wanted "manually", then enable the sync, then slide the slave throttle all the way forward. Extra comment: This was a procedure used when going from idle up to cruise speed/2200 rpm. I do make throttle adjustments with the sync on if I have to slow down a bit, or speed up a bit.
For no particular reason I used to throttle up manually. I quickly got tired of thrust differences steering the boat when the bow is rising to get on plane. Since then I just engage the Glendinning at around 1,000-1,200rpm, much easier.
 
As to why...

The Glendinning syncronizer is basically a mechanical differential. It has a set of gears that drive the slave engine to match the lead. If you pull the lid off the unit you can see the gears pulling the slave engine throttle to match the lead. It takes a couple seconds for this process to happen. Looking at the video, that's about how mine operates, and looks normal.

I usually only turn the sync on after I'm on plane and have the engines at about the same RPM, as I don't like one coming up slower than the other while coming on plane. A also use it at idle speed as there is a slight difference in the idle RPM under load that produces a slight vibration, as using sync at this speed gives butter smooth operation.
 
So what I'm gleaning out of this conversation is that it is a personal preference thing. Whichever has been your custom, how you learned, or how best your boat performs is fine. Would y'all agree?

Jaybeaux
 
So what I'm gleaning out of this conversation is that it is a personal preference thing. Whichever has been your custom, how you learned, or how best your boat performs is fine. Would y'all agree?

Jaybeaux
That seems to be the case. I'll do the air sep cleaning idea, and then try it out manually advancing the throttles and see if it makes a difference.
 
So what I'm gleaning out of this conversation is that it is a personal preference thing. Whichever has been your custom, how you learned, or how best your boat performs is fine. Would y'all agree?

Jaybeaux
No!!... I think everyone should do it my way :)
 
From my training with Captain. He recommended to get up to where you wanted "manually", then enable the sync, then slide the slave throttle all the way forward. Extra comment: This was a procedure used when going from idle up to cruise speed/2200 rpm. I do make throttle adjustments with the sync on if I have to slow down a bit, or speed up a bit.

I was taught similar as Jaybeaux, to bring both engines up, get on plane, then turn on the sync, but to pull port throttle all the way down to idle position. Maybe I'm confused about what engine is the slave? My current understanding is, the starboard engine throttle is controlling both engines. The Se Ray post from Blueone also states to move the slave throttle to full. Being curious I dug into my Cummins manual and found this.
 

Attachments

  • engine sync 2.pdf
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The Se Ray post from Blueone also states to move the slave throttle to full. Being curious I dug into my Cummins manual and found this.
Sounds like we might have different sequencers... or they changed the procedure 2 years later
 
QSC throttles are electronic "fly by wire", and I am pretty sure 450C and 480CE are cables. That would explain some differences.

On the QSC you set the port throttle (slave) to as fast as you want the engine to spool (i.e full throttle is the recommended position) and then advance starboard throttle as desired. Since the QSC is all electronic they stay very close to in sync the whole way up.
 
QSC throttles are electronic "fly by wire", and I am pretty sure 450C and 480CE are cables. That would explain some differences.

On the QSC you set the port throttle (slave) to as fast as you want the engine to spool (i.e full throttle is the recommended position) and then advance starboard throttle as desired. Since the QSC is all electronic they stay very close to in sync the whole way up.
Yes, I am cables and all mechanical
 

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