Synchronizer gauge stopped working

[AllanS]

I have a pair of Cat 3208’s in my boat. The throttles are synchronized with a Glendenning sync box. That unit works well, and always has. However, the synchronizer gauge (the one where the needle points to Starboard or Port) has stopped working and the needle points straight up. I’ve checked the wiring connections behind the dash, loosened them and cleaned them, but no luck. How does one check the integrity of one of these gauges?

 

[dtfeld]

Did you check the sync module connections as well? The sync module is a black plastic puck about 5” in diameter and is usually buried up under the dash. That module is known to fail, and is made by Teleflex. I’m unaware of any test/troubleshooting.

http://www.clubsearay.com/index.php?threads/troubleshooting-sync-and-tach-gauges.71400/

 

[AllanS]

Are you pretty sure my boat has a sync module? As I look at the sync gauge connections, it is fed by + and ground, of course, but the other two wires (both grey in color) come directly from the port and starboard tach gauges (also grey). My tach gauges generally work, a bit erratic at times, but generally settle down to believable rpm values. Does the sync module you reference feed the tachs?

 

[dtfeld]

Tachs feed the sync module...sync module drives the sync gauge.

 

[AllanS]

Ok, now I’m more confused than before, since I see both my tach gauges feeding the sync gauge.

Stepping back in the process, my tach signals seem to originate from cables that come from the front of each engine, and feed into the Glendenning sync unit in the engine room. Does that make sense?

So is it possible that the sync module you reference resides there, and then feeds both tach gauges and sync gauge in the helm?

 

[AllanS]

Found a discussion of tach output and Glendenning sync on boatdiesel. Seems that mechanical send cables from engines attach to Glendinning unit, and the Glendinning has has a sync module that feeds the helm gauges. Discussion was that the most common cause of poor or negligible helm tach readings are worn or broken mechanical tach sender cables. I think I have a starting point to investigate. Thanks for pointing me in the right direction.

 

[AllanS]

Soooo, any idea why my starboard hour gauge stopped but my port hour gauge works fine?

 

[dtfeld]

Found a discussion of tach output and Glendenning sync on boatdiesel. Seems that mechanical send cables from engines attach to Glendinning unit, and the Glendinning has has a sync module that feeds the helm gauges. Discussion was that the most common cause of poor or negligible helm tach readings are worn or broken mechanical tach sender cables. I think I have a starting point to investigate. Thanks for pointing me in the right direction.

Your boat is several versions older that what I was looking at, but post some pics of your dash and wiring behind, that is usually helpful.

Typically, the Glendinning Synchronizer mechanically syncs the engines, but does not interface with the dashboard tachometers/sync gauge which are usually electric. The tach and sync gauges are typically driven off a electrical pulse counter on the engine flywheel (typically supplied by CAT). The sync gauge compares the pulse count and indicates the differential on the sync gauge. If that's not it all I have to say is I learn something new around here everyday

Is your hour meter missing (no display) or doesn't increment time (stuck @ XXX.X hours) ? Sometime a tach needs a minimum RPM in order to start the clock. This stops the hour meter from running if you have the engine switched on but not running.

 

[AllanS]

Ok, I’ll take some helm pics soon. Was at the boat this morning and looked over the Glendinning unit. You’re right, it’s just a mechanical interface. No wires leading to the helm. I do think it’s time to replace my tach cables that run from the front of the engine to the Glendinning, just for good measure.

Can you describe where I can find the electrical tach sensors near the flywheel?

Regarding the hour meter, it is stuck at a fixed number (131.7). This number is so low because I replaced all the helm gauges a year or so ago. So it’s a relatively new gauge, that only has + and - connectors. I’m going to start by measuring the voltage being supplied with the engine on, and also apply 13+ v across the gauge connectors to see if it starts counting again. Maybe the lack of tach signal coming to the sync gauge is related to the issue with the hour counter?

 

[dtfeld]

Ok, I’ll take some helm pics soon. Was at the boat this morning and looked over the Glendinning unit. You’re right, it’s just a mechanical interface. No wires leading to the helm. I do think it’s time to replace my tach cables that run from the front of the engine to the Glendinning, just for good measure.

Can you describe where I can find the electrical tach sensors near the flywheel?

Regarding the hour meter, it is stuck at a fixed number (131.7). This number is so low because I replaced all the helm gauges a year or so ago. So it’s a relatively new gauge, that only has + and - connectors. I’m going to start by measuring the voltage being supplied with the engine on, and also apply 13+ v across the gauge connectors to see if it starts counting again. Maybe the lack of tach signal coming to the sync gauge is related to the issue with the hour counter?

There are a set of power wires on the Glendenning unit that powers the solenoid from the helm, but not the tach signals. The biggest service item on the Glendinning sync are the flex shaft connection to the flywheel and the right angle drives if not greased reguarily. I'd start with those first, but maybe just as spares if it working.

The tach senders usually are a small threaded cyclinder with 2 leads coming out. on the flywheel housing. I've got 3126's so not overly familiar with the 3208's but CAT usually doesnt stray far from home design wise. However, if you have your engine serial numbers use the parts manual at parts.cat.com to find the drawing showing where and the exact part #.

If you went back with the exact same Teleflex tachs, it may be dead again, or not getting power/voltage as you suggest. Most of us with CAT diesels have upgraded to Aetna Engineering tachs. A little more $ upfront but accuarate (+/- 1RPM) and sem to last forever.

I found the Teleflex tach troubleshooting guide...there is one for dual diesels.

chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/https://www.projectk.co.jp/marine/pdf/teleflexmeter.pdf

 

[Skybolt]

Hi @AllanS - I believe your engines have an old school tach sender that generates a signal, I have the same on my Detroit's.

https://parts.cat.com/en/catcorp/5N...J7H5ssfh2Tjd719LcG4aAtI8EALw_wcB&gclsrc=aw.ds

What @dtfeld is talking about is a mechanical engine synchronizer like a Glendenning. Do you have a mechanical engine synchronizer? You would have a switch to engage it and then raise one of the throttle levers all the way up and only control the rpm with a single lever.

If you don't have that and it is an electrical gauge synchronizer with the 5" black puck Dave was talking about, that would have both engine tachometer sender wires going to it. The mechanical one that Dave is referring to has a cable from each engine going to a gold box in the engine room and your throttle cable(s) are also going to that box then to the engine(s).

If you have the old gauge style (very popular on gas engines) and both tach's work properly then the gauge is bad. If both tach's do not work properly then that needs to be sorted out first then the gauge can be assessed.

 

[AllanS]

Yes, Skybolt, I have the mechanical synchronizer that you describe in your first paragraph. Seems to work well. I just used it this week for a 6 hr trip and it worked flawlessly.

The issue is that both helm tach gauges can give wildly erroneous rpm readings at some times, and the helm tach synchronization gauge stopped working completely. I suspect the electrical tach sender units, or this puck that both of you refer to, and hope I can find them on the engines to check their condition.

 

[Skybolt]

Yes, Skybolt, I have the mechanical synchronizer that you describe in your first paragraph. Seems to work well. I just used it this week for a 6 hr trip and it worked flawlessly.

The issue is that both helm tach gauges can give wildly erroneous rpm readings at some times, and the helm tach synchronization gauge stopped working completely. I suspect the electrical tach sender units, or this puck that both of you refer to, and hope I can find them on the engines to check their condition.

Why worry about the sync gauge in this situation? Personally I would remove it, it's of no need. When the Glendenning is engaged both of your tachs should be in sync. If your tach's are acting erroneously start by replacing the electronic sender(s). If that doesn't fix it, then replace the tachs. I did that and went with Aetna Engineering tach's and senders.

https://www.aetnaengineering.com/model-8905r-lcd-tachometer/

Your tach's run off of the electronic senders that have a pass through connector for the cables that go to the Glendenning sync. The link I posted in the first post has what Cat uses.

 

[AllanS]

Why worry about the sync gauge in this situation? Personally I would remove it, it's of no need. When the Glendenning is engaged both of your tachs should be in sync. If your tach's are acting erroneously start by replacing the electronic sender(s). If that doesn't fix it, then replace the tachs. I did that and went with Aetna Engineering tach's and senders.

https://www.aetnaengineering.com/model-8905r-lcd-tachometer/

Your tach's run off of the electronic senders that have a pass through connector for the cables that go to the Glendenning sync. The link I posted in the first post has what Cat uses.

Yeah, good point. I guess I’m obsessed with having everything work as it should. BTW, I don’t think my tach sensors are the pass-through type, as I was looking at those cables today and didn’t see sensors located between the engines and Glenginning unit. I think they must be the magnetic sensors at the flywheel that Dave describes…if I can only find them!

 

[Alex F]

I had my glendenning sync acting up couple of years ago. Upon troubleshooting, I've discovered that this Tac Drive Coupling went bad. I think it was around $50-60 part which was easy to replace.

The issue was translated into the main engine (PORT) failing to send the proper signal to the engine sync. This coupling is physically turning the cable "telling" the sync at what RPMs to spin the slave (STBD) engine.

Even thought the pic is not for my engine model, but it gives you good idea. I also suggest calling glendenning. They're offering excellent customer service and will help you troubleshooting.

 

[Skybolt]

Yeah, good point. I guess I’m obsessed with having everything work as it should. BTW, I don’t think my tach sensors are the pass-through type, as I was looking at those cables today and didn’t see sensors located between the engines and Glenginning unit. I think they must be the magnetic sensors at the flywheel that Dave describes…if I can only find them!

3208's usually had the described tach sender and cable come off of the front of the engine. Possibly your electronic sender(s) are on the Glendinning itself. If not there then it's a fly wheel pickup as Dave describes. Although those type of senders were not around in 89'.

 

[dtfeld]

This is the magnetic tach pick up for a marine CAT 3208. If you are getting erratic tach readings, then I suspect the tachometers themselves. I would go back with Aetna's they are about 2x the price of the teleflex but will likely last the lifetime of the boat. Additionally, they read extremely accurately (+/- 1 RPM) where as the teleflex I had were probably +/- 200RPM. Running at the right RPM is important for these old diesels...dont want to beat them too hard.

That's not to say the sync module is still working as it too might be bad, and no matter what I've tried, mine is only marginally worthwhile, it never points strait up even when the Glendinning sync is engaged. I use it only to keep the engines roughly synced while coming on plane, but let the Glendinning sync do the work once at cruise. I have the Aetna's and they usually read spot on. If I ever redo my panel, I'll likely remove.

 

[Skybolt]

Just an FYI, the "Hocky Puck" sync module does have an adjustment pot for "Syncing" the engines with an external tach.

@AllanS Unless the PO replaced the tach senders, quite possibly, then you don't the magnetic pickups. Pick's of the Glendinning and engine tack off would help a lot to answer these questions.

 

[dtfeld]

So looking at the CAT parts manual, the tachometer is attached to the front of the engine and best I can tell, this looks like a mechanical connection (similar to the Glendinning flex cables). If you have electrical tach, likely this adapter has a flex cable that drives the Glendinning engine sync (mechnical drive), and somewhere along those shafts are adapters that convert the RPM reading to an electric signal to drive the tachometers/sync guage at the control stations.

The Sea Ray parts manual show a sync gauge and a sysnc module, so I'm betting there is a sync module in the system. First order of business is to get working tachometers...

 

[AllanS]

Thanks for all your follow up research on the 3208, Dave, and both of your thoughts what might be what system I have. Looks like I need to take a closer look at the mechanical cables that are attached to the front of my engines, with pics, and see if there is any evidence of a sender that is converting the rotational movement into an electrical tach signal. My recollection of looking at where the cable attaches to the engine is it was just a simple connector, no sender with wires. I’ll look closer at the cable ends that connect to the Glendinning unit next. I know my tach gauges are electrically driven, so there have to be electrical sensors somewhere on the engines, which from what you guys report, are most likely from the mechanical cables at the front of the engine, possibly on the Glendinning unit, or magnetic senders near the flywheel. If I can find the tach senders, then I should be able to trace these to a synch module, correct? Interesting that the dash illustration that Dave provided shows the synch module E37 at the same location as the synch gauge.

Dave, those Aetna tachs look tempting, but I think I need to first convince myself that the tach signals are of good quality before I spend good $ on new tach gauges.