Help - Lost RPMs

[marc2061]

Originally Posted by jawz12

braid line does the same thing...it will get between the shaft and the cutlass as well as the shft log....the braid will tear up the shaft too...

this will def do it,happens here in fla all the time the braided lobster line actually melts into a mess right behind the prop

[Questsportfishing]

first off make sure that all your fuel valves are open all the way and your racors are clean! new filters and make sure the inside ball / spinner inside the racor is clean if that thing gets crudded up you will loose fuel flow that equals out to fuel pump problems also! Change out your 'secondary' filter also and make sure you have the right filters aboard the boat (sounds like you are going away to fish anyway) you never know what you get with 500 gallons of fuel.. make sure all return lines are not crimped and that the valves are open back to the tank. Check your airseps to make sure they are clean or the engine socks if you have a silencer kit. pass your hand over this part of the system it is very important! Now get a mask and snorkle out and get your butt over the side and look hard at where the shaft goes into the boat see if it is rubbing or it is lined up in the middle. Broken motor mounts or bad alignment can case more problems! if you cannot turn the wheel by hand with a little bit of power then something is binding.. a good yard can install cutlass bearings while your hanging in the straps.. sorry just a fact. I even change them with split pipe type removers and a big hammer.. *most yards are equipted with hydralic removers. make sure your bottoms clean and your gear is clean! See how mant friends you have and get them all scrappers and 3-m cloths to scrub your bottom. don't mess with cup till you find your rpm! good luck!

[Banshee]

Paul,
Mike Hastings has the cutless tool and most of the bearings in stock. So does Branch, Both are good!!!! 14 seasons you are due. Cannot turn the shaft, I agree with other, alignment, bad motor mounts, etc. BOAT Break Out Another Thousand, brother!!!! or Broken Or About To.
Good luck,
JW

[Nimrod]

Thanks for all of the input and information.

Here is a little more detail:
CLARIFICATION: Starboard shaft did get 'hot' to the touch. Hot referenced reaching operating temperature.
Both stuffing boxes are adjusted properly and not getting hot.
Both engines are no loading at or above factory spec (2700 port / 2500 starboard).
WOT should be 2300 but 2000-2100 is all we are currently getting (starboard seems to be holding the port back).
Engine alignment is on the list of things to do when cutlass bearings are being replaced.
All mechanical and fuel related aspects were checked out by a top notch Detroit guy. But double checking won't hurt.
Wheels will be PropScanned when she comes out for bearings.
Running gear is clean and clear of line, etc. but a further inspection will be done when she comes out.

Thanks again. Keep the ideas coming and I will report back as to what we find.

[Nimrod]

Additional clarification/correction - we are only down 100-150 RPMs at WOT (2180 port / 2150 starboard - should be 2300).

[JD5652]

Originally Posted by Nimrod

Thanks for all of the input and information.

Here is a little more detail:
CLARIFICATION:
Both engines are no loading at or above factory spec (2700 port / 2500 starboard).
WOT should be 2300 but 2000-2100 is all we are currently getting (starboard seems to be holding the port back).

Paul-

This has nothing to do with the starboard drive train binding, but you might want to have it checked out while you're doing the other maintenance.

According to my J&T Manual, the No Load WOT for the 8V92 is 2500 RPM. Normally you want to set the No Load WOT RPM at approximately 150 RPM above the factory spec to ensure that you are propped properly once you load all your gear, fuel, ice, etc. on the boat. Based upon this, the port No Load WOT RPM looks good, but the starboard No Load WOT RPM is about 150 RPM low at 2500 RPM.

Again, according to the J&T Manual, the Full Load WOT RPM should be 2300 RPM. This should be checked with the synchronizer off. Each motor should be able to achieve their own Full Load WOT RPM independent of the other engine. If you're only getting 2000-2100 on BOTH engines, then you may have an overpropped condition in addition to the binding.

I don't "think" that one engine can "hold" the other engine back on RPM's. You may not get the speed you're looking for, but I'm pretty sure each engine should be able to achieve their rated RPM independent of the other engine RPMs.

All the above can be confirmed by first doing a full rack adjustment, valve adjustment, injector timing and throttle/governor adjustment. Basically a full tune-up.

Just my $0.02.......

Let me know if you would like the spec data sheets for your 8V92's.

[Questsportfishing]

just curious .. don't take someone elses word for work done .. and always check out and look hard at your engine room and check yourself before ya go. and do keep in mind there are more parts to a racor than just the filter.

[Fortunate One]

Paul,

If as you stated the from the gear forward is fine then, my guess is bad engine mount throwing off the alignment.

What else would cause the saft to heat up besides friction as a result of an alignment problem. The fact that it takes a wrench to turn it is also an indication. Like JD indicated a worn cutlas bearing should not cause the shaft to bind.

Although that's not to say you're not dealing with a damaged strutt or bent prop. I suspect it's a running gear issue.

Let us know what you find.

Mike

[mymojo]

Funny this comes up now. I was running this weekend and rpms were down on both engines 200 rpm or so. Happened quickly as the weekend before all seemed ok. Changed out the racor filters and air & crankcase filters and took her back out tonight. The rpms are back to where they should be. Needless to say I was very pleased something as simple as this did the trick. Hope its that easy for you.

[Nimrod]

I was out of town last week and not onboard for the seatrials with mechanic. Here are some comments from the rest of the crew that were there.

COMMENTS:
Shaft - Does not get hot. It is and has been for at least a number of years considerably stiffer to turn than the port shaft and after running for an hour or so becomes extremely difficult to turn.

RPM's - Factory specs are NO LOAD 2500; WOT FULL LOAD 2300; CRUISE 2100 Currently Port NO LOAD 2700 - Star NO LOAD 2500 (used to get 2600) Port WOT FULL LOAD 2180 - Star WOT FULL LOAD 2150.

Bottom - Diver reports bottom and running gear clean 2 hours before seatrial.

Mechanical - Injectors all firing; Throttles fully opening; Shut Offs performing properly; Govenors performing properly; Fuel pressure checks out.

NOTE:
Fuel Filters were changed in the fall and have less than 5 hours on them - did not recheck (but will)
Line wrap is a possibility
Disconnecting shaft from tranny is a good idea
Double checking fuel valves should be done
Fuel siphon tubes probably should be checked
Fuel lines should be OK