Lost
 

OK , I give :( . I've been battling this problem all season and getting nowhere :mad:
Past two years I've been running 28 Bravos and 3000 rpms got me 50 mph. This year it gets me 40 mph and I have to stagger my sticks to get both at 3000. Something is slipping in the right engine/drive/prop. Found some rubber in bilge so I changed the coupler...no help but now clean. Threw on a spare drive...no help. Tried spare props...no help. Reversed rotation(turn in instead of out)...no help ,but did get a roostertail :D. Removed speedo pu...no help. Yesterday lifted boat to inspect bottom under trailer bunks and all seems ok.
At 3000 rpms my sticks are staggered almost 2 inches. If I run the right engine up to 4000 , nothing else changes (just revs more), if I run the left engine up to 4000 the boat speed increases and the right side increases also because I'm lightening the load on it.
Finally , slam the sticks to the dash and the right one is turning 5900 and the left 4800 and a top speed is off a good 10 mph.
I also checked the tachs with a third tach and they are ok and my speedo has been and still is within 1 mph (usually lower)
of my GPS.
Virtually everything has been changed or swapped or reversed twice with the exception of the engine coupler and the bilge is clean. My parts guy swears in 20 years he has NEVER seen a bad new coupler but will concede he has seen new parts bad. It has also not gotten any worse and if its been slipping for 10 hours now you woould think it would HAVE to be getting worse :confused:
I also tried 30" Bravos and the only change was 200/300 less rpms on both engines.
The poor left engine is down in rpm because its doing most of the work.
With the great minds on here are there any other ideas? I'm totally F'n lost.
Sorry for all the reading.

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This may be somewhat remedial but have you checked the throttle linkage/cable to make sure both are adjusted properly and that WOT is actually WOT? I was going to say it was prop related and maybe a spun hub but since you changed that...that option isn't valid either. How about fuel filter or anti-drainback valve? Fuel pump? Have you checked fuel pressure?

Hmmm...this does sound odd.

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Have you checked the ignition secondary? A bad/arcing wire or cap wil cause high tach readings and loss of power.
Gary

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Thinking out loud here.. If the right engine/drive is free wheeling.. and the left has the load, what happens if you take both up to 4000k.. and then pull back on the left engine.. see if the righ one ever does carry the load.

What i am saying is, will the boat stay on plane with one engine? If it stays on plane with the left one and not the right one, then bad water to the prop? Can you turn the wheel and see a difference in load to right or left?

If you had a drive line slipping problem, it would seem to break loose and free rev at some point. I cant see a couple holding on "sort of". Can you mount your wife or gf on the swim platform and have her look at the water getting to each prop?

Like I said, just thinking out loud. You have tried adding load to the left motor. Try subtracting it and see if the right one ever ponies up to holding any load at all..

With all you swapped, it seems not be a hardware issue.. I am thinking water to the prop issue..

Good luck.. this boating thing is suppse to be fun, not perplexing..

Dick

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Could that engine be down on power due to weak/broken springs or something else going away?
Shawn

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Dave , throttles are both wide open when sticks are.
Gary, new caps and rotors.
Mr gadgets, My thought too. Thats why I removed the speedo pu and inspected the bottom of the boat. Also why I tried turning the props in , hoping they would pu water differently.
When I slow the left engine down , the boat slows and the right engine slows. Don't know if it will stay on plane or not. I havn't tried that.
Shawn, that was my original thought back in May but I realized when I put my GPS back in the boat the speed was down. For 2 years 3000 got me 50mph now 40. Same speedo same GPS.
The slower engine will push the boat faster when throttle is advanced the right one will not , just the rpms increase.

Good work guys...keep the questions coming :cool:

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Have you done a compression test on the engines??? may give you some clues about the engines health.....also try hooking up a vacume gauge to both engines to see what they are doing when under load......

Inspect the prop hubs as well.....

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Engines pump 180 across the board. Changed to 30" Bravos and lowered both engines 200/300 rpms.
Like I said before hit the right engine and rpms increase and nothing else. Left engine will increase boat speed.

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have you checked the timing and timing advance?

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Yep. Also advance the throttles to 3000 in neutral and the sticks are side by side. Advance the over 3000 IN gear and the left engine moves the boat faster , right engine just revs faster(no change in speed)

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I did spend about a half hour under the boat this evening examining everthing and did make a small but stupid discovery. The speedo tube that connects to the outdrive was not connected and hanging between the hull and the outdrive. Easy to spot from underneath looking back but not particularly noticable from up top. It also had the plastic end on it. Could this be the mofo that's been causing my hair to turn grey or what...next time out will tell.

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Hey Mo, you sure you don't have one of those famous Delaware River floaters hanging off one of your drives :eek: :D

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Cal ... I can understand the speed indication with the speedo tube ...but that would not account for different rpms ? I dont think its an issue but as CT stated .... I did have a board hang up on my drives last year and it would not let the drives down and I could not get up on a plane.... Now I know you would see something blocking drives but what about the drive positions ? maybe something keeping drives out of posistion ? I doubt it but just .02 ....

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I don't use the speedo pu in the drive but if the tube and plastic end were in the water in front of the drive that may disrupt the water flow just enough to be sucking air down and allowing it to cavitate :cool:
Like Cool Trips said , we pick up a lot of stuff in the Delaware and we're used to stopping and reversing to wash of the drive but this was ATTACHED to the boat and no amount of"backwash" would remove it. I can't wait to try again. I'm really excited :evilb:

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Are you referring to the Volksbwagons that are floating down the river ?? :eek:

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No , the bodies :eek:

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Actually the floaters are not the problem. They are like dodging the crab trap makers on the ChesBay :D The problem is the "almost" floaters you can't see.

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Ouch! Been there done that :(. Broke a gimble ring and bell housing in '02 :mad:

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Mopower..... YOU ARE SATAN AND ARE TRYING TO GET OSO'ers TO BLOW THEIR MINDS FIGURING OUT THIS PROBLEM!....... :D

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Check Your Compression Again,there Is Now Way That All 8 Cyclinder Are The Same,compare Them To The Other Motor Aswell,then Do A Leak Down Test,running Comression Can Be Differant Than Cranking Compression,if They All Come Up The Same Again,use A Differant Guage,if All Is Good With The Engine,check The Clutch In The Upper Housing In Your Bravo Drive,they Do Wearout!good Luck

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From what you described its obviously not a motor problem,a weak motor wouldn't pick up rpm's and not pick boat speed up like you described. I can't see the speed tube floping around making any difference either. My max machine drive has a billet block odf aluminum in front to support gimbal from breaking,it goes where speedo tube is supposed to go and until recently my speedo hose was flopping around in front of drive,made no diff when i finally trimmed it off.. I can't see a cone clutch in the drive slipping a controlled amount but it wouldn't be hard to swap drives side to side,i would try that if anything. If not the only suggestion i got is good insurance,5 gals of gas and a bic lighter,Smitty

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Reed , I've been F'n with this since May...I don't have a black hair left...oh wait a minute , I do see one or two left.

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The comp. is not exactly 180 on every one , but it was simpler do say that than type out all the reading since I'm a one or two finger typer :D. Also swapped drives but reread post #14 I may have found this booger. Will try maybe today , probably tomorrorw and thanks

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well ?? ........... tap tap tap ....... :D

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Could your engine coupler be slipping?

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Replaced speedo tube on right drive that was dragging in the water....no help :mad:

Quikdecision, I already replaced the coupler the beginning of July.

My next try is swapping drives right to left. Last time I just put a spare drive on the right but I know damned sure the left is good. It certainly is looking like the new coupler could be slipping too but the merc mechanic who got it for me says he's never see a new one slip.

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Bummer ......didnt you do some motor work last winter ?

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Mopower,
what kind of drive showers do you have? Any chance they are sucking instead of blowing?? I know just an expression. I made one once and I couldnt get the bow up.. took it off and bingo back in business.. Could something have happened to a drive shower pick up?

What do you have on the transom.. How about a nice pic, like the one with the guy with all that hair.. man I have hair envy..

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Simrek showers and I already tried a spare drive that did not have a shower OR even holes for one.
Tuesday I'm gonna swap drives side to side just fo the helluvit. I KNOW the left one is good. I did think of the shower problem

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Yes , new heads. The engines are running fantastic. Start easy , no funny noises , no leaks , just this damned slip problem.
I did try one engine at a time today. left @3000 10 mph GPS. Right @ 3000 8 mph GPS and I could easily rev it higher with no additional speed.

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you could rev the right with no more speed ? How bout the port ? ..... to me ....its gota be a) coupler b) hub c) clutches...

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Exactly.
Port engine will move the boat faster
a) changed the coupler
b)changed props 3 times including turning them in and out.(28" and 30" Bravos)
c)threw a spare drive on the right side.
d)examined the bottom of the boat.
e)removed speedo. pu since it's on that side.


I'm seriously giving thought to swapping engines and drives right to left. This will determine if it's mechanical or water flow to the prop , but man , it's prime season here now and i don't feel like going through all that...

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Sure sounds like the coupler to me, only you should smell rubber burning if the coupler is slipping.

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You're right Joe , I agree , but I just changed it the wednesday before July 4th for the same reason and it made no defference.at that point I did have some rubber in the bilge. I also asked a friend who is a Merc mechanic if he ever saw a "bad" new coupler and he said not in his 20 years experience. He DID concede he has see other new parts bad :rolleyes:

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you need to talk to someone that knows the drives .....I am not sure if the clutches can slip .....or Swap Drives .... thats got to tell you something ...cpl hours of work .....

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I already put a spare drive on the right but before i get too crazy I am gonna swap drives left to right. I KNOW the left on is good :cool:

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I know this is real simple, but You do have solid hubs in those props, right?

Did props get mixed up somehow? make sure they are what you think they are. I fought that for 3/4 of a season before I found that out once.

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I have a set of 28" and 30" bravos with Flo Torq hubs. Tried both sets and new hubs and even swapped sides (tops in instead of out)