Not getting RPM(39)s 4588-gctid374638

[Guest]

Visiting this again. I have researched the posts and have confirmed the following on my 87' 4588:

Throttles are pulling actuators to full open on injection block

Used photo tach to confirm accuracy of tachs on boat

Nuetral engines rev to 3050

Props do show 22 21p

Temps are 165 on the button

Scraped Barneys off props, trim tabs, and rudders but bottom does need cleaning

My WOT rms's are about 2640 on both motors. My yacht has the 445 gallon tank, 200 fresh, and 48 holding and the fuel and fresh are both full. I have a 500 lb dingy/motor on the back deck. Full canvas up top. A couple of extra couches. A large bank of golf cart batteries for the inverter.

I know I probably lost 100 rpm from the bottom being dirty since last summer when I bought the boat. At that time I was showing around 2700-2750 rpm's but I have not been able to get her above that. Do I just need to pitch her down an inch or two because of my loading?

Any thoughts?

[Guest]

You need to look at the motors, how many hrs? when were they last tuned up?

Call Earl and have him come and see you and work his magic. then if the motors are in good tune and injectors good yes you need to re-pitch the props or you will spending some $$ on motor rebuilds.

Fill in your bio so we know where you are at!

[smitty477]

"At that time I was showing around 2700-2750 rpm's but I have not been able to get her above that. Do I just need to pitch her down an inch or two because of my loading?"

Earl is your best bet as Nelie clearly points out.

What is the year of your boat, hours on engines , are the engines stock, do you have a maintenance history available, and do they have dry turbo's on them?

You were never at the correct rpm's and it appears you may not have too much history on the boat to go by.

There is not nearly enough info here to answer your question above.

If it is possible to proviide additional detailed background perhaps some answers are possible.

These would be just a few of the pieces that would put you in the right direction....

- Are there any other symptoms at achieved rpm? (smoke, noise, surging, overheating, etc)

- Can you completely eliminate fuel delivery yet? (fuel condition, lines , filters, vents, air leaks, injectors, pump,etc)

- Props are stamped . do you trust that is correct or have you had them checked?

- Have you had the boost pressure checked, the intake air system OK, etc?

- At what rpm(s) have the tachs been checcked at?

FWIW - I believe that the 45 has fuel tankage of 504g and no load rpms need to be 3,200-3,300 so as to ahcieve 3,000+ in gear loaded. Your water tanks will hold just over 200g but the amount of water you are carrying will be closer to 225g.

Hope this helps

[Guest]

smitty477 wrote:
no load rpms need to be 3,200-3,300 so as to ahcieve 3,000+ in gear loaded.

That is interesting. To answer a few questions...The motors have 2700 hours on them with a tune up and new manurisers early last year a few months before I bought the boat. It is a 87'. It just has the mesh intake screen and I can't imagine it gets clogged (looks clean). No noises, surging, or black smoke that I have noticed at WOT. I have not changed the fuel filters so I guess that is next on the list...also I could try pulling the tank lines and cleaning the screens. Props are stamped but I have no confidence in that except I don't know a prop maker in the world that would re-pitch without re-stamping. The turbos are oiled and have coolant lines to them.

I checked the RPM's at idle, 1500 rpm, 2000 rpm, and WOT and all were very close on both motors. I have not installed boost gauges yet.

I have read that with these motors that you actually lose boost when dropping pitch and gain boost when propping up? Is there a way to measure the pitch myself?

I live in Anacortes, WA.

Todd

[smitty477]

Trying to do this site unseen has a bunch of pitfalls but lets see if we can make any headway....

"The motors have 2700 hours on them with a tune up"

I am guessing this covered at least renewing injectors, valve clearance , fuel timing, and all air restrictions (Air filter, preheater, intercooler,etc)

"or black smoke that I have noticed at WOT"

Making some assumptions and all things being equal if tachs and all else is right - but still you are not making blk smoke at 2,700 full throttle application so a good guess would be fuel limited problems.

"I have not changed the fuel filters so I guess that is next on the list"

Normally this would remedy fuel limited issues but you also seem to have had this issue for a long time and on both engines at the same time?????

So,I am not so keen on that diagnosis as the simple solution.

Do you have your throttle cables connected to any type of 'automatic' engine synch system?

Has anyone 'adjusted' any fuel pump adjustments other then the no-load high idle screw? (are the protective caps off or damaged?)

Have you checked (carefully and gingerly) the turbo compressor wheels for easy movement? For radial and axial play? Inspected with a bright flashlight for damaged or gunked up blades?

Can you confirm a high pitched 'whine' at engine speeds above 2,200 from the turbo's?

Do you have known good fuel?

Did this boat ever have a history where it ahcieved rpm's above 2,700 since new?

"I have read that with these motors that you actually lose boost when dropping pitch and gain boost when propping up? Is there a way to measure the pitch myself?"

Yes - but that is only when the engines are first configured for a fully loaded condition, you do not seem to be near that yet.

"no load rpms need to be 3,200-3,300 so as to ahcieve 3,000+ in gear loaded.That is interesting"

These mechanical govenors have an inherent 'droop' between the no-load rpm and the loaded full fuel delivery rpm. Oversimplifying it you would end up with about a 150 rpm droop at about 3,000 rpm's (1/2 crank speed).

Try to figure the fuel and smoke questiuons first as that appears to be where your data is heading us so far.

ps - "I know I probably lost 100 rpm from the bottom being dirty since last summer when I bought the boatps -"

Was the bottom and running gear completely clean when you achieved the approx 2,750 rpms? Did you get blk smoke then?

Hope this helps

[smitty477]

"'a tune up and new manurisers early last year a few months before I bought the boat"

Just thinking about this a minute raises a number of questions....

- Can you get the detailed information on this work?

- Can you contact this mechanic and ask his assessment on current condition?

- Why would a large amount of 'major' work be performed just prior to selling?

Hope this helps

http://www.propellerhub.com/ - for propeller pitch information.

[Guest]

The owner did the work along with new interior for a trip up the inside passage. Unfortunately, he passed away before he got to go. The family didn't want the boat or the debt tied to it so I bought it.

T

[mmichellich]

twiersum wrote:
The owner did the work along with new interior for a trip up the inside passage. Unfortunately, he passed away before he got to go. The family didn't want the boat or the debt tied to it so I bought it.

T

What position are your trim tabs while running at WOT? At WOT I get about 150 RPM higher by raising the tabs on our 47. At lower RPMs, the tabs work the other way, i.e.more tab, slight increase of RPM with fixed throttle.

[smitty477]

Perhaps the company that had the vessel in lease knows of people who worked on or checked out the boat during their usage.

Or perhaps the marina which stored and/or pulled the boat has some indication on whom may have info on the boat.

Getting some history on the boat will make some of this a bunch easier.

I am trying to upload scans of the govenor and droop descriptions here to the BOC but it is not allowing the files sizes.

Maybe I can figure this out later.

PM your e-mail and I will send you the scans.

Hope this helps