New (to me) Tahoe Q4 question

[the_smoo]

hi all,

used this site in my research for a "new" used boat. Settled on this boat. Its a 2004 with the 3.0L mercruiser engine. Had it out twice now tubing with the kids and couldnt be happier.

Its running a 14.25X19 4 blade prop. Top speed is around the 38mph mark, but the tach only says 3000rpm... I am sure that cant be right. I had the GPS to make the 38mph..

I would of thought that the tach would have been up over 4000.. faulty tachometer?

cheers, dan

 

[yourboatmyboat]

Re: New (to me) Tahoe Q4 question

The 4 blade prop is too much for a 3.0 engine and is holding it back. A 14.25x21, 3 blade prop would really help. The drive unit should be a 2.00 ratio , it will be stamped on the right side of the drive near the Mercury graphic. By the way, nice boat.

 

[Mordekai]

Re: New (to me) Tahoe Q4 question

You can always bring your boat to a dealer and have them check your engine RPM with an eletronic meter vs what your guage is reading.

On a side note, I'd kill to be able to do 38 mph @ 3000 rpm, wouldn't that be pretty fuel efficient?. Holeshot is of no concern to me as I only tube.

I was tempted to go down to a 20 pitch 4 blade prop on my q4 as I'm maxing out at 40 @ 4900 rpm (possibly trimmed out too far).

 

[yourboatmyboat]

Re: New (to me) Tahoe Q4 question

Normally a 4 blade prop is for a higher horsepower application. On lower H.P. motors tha engine loses power with the 4th blade. The prop size numbers put into perspective are , a 14.25 x 21 prop the first number is the diamater and the pitch of 21 means that the boat will move 21 inches per revolution at 600 rpm. Go to Mercury props site as per props recomidatios according to horsepower

 

[the_smoo]

Re: New (to me) Tahoe Q4 question

spent the day on the water yesterday... definitely the tach not functioning correctly.

With just me in the boat and no load, managed to top out at 42 mph. Happy with that.

The boat comes out onto the plane at about 15mph.. cant trim out too much after that as it start to porpoise.. also have the wander at low speed, but that does not bother me much..

will be looking into smart tabs maybe next summer.. for now, we are having a ball!

 

[yourboatmyboat]

Re: New (to me) Tahoe Q4 question

Laying in the floor of the boat looking under the dash you can see the back of the tach. There will be a black knob with a slot. One end of the slot will have an arrow. Make sure the arrow end points to 4C, a flash light will be handy. There will be P settings also , these are for outboard applications. Each C setting will represent 4C for 4 cylinder, 6C for 6 cylinder, and 8C for 8 cylinder. Just use a screwdriver in the slot to turn knob.

 

[the_smoo]

Re: New (to me) Tahoe Q4 question

yourboatmyboat...

thanks mate... have been working on my boat all day fixing minor things after my first few runs in it.

jumped under the dash and sure enough, the tach was set to 6C.. it must have been that way for a long time.. previous owner had since new since november 2004.. probably never even noticed..

set it back to 4C... should now be all good to go! will test her out next weekend... thanks for the tip!

on a side note, whoever does the wiring for tahoe needs a spanking... the loom under there is bad... I was a Navy tecnician for 10 years and now an engineer.. that loom is now next on the fix it list!

dan

 

[the_smoo]

Re: New (to me) Tahoe Q4 question

and another thought,, the boat idles low but did read 600rpm on the gauge.. might need to adjust the idle..

 

[yourboatmyboat]

Re: New (to me) Tahoe Q4 question

I was in the Air Force for 4 years as a Jet Mech. I agree on th not so premo wiring.

 

[TahoeQ4Pilot]

Re: New (to me) Tahoe Q4 question

Hey, whats the deal....former US Army Bradley Fighting Vehicle mechanic here. Is the Tahoe the servicemembers choice?

I havent had much problems with my tach, but last time out it seemed to max out at 3k, instead of the normal 4k. I tapped the face in it swung up to the normal spot. So now I am gonna climb under the dash ad look at my settings. Thx

 

[mccownk]

Re: New (to me) Tahoe Q4 question

I installed a digital guage in place of the tach. Its a Smartcraft system monitor. Only works if you have the MPI model motors. Covers RPM's fuel consumpton trim and more...