300pm How Tight Should My Alt Belt Be???

**PARKER RABE** · 02-22-2006, 07:28 PM

Anybody Know ??? Should I Put A Crow Bar Behind It ?, I Have Know Idea About These Damn Things ? , I Could Hear It Squeeling ,its Real Loose Now And Have Rubber All Around My Alt And Flywheel , I Think I Need A New Belt Too ...

**Ted Stryker** · 02-22-2006, 07:32 PM

You may want to ask Simon, He'd have to at least have an opinion...

**natzx7** · 02-22-2006, 08:01 PM

Put the crowbar down, Parker. You will break your motor with that. If you have alot of belt dust your belt is worn out from slipping or misalignnet.

**Euroski** · 02-22-2006, 08:13 PM

Go with a new belt first. The you kinda got to have a feel for the belt. Use your thumb and adjust it for about 1/2 deflection midway between the pulleys.

**PARKER RABE** · 02-22-2006, 08:17 PM

GOT A NEW BELT ON ORDER ! SO IT SHOULD HAVE ABOUT A HALF INCH OF MOVEMENT ? IM LOST ? WHAT GONNA HAPPEN IF I GET IT TO TIGHT ?

**sosmerc** · 02-22-2006, 08:18 PM

I have asked this question myself in the past. The factory manual says:
"With an automotive belt tensioning tool, adjust belt tension to 80 lbs."
So I bought a "cheezy" belt tension guage from Gates. Tool number is 91107 and it is called a Krikit IV-Belt Tension Guage.
I still think it is really a shame that Merc didn't use an automatic belt tensioner on the ProMax 300 like they do on all the rest of the belt driven alternator/compressor configurations such as the 300X, and all 3.0 litre Optimax engines.
Inspect that belt often!

**natzx7** · 02-22-2006, 08:21 PM

1/2 inch is good . if you overtighten the belt you could wear out the bearings in the alt.

**PARKER RABE** · 02-23-2006, 08:22 AM

so get it tight and grab it right in the middle and half inch of play is good?

**Hot Shot Merc** · 02-23-2006, 08:25 AM

Parker dont try and install it yourself.You might lose another finger

**Tony Brucato** · 02-23-2006, 09:22 AM

Parker,
You might want to take the intake off and clean all of that rubber out of there.
It's a pretty common occurrence for the 3 liter motors to ingest all those rubber particles and clog up the idle bleed system. The results are a very rough idle.
Behind the reed plate there are channels cut in the block that accept all of the check valves and such. This is where all the rubber gets trapped and clogs the check valves.

**Liquid Force** · 02-23-2006, 02:24 PM

This thread is well timed, I have a pair of 300PM that have belt dust every where, I will pull the inlets and have a look down there...

**PARKER RABE** · 02-23-2006, 06:42 PM

Tony....... Mines Got An Svs Does That Make A Difference ?

**Tony Brucato** · 02-23-2006, 07:30 PM

That makes no difference, the rubber still gets sucked into the motor.

**PARKER RABE** · 02-23-2006, 07:47 PM

ITS BACK FRIES A LITTLE ABOUT 700 IDLEING IN GEAR , GOT TO BUMP IT TO 1000 RPM TO SOUND GOOD , I KNOW I DONT HAVE THE TPI ADJUSTED RIGHT, IT BURNES SO MUCH GAS ITS CRAZY , EVERYTIME I TAKE IT OUT IT HAS BLACK CARBON ALL OVER THE BACK OF THE COWL , BRENDAN POWERS LEANED THE MOTOR OUT A LITTLE FOR ME , IT RAN ALOT BETTER SO FAR , I JUST DONT WANT TO GET IT TO LEAN , CANT AFFORD TO BLOW IT UP !

I DONT KNOW CHIT ABOUT 300'S

**Skatin** · 03-02-2006, 05:58 PM

I use Napa 25-7300 belts on mine. Or Gates 7300 11A0760...

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