Test prop question, '89, 48spl Johnson

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Beck

Petty Officer 2nd Class
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Feb 24, 2004
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165
Just wondering my oem refers to the test prop and you can run the engine 4 to 5 k rpm to check timing etc. I'm assuming that is in a barrel with water? I wouldn't think there would be enough back pressure to prevent run-away with just the muffs on it.<br /><br />To all diy, when the pros recommend getting an OEM manual, do it. I have a seloc and just got my OEM its explains step by step. <br /><br />Beck
 
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DJ

Guest
Re: Test prop question, '89, 48spl Johnson

Beck,<br /><br />It has to be in a tank. And yes, the muffs will not promote ANY back pressure. You also need the "load" of a test prop. <br /><br />Second choice, the waterway of your choice.
 
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Beck

Petty Officer 2nd Class
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Feb 24, 2004
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165
Re: Test prop question, '89, 48spl Johnson

DJ <br /><br />Thanks for the quick response.<br /> <br />Then I would think a 55 gal drum cut in half would be sufficient?<br /><br />I feel silly asking this but want to make sure I fully understand. When lower unit is in barrel filled with water do I also use the muffs? As I am thinking the turbulence created by the test prop may somewhat hinder water intake for engine cooling?<br /><br />Thanks again,<br />Beck
 
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DJ

Guest
Re: Test prop question, '89, 48spl Johnson

Beck,<br /><br />A 55 gal. drum is sufficient for IDLING only. And no, you do not need the muffs in a barrel.<br /><br />By the way, there are no stupid questions-only those unasked.<br /><br />Even with a test prop, your '48' will blow all the water out of a 55 gal. drum in one rev.<br /><br />Timing is best left to a dealer with a real deep and large tank, or a big dyno.
 
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Beck

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Feb 24, 2004
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165
Re: Test prop question, '89, 48spl Johnson

DJ,<br /><br />Then I guess it off to the launch and leave the boat on the trailer? I think the timing is on, just want to check.<br /><br />Thank, <br />Beck
 
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BoatBuoy

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Re: Test prop question, '89, 48spl Johnson

Beck, if you leave the boat on the trailer, your boat might not plane. If you leave it connected to your vehicle, and run it in gear at 4-5K, you might have it on top of your vehicle. Be careful.
 
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Beck

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Re: Test prop question, '89, 48spl Johnson

BoatBuoy, I understand what you are saying.<br /><br />Perhaps that means a test prop and at the launch on trailer or in the water? I heard that some leave it on the trailer backed in the water. In fact the last time the omc dealer check my engine they said they ran it in the water while on the trailer. They ran it for 30 minutes and it ran perfectly. It never did miss, come to find out they used their fuel line and tank. Mine was leaking at the engine, they didn't tell me it was leaking. They charged me $60 and the next time I went out I found out it leaked. That was the miss that had developed. Sorry I got off the subject somewhat. I'm just gunshy with the dealer. $60 worth.<br /><br />Beck<br /><br />PS: Anyone have an idea what a test prop cost?
 
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Beck

Petty Officer 2nd Class
Joined
Feb 24, 2004
Messages
165
Re: Test prop question, '89, 48spl Johnson

BoatBuoy, I understand what you are saying.<br /><br />Perhaps that means a test prop and at the launch on trailer or in the water? I heard that some leave it on the trailer backed into the water. In fact the last time the omc dealer check my engine they said they ran it in the water while on the trailer. They ran it for 30 minutes and it ran perfectly. It never did miss, come to find out they used their fuel line and tank. Mine was leaking at the engine, they didn't tell me it was leaking. They charged me $60 and the next time I went out I found out it leaked. That was the miss that had developed. Sorry I got off the subject somewhat. I'm just gunshy with the dealer. $60 worth.<br /><br />Beck<br /><br />PS: Anyone have an idea what a test prop cost?
 
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ledgefinder

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May 2, 2002
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916
Re: Test prop question, '89, 48spl Johnson

I routinely run on the trailer, wide open throttle with test props & regular props. (Well, OK, not lately since it's frozen solid up here.) Just make sure the transom strap(s) are reasonably tight. <br /><br />Good story on this. I was running a 115V4 on a test prop at a deserted reservior by us. With the cover and airbox off, a stationary 115 at 5400 rpm is pretty loud. I finished up my stuff, and shut off..then about 15 seconds later a bald eagle nailed a fish about 200 feet behind the boat. I don't know if the noise stunned the fish or what. This was at Colebrook Reservior, on the CT/MA line.
 
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rodbolt

Supreme Mariner
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Sep 1, 2003
Messages
20,066
Re: Test prop question, '89, 48spl Johnson

beck<br /> the correct test wheel serves two functions. the first is to properly load the engine at or near WOT for testing and diagnostic purposes. the second is as a power test. the factory has an RPM spec for a particular motor/test wheel combo. if the motor wont turn to its rated RPM with the proper test wheel you know you have a problem. very handy for repairing boats that you have never seen before. one of the first things I do is spin them upon a dyno or test wheel to insure its a motor problem or a hull/prop problem.
 
Dave Abrahamson

Dave Abrahamson

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1,497
Re: Test prop question, '89, 48spl Johnson

Originally posted by Beck:<br /> <br />PS: Anyone have an idea what a test prop cost?
Click to expand...
Yeah, Id like to know also. And where can you get em'?
 
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