With muffs are you forcing water through your engine

wickware

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Jun 20, 2009
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1,286
With muffs are you forcing water through your engine that would cool the engine with a good or bad impeller? Which means they are for dry-land testing or running but not for testing the condition of an impeller? jow
 

Frank Acampora

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Jan 19, 2007
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12,004
Re: With muffs are you forcing water through your engine

Sometimes, if you are real lucky and also have a good seal on the leg, the muffs will have enough pressure to dribble water out the idle relief vents with the engine not running. And, so much less fuel is used in idle or driveway testing that unless the impeller is shot, the engine will cool. A marginal impeller will appear good in the driveway and yet overheat at 3/4 to full throttle. However, a bad impeller will not be able to move water through the block and head and thus, the engine will overheat on muffs.

So, the answer is: It depends.
 

fucawi

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May 18, 2011
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1,039
Re: With muffs are you forcing water through your engine

even with a perfect impeller I have found the muffs to be unpredictable..use a barrel with the water about 6 in above the anti vent plate . or if the lower unit is off feed the water from the hose straight up the pump outlet pipe up to the engine....this is usefull if you want to run the engine to tune the carbs or do other adjustments.
 

jerryjerry05

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May 7, 2008
Messages
18,183
Re: With muffs are you forcing water through your engine

Not the way to test an impeller!!.You need to put it in the lake/river or ocean.
The very BEST way is to change it.That way you know it's good.
Some muffs don't fit good enough to get a good flow.
50 Force/Chrysler need a special muff.
Some cases I tape it in place.Smaller motors always go in a bucket or a cooler.
 

jason32038

Chief Petty Officer
Joined
May 25, 2009
Messages
555
Re: With muffs are you forcing water through your engine

It really does all depend like Frank says. Upgrade your muffs from 1/2" inlet to 5/8" with this http://www.lowes.com/pd_111954-306-01FGF_4294857235+5003694_4294937087_?productId=100 2899&Ns=p_product_prd_lis_ord_nbr|0||p_product_qty _sales_dollar|1&pl=1&currentURL=%2Fpl_1%2B5_429485 7235%2B5003694_4294937087_%3FNs%3Dp_product_prd_li s_ord_nbr%7C0%7C%7Cp_product_qty_sales_dollar%7C1& facetInfo=$1 - $5 It's as easy as removing the 2 clamp screws..removing old inlet from muffs and pushing this one in. Make sure muffs are dead center over water inlets and let the water run for a minute wide open before attempting to start. If you dont see any signs of water through the engine after 10 seconds shut it down.
 
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Jiggz

Captain
Joined
Oct 23, 2009
Messages
3,909
Re: With muffs are you forcing water through your engine

I don't think I understand the original question. But when on muffs and the engine is not running (stopped) and the impeller is in perfect condition, technically you cannot even force water through the cooling system since the vanes of the impeller will block the water passages. If the engine is running and the impeller is working perfectly, you can kinda push water through although most if it is actually pumped or pushed by the impeller. Or if the engine is running and the impeller had multiple broken vanes then water can be pushed through since the vanes are not blocking the water passage anymore. Or even at stop and the impeller has broken multiple vanes, yes you can push water because no impeller vanes are blocking the water passages.
 
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