Repower BR225 5.0 to 5.7

We recently had our 2006 Bayliner BR225 engine swapped after what we believe was an impellar issue at WOT resulting in rod or crank knock. We swapped out the long block 5.0 with a reman 5.7L carb and the tech swapped all items to the new long block. After swapping there were a myriad of issues involving proper cooling and it was finally found that there were parts of impellars lodged in the cooling system.

We took the boat out for the first time after getting it back and it was having issues staying running and finally would not start at all and we had to be towed in. The plugs were fouled badly and my tech swapped them out. It seems that there are still issues which cause the boat to run at 175 to 200 on the hose even after replacing the impellar and housing, manifold and riser gaskets, all sensors, distributor, 160 thermostat, and some other minor parts.

Now the tech says that the 2 barrel OEM carb and/or the flame arrestor may be causing the engine to not get enough air and is leading to over fueling. The flame arrestor does seem small to me, but I am have searched for two days trying to find a larger arrestor and new 2 barrel carb. I am attaching pictures of my current carb and arrestor.

My 5.7 MIE Merc (260HP) runs quite happily with its MERCARB 2 BBL TKS carb. Given this tech didn't know enough to look for chunks of the old impeller BEFORE restarting the engine would make me REAL leary to believe him about your carb. Find a better mechanic. BTW.... running a gas 4 stroke auto based marine engine for prolonged periods of time is a recipe for quite shortened engine life...just saying

sandkicker said:

My 5.7 MIE Merc (260HP) runs quite happily with its MERCARB 2 BBL TKS carb. Given this tech didn't know enough to look for chunks of the old impeller BEFORE restarting the engine would make me REAL leary to believe him about your carb. Find a better mechanic. BTW.... running a gas 4 stroke auto based marine engine for prolonged periods of time is a recipe for quite shortened engine life...just saying

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Do you mean running it at idle for long periods of time? I know for a fact he ran it until heat alarm came on 4 times. I am sure the .0003 bore on the reman doesnt help longevity with extra heat added

CajunComeau said:

Do you mean running it at idle for long periods of time? I know for a fact he ran it until heat alarm came on 4 times. I am sure the .0003 bore on the reman doesnt help longevity with extra heat added

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Sorry.... edit glitch... should read... "prolonged periods of time @ WOT".... don't think that little of an overbore would cause that problem. Think there are still some impeller pieces hiding out... check temp of exhaust elbows... If you can't keep your hand on them, they're too hot.... water flow issues. Sometimes impeller pieces partially block the water dump into the exhaust stream.

Still recommend another tech eventually.

Correct. The carb has nothing to do with it.

Jeff

Now the tech says that

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Ayuh,...... You need a Mechanic,....... Yer tech hasn't a clue,......

I think Bob nailed it,..... old impeller bits, where they shouldn't be,......

Or maybe a bad impeller,.....

Have any tests been run, to see where there's water flow, 'n where there ain't,..??..??

While the current carb, in tune, clean, 'n in good shape will adequately feed that motor,....
Yer leavin' 'bout 30 hp on the table, by not droppin' on an edlebrock 1409 carb, 'n 4bbl manifold,.......

...........

CajunComeau said:

We recently had our 2006 Bayliner BR225 engine swapped after what we believe was an impellar issue at WOT resulting in rod or crank knock. We swapped out the long block 5.0 with a reman 5.7L carb and the tech swapped all items to the new long block. After swapping there were a myriad of issues involving proper cooling and it was finally found that there were parts of impellars lodged in the cooling system.
Rule #1..... always retrieve any impeller fragments, no matter how involved it may be!

Now the tech says that the 2 barrel OEM carb and/or the flame arrestor may be causing the engine to not get enough air and is leading to over fueling.
Find a different mechanic!

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sandkicker said:

Sorry.... edit glitch... should read... "prolonged periods of time @ WOT"....
Absolutely correct! That's a recipe for a shortened engine life!

Still recommend another tech eventually.
Ditto!

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bondo said:

While the current carb, in tune, clean, 'n in good shape will adequately feed that motor,....
Yer leavin' 'bout 30 hp on the table, by not droppin' on an edlebrock 1409 carb, 'n 4bbl manifold,.......

A 5.7L SBC @ 4k RPM pulls in approx 364.58 cfm of air/fuel mixture @ 90% ve.

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sandkicker said:

Sorry.... edit glitch... should read... "prolonged periods of time @ WOT".... don't think that little of an overbore would cause that problem. Think there are still some impeller pieces hiding out... check temp of exhaust elbows... If you can't keep your hand on them, they're too hot.... water flow issues. Sometimes impeller pieces partially block the water dump into the exhaust stream.

Still recommend another tech eventually.

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Thanks to all who assisted me in this thread. The swap turned into a 3 time lower unit service, dissasembly of manifolds and risers for new gaskets, new thermo, impellar housing and 3 x new impellars.

The tech also did not swap the tube and dipstick onto the new block so I had to purchase a new combo. Where does this tube and dipstick go? I have looked all over the internet and cant find a clear picture of the exact location on the block. Different years and sizes of mercruiser seem to have different tube locations. Thanks again for all the help.