Omc 5.8 efi new engine noise

Galvez83

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Oct 31, 2019
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Alright i hope i find the answer here. A 1993 Omc 5.8 efi with a new engine. The problem is that the engine sputter and clanks like crazy under load and the mechanic has no clue as to what it is. Before i shell the $$$ i am hoping to get some help ending this nightmare. The youtube link is attached. Also any OMC mechanic new North Miami, FL that can look into this issue?

https://youtu.be/0Ig_0DRwHaA
 
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matt167

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Sep 27, 2012
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Yeah, the rods are knocking and want out. Sucks since you say new engine... I see it's a 5.8L fuel injected, which also means it's entirely NLA.

You can get another engine out of a 1990's Ford F series, change a few things and put your marine parts on and keep going. But be sure the boat is worth it.... Mercruiser swap would be a better idea, IF the boat is worth it
 

vasy

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Find a better mechanic if the one you have has no idea what to do.
In Florida, I'd take the boat to rapidomarine and they will swap out the block for you for a good price.
The one you have, sounds dead.
 

Lou C

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Who installed the new engine?
this mechanic or someone else?
have you tried running it with the outdrive off (water supplied to thermostat housing) to see if the noises are coming from the engine or drive/gimble housing?
A mechanic stethoscope will help find where the noise is coming from...
 

Galvez83

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I am in the process of replacing the fuel pressure regulator and high pressure fuel pump due to buzzing. Too late for Rapido Marine once the fuel issue is solved the company that i purchased it from said they would do a compression test and take it from there
 

Scott Danforth

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compression test has nothing to do with failed rod bearings. even with failed rod bearings the compression test will be normal.
 

alldodge

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It sounds like rod bearing until the rpms come up, then when the noise should get worst it starts going away. Post a vid of the motor just idling.

Check the firing order 1-3-7-2-6-5-4-8

351W_Firing_Order.png
 

alldodge

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It sounds good there. That wihne is kind of bad, and your saying its the fuel pump?
Hows the oil pressure?
 

Galvez83

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Oil and timing are on the dot. Both where triple checked by the team but they seems to be scratching their head and it looks like the engine is coming back out.
 

Bt Doctur

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The video in post 9 sounds normal but how long did you run it and during assembly and before it was run did you pre-oil the motor using the motors oil pump? Who assembled the motor were they experianced enough. Not unheard of to throw some rod bearings if something was missed on assembly. I had a motor come apart after only 22 hours.
Review the assembly work to see if any step was missed
 

Galvez83

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Update
All points to detonation as it has gotten more random. Things that where changed are the plugs, wires, both fuel pumps, gas tank emptied and cleaned then ran with rec90 fuel. Last but not least and this actually made it go away but the downside is that the engine wont start in neutral, the fuel injectors. We are making headway.......i hope.
 

alldodge

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engine wont start in neutral

Assuming this means its in neutral but need to give it more throttle.
If this is the case then look for a vacuum leak or the IAC (Idle air control), or the fuel pressure. Who did the fuel injectors and was there a print out?
 

Galvez83

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I purchased brand new injectors and installed them myself. The iac was removed and cleaned with throttle cleaner then left to clear out the cleaner. Yes in neutral no start only when in forward or reverse gear will it start. When taken back to neutral for idle it shuts off.
 

alldodge

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It use to idle, now it doesn't, and changes were injectors replaced and IAC cleaned. Where did you buy the injectors, and I hope not from ebay?
 
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