Replacing 1979 454 OMC
Printed From: CorrectCraftFan.com
Category: Repairs and Maintenance
Forum Name: Engine Repair
Forum Discription: Engine problems and solutions
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=35206
Printed Date: May-19-2024 at 9:42pm
Topic: Replacing 1979 454 OMC
Posted By: AnglersEdgeAJ
Subject: Replacing 1979 454 OMC
Date Posted: December-27-2014 at 5:45pm
Hey all
My 35 year old 454 OMC motor in my 79 BFN finally gave up and has a cracked block. Looking to replace it and have a line on a 2001 Merc EFI 454 and Im wondering if anyone knows what would be involved engine/trans wise for mating of this engine to my velvet drive.
Any help would be great.
THANKS
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Replies:
Posted By: phatsat67
Date Posted: December-27-2014 at 5:51pm
We have a great running 980 ish hour 454 that is currently for sale.
The Merc 454 probably spins the wrong way.
The biggest hurtle for you would be swapping out the wiring harness to mate up with the PCM plug but you'd get a revised cooling system that worked much better in the process. But, I can assist with a proper plug pig tail to wire into the boat. The engine is listed in the for sale section and has a video of me driving the boat it came out of.
You could probably just bolt on your OMC mounts and do a shaft alignment and be in business. Probably need some new exhaust hose to switch over the manifold styles.
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Posted By: 8122pbrainard
Date Posted: December-27-2014 at 6:29pm
AJ,
Sorry to hear about the problem. What happened to cause the cracked block? Bad winterizing?
Zach is correct that engine rotation needs to be considered. Zach's idea is sound with the engine he has but have you considered just getting a new short block and swapping components?
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/diaries/details.asp?ID=2179" rel="nofollow - 77 Tique
64 X55 Dunphy
Keep it original, Pete
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Posted By: MrMcD
Date Posted: December-27-2014 at 7:26pm
A 2001 year model 454 should also have a full round rear main seal, these use a different bolt pattern for the flywheel. ( you may have meant this 454 came out of a 2001 model Nautique made from 1980 to ? )
I think Full round rear mains were introduced in 1986.
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Posted By: AnglersEdgeAJ
Date Posted: December-27-2014 at 7:41pm
8122pbrainard
Bad winterization I believe is what caused it because they're havent been any overheats on it for a number of years now. I still have yet to pressure test the exhaust manifolds but the first run after winterization filled the oil pan with water. Replaced fluids and test ran again and same issue. Runs like a top but oil level is way over filled and milky after running.
I have thought about replacing with a short block but i'm nearing 2000 hours on the hour meter and I have put almost 1100 of them on it myself. So I was wondering if it would even be worth the time, effort, and $ to swap the components.
MrMcD
The Merc EFI 454 is a 2001 year engine. The 454 in my 79' BFN is what i believe to be the stock engine, an OMC 454.
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Posted By: 8122pbrainard
Date Posted: December-28-2014 at 9:18am
AJ,
I,d try to locate the source of the water first before kissing the block good by.
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/diaries/details.asp?ID=1622" rel="nofollow -
54 Atom
/diaries/details.asp?ID=2179" rel="nofollow - 77 Tique
64 X55 Dunphy
Keep it original, Pete
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Posted By: AnglersEdgeAJ
Date Posted: December-28-2014 at 9:28am
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I plan on it. But considering it was fine when i put it away for the winter and then had issues first run in driveway i figured thats almost what it had to be was a cracked block. Other than a cracked block or a cracked exhaust manifold, a head gasket typically wouldn't fail like that would it?
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Posted By: phatsat67
Date Posted: December-28-2014 at 12:45pm
It could fail that way but not nearly as common as a failed gasket into a cylinder(which generally makes it run badly). Another gasket failure point would be the intake water crossover.
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