Engine Swap, Mercruiser to Crusader

ojotaylor

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New guy here, I'm pretty sure I'm posting this to the correct forum. If not, I apologize. Long story short, I have a blown engine...water jacket cracked on both sides and a large crack on the block under the intake. The current engine is a Mercruiser 260, serial number 6794827. Everything else is fine on it, heads accessories, everything. It will even start and run, when it gets to operating temp, that's when the oil and water start mixing. I had a client of mine give me two crusader engines in running condition, he just felt it was time to change them. Both are 5.7 350 CID just like the mercruiser. From initial inspection, it seems this will be an easy swap. But I read somewhere in here that crusaders aren't interchangeable with mercruisers. The only numbers I can get off the stickers are these, Crusader serial 099041, Model CM350L, VO4237MM Crusader replacement block. I cannot find anything other than the year the crusader engines were made on the internet. I have an alpha one out drive in great condition that I was using with the mercruiser. Anyone have any experience with this kind of swap? Good/bad news? Any help would be greatly appreciated.
 

Bondo

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Ayuh,..... Welcome Aboard,...... Dependin' on the Vintages involved, swappin' the Long Blocks is plug, 'n play,.....

Changes happened in '79, '87, 'n '96,....

Swappin' bobtail motors, Ain't,.....

They're both GM 350s, but dressed entirely differently,....

Stripped to the long block configuration, they're the same motor,.....
 
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ojotaylor

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Thanks Bondo. That's what I was thinking. The heads are slightly larger, which doesn't affect anything. I put some parts next to it last night and everything seems to line up perfectly. I'm cleaning them up this evening and doing the engine swap this weekend.
 

Bondo

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The heads are slightly larger, which doesn't affect anything.

Huh,..??..?? Combustion chambers,..?? I thought yer swappin' Long Blocks,..??..??

Do ya know the Vintages of these motors,..??

The Merc number looks to be an older motor,.....
Know nothin' 'bout the Crusader numbers,....
 

ojotaylor

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Now that I'm deeper into this swap, got the blow engine out yesterday. I'm stuck now though. The flange that the flywheel connects to is different on each motor...turns out the two I acquired are short blocks and have been sitting so long that they are seized. I'm waiting on PB Blaster to do its job to free up one of them. The pistons are damaged as well so I'll only be using the block. My question now is, will I be able to use the crank out of my old block in the new block? The casting number on the one that is damaged, that I'm taking out is GM 14010207. The casting number on the one I'm swapping everything over to is GM10243880. The only difference I can see on the two are the connections from the crank shaft to the fly wheel...which is why I'm wondering if I can just use my old crank... I'm uploading pics in a second...
 

Bondo

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Ayuh,..... That's Why it's so important to know the Vintages of the motors,.....

The black motor is pre-86, with the 2 piece rear main seal,...
The rusty motor is newer with the 1 piece seal,....

No,... Neither the blocks or the crankshaft can swap between the 2,....

The newer motor could be used, but only as a Long Block Swap,......
 

ojotaylor

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Finally got everything back together and in the newer block. Now I'm on the hunt for a matching flywheel and engine coupler for the newer block with the one piece rear main. I've located one locally, $125 for the flywheel and $125 for the coupler. The mechanic said I was probably going to need a new starter. Can anyone explain this to me? The old flywheel was 12.75" with the bolt spacing around 3 5/8". Then new bolt spacing is 3". So if I purchase those parts, and the new flywheel is 12.75", it seems like my original starter would still work right? The flange of the crank on the new block is the same distance as the flange on the crank from the old block. Just trying to wrap my head around the new starter thing...
 

Bondo

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So if I purchase those parts, and the new flywheel is 12.75", it seems like my original starter would still work right?

Ayuh,.... I can't see how it Wouldn't fit,.....
 

ojotaylor

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Back again. Got the engine back together with the 14" flywheel, the triangle style coupling and the starter that goes with the larger flywheel. Dropped the engine back in and it seems to be seized. I didn't change the bell housing even though i went from the doughnut style coupling that bolts to the crankshaft lugs. Is that what is stopping the engine from turning over? I set the valve lash with the bell housing off and the engine would turn. I try to turn it manually with the bolt at the harmonic balancer and all it wants to do is tighten the bolt even with the spark plugs removed.
 

Bondo

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Dropped the engine back in and it seems to be seized. I didn't change the bell housing even though i went from the doughnut style coupling

Ayuh,.... The flywheel covers are not all the same,.....

Did you bother to check for clearance 'tween the new coupler, 'n the ole flywheel cover,..??
 

ojotaylor

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I sure didn't...kicking myself for that now. When I bolted the housing on, I didn't hear, see or feel metal conact metal...I know that doesn't mean anything.

This is my plan. I purchased some longer bolts that screw into the harmonic balancer today. I'm going to use them as leverage with a long pole to see if I can turn the engine manually either way before I pull the engine out again. I'll post another reply in about 5 hours when I get home to let you know how it goes. If I hear contact or feel it I'll known have to pull the engine again...if not I may have a failing starter.
 

ojotaylor

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I got home early. My little bolt test didn't work. So I hooked the engine up to my hoist for support and loosened the bolts on the bell housing maybe a 16th of an inch an VIOLA! We have movement!

Now to my next question. Should I bite the bullet, pull the engine and put the new bellhousing on once I get it or put 1/8-1/4" spacers in between the block and bellhousing?
 

Bondo

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Now to my next question. Should I bite the bullet, pull the engine and put the new bellhousing on once I get it or put 1/8-1/4" spacers in between the block and bellhousing?

Ayuh,.... Get the Right cover,.... It'll offer no support with the washers 'tween the flanges,....
 

ojotaylor

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Update...she's running!!! Ended up getting a new distributor cap (the old one was cracked at the #4 point) and a new starter. In my diagnosing I ended up moving the distributor 180 degrees off which made it not start and backfire through the carb. Flipped it back 180 degrees and she fired right up and sounds/runs smoother than ever. I'm putting it in the water this evening for a water test. Thanks for your help Bondo, this forum has helped more than anyone will ever know.
 
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