2000 mercruiser chevy 305 cracked, what next

[onebighead]

Next question. With this boat which runs fine, I see that the block is cracked and has been epoxied just below head. No water and oil mixing that I can find. Just slight seeping at site of crack. I think I may want to change this 305 vortec engine out to a 350 vortec. What would be my issues? Would the tbi be useable on a 350, could I use the same intake manifold, heads etc. ? thanks

 

[RogersJetboat454]

Re: 2000 mercruiser chevy 305 cracked, what next

Next question. With this boat which runs fine, I see that the block is cracked and has been epoxied just below head. No water and oil mixing that I can find. Just slight seeping at site of crack. I think I may want to change this 305 vortec engine out to a 350 vortec. What would be my issues? Would the tbi be useable on a 350, could I use the same intake manifold, heads etc. ? thanks

All ancillary parts (distributor, starter, alternator, engine mounts, coupling, etc) will swap over with no issues. The intake manifold should be the same from one Vortec V8 to the next, but I would carefully check it over for cracks (and corrosion) before using it, because they are prone to cracking when a freeze happens. Injection system may need to be modified. Don or Bond-o should be able to tell you all about that.

The heads off any freeze damaged engine shouldn't be trusted, not to mention that 305 heads don't belong on a 350 (305 heads have smaller combustion chambers, and the Vortec 305 wasn't a real Vortec). In other words, buy a Vortec 350 long block.

Exhaust manifolds and risers should be replaced, especially if they have age, and were on the engine when the freeze damage occurred.

 

[Bondo]

Re: 2000 mercruiser chevy 305 cracked, what next

All ancillary parts (distributor, starter, alternator, engine mounts, coupling, etc) will swap over with no issues. The intake manifold should be the same from one Vortec V8 to the next, but I would carefully check it over for cracks (and corrosion) before using it, because they are prone to cracking when a freeze happens. Injection system may need to be modified. Don or Bond-o should be able to tell you all about that.

The heads off any freeze damaged engine shouldn't be trusted, not to mention that 305 heads don't belong on a 350 (305 heads have smaller combustion chambers, and the Vortec 305 wasn't a real Vortec). In other words, buy a Vortec 350 long block.

Exhaust manifolds and risers should be replaced, especially if they have age, and were on the engine when the freeze damage occurred.

Ayuh,... I agree with everything stated,... I donno if the 305 'puter will feed the 350 properly, or Not...

I believe the hardware, aka; the throttle body, 'n fuel pumps won't care, it's the software I donno 'bout,...
Never tried it...

Big Ditto on the Heads, buy a Long Block motor, not a short block...

 

[55evinrude]

Re: 2000 mercruiser chevy 305 cracked, what next

I don't think a ecm from a 305 will work on the 350, because I know someone who also had a 305 and went to a 350 and the computer didn't like that. I believe it had problems with idle and going from in gear to neutral. don't know for sure maybe i'm wrong but thats just my 2 cents!

Nathan

 

[matt167]

Re: 2000 mercruiser chevy 305 cracked, what next

In the automotive world, the 350's used larger injectors, and the ECU programming is different. It will run, but not well. If I had to guess, in a boat engine, those problems will be amplafied, being the engines run 3-5k RPM pretty regular

 

[ENSIGN]

Re: 2000 mercruiser chevy 305 cracked, what next

I've tried making this change on a volvo penta TBI and can tell you that it will not work.The best advice I can give is either forget the 350 or get a used 350 intake manifold and carb.

 

[onebighead]

Re: 2000 mercruiser chevy 305 cracked, what next

thanks all for the replies. It looks like I will stay with a 305 as I found a good block and plan on rebuilding. I would have liked to build a 350 but unsure how computer would respond to differences in parameters. Also I could not find anyone with facts about those computer issues. I even tried a searay dealer and no help.

 

[Fishermark]

Re: 2000 mercruiser chevy 305 cracked, what next

boat which runs fine, I see that the block is cracked and has been epoxied just below head. No water and oil mixing that I can find. Just slight seeping at site of crack.

If you enjoy working on engines, etc it would be an enjoyable project to replace the engine with a rebuilt 305.... BUT many engines live long lives with the type of crack and repair you are describing.

A good cleaning and another layer of epoxy may do the trick.


Just sayin....

 

[Tail_Gunner]

Re: 2000 mercruiser chevy 305 cracked, what next

Model yr 2000 should have a mefi ecm. Post the numbers on the ecm for clarity.

OBD Diagnostics, Inc. - Custom MEFI Tuning

Give those guys a call tell them what you have and they will tune the ecm towards the motor you have in the boat.

Build the motor you want do not worry about tbi itself or the accy's there all the same..4.3...5.0...5.7 efi parts are all the same.

 

[RogersJetboat454]

Re: 2000 mercruiser chevy 305 cracked, what next

Build the motor you want do not worry about tbi itself or the accy's there all the same..4.3...5.0...5.7 efi parts are all the same.

Mostly the same...

I'm sure you would agree, the manifolds, injection, and distributor ain't going to be the same between a 4.3 and a V8.

 

[Tail_Gunner]

Re: 2000 mercruiser chevy 305 cracked, what next

Mostly the same...

I'm sure you would agree, the manifolds, injection, and distributor ain't going to be the same between a 4.3 and a V8.

Distributor manifold..nope same principle.. this motor the rest yep. Do a parts cross reference the only variance will be pulse width and timing on the ecu. I would be amazed if they varied anything for mpi ..why..marine intakes ae quite special they have oversized injectors and ports from the start

GM Performance :: View topic - lokking for a marine intake for an l31

Here to make it simple marine ecu's use common voltage reference why change? map sensors just read pressure..knock sensors pick up knock....fuel pressure is constant IAC etc.

My referecnce is injectors..sensors etc not manifold or dist

 

[onebighead]

Re: 2000 mercruiser chevy 305 cracked, what next

here are some pics of the engine in question.

 

[onebighead]

Re: 2000 mercruiser chevy 305 cracked, what next

sorry, but I can not seem to load pics to this forum. No matter what I try I get a message that file is too large.

 

[Bondo]

Re: 2000 mercruiser chevy 305 cracked, what next

sorry, but I can not seem to load pics to this forum. No matter what I try I get a message that file is too large.

Ayuh,... So resize 'em to 480x640...

 

[90stingray]

Re: 2000 mercruiser chevy 305 cracked, what next

We had an ol 78 webbcraft that had the same crack but in a 350 block... ran that way for years. Just had a little water in the bilge at the end of the day. Had a blast with that boat. Nowadays, i would prolly be looking for a different block like the OP. Just dont like things if they are not just as they should be. Goodluck!

 

[onebighead]

Re: 2000 mercruiser chevy 305 cracked, what next

Here are some pics of project for those interested. Lets see if these load now. (thanks for hint on uploading)

 

[NHGuy]

Re: 2000 mercruiser chevy 305 cracked, what next

If it runs right and you don't want to replace the motor get some marine tex to do the repair. Then repaint that rusty thing with some shiny black.
If the boat is beautiful and you have the money available, find a block.

 

[ENSIGN]

Re: 2000 mercruiser chevy 305 cracked, what next

It appears the PO did the proper PM (LOL).IT'll make a nice mooring anchor!