Cracked Block 5.7 Replacement options (Updated)

Joined
Jul 15, 2003
Messages
7
I just bought a 1984 Well Craft Elite 210 XL. I got a good deal on it but the block was not winterized good enough (water still in the block) and cracked (of course the freeze plugs stayed in). It runs but water leaks out. I would like to use it this season before it gets to cold however with the purchase I can't afford a rebuilt marine engine right now. I do have a rebuilt with low mileage 4x4 truck chevy 350 out of a 1977 model. It is a 4 bolt main and has about 30-40k on a rebuild. I was wondering if I swapped all the accessories (dist, alt, power steering pump, carb, oil pan and baffle, etc) on to it, if it would do the job. It has a mild RV cam in it already or I can replace the cam with one you guys suggest. I don't know if i need to replace freeze plugs or not as it is a freshwater only boat. I may be able to afford a rebuilt marine engine next season but was wondering if this would work.<br /><br />Had a little more time to climb around the motor today and take a look at it. There is water in the oil for sure. Pulled the dipstick and saw it on there. I did not however see any indication that the block was cracked. The manifold of the left side is cracked and has water seeping out of it when you tap on it. The other side looks like it might be developing a crack too. I also noticed orangy looking deposits on the side of the motor between the head and the block. I am not sure if they dripped down from the manifolds of if the head gaskets are leaking on both sides. I did not however see any indication that the block was cracked. I am guessing that the manifolds are a pretty spendy item. I was also wondering if they can be repaired. the crack is on the lower part and not near any bolt holes. Although it is a PITA I have welded cast before and had good results. Could this be where the water is entering the motor? Excuse my ignorance on Marine motors. I read something about a flapper valve that I think from what I understand keeps water from flowing back into the motor from the exhaust. I am guessing that the thing got water in it and blew the head gaskets and probably ruined the motor, but not a freezing and cracking problem like the PO stated. When he said you could see the crack in the block I think he meant the exhaust manifold and just didn't know what he was talking about. I am going to pull the heads to see how exstensive the damage is.
 

foxjohnc03

Petty Officer 3rd Class
Joined
Jun 30, 2003
Messages
79
Re: Cracked Block 5.7 Replacement options (Updated)

At minimum you will need a marine cam for the engine. Why dont you try welding the crack in the old engine. What can it hurt? It should last you through the season and maybe many more.
 

Ralph 123

Captain
Joined
Jun 24, 2003
Messages
3,983
Re: Cracked Block 5.7 Replacement options (Updated)

Very likely not - go to amazon.com and read the first few pages of Dennis Moore's "Small-Block Chevy Marine Performance"<br /><br />Here is a brief excerpt:<br /><br />... Forged pistons instead of cast, Steel crankshaft instead of cast iron, higher lift and longer duration camshaft, better connecting rods ..."<br /><br />You can get a reman marine 350 for about $1,100 - you just swap tin & carb, etc.
 

magster65

Commander
Joined
Sep 1, 2002
Messages
2,573
Re: Cracked Block 5.7 Replacement options (Updated)

In a pinch that engine will work but won't be ideal. I'd also try smearing marine-tex or something like it over the crack if it's only on the outside. I know someone who had his block crack in a Dodge van. He used marine-tex... at least 8 years ago now and it hasn't leaked a drop. The stuff's amazing.
 
Joined
Jul 15, 2003
Messages
7
Re: Cracked Block 5.7 Replacement options (Updated)

This crack is a little worse than just leaking water out it leaks water into the oil too... I am probably going to try and run it. I just can't afford the marine engine right now. If the truck motor dies it is not a huge deal.
 

akriverrat

Chief Petty Officer
Joined
Oct 31, 2002
Messages
588
Re: Cracked Block 5.7 Replacement options (Updated)

if it were me i would not hesitate to swap in the truck motor. most marine blocks do not use hi-po cams, steel cranks, etc. they do have brass casting plugs and ss head gaskets however. BTW, rv/truck cam is usually same or real close to marine.
 
Joined
Jul 15, 2003
Messages
7
Re: Cracked Block 5.7 Replacement options (Updated)

I talked to a local machine shop/ engine rebuilder and he said the same thing. He said they have done a bunch of marine engines and some had the upgraded crank and rods and some didn't. He suggested I cahnge the intake and all accessories that are sealed for marine use over to the truck motor. He also thought they may be able to repair the marine block so I will probably take it too him after I get it out and see what can be done. Can brass freeze plugs be found anywhere or do they have to come from a marine engine parts dealer? Also I am not sure what kind of steel the head gaskets are (standard fel-pro). If this boatis only going to see fresh water is Stainless steel a big deal?
 
Joined
Jul 15, 2003
Messages
7
Re: Cracked Block 5.7 Replacement options (Updated)

I put the update in the original message instead of a new post so please read the bottom of it.<br /><br />TIA<br /><br />-Steve :D
 
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