got some questions on 4.3 repair or replacement.....

[Lou C]

Hello iboaters,
Well my old '88 4.3 finally acted up in a big way. Its been in salt water raw water cooled for at least 15 years. I'm posting this here even though mine is an OMC boat because you get more traffic here, lol. What happened was this: difficult starting, rough running and after some diagnostic work I found water in cyl #2 (front starboard side). Yes salt water. I tried a spare ex manifold I had and it was not from that so I knew it was internal. I pickled the engine after draining all the water out. I just took it apart (not bad really, the intake removal was harder than the cyl heads). The engine spins over easy and there is no rust or scoring in the cyls. The head gaskets to me did not look blown. I think the valve guide area in the head rusted through. Question: is it worth it to try saving this one by bolting on a set of rebuilt heads, or is the block likely to be just behind the heads in terms of potential rust through? I have a few options beside that. One is to get a reman non vortec 4.3 from MM and use my old intake which is fine still. The other is to up grade to a vortec 4.3 with MM's partial engine package and add closed cooling (much more $$). Want to keep the boat just need some guidance on the best (not necessarily cheapest) course to take....
You can click on the full size pix for details...

 

[Oshkosh1]

I'd have my shop magna flux and vac test the head. Also, post some close ups of both sides of the HG and take them to the shop as well. The block should be fine unless there are some very obvious signs of pitting which from what I can see probably isn't the case.

IF you have the tools, I'd disassemble the heads and take a look at everything as well.

 

[alldodge]

With 15 years in salt, I would get another motor, new carte, used donner, truck, or get another fresh water motor and rebuild

 

[Lou C]

I took the parts to my local boat mechanic to see what he thought. He could see where both head gaskets were blown, but he thought the heads might be salvageable. So I'm taking them to a local speed shop that builds race engines and does marine work to see what they say....

 

[Lou C]

Dropped the heads off at SK Speed Shop in Lindenhurst LI. The guy there thought they were not too bad but we'll see what happens...

 

[bruceb58]

While you are at it, get rid of your batwing manifolds.

 

[Lou C]

Yep Bruce I'm going to convert it over to the center riser late OMC/Volvo style.
However I tested both sets of bat wings I have (each used about 6 years in salt) with acetone and neither one leaked.

 

[tpenfield]

Tagging along. I vote for the new long block, if you plan on keeping the boat. After 15 years in the salt, it would be hard to say what is left of the cylinder walls. I have become a firm believer in full closed cooling for salt water use. The engine blocks certainly hold up to the abuse of salt, but after 15 years I would imagine you are approaching the limits.

 

[Lou C]

Got the heads back, they found that there were cracks in the center cyl exhaust ports on both heads, and the water passages were eroded by corrosion to the point where the head gaskets might not seal properly. However the water got in via a blown head gasket, not a crack or rust through on the head as I initially though. The cyls with cracked exhaust valve seats did not have water in them at all.
So when I clean up the block deck really well I'll see how it looks. If it looks like the heads, then its new engine time. I really can't complain, the engine's 29 years old and did at least half in salt water. What more can you ask? My original OMC Cobra outdrive itself is doing just fine. I know a guy over on the Bayliner owners club board designed a full closed cooling system on a Ford 351/Cobra set up with Volvo style manifolds and it worked fine with the Cobra standard impeller. When I set up my system I will try to get an exchanger that is large enough for a V8 which should be more than enough capacity for the V6 with the manifolds on the full system as the V6 holds less coolant than the V8.