1990 Carburated 4.3 v6 merc...

First time poster and first time boat owner. Purchased a 1990 Wellcraft 186 with a 4.3 v6 merc. The engine took on water some how and is smoked. Looking to install another engine. I have read the other DIY Marinizing posts buy none that I read were specific to a 4.3. I was looking into using a engine from a s10 or blazer from a local scrap yard. I do know htat the alt, starter, dist, manifolds ect nned to be used and was planning on using those from the original engine in the boat. Question is if I purchase a 4.3 engine from a yard what on the long block also needs to be changed? Freeze plugs, cam?? How many miles are to much in your opinion for a used engine for a boat? Also I am a auto/jaguar technitian and have no problem doing whatever is needed.

Any help would be greatly appreciated.

Thanks,
Danee Popovski

 

You will also need a high volume, low pressure oil pump, camshaft, marine fuel injection or carburetor, the oil pan may or may not fit.

 

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If I decide to go this way should I look for a vortech or non vortech? Difference between them??

 

Vortec heads are better than the old style. They have a spiral ramp-like casting that makes the intake gases swirl and mix better in the chamber.

 

just wanted to make sure the intake would match up from either model. Also I guess I would have to run an electric pump?

 

The old heads have slanted bolts, the Vortec are vertical. The fuel injection on a car has a return line. Marine systems don't . There are several threads on that. Check out the regulations so you don't end up with an illegal and probably dangerous installation.

 

Thats not what I was sayin', kinda worded it wrong... sorry.

I have a complete 4.3 merc that is in the boat right now. It is a carburated model with all the marine accessories, alt, starter, waterpump, dist, carb, intake, exhaust. The engine took in water from an unknown source at this time (was going to look into it this weekend). I just basically wanted to buy a 4.3 engine long block out of a blazer or s10, install my accessories, brass freeze plugs, marine head gasket and cam if necessary. Ialso know that the newer blocks dont have a place for the machanical fuel pumps. Was just going to run an electric pump for the carb.

Now is that all I have to check is if my intake bolts go in vertical or in on a slant? Anything else to look for that you can think of?

I appreciate your help gonzo.

 

The electric pump needs a shut-off switch that works with oil pressure. Also, the starter solenoind has a bypass to power the fuel pump while you are cranking. Yes, the bolts are the only thing to check. There are two basic types of blocks, with or without counterbalance shaft. If they are the same, you could recycle the camshaft. Also, make sure to install the marine version thermostat.

 

So basically I'd be better off finding a engine no newer than 91 so it has the pump hole in the block...

Have you seen anything common that usually goes wrong with the 4.3l motors to take on water like this? I removed the left exhaust manifold and all the exhaust ports are very heavily rusted almost to the post of not being able to see where the valves meet the head. The boat was bought from Florida and has all the signs of being a straight salt water boat and no fresh water.

 

Yes, it is typical of an exhaust system that hasn't been maintained. Risers should be removed every three years in salt water use. They usually don't last more that about five years. It is not a problem of 4.3 but regular mainteinance on all types.

 

I guess a good start would be to remove the risers and check them first...

 

If there is rust on the exhaust side, throw them away. It is a false economy not to replace them at the recomended time. It just cost you an engine.

 

Well i pulled the entire engine apart...

The manifolds and risers are completely covered in rust on the inside from top to bottom. Heavy scale rust like I have never seen before. Does this mean they are cracked and junk or is it worth it to have them checked?

The rest of the engine is completely wasted also. Nothing salvagable except the accessories, alt, waterpump, starter, distributor, intake, carb all seem to be ok still. Pistons, rods, crank, cam, pushrods, rockers, valves, lifters are all completely rusted, BAD. I also took apart the outdrive because there was water in the oil everything on that seems to be ok and the water leak looks like it was coming in thru a ripped bellow that goes around the splined driveshaft that goes into the engine. That should be a easy fix with a complete seal kit and that bellow.

In your opinion do you think it will be ok to still go forward in marinizing a auto 4.3L? Are the risers the only problem or are the manifolds junk also?

 

The manifolds can be presure checkes fairly easily. However, scale rust means a lot of the metal is gone. I wouldn't mainrize a car engine because they are so many already marinized engines at fairly good prices. If the outdrive had water ot the input shaft, check the gimbal bearing and input shaft seals.

 

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Well here are a few shots of the exhaust manifolds and risers... Don't look to good.