4.3 block

[Dean M.]

I have a major problem. I bought this boat last year and it ran great and made the choice to put the money in to get it back in shape. I have had the boat polished and a new interior put in and the boat looks better that new. I had not had it out this year. I did start it in march before it went to the shop to be polished and everything was fine. To make a long story short I rushed to finish getting the interior in for this weekend and when I started it yesterday I soon found I was getting water in the oil in a big way. Since today is my birthday I think I could have done with out this gift. I'm broke from the $4,000 in cosmetics and now need to find a block. I would like to know if a regular 4.3 block from a truck can be used or does it have to be a marine block. I'm dying to get back on the water and will be doing most of the work myself. Any help would be great.

 

[CharlieB]

Re: 4.3 block

Depends on the year make and model,

Not all 4.3's are the same

Generally, industrial/marine engines are built heavier than automotive

Throughout the years improvements have been made, the Vortecs.

An automotive engine can work, for a limitedly shorter time than a marine engine, way pay to do it again in another year, maybe less, maybe more. It is NOT worth it.

You can get an exchange engine with a moderate core charge for the cracked block and have a warranty.

 

[baylinerbill]

Re: 4.3 block

Did you check your riser gaskets to make sure the aren't rotted and leaking?

Don't jump into a new motor right away. rule the other things out because if you don't and it was the risers the same thing will happen.

 

[180shabah]

Re: 4.3 block

it is most likely a head gasket or cracked block, exhaust issues tend to dump water on top of the pistons and cause hydrolocking.

As for using an automotive block, there is no reason not to, they are the same. There are still a few things to remember. Head gaskets(no steel) will need to be changed for marine use, as will the core plugs(brass) and cam if the donor engine did not come from a truck or van. Then just bolt on all of your marine externals hit it with a little paint and reinstall it.

 

[Silvertip]

Re: 4.3 block

Early 4.3's were not balance shaft engines. '92 and up "W" coded engines were balance shaft motors.

 

[180shabah]

Re: 4.3 block

Yes there have been several changes to the 4.3 over the years, but most of them will make little difference. The big thing to watch for is mechanical fuel pump boss. If you have a mechanical pump now then you will want to stick with an older block, to avoid the expense of switching to an electric pump.

The balance shaft makes a huge difference in vibration in the 1200-1800RPM range, but will not make any difference in compatability.

The "Vortec" engines are good for about 30 additional horsepower over the older head design. However, they require a vortec specific intake manifold and also tend to be more susceptible to water injestion so cam selection is a little more critical.

 

[Bansheex13]

Re: 4.3 block

The "Vortec" engines are good for about 30 additional horsepower over the older head design. However, they require a vortec specific intake manifold and also tend to be more susceptible to water injestion so cam selection is a little more critical.

What do you mean by "water injestion"? Can you explain that a little more,I am putting a new 4.3 in my boat now and would like to know a little more on that. What about a cam that came in a Blazer 4X4 (1997) would that be sufficiant or should I swap in my (1996) marine cam?

 

[bjcsc]

Re: 4.3 block

Dean M.: Where are you (geographically)?

 

[Uraijit]

Re: 4.3 block

What do you mean by "water injestion"? Can you explain that a little more,I am putting a new 4.3 in my boat now and would like to know a little more on that. What about a cam that came in a Blazer 4X4 (1997) would that be sufficiant or should I swap in my (1996) marine cam?

Water ingestion, is where the cam holds the exhaust valves open for too long, and causes the pistons to "suck" water into the engine through the exhaust.

If your marine cam is still in good shape, I'd swap it over (don't forget to break it in to the new engine though).

Like others have said, there's no reason not to use an Automotive block, as long as you replace the freeze plugs, head gaskets, and sometimes cam.

Happy birthday, BTW.