4.3 Liter Motor

I have a 4.3 liter in a 1992 Wellcraft that i just got at a deal. I now know why. the exhaust manifolds are cracked. There is water in a few cylinders and motor is stuck good. I have put Marvel Mystery Oil in cylinders and am waiting on that to work a little. The outside of the block looks great no signs of cracks at all. There is no water in the oil.

Where else could i check the block or could the water in the cylinders be from exhaust valves?

If the motor is busted will a 4.3 from a blazer work and if so, is it a direct drop in or do i need to use crank and internals from boat motor. I have found several Blazers on Craigslist for good prices

First post and have already found a ton of useful info on here.

Re: 4.3 Liter Motor

firecapt13 said:

I have a 4.3 liter in a 1992 Wellcraft that i just got at a deal. I now know why. the exhaust manifolds are cracked. There is water in a few cylinders and motor is stuck good. I have put Marvel Mystery Oil in cylinders and am waiting on that to work a little. The outside of the block looks great no signs of cracks at all. There is no water in the oil.

Where else could i check the block or could the water in the cylinders be from exhaust valves?

If the motor is busted will a 4.3 from a blazer work and if so, is it a direct drop in or do i need to use crank and internals from boat motor. I have found several Blazers on Craigslist for good prices

First post and have already found a ton of useful info on here.

Click to expand...

well you have a 50/50 chance of getting it loosened up and a 50/50 chance of it running if you do!
For how long and how well it will run ,nobody knows yet !

as far as cracks and water in the oil that is also yet be seen as you have not run it yet !


you have your hands full at the moment and if you do get it to run you still need manifolds and other parts too.

another 4.3 can be used with some part swapping and being setup properly!


fish

Re: 4.3 Liter Motor

Will only a truck motor work or a 4.3 from a car work. I didn't know if there was a difference in RPM ranges between car boat and truck

Re: 4.3 Liter Motor

Truck block would be best since the cam is close to marine

Re: 4.3 Liter Motor

Another question. If looking for an engine from a truck or van that I do not want to rebuild what is a mileage range that will be ok for a boat

Re: 4.3 Liter Motor

I imagine the best or Only answer to that would be AS Low as possible on the mileage !

fish

Re: 4.3 Liter Motor

I went through a similar situation a couple of years ago on my 1989 VIP Valiant. I do think that the gaskets are different on a marine engine, and I am pretty sure the marine engine will have a stainless steel crank, but don't hold me to that. You can get an engine on out of an old blazer, but I don't think that is the route that I would take unless you are going to unload this thing on somebody else soon. Chances are, you are going to find an engine with over 100K miles, with heads that need to be redone, gaskets that leak, and no idea of the maintenance history. Do yourself a favor and have a good machine shop sell you a a new engine; remember that chevy blazer didn't run at 3500 rpms under a constant engagement like it will in your boat. Bottom line, installing a worn out 4.3L is just going to give you more headaches than save you money. And really, you can get a 4.3L GM for a pretty good price; the only difference is that you will have problems finding a block that has the fuel pump hole. On mine, I simply installed a good quality electric fuel pump (and installed it properly, near the tank.) I have a good friend that owns a machine shop that made me a great deal on a motor, but you can also find these things all day online, but you will problaby do better at a machine shop. If you are near Missouri, let me know and i will give him a call and see if he can hook you up with a motor!

Re: 4.3 Liter Motor

Ayuh,... And with All the changes the 4.3l went though,...
It'll have to be the Same Vintage...

Re: 4.3 Liter Motor

firecapt13 said:

Another question. If looking for an engine from a truck or van that I do not want to rebuild what is a mileage range that will be ok for a boat

Click to expand...

Check the engine, not the mileage. Does it knock and rattle? Compression?

The internals are the same in boat and truck engines. No forged cranks, "special" bearings, etc....

Re: 4.3 Liter Motor

Getting an engine from a Blazer of S-10 of that same vintage means you may have a "Z" or "W" engine. The "W" engine has a balance shaft and has the spider style fuel injection system. That stuff would need to be swapped for your current setup. Nothing wrong with the non-balance shaft engine but it is rated at lower HP than the balance shaft motor. An AWD Astro/Safari Van generally has the "W" motor.

Re: 4.3 Liter Motor

I found a motor in a Astro that runs good no smoke or knocking. only has 130,000 miles on it. It is same year as the boat and is carb engine not FI.

Re: 4.3 Liter Motor

firecapt13 said:

I found a motor in a Astro that runs good no smoke or knocking. only has 130,000 miles on it. It is same year as the boat and is carb engine not FI.

Click to expand...

Ayuh,... You need to reduce it to the Long Block configuration, then bolt on the rest of your old motor Stuff to it...

Don't use the carb, nor Anything else from the Van...

Re: 4.3 Liter Motor

Ok update:
I have pulled the intake and one head from the motor. The inside of the intake valley and cam, push rod, lifters all look new. There is no gunk or rust at all. The cylinder walls on this side have some rust on it, i think it can be freed up and honed out. The head looks good as well as the intake, some rust in waterways but it doesn't appear to be cracked. I talked with a friend at a machine shop and he is going to pressure test heads and block for me.

I still can't get motor to turn. It is still in boat. Is there anything in the outdrive that could be locked up causing the motor not to turn. When in neutral the prop spins free and when you put it in gear prop spins one way, i was told that is correct. Could upper unit be locked up and how do you check

Re: 4.3 Liter Motor

Is there anything in the outdrive that could be locked up causing the motor not to turn. When in neutral the prop spins free and when you put it in gear prop spins one way, i was told that is correct. Could upper unit be locked up and how do you check

Click to expand...

Ayuh,... Remove it....

Re: 4.3 Liter Motor

Update:
Pulled the outdrive today with no problems. It was pretty easy. Also pulled the rest of motor out of boat. Ready for rebuild or replace. I haven't found a crack anywhere on this block that would let the water enter the top of some cylinders. I am going to clean and pressure test block and heads.

While I have unit apart what do I need to check in the gimbal housing or in the outdrive itself. I was going to do water pump in lower unit.

Re: 4.3 Liter Motor

...cause water on top of the pistons usually comes from leaky exhaust...

Re: 4.3 Liter Motor

That is my hope is that it is just from exhaust. Rest of motor looks good. Both exhaust manifolds are cracked.

Re: 4.3 Liter Motor

Ok block is cracked. What other engine options are there for replacing an engine. If i go with inline 6 or 4cyl do i have to change outdrive or what other parts. Trying to decide on a donor boat for salvage parts or going with blazer or van

Re: 4.3 Liter Motor

I replaced my engine last summer with a 4.3L longblock from Rapido Marine in Fl.

it cost me $1,300. plus $150 shipping.

check out thier website at : www.rapidomarine.com

if you order from them, be sure to check that the valves are adjusted properly before starting the engine.

good luck.

Re: 4.3 Liter Motor

firecapt13 said:

Ok block is cracked. What other engine options are there for replacing an engine. If i go with inline 6 or 4cyl do i have to change outdrive or what other parts. Trying to decide on a donor boat for salvage parts or going with blazer or van

Click to expand...

Ayuh,... 4.3ls are a Dime a Dozen,... Why would you want to Change,..??