1989 vs 2008 4.3 differences

[1987sylvanoffshore]

What exactly is different between the 2 engines (just the bolt on stuff) ?
More specifically are the power steering and alternator brackets the exact same or different from the older motors 1989 vs 2008? Flywheel the same size? I’m purchasing a 2008 and want to see it those items mentioned can be swapped from my old engine of if I’m going to be looking for new ones. Thanks

 

[matt167]

4.3 has many fairly major differences between those years.. Just going from 1989 to 1993 there were some fairly major improvements..

I think even the intake manifold is different. I know it would be on a 5.7L for sure, which is a Vortec head vs pre vortec difference

 

[Scott06]

Main difference would be later engine will have vortec heads roller cam and balance shaft And serpentine belt system. 2008 will make 190/220 hp (2 bbl/4bbl) vs 175/205 for the older one. balancer and flywheel will not swap. Starter alternator and ps pump may swap but you need to look at them side by side.

this was assembled by another member https://forums.iboats.com/threads/complete-history-of-the-4-3-liter-with-casting-numbers.693935/

 

[nola mike]

Most things will swap over with varying degrees of difficulty. You'll need to swap the balancer, you'll need new water pump and new intake manifold, a bunch of metric nuts and bolts. I thought the flywheel would swap, but I used the one from my donor. Alt, ps, tstat, exhaust straight bolt on.

Check my swap thread for more heartache:

Nola Mike's 3.7/470 --> 4.3L swap thread

Sorry I had to be the bringer of bad news but better to find out now than later. Believe it or not my vision got better after I passed 60! Especially close up. The opposite of what happens in the 40s.

forums.iboats.com

 

[MichaelBC]

Hello,

I am just about to finish such a swap.

My original engine is from 1993, so no Vortec heads. The new engine is just factory new with Vortec heads, balancer shaft and roller rocker arms.






So I can tell you the difference between new and 1993.
Balancer - same
Flywheel - same
Flywheel cover same
Exhaust manifold - same
Starter - same
Oil dipstik is different but old one could be used
Old circulating water pump does not fit on the new engine
Intake manifold does not fit. The old one has less bolts
The new one has this serpentine belt and the alternator on the other side when it is built by facory. But all the holes and threads to mount the brackets the old way are there. THe only issue is that GM seems to have randomly mixed metric and imperial threads. So the flywheel cover, engine mounts and starter are metric. The water pump is imperial.

So what needs to come new is only the water pump.

Old water pump is in the back




So the flange with 3 holes does not fit here on the new engine.




The old engine looks different




New oil dipstick with drain hose


Old version


The new dipstick hose is much to high and I will have to cut it and also the dipstick so I can close my engine cover.


The new engine also has a coolant drain thread only on starboard side. the one new to the oil filter is missing. The old engine had one on both sides.

 

[Scott06]

Yeah the mixed US and Metric sizes is pretty funny, not sure why GM did that as the US size 3/8" x16 is so close in size to the M10 on the metric blocks.
Usually the block casting number will have an M in it like mine was a 090M for metric.

 

[nola mike]

Yeah the mixed US and Metric sizes is pretty funny, not sure why GM did that as the US size 3/8" x16 is so close in size to the M10 on the metric blocks.
Usually the block casting number will have an M in it like mine was a 090M for metric.

That freakin killed me when I did mine. Couldn't figure out why my bolts were stripping out when I torqued them down. Sometimes. And you shouldn't need to cut the dipstick, just the tube.

 

[Scott06]

That freakin killed me when I did mine. Couldn't figure out why my bolts were stripping out when I torqued them down. Sometimes. And you shouldn't need to cut the dipstick, just the tube.

When you yank the 4.3 and put in a 5.7 the bolts will all be us sized so no worries...

 

[MichaelBC]

That freakin killed me when I did mine. Couldn't figure out why my bolts were stripping out when I torqued them down. Sometimes. And you shouldn't need to cut the dipstick, just the tube.

If I cut the tube only then my dipstick will go in to deep. So from my understanding I will need to cut of the the same length of the dipstick as I cut of the tube, so the end of the stick is on the same level again.

 

[nola mike]

If I cut the tube only then my dipstick will go in to deep. So from my understanding I will need to cut of the the same length of the dipstick as I cut of the tube, so the end of the stick is on the same level again.

At least on mine, the dipstick was shorter than the tube already and didn't need to be cut. The tube extends to the bottom of the oil pan on the marine engine so you can suck out the oil. If you cut the tube you'll need to access the drain plug to change the oil (I don't think a hose through the dipstick tube will make it to the bottom of the pan). I used an oil drain hose that I can pull through the bilge hole.

 

[Scott06]

At least on mine, the dipstick was shorter than the tube already and didn't need to be cut. The tube extends to the bottom of the oil pan on the marine engine so you can suck out the oil. If you cut the tube you'll need to access the drain plug to change the oil (I don't think a hose through the dipstick tube will make it to the bottom of the pan). I used an oil drain hose that I can pull through the bilge hole.

Maybe take a tubing bender and bend it to the side so you can keep the hose connection for sucking oil??

 

[Lou C]

Hello,

I am just about to finish such a swap.

My original engine is from 1993, so no Vortec heads. The new engine is just factory new with Vortec heads, balancer shaft and roller rocker arms.




View attachment 338864

So I can tell you the difference between new and 1993.
Balancer - same
Flywheel - same
Flywheel cover same
Exhaust manifold - same
Starter - same
Oil dipstik is different but old one could be used
Old circulating water pump does not fit on the new engine
Intake manifold does not fit. The old one has less bolts
The new one has this serpentine belt and the alternator on the other side when it is built by facory. But all the holes and threads to mount the brackets the old way are there. THe only issue is that GM seems to have randomly mixed metric and imperial threads. So the flywheel cover, engine mounts and starter are metric. The water pump is imperial.

So what needs to come new is only the water pump.

Old water pump is in the back

View attachment 338865


So the flange with 3 holes does not fit here on the new engine.

View attachment 338866


The old engine looks different

View attachment 338871


New oil dipstick with drain hose
View attachment 338872

Old version
View attachment 338873

The new dipstick hose is much to high and I will have to cut it and also the dipstick so I can close my engine cover.


The new engine also has a coolant drain thread only on starboard side. the one new to the oil filter is missing. The old engine had one on both sides.

this concerns me because I question how the port side of the block could fully drain without a drain on that side. There is a boss machined there that on some engines you might find a knock sensor screwed in and that might have to be removed to drain it. I'd look closer and would be really surprised if there is not a drilled hole there, maybe filled with a square or allen plug?

PS with a nice new engine like that all clean on the inside I'd install a closed cooling system, it will make the engine last 2x as long if you boat in brackish/salt water and make it easier to winterize as well.

 

[nola mike]

Maybe take a tubing bender and bend it to the side so you can keep the hose connection for sucking oil??

Bend what to the side? There's a baffle in the pan preventing anything from reaching the bottom. Merc uses a whole different tube assembly on the newer engines. Although I guess I'm not sure if the new pan started with the vortec heads or earlier

 

[MichaelBC]

At least on mine, the dipstick was shorter than the tube already and didn't need to be cut. The tube extends to the bottom of the oil pan on the marine engine so you can suck out the oil. If you cut the tube you'll need to access the drain plug to change the oil (I don't think a hose through the dipstick tube will make it to the bottom of the pan). I used an oil drain hose that I can pull through the bilge hole.

There are three reasons why I do not care too much about the thread on the top to suck oil out.
- I do not own such a pump
- The dipstick tube is combined with an oil drain hose that can be pushed through the bilge hole
- My oil pump has a thin long hose than can be pushed through the dipstick tube to the bottom of the oil pan.

If I cut the tube only then the dipstick will go too far in.

 

[MichaelBC]

this concerns me because I question how the port side of the block could fully drain without a drain on that side. There is a boss machined there that on some engines you might find a knock sensor screwed in and that might have to be removed to drain it. I'd look closer and would be really surprised if there is not a drilled hole there, maybe filled with a square or allen plug?

PS with a nice new engine like that all clean on the inside I'd install a closed cooling system, it will make the engine last 2x as long if you boat in brackish/salt water and make it easier to winterize as well.

Well, maybe my wording was wrong. The old engine had this shitty blue plastic plugs on both sides like you can see here.





I call them shitty because on two of them the top just fell off already and cooling water was running into the bilge. If they were solid instead of hollow inside then the damage would not be that much. So I filled the little holes with expoxy resin on the new ones.

The new engine has one bolt on starboard side.....



.... but no thread like this on port side.




Maybe if you would remove the big plug near the oil filter, that would drain the engine.




I am also not too worried about this as I did buy a closed colling system already for the old engine and will swap that to the new one. So there is no need to drain the engine for the next couple of years as I am running it with anti freeze for rust protection and during winter my boat is in a heated garage hall.

 

[nola mike]

My mistake,I thought you were bringing the old oil tube over. You already have the correct one on there. Yes, like Scott said bending the tube if possible would be the cleaner solution, but cutting both should be ok as well. Obviously you'd need to scribe some new marks on the bottom of the dipstick. That hole on the port side certainly looks like a drain, but like you said it's probably a moot point with the closed cooling. Still might be worth verifying while the engines out though

 

[Lou C]

Well, maybe my wording was wrong. The old engine had this shitty blue plastic plugs on both sides like you can see here.

View attachment 338940

View attachment 338941

I call them shitty because on two of them the top just fell off already and cooling water was running into the bilge. If they were solid instead of hollow inside then the damage would not be that much. So I filled the little holes with expoxy resin on the new ones.

The new engine has one bolt on starboard side.....

View attachment 338942

.... but no thread like this on port side.

View attachment 338943


Maybe if you would remove the big plug near the oil filter, that would drain the engine.

View attachment 338944


I am also not too worried about this as I did buy a closed colling system already for the old engine and will swap that to the new one. So there is no need to drain the engine for the next couple of years as I am running it with anti freeze for rust protection and during winter my boat is in a heated garage hall.

View attachment 338945

Yep that recessed hex head plug is the drain. Knew it had to be there! Good you have closed cooling already.

 

[MichaelBC]

As it is easier to do as long as the engine is outside the boat, I decided to cut the hose today.

I found the mark hard to see already on the old dipstick and so I cut some gaps into it which made it much easier for me to see the level area.


So I will just do that on the new one too.

I cut of about 11 cm.



Then I used the cut off hose as a measuer for the stick, plus the thickness of the cutting disc.



Mark it,

Cut it, twist the edge, cut the marks ... done.

 

[MichaelBC]

Today I found another thing that can not be swapped.
The brackets of the electrical connector and the oil monitor were fixed with the bolts of the intake manifold. The distance of the holes does not match the Vortec bolts distance. So will think of a different place where to mount this. Both do not neccessarily need to be mounted to the engine.

 

[Scott Danforth]

some light reading. however I would have suggested swapping the entire bobtail

complete history of the 4.3 liter with casting numbers

thought I would post the complete history of the 4.3 liter that I could find. These are links and articles that I have bookmarked for my own use, however they should help many people. it may help some people when looking for parts or sourcing a salvage yard motor or a reman. keep in mind that...

forums.iboats.com