Hydrolocked 4.3 Options

[atv_freak]

I recently bought a 1990 Maxum 2150 that is in exceptional condition except for the hydrolocked 4.3L Mercruiser engine. I have a running 4.3L OMC engine sitting in my garage from a recent rebuild attempt to a Donzi hull (I quit once I found the Maxum).

I got the engine out of the Maxum this weekend, started tearing it apart (it already had the heads and intake off) and verified that there are multiple bent piston rods.

My original plan was to swap all the Mercruiser stuff over to the older OMC engine and drop it into the Maxum, but I'm not sure if it is going to be that simple.

So here is what I'm working with and I would love some advice!

The hydrolocked engine was a new crate engine a couple of years ago and has around 40 hours on it now.
12600234 block
12557113 heads
12550460 intake

The running engine was supposedly rebuilt a couple years ago after freeze damage and has around 100 hours on it now (but considering the previous owner, I'm taking that as worth a grain of salt). It seemed to run fine for the couple of hours that I used it before I pulled the boat off the water due to structural issues.
10227196 block
0238181 heads
6269732 intake

My big issue with running the rebuilt engine the way it is, is it (from what I've read) does not have vortec heads and is a 12 bolt intake/2 barrel carb. I'm afraid it is going to be under powered for the Maxum. So I'd like to swap the vortec heads and 8 bolt intake/4 barrel carb over and enjoy that extra power (though probably still a little under powered for the size of the Maxum). If I do that, do I need to replace the rocker arms and pushrods (all those parts from the vortec heads are sitting in a box so I can't put them back in their original spots)?

I've had a couple people tell me to just replace the bent connecting rods and run the hydrolocked engine (assuming the cylinders and pistons are still in good shape).

 

[Scott Danforth]

the 4.3 has had 5 major and 35 minor redesigns over the years and the motor was built from parts from various engine plants over the years

the 10227196 block is a 1993-1995 with strut bosses and a 6 or 10 bolt front cover
the 12600234 block is 2006-2011 balance shaft with knock sensor holes

If it was me, I would sell both and build a V8. pretty sure youre going to need the knock sensor holes, other than that no reason not to use the 1993-1995 block.

However you could get a new reman kit for $850 (including rods) take the 12600234 block and rebuild it.

either way, you need to find out the cause of your hydrolock. most likely its your exhaust manifolds. if you have the 1-piece batwing manifolds, there is your smoking gun.

 

[harleyman1975]

I am on the "rebuild it" bus.

 

[Bondo]

Ayuh,..... I see a couple options,.....

#1, take the Merc long block motor to a reliable Machine Shop, 'n have them tell ya what it needs,....

The other option is to strip the older motor to the Short block configuration, 'n install the later model top end, All of it needs to be swapped, heads, valve train, all of it together,....
The older motor, Should have roller lifters in it, so that's good,....
The push rods go with the heads, not the block,...
Don't worry 'bout not matchin' original positions, they'll be Ok, if Ok when installed,...

 

[atv_freak]

If it was me, I would sell both and build a V8. pretty sure youre going to need the knock sensor holes, other than that no reason not to use the 1993-1995 block.

However you could get a new reman kit for $850 (including rods) take the 12600234 block and rebuild it.

either way, you need to find out the cause of your hydrolock. most likely its your exhaust manifolds. if you have the 1-piece batwing manifolds, there is your smoking gun.

I would love to go the v8 route... but that might have to come a little ways down the road.

As far as the exhaust manifolds, I'm planning on picking up some acetone and checking for leaks. As long as that test is good, I'm going to have the surfaces trued up (or at least call around and get some quotes) since they are aftermarket GLM manifolds and that seems to be the biggest problem with them.

The other option is to strip the older motor to the Short block configuration, 'n install the later model top end, All of it needs to be swapped, heads, valve train, all of it together,....
The older motor, Should have roller lifters in it, so that's good,....
The push rods go with the heads, not the block,...
Don't worry 'bout not matchin' original positions, they'll be Ok, if Ok when installed,...

This is what I was hoping I could do, I just wasn't sure with all the 4.3 differences. So the cam would have to swapped over as well? If so, does it need another break-in period?

 

[Rick Stephens]

Roller cams don't need much in the way of break in. Swap it over and run it. Be extra careful on inspection of the exhaust.

 

[Bondo]

So the cam would have to swapped over as well? If so, does it need another break-in period?

No,... The cam, 'n lifters oughta be fine, the push rods, 'n everything else above 'em gotta be swapped,...

Roller lifters don't need to be broke in, like flat tappets cams, 'n lifters,....

 

[bruceb58]

As far as the exhaust manifolds, I'm planning on picking up some acetone and checking for leaks. As long as that test is good, I'm going to have the surfaces trued up (or at least call around and get some quotes) since they are aftermarket GLM manifolds and that seems to be the biggest problem with them.

Personally, I would get rid of these GLM manifolds

 

[NHGuy]

The GLM manifolds exhaust tract is designed nicely. Reason I am calling them well designed is that the insides of the manifolds have directing vanes instead of just an open chamber. So they are somewhat header like.
You just have to get the mating surfaces to the risers true. When you are certain no cooling water can enter the exhaust tract, it's safe to run.

 

[atv_freak]

Alright guys, thanks for the advice! I gotta order some gaskets and get the manifolds squared away and I should be ready to put everything back together.

 

[bman440440]

No Title

The GLM manifolds exhaust tract is designed nicely. Reason I am calling them well designed is that the insides of the manifolds have directing vanes instead of just an open chamber. So they are somewhat header like.
You just have to get the mating surfaces to the risers true. When you are certain no cooling water can enter the exhaust tract, it's safe to run.

I have a new set of GLM's on my boat... and love them... I have over 125 hours on them in about 2 months and decided to break them apart and check things out and everything is in top shape!! I do believe that the older GLM's had some issues but they seem to have fixed the issues.

 

[atv_freak]

I was looking through my phone pictures this afternoon and it turns out I have HGE manifolds... guess I got confused after researching them with all the different three letter manifolds!

 

[atv_freak]

I just can't catch a break! This is in the running engine!

 

[Rick Stephens]

I just can't catch a break! This is in the running engine!

picture link broken at PB

 

[atv_freak]

Hmm... not sure what is going on. I'll have to look into it when I get home (don't have the password saved on the work pc and I can't remember it)!

The picture is of one of the pistons... it has a good size chunk missing on the top edge.

 

[Rick Stephens]

That sucks. Happened a while ago though. Looks like it was running that way for long enough to carbonize a lot of oil. Next hole looks perfectly clean. Might just be a bad spot on a piston. Happens.

 

[atv_freak]

Look like Photobucket decided to start working... so more pics.

Here is the broken piston... looks like it is just a stock Mercruiser/OMC/Volvo piston. Found a couple on Ebay... stick a used one in there and run it?



I tried googling these numbers for the pistons in the hydrolocked engine but I couldn't find anything... any idea what these are?





And the connecting rods (at least three of them are bent)... wasn't able to find much info on these either.

 

[Rick Stephens]

I thought this was the running motor.. this is the hydro'd motor. No wonder the piston broke. Get a full set of rods and pistons for a V8. Cheap.

 

[atv_freak]

Sorry, that wasn't very clear... the first picture is of the piston from the running engine. The next few pictures are of the pistons/rods from the hydrolocked engine.

 

[atv_freak]

Looks like everything in the hydrolocked engine is stock mercruiser parts as well...