4.3l Block Crack - repair or replace? [Decided to Replace - Adventures begin]

[Struc]

Bought this boat in July, and had it out a few times this summer, and it runs pretty good. However, not knowing much history, now that the boating season is over, I wanted to pull the engine for a winter refresh project. At least one exhaust manifold has a crack, and it didn't idle the best (probably needs a carb rebuild), and I get a little oil film in the bilge area too. Figured I would pull it, strip it down to the short block, and replace all the seals, etc. Well, that was the plan anyway.

Upon getting the exhaust manifolds off, I was able to see something that I was not very happy about.

It's just below the head mating surface on the block. The "Napa" sticker you see is the starter, and the black tube is the dipstick tube.

The engine actually runs really well, and has good compression numbers: 165, 170, 165, 165, 180, 180

Has anyone ever taken a block to get welded up? Or am I just being cheap? Obviously from the rust the crack is into the water jacket, but it can't be too bad or I'd see a much bigger stain there. I also didn't observe any water leaking down on that side of the engine, unlike the other side which had the bad exhaust manifold.

It is the original 4.3l engine for this 1988 Sea Ray, so it is 23 years old, with no signs of having ever been pulled - serial number was in the owners manual - OC326690, and matches the tag on the back of the engine.

If replacement is the only answer, I'm considering going Jimmy/S10 hunting to find a rebuildable core engine. Just need to stay in that 1988-1992 time frame, right?

 

[joewithaboat]

Re: 4.3l Block Crack - repair options, or replace?

Re: 4.3l Block Crack - repair options, or replace?

4.3's are pretty common your local core supplier/wrecking yard should have plenty.

Here is a pretty good overview of 4.3 changes. Keep in mind boat year models usually lag behind autos a bit.
http://www.hotsixes.com/index.php?option=com_content&view=article&id=14&Itemid=12

Repairing a cracked block, for a common block, is not a good option. Replace it!
Good luck!

 

[Bondo]

Re: 4.3l Block Crack - repair options, or replace?

Re: 4.3l Block Crack - repair options, or replace?

Repairing a cracked block, for a common block, is not a good option. Replace it!

Ayuh,.... Agreed....

But, if it's the Only crack, ya might get abit of mileage outa epoxying it up...
I can tell ya, Welding don't work, 'n is usually epoxyed over if attempted...

 

[dollarten]

Re: 4.3l Block Crack - repair options, or replace?

Re: 4.3l Block Crack - repair options, or replace?

Struc , Another way of fixing the crack is a process called pinning" . It consists of drilling and tapping one small hole at a time , usually about an 1/8 inch about a 1/2 beyond the crack . You then tap the hole and screw in a little cast iron screw . They look like little set screws and are screwed in tight so a little material is sticking above the block . You then drill the next hole to be tapped and plugged so you drilling and tapping into the first one . You are overlapping the previous one , so to speak . You keep repeating this process until you drilled , tapped, and plugged your way right across the crack using loctite in everyone , of course . after you are all done , you grind off the protruding plugs and you are set to go This might sound complicated at first but is a old process and is still used today to restore rare castings ........ Check with some of local engine re builders in your area . They might help you out . This might save you a lot of work by saving your good running engine

 

[Bondo]

Re: 4.3l Block Crack - repair options, or replace?

Re: 4.3l Block Crack - repair options, or replace?

Struc , Another way of fixing the crack is a process called pinning" . It consists of drilling and tapping one small hole at a time , usually about an 1/8 inch about a 1/2 beyond the crack . You then tap the hole and screw in a little cast iron screw . They look like little set screws and are screwed in tight so a little material is sticking above the block . You then drill the next hole to be tapped and plugged so you drilling and tapping into the first one . You are overlapping the previous one , so to speak . You keep repeating this process until you drilled , tapped, and plugged your way right across the crack using loctite in everyone , of course . after you are all done , you grind off the protruding plugs and you are set to go This might sound complicated at first but is a old process and is still used today to restore rare castings ........ Check with some of local engine re builders in your area . They might help you out . This might save you a lot of work by saving your good running engine

Ayuh,.... Pinning is Not an option, as it'll cause the block deck to bulge at that point, 'cause the pins are driven under pressure, forcing the surfaces apart...
While the block may not leak, the head gasket wouldn't seal properly either...

The ONLY choices are Epoxy, or Replacin' the block...

 

[joewithaboat]

Re: 4.3l Block Crack - repair options, or replace?

Re: 4.3l Block Crack - repair options, or replace?

I agree on the pinning, i have done it quite a bit on RARE castings. I worked in a hiperf. auto machine shop for a bit. It WILL bulge the area and generally requires machining of any areas that are nearby.

Welding cast iron ALMOST NEVER WORKS waste of time for this!

I didnt mention JB Weld cause people usually throw stones.

If you already have the engine out, thats half the battle, you already know the best course of action.

If you want to wing-it...
I have used JB Weld with great success when was young and poor. It will hold back water in a raw water cooled boat because it doesnt have pressurized cooling system. I even used it in the valley of a v6 buick that lasted two seasons. Anyway if you do that i would drill a hole at each end of the crack, tap & plug it with a epoxy coated allen head cap screw. Then grind a small vee i the length of the crack clean very well (laquer thinner) and apply JB Weld. Without drilling the ends the crack will likely grow.
Best of luck!

 

[Struc]

Re: 4.3l Block Crack - repair options, or replace?

Re: 4.3l Block Crack - repair options, or replace?

Thanks for the advice guys. I was planning on spending $100-$150 for gaskets, etc. It's hard to make that jump to $1000+ for an engine + rebuild, but it is probably the way to go.

Alternatively, what are the upgrade options for this motor. I know about the Vortec heads / balance shaft blocks / etc. Do any of these options bolt right in without having to change the starter, flywheel, bell housing, or anything else, or can you point me to a good thread? I'm pretty happy with the performance of my engine, but am thinking going to a newer, more effecient engine wouldn't be such a bad idea, unless it's going to cost an arm and a leg to get there.

Thanks again!

 

[dollarten]

Re: 4.3l Block Crack - repair options, or replace?

Re: 4.3l Block Crack - repair options, or replace?

I did see that the crack is quite close to the head but with the head bolted on it should make the deck part of the block figuratively speaking , that is until you remove the head you would have to resurface the deck. I'm just making a suggestion . Cracked blocks by any other name are , cracked

 

[joewithaboat]

Re: 4.3l Block Crack - repair options, or replace?

Re: 4.3l Block Crack - repair options, or replace?

I did see that the crack is quite close to the head but with the head bolted on it should make the deck part of the block figuratively speaking , that is until you remove the head you would have to resurface the deck. I'm just making a suggestion . Cracked blocks by any other name are , cracked

?????

 

[joewithaboat]

Re: 4.3l Block Crack - repair options, or replace?

Re: 4.3l Block Crack - repair options, or replace?

Thanks for the advice guys. I was planning on spending $100-$150 for gaskets, etc. It's hard to make that jump to $1000+ for an engine + rebuild, but it is probably the way to go.

Alternatively, what are the upgrade options for this motor. I know about the Vortec heads / balance shaft blocks / etc. Do any of these options bolt right in without having to change the starter, flywheel, bell housing, or anything else, or can you point me to a good thread? I'm pretty happy with the performance of my engine, but am thinking going to a newer, more effecient engine wouldn't be such a bad idea, unless it's going to cost an arm and a leg to get there.

Thanks again!

You could just drop your short block off at the machine shop with a good replacement block core. Go .030 over, turn the crank .010 .010, new rings bearings and pistons. You could be back in buisness for much less than 1000.00 I would think.
You could also buy a wrecking yard late model vortec, roller cam motor. Do to it what you had planed to do with your original boat engine... just check it out new gaskets etc.
I always look for an engine from a clean but wrecked car, figuring the engine is not what put it there.
If you just want easy....
http://www.michiganmotorz.com/vortec-marine-engine-1996current-p-186.html

 

[trevtt600]

Re: 4.3l Block Crack - repair options, or replace?

Re: 4.3l Block Crack - repair options, or replace?

Struc:

I just got done fixing my cracked block in a Volvo Penta 5.0. Motor only hade 300 hrs and ran perfect. I did get lucky and it did not crack the inner water jacket. I did buy this boat knowing it had this crack. I used a product called Lock'n'Stitch. They sell you a kit for around $150-250 thats comes with everything from the drill bits, taps, thread sealent, tapping fluid, and then their specialty screws that actually do the sealing. Here a few pictures.

 

[joewithaboat]

Re: 4.3l Block Crack - repair options, or replace?

Re: 4.3l Block Crack - repair options, or replace?

Struc:

I just got done fixing my cracked block in a Volvo Penta 5.0. Motor only hade 300 hrs and ran perfect. I did get lucky and it did not crack the inner water jacket. I did buy this boat knowing it had this crack. I used a product called Lock'n'Stitch. They sell you a kit for around $150-250 thats comes with everything from the drill bits, taps, thread sealent, tapping fluid, and then their specialty screws that actually do the sealing. Here a few pictures.


View attachment 119484View attachment 119485View attachment 119486View attachment 119487

WOW!!! That looks like 50 or so plugs. Did you do that with the engine in the boat?
A+ for effort! Good Job.
I think that the o/p's crack is too close to the deck surface. Might cause deck to move and pop a head gasket? Maybe not.

 

[trevtt600]

Re: 4.3l Block Crack - repair options, or replace?

Re: 4.3l Block Crack - repair options, or replace?

Thanks Joe!! Your good. 48 plugs actually. And yes, I did this on my side with motor still in boat. Not sure about his crack location. I know the plugs I used did not exert any spreading pressure. They actually pull the crack back together. I used the C series pins instead of the L series pins.

 

[dollarten]

Re: 4.3l Block Crack - repair options, or replace?

Re: 4.3l Block Crack - repair options, or replace?

I was making a rebuttal about bondos comment about that pinning s not an option and figuring if the cyl. head is left on that is should not raise the deck area up . It was really an oops , and I should have put the comment after bondos reply

 

[Struc]

Re: 4.3l Block Crack - repair options, or replace?

Re: 4.3l Block Crack - repair options, or replace?

Trev - WOW. That is some fantastic work there. Thanks for the info. I just don't see that this engine would be worth putting that much effort into - well, at least this block.

There are plenty of 4.3l engines around in boneyards - I just have to search for something priced well. I gotta think I can pick one up for $200 or less, and then rebuild it with parts from my engine (and from my parts boat for that matter - all that stuff is over in storage). I picked up the boat for really cheap, so I don't feel too bad sticking a little $$$ into it to make it reliable. I see them selling for $5k around here in decent condition, and I'm only into it (even with the parts boat price) for under $2500.

Still looking for some answers, though, on what other years of 4.3's would bolt in w/o serious modification or replacement of parts (flywheel housing, starter, flywheel, etc). Will older parts from my engine bolt to a newer 4.3? Intake? Distributor? Fuel pump? Water Pump?

Again, not necessarily looking for a ton more HP, but would like to use newer technology if I can without breaking the bank.

 

[joewithaboat]

Re: 4.3l Block Crack - repair options, or replace?

Re: 4.3l Block Crack - repair options, or replace?

Still looking for some answers, though, on what other years of 4.3's would bolt in w/o serious modification or replacement of parts (flywheel housing, starter, flywheel, etc). Will older parts from my engine bolt to a newer 4.3? Intake? Distributor? Fuel pump? Water Pump?

QUOTE]

That link i gave you in post #2 gives you most all of that info i believe... the year models are sometimes a year or to off, Boats seem to lag behind a bit. The later model higher hp stuff will be electric fuel pump, vortec heads, so your fuel pump and intake are different.

You can use this marine parts link to check your parts vs other newer stuff and posssible differences.
http://www.michiganmotorz.com/marine-parts-accessories-c-32.html

Good luck!
PS i have a 1996 4.3 4brl merc/alpha in a 19 foot bowrider and am pretty happy with the power and fuel economy. I am thinking of adding vortec heads however.

 

[Struc]

Re: 4.3l Block Crack - repair options, or replace?

Re: 4.3l Block Crack - repair options, or replace?

Still looking for some answers, though, on what other years of 4.3's would bolt in w/o serious modification or replacement of parts (flywheel housing, starter, flywheel, etc). Will older parts from my engine bolt to a newer 4.3? Intake? Distributor? Fuel pump? Water Pump?

That link i gave you in post #2 gives you most all of that info i believe... the year models are sometimes a year or to off, Boats seem to lag behind a bit. The later model higher hp stuff will be electric fuel pump, vortec heads, so your fuel pump and intake are different.

Cool, thanks for the extra info. I did read that link you posted, but there wasn't a lot of info about what parts were compatible - it just talked about the differences between the years, or mainly what changed from one generation to the next.

My main concern is the flywheel, flywheel cover, and starter, and how that will all work if I replace the engine with a newer one, so I guess I have more research to do.

 

[Bondo]

Re: 4.3l Block Crack - repair options, or replace?

Re: 4.3l Block Crack - repair options, or replace?

My main concern is the flywheel, flywheel cover, and starter, and how that will all work if I replace the engine with a newer one, so I guess I have more research to do.

Ayuh,... You Should have a 1 pc. rear main seal now, which is the same through current production...

 

[Leedanger]

Re: 4.3l Block Crack - repair options, or replace?

Re: 4.3l Block Crack - repair options, or replace?

I agree on the pinning, i have done it quite a bit on RARE castings. I worked in a hiperf. auto machine shop for a bit. It WILL bulge the area and generally requires machining of any areas that are nearby.

Welding cast iron ALMOST NEVER WORKS waste of time for this!

I didnt mention JB Weld cause people usually throw stones.

If you already have the engine out, thats half the battle, you already know the best course of action.

If you want to wing-it...
I have used JB Weld with great success when was young and poor. It will hold back water in a raw water cooled boat because it doesnt have pressurized cooling system. I even used it in the valley of a v6 buick that lasted two seasons. Anyway if you do that i would drill a hole at each end of the crack, tap & plug it with a epoxy coated allen head cap screw. Then grind a small vee i the length of the crack clean very well (laquer thinner) and apply JB Weld. Without drilling the ends the crack will likely grow.
Best of luck!

Let people throw their stones. While no it's not perfect, JB is pretty incredible and I'd certainly try it before I went and put a new motor in. People often panic about JB weld where they should be panicing about just winterizing properly in the first place, I'd JB weld myself. I have an uncle that always welds and they always seem to hold. He starts with a half weld of nickel and then goes to just a general rod. After that I've seen him grind and smooth with a lil JB at the end for aesthetics (maybe it's just the JB at the end that's holding...lol). Regardless it never fails unless the crack went internal...I'm no shop smith though so take my advice as hear say only....good luck.

 

[Scott Danforth]

Re: 4.3l Block Crack - repair options, or replace?

Re: 4.3l Block Crack - repair options, or replace?

being an '88 you have many options. find a 87-95 4.3 block, or my recommendation would be to find a low mileage 4.3 from a truck after 96 (vortec heads). then get a vortec specific intake, change the head gaskets to marine versions, change the core plugs (sometimes called freeze plugs) from steel to brass, and put in a marine cam. all your other "stuff" will change over to a vortec headed motor except your intake manifold.