4.3L v6 engine block cracked

[onebighead]

I have a 4.3L that I have found to have a cracked block on right side just above dipstick area. Has anyone used marinetex epoxy with much luck? Am I up the creek, and forced to find another block, and if so would any 1990 model work?

 

[69seabreeze]

Re: 4.3L v6 engine block cracked

I'm no expert, but on our trucks we have had good luck using JB weld for some repairs. Never on the block, but we cracked the intake manifold on our suburban and it's still holding up 10k miles later. Also used on the exhaust on my diesel blazer. I believe it holds up to 600 degrees.

 

[ne7800]

Re: 4.3L v6 engine block cracked

I'm no expert, but on our trucks we have had good luck using JB weld for some repairs. Never on the block, but we cracked the intake manifold on our suburban and it's still holding up 10k miles later. Also used on the exhaust on my diesel blazer. I believe it holds up to 600 degrees.

i was going to suggest JB weld as well a friend used it on the cracked block of his race car

 

[tmh]

Re: 4.3L v6 engine block cracked

Do a search here for "JB Weld" and you'll find MANY threads discussing this. I recently asked the same question and it seems some have seen JB Weld work, some Marine Tex and some other brands. Lots of interesting reading.

My conclusion is that it is definitely worth a try to repair with one of these products if it's an older boat and really not worth an expensive re-power. prep work is the key, as you'll read. I'm still not sure which product I will use though - maybe they both work fine if prepped right.

Good luck.

 

[achris]

Re: 4.3L v6 engine block cracked

Cold stitch weld. Using a MIG on a relatively high current and don't let the block get hot.

 

[180shabah]

Re: 4.3L v6 engine block cracked

If you have no internal cracking, then do it. Marine tex and JBWeld are both good choices, but the key to success is cleanliness and preparation.

 

[Ducatinut]

Re: 4.3L v6 engine block cracked

Cold stitch weld. Using a MIG on a relatively high current and don't let the block get hot.

I've also had good luck with heating the surrounding material (with a rosebud tip and medium heat) and stick welding with a high-nickel rod (like Chris said, short beads to minimize local hot spots). Chamfer and chase all the formed cracks with filler. I usually then coat the entire area with JB Weld or similar epoxy - spread it out and heat it gently with a torch or heat gun so that it wicks into any voids.

Welding will push the carbon to the edges of the weld and make it brittle. Use lots of preheat and weld in short bursts to minimize the effect.

Later, be sure to watch for water in the oil. Internal cracks are little harder to fix...

BR,

Chris

 

[chiefalen]

Re: 4.3L v6 engine block cracked

You have any seepage out that crack?

If no, you can drill holes on each end of the crack to stop it from spreading and sanding it real clean. Wash it with aceatone make sure its dry and go at it with jb weld.

When the jb is dry sand it and put another coat, let it dry and paint it.

 

[onebighead]

Re: 4.3L v6 engine block cracked

Thanks everyone for all the good information. We will see how it goes. I will probably try to figure the easy way, if it looks possible.