Rusted Block

[Intermediate Mariner]

Morning Gents,

I'm the type of guy who HATES to throw anything away (look for me so join the next season of hoarders!)... I always like to think there is a fix.

In evaluating some powerheads, I have one that was locked up. After pulling head and crankcase cover I seen that there was a busted rod nut that apparently caused something to go awry. In any event it is full of globs of rust and crankshaft is rusted pretty good.

HOWEVER, anywhere you check you can flake rust off with fingernail including crankshaft. This tells me that it's just surface rust. There is also some corrosion on the cylinder walls but can easily scrape and cylinder walls feel smooth.

I'll bet the block is good and I also bet that if I soak the crankshaft in muriatic acid it'll be as good as new too.

I learned the hard way not to put aluminum in muriatic acid (it literally ate a gearcase for lunch and darn near exploded!!).

I seen that "CLR" is not recommended on aluminum but that aluminum jelly donesnt work worth a darn. Plus there is a fair amount of calcium in the water areas (this is a '61 evinrude 40 hp).

What can I soak the block in to have it come out glistening?

Can I canabalize pistons AND bearings from another powerhead and just replace rings?

Thanks!

Shawn T
Wichita KS

 

[HVAC Cruiser]

Re: Rusted Block

Welcome to iBoats Shawn,

This post is best in the engines/outboards section, one of the mods will probably move it for you.

With the crank I would start by just washing it with dish washing liquid and a real stiff nylon brush to get the surface rust off. The journals I polish with some crocus cloth.

I would wash the block the same way and just run a hone on the cylinders to remove the surface rust and put a cross hatch back in. you don't want to scrape the cyl walls with anything that would mess up your oil control. Are the pistons shot, or can they be saved? maybe find out how much your local automotive machine shop would charge to bead blast them. I wouldn't use used bearings and rings, they are cheep enough to buy new, and to critical of a component to skimp on.

Good luck and post pics we love pics

 

[Intermediate Mariner]

Re: Rusted Block

Thanks Crusier,

Yeah my local cyl repair shop told me $70 on bead blast so I would like to do it myself somehow and save the 70 bucks!

Can I just do a weak CLR bath?

Hmmm, crocus cloth, thanks for the tip... is that different from emery cloth?

Pistons may be good but I will definitely replace bearings at your suggestion.

Thanks again.

 

[HVAC Cruiser]

Re: Rusted Block

Thanks Crusier,

Yeah my local cyl repair shop told me $70 on bead blast so I would like to do it myself somehow and save the 70 bucks!

Can I just do a weak CLR bath?

Hmmm, crocus cloth, thanks for the tip... is that different from emery cloth?

Pistons may be good but I will definitely replace bearings at your suggestion.

Thanks again.

You can give it a shot with CLR. wow $70 that sounds expensive. I just had a set for my 383 done it cost me $45 to press on and off and $45 for glass beading that was for 8 pistons.

Crocus is a very very fine cloth much finer than emery usually brown in color. the idea is not to change the journals diameter, remember your dealing in ten-thousands and the of an inch clearances with bearings. you tear a long strip a little less than half the width then wrap it around twice and polish it like a pair of shoes. this way you are polising 360 deg at the same time.

 

[Intermediate Mariner]

Re: Rusted Block

Check out this one. There were TWO broken rod bolts but only one came off. Still trying to figure were all the water came from (the head gasket was good)... also no damage from a flying bolt head anywhere. One of the rods rusted to the piston, a real mess... but the cylinder walls seem good. Was thinking about trying to save the block.