cracked crank case cover help

[mas942]

:redface:Made a dumb mistake removing the reed valve assembly on my 1985 175 black max v6.I went to separate the reed valve assembly and the crankcase cover with a paint scraper/rubber mallet and cracked the crank case cover,no pieces came out and it didn't chip,but left a 1 inch crack .

Can it be tiged or fixed any other way???

 

[achris]

Re: cracked crank case cover help

Usually that would condemn the cover and the cylinder block. They are matched. If you know someone really good with the TIG, then I would give that a go. Just be aware that putting too much heat into the cover will distort it and it will never seal right again. Slow and steady on that one I'd say. Also be aware that the ends of the con-rods comes really close to the cover, so don't leave too much extra metal inside the cover.

Good luck and keep us informed.

Chris...............

 

[External Combustion]

Re: cracked crank case cover help

Drill a small hole at the end of the crack to keep it from spreading further. Machinists call this stop drilling. You then can either TIG it or use an epoxy such as JB Weld or Loctite's Mataloy to seal the crack. If you TIG and there is some distortion you can either file it by hand or have a machiists mill it flat.

Hand filing is not as difficult as it seems. Put some Prussian Blue on the part, place it on the block, tap it firmly, pull it off and file only the areas that squish out the Prussian blue. Repeat the process until you have contact all the way around. Use a new bastard cut file (one that has never been used to cut steel) and you will soon have a perfectly fitting part. (clean the file of filings after every few strokes.) If you can not find Prussian blue at your parts store, steal one of your wifes lipsticks. The louder the color the better, just don't let any of your buddies catch you with it!

Matched parts are just that, hand matched. Yo will be doing the matching when you make the repair. Don't throw away a good block when a bit of filing and a good gasket sealer such as Formagasket #2 will set you back to right.

I piddle around with antiques where new parts are not an option. This is done all of the time.

Good luck!

 

[mas942]

Re: cracked crank case cover help

Thanks for the come back, in your opinion is TIG better long term than epoxy or does it matter?

 

[achris]

Re: cracked crank case cover help

If you can not find Prussian blue at your parts store, steal one of your wifes lipsticks. The louder the color the better, just don't let any of your buddies catch you with it!

When I worked in the computer industry I carried in my toolkit a bottle of nail polish, for sealing small parts, much like loctite. Also for sealing pots after setting them. Did I catch he11 from some of my mates for that!!!

Chris.........

 

[External Combustion]

Re: cracked crank case cover help

mas942:

I have used epoxy to repair head cracks (outside water jacket) that have lasted over 25 years now. I would stick with Metaloy or the JB weld that is for aluminum so you will have the right coefficent of expansion. That done I think that the epoxy route would be easier for you.

Personally I would TIG it, but then again all I have to do is step out my back door into my machine shop to do easy welding and machining.

Save some bucks and epoxy it!

PS: Scuff up the metal that you are going to put the epoxy on with 50 to 80 grit sandpaper. This gives the glue a tooth to hold better on.

 

[DJ]

Re: cracked crank case cover help

What a bummer. I an imagine how you felt.

Great advice above. I would do the JB Weld. You have nothing to lose and everything to gain, if it works, which it probably will.

 

[mas942]

Re: cracked crank case cover help

I was ticked, Its not like I didn't know better.

I have a buddy thats a pro welder, I'll have him look at it.

I think I'm leaning towards the epoxy,was an Autobody Man in a past life so fixing it doesn't look like a big deal, just was concerned about it holding up under pressure over the long run.

Should I drill a relief hole at the end of the crack if I use the JB Weld.

Thanks for all your help, Mike Sr

 

[DJ]

Re: cracked crank case cover help

I was ticked, Its not like I didn't know better.

I have a buddy thats a pro welder, I'll have him look at it.

I think I'm leaning towards the epoxy,was an Autobody Man in a past life so fixing it doesn't look like a big deal, just was concerned about it holding up under pressure over the long run.

Should I drill a relief hole at the end of the crack if I use the JB Weld.

Thanks for all your help, Mike Sr

I don't think I would drill the relief hole because the crack was not inherent stress related. You created it. I doubt it will go farther.

 

[joed]

Re: cracked crank case cover help

Fixed a lawn mower crank case 30 years ago with epoxy. Still running.

 

[Lakester]

Re: cracked crank case cover help

hello,

if it was mine, i would stop drill it first [std ops in aviation alum work] and use a COLD SEALER. monitor it for service once done.

and... if it was mine, i would also do my drilling smallest drill bit up to the final size... maybe a 1/16th. and i would run a HD vacuum next to my drill bit so i could catch all the drill shavings. drill slow and shallow low pressure on drill bit. TAKE UR time... especially when about to punch thru. if u can, maybe do final bit twiting by hand... "suck dem shavings!!"

then with the vac running, i would put a V down the crack to give jb or what ever u use [id try jb] maybe 1/8th in V... a nice new home.

then into sides of V i would drill holding holes. very shallow maybe 1/32nd, certainly 1/16th would be ok, imo. then i would work a tool of some kind into the holes to enlarge base. mabe a small spring center punch to upset some. this is to give jb/epoxy addl holding points.

then i would clean area SUPER clean with laquer thinner. and lay in small about of jb. id put tape over cracked area if trying to put jb into a vertical crack. addl jb will bond fine to prev jb application. upset a bit with emory and clean. u can work the jb while still "wet" to keep it up n down in crack. and then when it starts to set, push tape into v. well, u get the idea.

i would do this until i had a nice rounded bead of jb in the worked cracked area. i would do this until it flowed some into the surrounding metal surface for add'l holding looking sorta like a nice beaded heliarc alum bead.

but first i would make some sample runs of jb. a) 50/50 mix. b) 55 jb; 45 catylist. see if a bit less catylist will be stronger when u do a break test. flex them, see if less catylist is stronger. i know too much weakens chemical action in it. but if u just go 50/50 no doubt it will be very strong!!

i have an extensive, indepth working background in using jbWeld on aluminum castings that were modified and reshaped with jbWeld. done as i am suggesting, u will have the strongest bond/repair possible with the jb. my applications were in automotive use. in high temp areas of around 200F... in an fuel/oily environement. in every case, [hundreds using this method, -0- mods failed!! ]

good luck, and post some pix of ur work for us to see.

u can always go back to heat/TIG, but do a COLD process first. no doubt, it will work just fine...

regards,

lakester

 

[mas942]

Re: cracked crank case cover help

I'll take all your advice and post pictures when I'm done.

Thanks again!

Have a Happy New Year

 

[jebeebe]

Re: cracked crank case cover help

use wd-40 for a coolant when drilling. Works better than oil on aluminum. Twenty years a machine builder............Jerry