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Aluminum engine block rehab

17K views 25 replies 12 participants last post by  makoman1860  
#1 ·
i seached on the internet but could not find a source that told me that 356 cast aluminum is weldable to 6061. this is my last stop, what do you guys think?
 
#3 ·
id use 5356 for 6061 because i just took a weld procdure and i guess 4043 can have some wierd side effects.
 
#4 ·
I couldn't find 356 mentioned in any of my reference books. Lincoln says and I quote, "Aluminum castings, as a rule, may be satisfactorily welded". Since 6061 is also weldable it should work just fine. I have repaired a couple of GM engine blocks and a couple of transmission housing that were satisfactory. I also repaired a hole in a Harley Davidson Sporster tranmission with 6061. I have no idea what number the cast aluminum in any of these was.
 
#5 ·
this fellow i work with is planning on sealing up his water jacket i told him to chose one of two options

a. grind out the jackt so i can fit the large cup needed to avoid heat buildup and tungsten explosions:realmad: on a high amp weld like this (even with preheat)

b. cut and bevel inserts to be welded to seal it up. the material we found in our shop was 6061

i have some experience repairing blown cylinder heads on 356 but any pointers
would be appreciated as i have never attempted this specific fix. I love learnin and talking some metullurgy the knowledge always seems to help me out in the workplace:cool:
 
#9 ·
no damage, he plans to seal up that jacked then deck it down and re-bore the cylinder to add compression.

quick question: what do you reccomend as a preheat procedure since i can not find any agreeing sources.

i did a 500 one hour preheat with a 30 minute postheat last time i repaired some 356 heads
 
#10 ·
personally i would block the coolant jacket by means other than welding. Doesn't matter how you go about it welding aluminium will soften the HAZ.

heads and blocks are welded all the time after a blow up/ to repair corrosion without any ill effects but an unwelded block/head will be harder- a good thing with regards to gasket integrity

i would be looking to do this without welding- there's products around specifically designed for this job that drag racers use. stiffens the block too

i assume as re-bore is planned the block is linered, not nickasil?
 
#12 ·
you mean like aluminum filler for engine blocks right?

not sure about you bore question engines was never a hobby of mine, far out of my price range, although very interested for when i have the $$$$$ i've helped out on some homemade turbos for guys at our shop very very cool(of course all the engine guys are nice to the shop tig welder:rolleyes:). seeing other peoples cars progress has made me want to do it myself.
 
#18 ·
not sure about you bore question engines was never a hobby of mine, far out of my price range, although very interested for when i have the $$$$$ i've helped out on some homemade turbos for guys at our shop very very cool(of course all the engine guys are nice to the shop tig welder:rolleyes:). seeing other peoples cars progress has made me want to do it myself.

a plain aluminium bore wouldn't last too long, very poor bearing surface. Cast iron liners are a common solution, can be either 'dry' or 'wet'. Another solution is to 'plate' the aluminium bore to give a better bearing surface for the rings. Nikasil is one such coating but it didn't play well with high sulphur fuel (of the early-mid nineties) combined with short journeys- BMW and Jaguar both suffered quite a few premature engine failures. BMW (at least) switched to Alusil coatings
 
#15 ·
I think I can help with this as it's something I do occasionally.
To avoid the welding issues when plugging the deck I use some crack repair plugs from irontite or I make some screw in pipe plugs. After installation the block is resurfaced. Some of the jacket holes won't be round so you have to drill or bore them round first in order to tap them.

If the water jackets are to be completely filled then you want a product called Hard Block, available on the net or through one of the HP catalogs.

Link to irontite: http://www.irontite.com
 
#16 ·
ok yes 4043 will be fine as long as its not anodized haha 6061 w/4043 filler will tur JET BLACK after being anodied no matter what color even clear.
 
#20 ·
need information.

I have a HD motorcycle and there is a crack that comes out from an over tightened pipe plug on the bottom of the cast aluminum engine casing. Check out the attached photo and the crack doesnot extend beyond what you see in the photo. What would be the best way to repair without removing engine from frame. Some have suggested tig welding others JB weld epoxy. I've also read about a product called hts-2000 which is used with oxy-acetylene torch to repair cast aluminum engine casings? I need some advice help!!!!!
 

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#22 ·
In frame is not going to be an easy welding repair, dealing with oil in casting. If weld is not full pen, oil will follow threads out. To gouge through and recut leak proof threads without being able to preheat and weld crack side up will be a trick, not impossibe but not fun. Disassembly, with good gouging,cleaning, and pre/post heat would make an excellent repair. Or epoxy cover it untill it can be properly repaired.
Peter
 
#21 ·
A356 filler will age harden, casting will get close to orig with time.
350 pre/post heat
Watch temps, block will cool quickly upon removal from oven to weld. 5 Mins will be about max weld time before reheat.
Skip weld to prevent over heating.
This is what I do at my shop for a living- also the machine work. Cast Iron too.
If mods are just for compression gain I would think about custom pistons instead!
Peter
 
#25 ·
Thanks for the information guys. As for doing the repair with engine in place, I can still remove the plug and drain any excess oil and turn the bike over on its side with some type of cushion to prevent damage. The tube you see in the picture is the frame and above that one of the exhaust pipes which is easily removed for access from above the crack. The bike only has 15K miles and in the last month I have just completted chroming it out to be a show bike. In fact I won second place in a recent bike show. I want to do it rigtht but unforunately I have spent all the extra money and time off I had on the chroming so removing the engine is not the best option at this stage. Please keep the helpfull opt
ions coming and thanks again.
 
#26 ·
Hahaha oh wow that brings back memories. I used to work at a Harley shop in my younger days and it was always a running joke how someone would spend huge $$$ to chrome out their bike, then the engine would decide throw a fit, and the guy had no money for the rest of the summer. It was a weekly deal! Either that or it was always the motorcycle with the most cheap chrome covers over EVERYTHING, that would spring a leak, and the poor mechanic would spend 3x as long to repair the problem dealing with all the stupid chrome covers to get to the actual problem. Too bad we could never charge the customer for the added trouble as we had to stick to flat rate. As far as fixing your case leak, good luck. I have chipped off lots of JB weld from the same area on customers motorcycles, thermal expansion seems to be too much for JB weld. But maybe you can scrape by with it. Good Luck!