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Stihl Cracked Crankcase repair?


Karlitos
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Evening all, I've had a quick look but can't find any answers to my question on the forum - I have a 461 with a cracked crankcase (see pic) 

 

It isn't anything too major but it is over the oil tank and leaks a bit of oil - any suggestions as to a repair solution rather than spending £160 on a replacement crankcase?

 

I've come across a product called JB weld but not sure if anyone has any experience with this? I'd appreciate any thoughts and suggestions, I'm sure spud will know if it's worth a try.

 

Thanks

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Think they are made from a magnesium alloy (spudulike may give a 100% answer on this) you could take the saw to a welder and get them to grind/V it out and weld up for a more permanent repair, or clean/scrape it out and JB weld it as you suggest, JB weld is oil/solvent resistant so “should” work.

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11 hours ago, Ratman said:

Think they are made from a magnesium alloy (spudulike may give a 100% answer on this) you could take the saw to a welder and get them to grind/V it out and weld up for a more permanent repair, or clean/scrape it out and JB weld it as you suggest, JB weld is oil/solvent resistant so “should” work.

Thanks, I think I will try JB weld first and if that doesn't work I will look at other alternatives like possibly soldering/welding it, altho I imagine this will be quite tricky due to the wall being fairly thin and the metal quite soft in comparison to other metals.

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Thanks, I think I will try JB weld first and if that doesn't work I will look at other alternatives like possibly soldering/welding it, altho I imagine this will be quite tricky due to the wall being fairly thin and the metal quite soft in comparison to other metals.

A capable welder/gas torch man would be fine sorting it for ya [emoji106]
Another option would be to clean it up thoroughly and use a alloy epoxy.
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21 hours ago, Ratman said:

Think they are made from a magnesium alloy (spudulike may give a 100% answer on this) you could take the saw to a welder and get them to grind/V it out and weld up for a more permanent repair, or clean/scrape it out and JB weld it as you suggest, JB weld is oil/solvent resistant so “should” work.

Yes I thought magnesium allow. You would have to clean it up and I'm told it is better to file and gouge as a grinder can carry debris into the work. I'm not very competent with TIG and the faff of preparation and getting the kit out would put me off.

21 hours ago, Haironyourchest said:

I'd braze it with aluminium alloy wire. All you need is the filler wire/rod and a map gas torch, there are plenty of vids on YouTube how to do this, and it's nearly as strong as a weld. 

Would you point me to a video? Again the amount of preparation would put me off

10 hours ago, Karlitos said:

Thanks, I think I will try JB weld first and if that doesn't work I will look at other alternatives like possibly soldering/welding it, altho I imagine this will be quite tricky due to the wall being fairly thin and the metal quite soft in comparison to other metals.

I'd empty and clean the tank, scrape it back to bare metal along the crack, dowse it in brake cleaner to get oil out of the crack and use some thin epoxy stippled into the crack, then rough the paintwork up to key it and apply strips of carbon fibre  tow at right angles to the crack and covering the dented area, ugly but effective.

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I have recently found some stuff called Milliput, it is totally weird in that it is like a two part epoxy but it can be smoothed with water.

Looking at your crack....so to speak:scared1: I would degrease both sides of the crack (just remove the oil cap to access the inside), and then push the filler from the inside and outside leaving a thicker coating on the inside. The oil tank gets a bit of heat but not much pressure so either Milliput or JB should be fine.

Welding - likely to make it look pretty nasty and be a right old ball ache I think.

I would take the easier option first - at least it is the top of the tank!

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