Welding engine block
Discussion
when I removed the alternator bracket this weekend (as part of the winter refurb) I found that the boss for the bolthole nearest the waterpump was fractured and a small piece dropped off when the bolt was removed. Its a neat enough break to just go straight back in place, if I can weld it to hold it there a 6mm tack on each side of the break will be OK I think.
My question is: has anyone done any welding (electric arc) of this sort on the block before and what should I consider/beware of...
I'm not looking for the obvious risks, fire risk, sparks, brake/fuel pipes etc, more sensor/ECU damage
- obviously the alternator is off, the battery is off... would the current damage anything else ???
My question is: has anyone done any welding (electric arc) of this sort on the block before and what should I consider/beware of...
I'm not looking for the obvious risks, fire risk, sparks, brake/fuel pipes etc, more sensor/ECU damage
- obviously the alternator is off, the battery is off... would the current damage anything else ???Presumably it's a Cast Iron Block? Ally? Steel??
www.twi.co.uk/j32k/protected/band_3/jk25.html
www.lincolnelectric.com/knowledge/articles/content/castironpreheat.asp
www.twi.co.uk/j32k/protected/band_3/jk25.html
www.lincolnelectric.com/knowledge/articles/content/castironpreheat.asp
Edited by dilbert on Monday 8th January 13:16
I figured it might be. Someone with real knowledge will be along in a mo. In the mean time, the two pages above might help.
All I know is that Cast Iron can be a tricky beast. The weld has a tendancy to cause the surrounding material to crack.
You may find that it's better to get a steel insert made. Have the block accurately machined, and press fit the insert. Even if you adopt the weld approach you may still have to go the insert route, to prevent future failure.
All I know is that Cast Iron can be a tricky beast. The weld has a tendancy to cause the surrounding material to crack.
You may find that it's better to get a steel insert made. Have the block accurately machined, and press fit the insert. Even if you adopt the weld approach you may still have to go the insert route, to prevent future failure.
Yes thanks for the info on those pages... i reckon its such a small weld required - as I say a couple of 6mm tacks would do it - that I reckon heat will not be an issue as it will be very localised (now wait for correction...). It might be better to put a stud in the remainder of the boss and weld/glue (?) that in place. I'll see if I can post a picture of the problem here later. 
GreenV8S said:
Would you consider JB Weld (liquid metal) as an alternative?
yep I would consider anything... have a look at this picture of the damage (hope it works)
K
[pic] http://ketvrin.myphotoalbum.com/[/pic] Picture now removed - job done!
Edited by ketvrin on Monday 8th January 14:37
Edited by ketvrin on Tuesday 13th March 07:50
Edited by ketvrin on Friday 16th March 12:36
Hmmm, awkward.
Clearly you have to do what you're going to do.
Given the options so far, I think I'd opt for brazing that. The adhesive sounds good, but I think I would be worried about it staying put, given the geometry of that particular situation. I suppose there is nothing to loose by trying (except getting rid of it completely if you decide to go a different route afterwards).
I just have this vision where you touch the welding stick onto the job, and the thing shifts (or vanishes) whilst the operation is taking place.
Overall my gut instinct tells me that the brazing approach is much more gentle, and controllable for a problem of that size and type.
Irrespective, workholding is always going to be an issue.
Edited to add. Maybe with the brazing solution, the answer is to put some mild steel pins (2 x 2.5mm) to hold it in place. Preheat gently with Propane, and braze with Oxy Acetylene and a "Nickel Silver" (Copper Nickel Silicon) filler (per the article above).
http://mmd.foxtail.com/Archives/Diges
Clearly you have to do what you're going to do.
Given the options so far, I think I'd opt for brazing that. The adhesive sounds good, but I think I would be worried about it staying put, given the geometry of that particular situation. I suppose there is nothing to loose by trying (except getting rid of it completely if you decide to go a different route afterwards).
I just have this vision where you touch the welding stick onto the job, and the thing shifts (or vanishes) whilst the operation is taking place.
Overall my gut instinct tells me that the brazing approach is much more gentle, and controllable for a problem of that size and type.
Irrespective, workholding is always going to be an issue.
Edited to add. Maybe with the brazing solution, the answer is to put some mild steel pins (2 x 2.5mm) to hold it in place. Preheat gently with Propane, and braze with Oxy Acetylene and a "Nickel Silver" (Copper Nickel Silicon) filler (per the article above).
http://mmd.foxtail.com/Archives/Diges
Edited by dilbert on Monday 8th January 17:32
That does look tricky.
I think I'd be inclined to braze rather than weld for the reasons mentioned above. Rather than attempt to repair the boss itself how about brazing a stud in place? might be easier and perhaps stronger.
Whichever approach you use, when you come to replace the bracket use loctite and just nip the fastener up enough to compress the spring washer, apply much torque and I fear it will all fall apart again.
The boss is actually on the head so as a last resort you could seek out a replacement.
K
I think I'd be inclined to braze rather than weld for the reasons mentioned above. Rather than attempt to repair the boss itself how about brazing a stud in place? might be easier and perhaps stronger.
Whichever approach you use, when you come to replace the bracket use loctite and just nip the fastener up enough to compress the spring washer, apply much torque and I fear it will all fall apart again.
The boss is actually on the head so as a last resort you could seek out a replacement.
K
gentleman geoff said:
Blimey Kevin, this looks awkward - I thought you were just changing the headlights! Hope you get it sorted in time for spring - it would be good to have a run out with another local S.
Happy New Year
Happy New Year
Hi Geoff and HNY to you too... I decided to use the time to strip off as much as necessary to do my "bonnet-off" restoration. chassis looks OK (so far) need new top ball Joint on offside (saab 900 ???) otherwise its just bits and pieces, elbow grease removing the old wayoyl and scraping, brushing off the knackered paint, applying rusteater and smooth hamerite. My hands are in sh1tstreet already
I think I will opt for the stud fixed in place instead of replacing the broken boss. May be fix the stud in place then cross-drill through it into the casting and fit pins or screws. I dont have access to gas bottles for brazing and dont like to hand my pride and joy over to just anyone, so watch this space.
I'll add a couple of more pics of the strip down so far in a day or so (in case anyones interested...)
I cant see you have much to lose by trying a weld, I would grind the outside edges of the cracks so that when the piece is put back in place there are 2 Vs that you can fill with weld,put the stud in place before you weld then if you melt too much metal it wont stop you getting the stud in afterwards.I dont think heat would be too much of a problem from the size of the weld needed.You can get problems if there are any air pockets in the casting but you'd have to be bloody unlucky to hit one on a piece this size, also make sure you use a rod suitable for cast Iron.
Thanks again for the advice chaps... so far no-one has commented on my original worry though which was will the current involved in welding do any damage to any of the electrics, given that I have removed the alternator and battery and everything else will be switched off... what about sensors and the ECU ? any risks to them do you think ?
dilbert said:
In theory it should be O.K., but I think I'd be tempted to just disconnect the ECU, and any other big expensive electronic systems (radio) by their main connectors.
Fully agree, It may seem obvious but make sure your earth clamp from the welder is fixed to the engine, dont use the negative lead that would normally be on the battery terminal, I have seen this done in the past as its easier to do than finding a good point on the engine.Doing it could possibly cause problems for sensors etc
clarenceboddiger said:
dilbert said:
In theory it should be O.K., but I think I'd be tempted to just disconnect the ECU, and any other big expensive electronic systems (radio) by their main connectors.
Fully agree, It may seem obvious but make sure your earth clamp from the welder is fixed to the engine, dont use the negative lead that would normally be on the battery terminal, I have seen this done in the past as its easier to do than finding a good point on the engine.Doing it could possibly cause problems for sensors etc
Hmmm... I though as much. OK ECU will be disconnected and earth as near to weld on engine block as possible. thanks for the advice lads
Remember this ?
well I finally got around to it last weekend, disconnected ECU, located stud in remaining thread (one) cleaned off the area to be welded with a dremel and used an iron rod to tack the stud in place, tightened the nut until it gripped the lockwasher and loctited the whole shebang in place, job done !
I have added a couple of pics to My Photo Album for reference.
well I finally got around to it last weekend, disconnected ECU, located stud in remaining thread (one) cleaned off the area to be welded with a dremel and used an iron rod to tack the stud in place, tightened the nut until it gripped the lockwasher and loctited the whole shebang in place, job done !
I have added a couple of pics to My Photo Album for reference.
jimed said:
I tried your link for the piccy above Kevin but got redirected to say you were a naughty boy and they have moved you to the attic ..hmmm. I hope all stays well though with the repair.
Jim
Jim
cheers Jim... try the new link now, the old link expired when they wanted me to buy something to keep it alive, so I let them close it and then re-registered... rocket science eh?
here it is and the latest is always on my profile page.
http://ketvrin.myphotoalbum.com/
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