OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Briggs & Stratton Engines Is this Briggs too far gone?

Picked this briggs up as a freebie. Apparently it was taken off a rotary-hoe.
Guy said they tried fixing it, had no luck but said it was working recently and is probably only good for parts now.






Luckily for me someone had drained the oil and fuel and the pull rope is broken so I couldn't start it. After I washed it down, I noticed all the mud stuck to the block, which I first thought was rust.




Took the cowling off and bingo, one of the coil mounting points had broken off and they tried using JB weld? to repair it. Feels quite solid, but how the hell did that happen in the first place?. I'm guessing that the air gap is way out of spec now. So, is this engine salvagable? I think it may be a 3.5hp, with a points and condenser and a 3/4" shaft (keyway in really good shape).

The coil gap does look a bit on the large side especially on the right hand side as viewed in the picture. I have Gilson Rotary Hoe sitting here that has a 5 HP with no spark but I hope to get it going replacing the coil with a later magneto type rather than the old points and condensor type when I can get my hands on one. Maybe something got jammed between the flywheel and the coil leg to snap the mount like that.

Definitely go with the magneto, you'll never have to take the starter clutch and flywheel off again, just to check the points gap or condenser.

I managed to get a spark by setting the air gap correctly. Used a spare points coil from another Briggs. It must have a short somewhere because I had to disconnect the wire running from behind the flywheel to a tab on the carb.
It would only spark with that wire removed.

I am going to go the full monty on this one (do a solid rebuild) because I reckon it is in good shape. Already proceeded to remove the head and the bore is in excellent condition, no noticeable scoring and some hatch pattern still showing. Carb linkages and spring need replacing.

By my standards that cylinder block is garbage, with the coil mounting boss broken off. I haven't seen a truly workable fix for that short of argon-arc welding it back on, then remachining it. A second-hand Briggs of that vintage is only worth between $10 and $20, which won't justify the cost of repair.

I was thinking of using aluminum brazing rods to give the mounting more strength. I assume that it the mount fails during operation it would be catastrophic?

Anyway, there have been many poorly executed attempts to repair this engine, surely a few more won't hurt. Indeed when I first saw the mounting in that condition, I didn't think it was worth repairing. Now it is just about the challenge to get it to run - with minimal outlay.

What I have seen and experienced of aluminium brazing, including when it is done by a qualified welder, suggests that it is stronger than glue but considerably weaker than, say, lead.

Failure in service of that coil mounting would be likely to permit vibration of the coil which would result in fatigue failure of the other coil mounting. The coil would most likely then rotate with the flywheel and become jammed between cowl and flywheel, stopping the engine and necessitating the replacement of both coil and cowl. However there is a possibility of the fan becoming involved, which would probably result in the coil being projected vigorously through the cowl. This would be quite dangerous to nearby personnel. I would therefore classify what you propose as too dangerous to be seriously considered. However, you are doing it, I'm not - and I wouldn't. It is your responsibility.

Depending on what your application for the engine would be you could always use the points under the flywheel to control an automotive style coil and run it off a 12v battery, forgetting the damaged mount posts altogether. It would be a good proposition if you were making a small 12v generator project, we have run a alternator mounted on the front of a 3.5hp briggs (on an old edger frame) on our caravan batteries in the bush for a good 18 months now.

Hi MrMckay,

I don't have an application for the engine atm. Do you have any pictures of your setup using the Briggs? It is definitely handy having a portable power source.

I agree with Grumpy on the aluminum repairs.

I have personally tried numerous times using those aluminum blazing rods with very poor results. Most times temp to melt the rods and to get blazing to adhere properly are simply too close with the material being welded melting away. And those times I did get it to adhere the joint failed under use, at least the test subjects where part yard units that use for testing and training of new ideas.

Grumpy does have a point and I don't have any experience whatsoever brazing aluminium. Only ever brazed copper pipe fittings together using flux and a butane torch. It would be quite difficult to apply heat evenly in this case because there is not much room to manoeuvre. I wonder if a fastener like a stud might do the trick instead? There is still a bit of mount left near the cylinder wall to tap some threads.

I have canned the rebuild. Going to swap out crankshafts between engines. This is a crankshaft with a good keyway and it can replace another crankshaft in a similar engine (was just rebuilt) that has a damaged keyway. No messy brazing for me!

Took one last look at that problematic coil mounting post on the engine block. Heated it up and part of the aluminium fell off. I was surpised to find that someone had already tried to put a 4mm stud in. They seem to have ran out of luck gluing the post back on and they must have drilled out or stripped the threads in the aluminium.

Because the stud seemed secure enough, I went adhead and made an aluminium stand off using some scrap aluminium rod. I am a bit disappointed with the job they did with the stud, it has a bit of flex, which may or may not be an issue. I probably would have gone with a 5mm stud for rigidity, flattened the rough aluminium where it broke and then tapped the threads. Didn't want to try removing the stud, because it might do more damage and I am not 100% sure that it is glued or screwed in. I know the whole engine it is only worth $20 but it seems a shame to throw away an entire block, considering the bore is in really good shape. Here are the results:

Looks like a good repair job. A lot better than that glue up tried before.

I usually try things like this during the off season here if its my equipment as customers are wanting their equipment working right away here and not willing to wait.

I wouldn't have done it that way, just because I'm an old guy and have had lots of repairs fail so I don't do things that don't look as if they will work as well as it did when it was new. To me, that doesn't look as if it will work reliably in the long haul. However as long as you aren't doing it for a customer and aren't going to sell it, you don't seem to have anything to lose by trying it. Worst case, it breaks, you figure out why it broke, and you become a better repairer. If you just scrap the block, you don't learn anything.

While I wouldn't repair this particular block,I am a repairer of items that most would not generally attempt. This is mainly due to the rarity of the mowers I collect and restore. This is exactly how Id approach this repair.

I understand your caution in removing the stud if it was already secure,as for sure if it was glued it would rip the thread, requiring a helicoil and more time.
Of course if you were starting from scratch,you would face off the remaining bracket and drill and tap your own stud. Since the bracket is low down the bore,and within bonding heat range, I would have used ht thread lock on your new pole or a ht retaining compound would have given it a stronger bond.

I think you've done a great job.

Whether the repair is worth the effort is up for debate, but I think Irrelevant, because as Grumpy has said, if you dont try you dont learn! Nor do others get to see alternate ways to solve seemingly unfixable problems.

Mal, aside from not knowing the quality of the thread, we end up without the lateral rib that Briggs provided, to stabilise the mount and prevent fatigue damage from vibration in that plane. The rib is still in place on the other mount, and as long as the bolts are tight, the coil's laminated core is tying the two mounts together, transferring some load to that other rib, but it all looks fairly chancy to me.

I agree that for some really rare items, the sky is the limit on how much work you do to repair them. The poor unfortunate souls who maintain 1930s Bugattis face many awkward challenges, and regard long sessions on a milling machine as part of the fun of ownership, but they would not do it if they had a choice of picking up a complete engine in good condition for $10-20. (Actually some of them would refuse a new engine, since the numbers wouldn't match their provenance documents, but any un-numbered parts are a different story.)

Agreed Grumpy, chancy Yes....But as far as the repair goes,it would be as strong as any of this type could be in this circumstance.

I feel if it were a lone post, then the repair would border on definate failure. As you say,with distribution of load to the other pole gives it a good chance. Again, I like the fact he tried,and the method of repair he used to ensure the best chance of success

The word rarity has the ability to make us look outside the norm of seemingly impossible repairs in order to ressurect damage parts.

I had to factor this into the 36 Velocette Im restoring, as first and foremost safety is the issue in this project. Repairs had to be stronger than original.

Your points are very valid, especially when safety, cost and a high chance of success are all taken into consideration...

It is not perfect by any means and because I didn't do the repair from scratch, it is not ideal. However, it should hold up well for a while. Here is a video of that all-important spark, using the old spark plug that came with the engine too :

[video][/video]

will try a similar repair myself, my block is not as damaged as the one shown here, just the coil screw post is cracked at the top, now I can try to repair it,