View Full Version : Aluminum bore question

09-07-2010, 07:23 PM
Is there anything at all that can be done to reasonably fix an aluminum bore? It's a low hour engine, the top ring failed for some unknown reason scratching a few lines in the bore.

I'm 95% sure to junk this engine but open to suggestions just in case.

09-07-2010, 07:34 PM

If oversized pistons and rings are offered from the OEM, Bore it and keep going.....

09-10-2010, 05:16 PM
Thanks Rob,

anyway the unit is an old 12.5 Briggs flathead. I doubt it has over 50 hrs on it and still owes me money. Was at the dealers yesterday and there is an oversized piston for it but the pricing was ludicrous.

I'm not confident in my abilities to do an aluminum hone that will last. So I just gave it two strokes with the hone, basically de-glazed it that's all and put new rings in. We'll see how she runs tomorrow.

Rob, maybe you can help figure out what caused this, there's a weird wear spot on the left side of the bore, never seen anything like it.

09-10-2010, 09:12 PM
You mean the cheap engines don't even have any sort of lining. I thought they at least annodize the surface to get a very thin layer of hard material!! Aluminum is so soft for bore!!!

09-11-2010, 10:19 AM

It kinda looks like something may have gotten between the piston and cylinder during assembly ?

Maybe a ring was burred during assembly ?

Boring a aluminum cylinder is no different than a lined cylinder, You just need the proper stones for the aluminum bore.

09-17-2010, 05:47 PM
Well I finally ran the chipper yesterday, it starts great now and power has been restored but it's burning oil making it smoke under load. The oil got dark within the four hours I used it, so oil changes will need to be frequent but I'm planning on using it as is then buy a new engine if needed.

I found out that though these are aluminum engines, bore surface is somehow treated, it's not a real coating but does give some hardness. While these engines can be bored and run fine they last a tad less than the original. The piston itself is coated and employes different rings than sleeved units.

I also found scratches on most running surfaces especially the big rod end. The dealer quoted $31 for rings, $98 for oversize piston and $276 (WTF?) for the rod should I want it. So I went with rings only, these were standard size and fit perfectly (ring gap was in spec.). Apparently they can't scrape off the oil trapped in the damage grooves and it burns off on power stroke.

09-17-2010, 06:26 PM

Post the model and type numbers off this thing, I GOTTA see this $276 rod !!! :dizzy:

09-17-2010, 11:59 PM
You should use just straight 30 wt oil. Stay away from multi vis. like 10W40.

09-19-2010, 10:10 AM
It's an old Briggs model 254412 L-head, type 0576.

Just found aftermarket parts for it at about 1/3 dealer costs.

09-19-2010, 10:38 AM
Hmmm..... Don't know what they were trying to pull !

Standard piston & ring kit #499282 list @ $52.30

Standard rod assembly #490348 list @ 29.95


09-20-2010, 06:52 PM
Beats me, the place I went to has solid reputation. A new guy was the counter at the time, but then again I don't recall any of them lasting for long. They go through guys like crazy. Maybe he looked up a wrong engine, who knows.

Anyway I found this offer :
Well, not exactly this but phoned the guy and he can ship a package for the horizontal version both 0.1 and 0.2 overbore, thinking the 0.1 should be enough. I'll get on it after season, don't have time right now. What do you all think of these kits, should be reasonable quality?

I'm starting to get what might have killed this thing. I bought the unit used and it has an added rpm control. It did and still seems very slow on idle. Never gave it much thought about splash lubrication :hammerhead:.

09-20-2010, 09:18 PM
If he will sell you the right kit for your engine at the same price go for it !