OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Briggs & Stratton Engines Seized engine - No oil

The engine on this mower was locked up tight. (No oil)
I was going to put another engine on this base, but after reading a few threads on this site I had a go at trying to free it up.
I sat the mower with the plug hole up and poured in 2 stroke fuel, replaced the plug and started hitting the blade plate each way with a soft mallet.
It eventually started to move a little.
It slowly started to move more & more until it was unseized.
I pulled the starter and it fired because of the 2 stroke fuel id poured in.
My question is: should I run this engine for the first time with some 2 stroke mix for a while, before loading the engine up?

Personally I would just run it with making sure the oil is full, just vary the speed for the first minute or so then treat it as normal. No doubt now it will consume oil from wear caused by having no oil...

It is a shame the lady let it get low on oil.
My first thoughts when I saw it where "it is old".
But then I pushed it around and realised it was light to push and well balanced.
It is complete and in good nick.
I like it.

I will let you know how it turns out.

I think you did more damage than the old lady did, by forcing it as a way to free it. The cast iron piston rings were bonded to the aluminium bore, and by forcing it to turn you simply dug longitudinal grooves down the bore. If it isn't locked too badly you can often free it by gentle persuasion, but applying brute force to cast iron locked to aluminium is much the same as applying a cold chisel and hammer. Chances are it will now be an oil burner, and new rings wouldn't fix that.

Ok Grumpy, I will pull the head off today and take a picture of the bore.
Thanks.

Thanks Mark, whatever it looks like there will be plenty of members who are interested, including me.

Here are the pictures of the bore.
Any advice on how to proceed from here, as always, is much accepted by me.





I really like this old mower and will be working on it today.
I noticed wires going from the magneto under the flywheel, first time I have worked on one of these with points.

Mark, I seem to be seeing chunks of aluminium swarf - see red circles:



I suggest you look closely and see if those silver bits actually are aluminium swarf. If they are, it seems as if the engine may have seized close to bottom dead center, and you haven't run it since it happened, so the bore has not yet been damaged appreciably further up.

If there is aluminium swarf jammed between the piston and the aluminium bore, you need a way to get it out without scratching the bore. This may mean removing the piston from the cylinder and cleaning up piston grooves, rings, and bore. Even if this turns out to be what happened, after clean-up it should be OK because any bore damage is at the bottom of the stroke, which doesn't matter as much as further up.

Please post to tell us whether it is aluminium scrapings, and what you plan to do about it.

Briggs changed from breaker points to Magnetron (electronic) ignition in 1982. I see that yours was made in 1979, so it is no surprise that it has breaker points.

Grumpy, your red circles are the flash reflecting off oil.
No swarf seen, had to get a magnifing glass, eyes are not what they used to be.
The engine no. I have embedded into the image at the start of the thread.
Engine no. 92908 1963-02 79112705
Engine is about to have its 33rd birthday, how cool is that.

At this stage I will pull the flywheel to examine the points.
Decoke all.
Inspect valves, lap them if needed, check gaps.
Clean tank & carby.
Clean & reset magneto.

I am on a seesaw, do I split the case and inspect, remove and clean rings.
Or
Do everything I can from the outside, fresh oil and test run.

If there is no sign of aluminium swarf, given that it took a major effort to break it loose, it is possible that it was the big end bearing that seized, not the piston rings. That would be a bit harder to fix: replace connecting rod, and linish the aluminium off the crankshaft. All in all, probably the most practical thing to do is just tune it up, and use it. The bore looks fine, it does not seem to have been seized there.

The 92908 is my favourite Briggs engine. I suggest you don't separate the fuel tank from the carburetor unless you need to, because it has an automatic choke and you have to preload the fuel pump diaphragm to reassemble it if you take it apart. The choke should work very well indeed if it isn't maltreated. I think 1979 would be before the plastic version of the carburetor, so the only worry with it is that if it warps you will have to file it flat, but that is not very difficult with the metal body carburetors. The plastic ones are reputed to warp much more and be difficult to repair if it happens.

When you pull the flywheel and open the breaker points compartment, look for oil in the compartment. The points are operated by a plastic pushrod that runs through into the crankcase. Eventually it wears, and lets oil in. When enough oil gets in the compartment it immerses the points and stops the ignition. It is easy to replace the pushrod, but if the aluminium bore it runs in is worn, you are supposed to ream it out and bush it. That requires a special reamer, and is not worth doing.

Ok, big end bearing seized makes sense.

Great tips for the carburetor & breaker points.

I have had trouble with these in the past, I normally strip them to clean everything, but the result for me is they are hard to start, but once started they run fine.

I havnt separated carby from tank yet, I will leave it for now.

By pre-loading do you mean, the wire attached to the diaphragm?

I will watch out for warping.

The flatness standard for both the bottom of the carburetor and the top of the fuel tank is not more than 0.002" low in the center, measured with a straight edge across the carburetor or tank from side to side, and a feeler gauge in the center.

The choke preloading is done by opening the choke as far as possible (past fully open) and holding it in that position while doing up the carburetor-to-tank mounting screws. It is well worth servicing that carburetor with the Briggs & Stratton Service and Repair Instructions 1984, open in front of you. The specific automatic choke instructions are on pages 39-43.

A 92908 should start first or second pull, even after sitting in the shed for a couple of months. If it doesn't, it needs fixing.

That idle scew in the photo there is wound in way too far, it looks as if somone has already messed with it beforehand

I have got it all back together now, I tried to start it and it wouldnt start, so I wound the screw out that Joe noticed and it starts easily now.
(well spotted).
It also had a brand new spark plug.
I havnt cut any grass with it (Raining here).
But I think it sounds fine.
I did as you said Joe & ran it through some varying revs.
Tomorrow I will fit the flywheel grill, I snapped a screw off.
The points gap was at 0.0017 & there was oil in there.

You might check the carburetor mixture adjustment while you are at it. Carefully note where the screw slot is pointing, then turn it clockwise gently until it bottoms lightly, noting how far it turns. (Should be about 1.5 turns.) Then put it back where it was, and see if it runs better slightly leaner or richer. Turn it clockwise an eighth of a turn and listen to the exhaust smoothness. If it is still just as smooth, go another eighth of a turn. Repeat until you notice it slow down slightly, or perhaps hunt (cycle in speed). That is the lean limit. Turn it anticlockwise in eighth turn steps until it starts to slow down. That is the rich limit. Set it halfway between lean and rich limits.

Fantastic, I will fine tune it tomorrow, I got alot out of today, thanks Joe & Grumpy.

Don't forget to clean and inspect the air filter.

This morning I have fitted flywheel cover, repaired starter, replaced governor spring, serviced wheels.
Started from cold first pull, gave it a run & changed the oil.
Grumpy I will fine tune it, I will wait until I can cut some grass first.
It idles and runs fine as it is for now.


Broken starter cog & original governor spring.



I changed the governor arrangement to this.



I consider myself fortunate to get this result, I will mow the yard a few times to see how the engine turns out.

Mark, it will take a lot of luck for that governor spring arrangement to give the correct governor speed characteristic - the link was correctly installed in the first place, it just needed a new spring. Here is the illustration from the manual:



With your substitute spring the chances are the maximum engine speed will no longer be 3,500 rpm - it might be quite a bit different. If it is now a lot higher, there are both safety and longevity issues.

I have just double checked the new govenor arrangment on one up the back and it is indeed correct, I have posted a photo of this exact mechanism before on the forum but cannot find it now...