Challenging Briggs and Stratton Question - Expert Needed

[Spence]

I have a Briggs & Stratton 446777 0246 E1 twin cylinder engine. It does not seem to be getting power out of cylinder 1.

Details - Last week it broke the exhaust push rod. I opted to replace the whole cylinder head because of the valve guide pushing out of the aluminum cylinder head thus breaking the rod. After finishing the replacement, I started the engine. It runs. Hooraah!

It still sounded weak. So I pulled the spark plug wire on cylinder 1 and the motor ran at about the same level. I replace and pull the wire on cylinder 2. The motor dies quickly.

I replace the wire and start again. I repeat the exercise and it will run with cylinder 2 alone but it will not run with cylinder 1 alone. Both cylinders appear to have spark. The spark plug on cylinder 1 appeared relatively clean. It had no apparent damage or carb build up.

The carburetor is getting fuel because the engine would run at least on cylinder 2. I pulled the valve cover on cylinder 1 and cycled the engine and the rockers, valves, and push rods all seemed to be operating.

How can I verify the operation of cylinder 1? Should the engine be able to cycle on cylinder 1 alone the same as cylinder 2 alone?

[38racing]

have you done compression check on cylinder 1?

[Carl]

Yup, the Intek engine is a weird duck.
You say both cylinders have spark. Time to go to the Vo-ed, Briggs site Bruce has posted and download this manual. 273521 and follow the tests noted for that engine.
Could have a partially broken flywheel key. As noted in the book, Page 6 and 7 section one of the manual, "On Magnetron equipped engines, spark will still occure with a sheared or partially sheard flywheel key."
Since you note the engine will run on one cylinder it could be a compression or fuel problem or just a bad plug on that cylinder.Go figure, you learn something new every day.
Think I will take this book with me and read it on my trip. Isn't it funny, when we apply ourselves, we never stop learning. Carl

[kensmobile]

Most likely your not getting any fuel to the dead cylinder. If you have good compression and spark for that cylinder, then you need to check the carburetor.

The type of carburetor on this engine, feeds each cylinder individually. It's possible to have a plugged jet for just one of the cylinders, while the other will operate just fine. It's kind of like having a separate carburetor for each cylinder.

[Spence]

Thanks for the input. I informally verified that I am getting compression. Removed the spark plug to see if I have any compression. I could feel air pushed from the cylinder. As luck would have it, I broke the spark plug while doing it. I transferred the spark plug from cylinder 2 to see if it would run on its own. It would not. So I am going to assume that the spark is fine after I replace the one I just broke.

Fuel to the dead cylinder. What is the easiest way to check? It does not appear that I can remove the plastic intake from just one cylinder head.

How is the timing set on these engines? Could I have knocked something loose while replacing the cylinder head?

I was unable to locate a link to the repair manual.

Help appreciated.

[bluemower]

Hello Spence,

Did you stuff a rag in the intake manifold when you took this apart?

Before the valve guide failure, I assume the engine ran ok. After you replaced the cylinder head, most probably something was overlooked. Is there any possiblity, one of the pushrods was not properly seated against the cam follower and in fact - that valve is not operating? In this case, the cylinder would still display compression.

If the valve clearance was too tight, and the valves were not closing, the cylinder would not fire. Rotating the engine with the sparkplug removed would still result in some air being expelled from the sparkplug hole.

Since the carburetor and fuel system was ok prior to the valve guide failure, chances are it is still performing ok. You have already verified ignition on both cylinders and you moved a good sparkplug to the new cylinder head. You might prime the dead cylinder by squirting about 5 drops of fuel in the sparkplug hole to see if the cylinder will fire. An old eye dropper would work well for this check.

If these ideas do not work, place the cylinder on TDC and watch the action of the valve rockers as you rock the crankshaft back and forth. Both rockers should move at the same time when the piston is TDC.

[Carl]

To find the manual at the top of the page, click on Board Index, when the page comes up, click on small engine links forum, next page click on Small engine companies. Then find Briggs & Stratton Power Portal, follow bruce's note to sign in on the Briggs site, then look for manuals. You will need the model numbers like you gave for this thread. Once you find the book, download it. Carl

[Spence]

Things I can check and things that I can not...

I am not sure of how to check the sheared fly wheel key. As a home owner and do it yourselfer, I am not familiar enough to validate that portion.

Stuff the rag in the intake? Yep, sure did. At least, I did while I was twisting bolts and mounting hardware. When I started the mower, I removed it and have not put it back in between operations.

I removed the carburetor and inspected to the best of my ability. Everything looked clean with just a little moist sheen to it. No debris that I could find.

Question: How would I adjust timing on the valves? Is that done with the screws on top of the rocker arms? The rocker arms were loose in the box when I purchased it. I simply mounted them assuming that everything was preset. (I know but give me a break for at least attempting to do and learn rather than sit around waiting for a handout like many people these days.) So - do those screws control the valve positions and timing or should I look elsewhere to adjust.

I believe that I am getting combustion, but not at the right time to provide power.

Thanks again... a raised glass of beer, wine, coffee, water, or what ever your refreshment of choice be to all who have taken their time to read and provide input so far.

[kensmobile]

Question: How would I adjust timing on the valves? Is that done with the screws on top of the rocker arms? The rocker arms were loose in the box when I purchased it. I simply mounted them assuming that everything was preset. (I know but give me a break for at least attempting to do and learn rather than sit around waiting for a handout like many people these days.) So - do those screws control the valve positions and timing or should I look elsewhere to adjust.

I believe that I am getting combustion, but not at the right time to provide power.

You cannot really change or adjust the valve timing by removing the head. You can adjust the valve lash (clearance) by adjusting the screws on the rocker arms. If you did not set the valve lash when you reinstalled the head, this could very well be your problem. You need to set the valve clearances with the piston 1/4" past TDC on the power stroke for the cylinder your setting to .004" - .006" for both the exhaust and intake valves.

The flywheel key could affect the ignition timing, but if it's running on one cylinder and not the other, I doubt that's the issue. To check your flywheel key, you need to remove the retaining bolt and washer from the flywheel and look at the key way in the crankshaft and flywheel, they should be lined up. If the key way is off any, then the key may be broken and in need of replacement. If you remove the flywheel bolt, be sure to properly torque it back before starting the engine, as a loose flywheel will shear a key.

Here is a link to the manual for your engine:
http://www.mymowerparts.com/pdf/Briggs% ... RATTON.pdf

[Spence]

To find the manual at the top of the page, click on Board Index, ... Carl

Got it the information. Thanks Carl and thanks to Bruce too should he ever read this thread.