I have a B&S 446777-0165-E1 twin cylinder engine. It appears to be running on one cylinder, here are the symptoms:
Has spark to both cylinders (tested by mechanic). Appears to be getting gas to both cylinders (tested by mechanic).
Starts easily and sounds like it's running on both at startup.
Within a few seconds, the sound of the engine changes, appears to run more smoothly.
With both plug wires in place and the engine running, if the "bad" cylinder spark plug wire is removed, nothing changes.
With both plug wires in place and the engine running, if the "good" cylinder spark plug wire is removed, the engine dies.
Mechanic did a compression test. Says that the "bad" cylinder is showing 150 at cranking/startup, within a few seconds drops to 120, then to 60 and stays there.
Wow! That's some pulling power... Did you think to pull the plug(s) and have a look at the condition of the one on the bad cylinder compared to the strong one?
Some folks use white vinegar for soaking a carb body prior to a rebuild. Cheap and not noxious.
I trade my carbon credits for a can of spray carb cleaner.:wink:
To check rocker arm movement simple pull off the valve cover and turn engine by hand. It will be obvious if you have a problem. The vapor in the carb when shutting down is normal.The decompression built into the cam opens the intake valve about .002 allowing a small bit of gasses back into the carb. It sounds weird, but once the engine starts it kind of drops out of the picture.
I payed (791230 1 CARBURETOR 103.52 )for my carb online. www.Tulsaenginewarehouse.com
You are correct about the compression check.It should hold the max pressure in the gauge until released. Assuming that your compression is ok and the cam is ok ,i would really lean towards a carb. My engine had been run on 1 cylinder for a while due to a wiped lobe on the cam and i believe that ruined the carb somehow.
One other thing you can check is the flywheel key(partially sheared) and the breather check valve(stuck closed or open).
Yes, one of the main reasons we bought this tractor was to blow snow. There are a million things about the tractor and snowblower that have a tendency to break (some really, really bad design elements), but when everything's working, it can't be beat.
I did pull the plugs and noticed that the one that's firing looks good, the other looks wet. But, that was before I replaced them (and the oil), so I'll try to pull them again and have another look.
I'm really leaning toward replacing the carb now, especially if I can get it for that price! I did a pretty thorough cleaning a few years back (took it off and sprayed/toothbrushed the daylights out of it), but I've never given it a real rebuild and cleaning. I never use fuel stabilizer, but typically I do change the fuel filter annually.
I've never touched the breather, so that's an obvious culprit. The book says to pull the flywheel to remove the breather, is that really necessary? I can see all three bolts...
I have a really old Tecumseh on a rototiller, had to replace the carb and breather on that a while back, runs excellent now, so maybe that's what I'm looking at here too.
Simple would be good (as opposed to valve job, or worse)...
If the symptoms remain the same... runs ok til reaching operating temps.... I would look at the pick-up assembly or check for a hung valve (weak or broken spring). If the cylinder does not fire at all, even when cold, I would replace the pick-up assembly for that cylinder.
I know I've typed a lot here, but I did run the engine on just #2 (the bad cylinder), it starts and runs poorly at WOT. Adding choke doesn't help. Stalls when dropped to idle speed.
It will basically run on #2 for quite a while, but the throtte (governor?) hunts and surges, and it backfires (through the exhaust I think).
It won't run on #2 if #1 is also plugged in and running.
Keep typing away, my friend. The more you type the better to give clues to your trouble. I'm having trouble with the carb issue... unless you have a real "hot rod" you only have one carb and equall intake lengths. How is the intake gasket at the head on the bad cylinder?? Might not mean much because the plug is wet and (to me) indicates bad spark or no compression. Make sure the pick-up coil is gapped to the correct setting and firmly mounted with no corrosion on the mating surface that it is bolted to.
OK. No one has answered this question, maybe you can. I tested the spark using an automotive test light, not the Briggs spark test tool. The spark looked good by the light, do you think I need to try the Briggs tool?
I did check the armature gap, seems OK. I could remove it and wire brush it, it was looking somewhat corroded on the top and sides.
Do you think it would it help to swap the armatures from #1 to #2 (and vice-versa) and see if that changes anything? The parts diagram shows one part number, so I would assume it's the same on both sides. I think that at least that way, I'd know whether to spend the $40 on a new armature.
sounds like the valves need refacing and seats recut - to be sure have someone leaktest the engine on both cylinders - you will hear a bad inlet valve seat @ carb
a bad ex valve @ ex , -blowby the rings @ the c/case breather ( some is usually normal ) but excessive is not , if it is excessive worn rings on that cyl you will hear/ see a blown cyl head gasket @ push rod tunnel - check for bent push rods - have both coils tested on coil testor @ shop under a 6 -8 mm gap this stresses the coil , check the diodes in the wiring harness that come from the coils , could also be sticking valves in their guides ( valve service o/haul -leak test should pick this up )
try cleaning out the carby - assemble with new kit
hi the cylinder with the least compression after a couple of minutes is the culprit
leak test that cylinder before removing head to ascetain whick valves are causing the problem ie popping intake , chuffing exhaust but leak test will also let you know how bad the rings are on that cylinder by the amount of hiss ( good rings will have some ) but not too much
general rule the components with the greatest amount of leakage past is the main compnent to look at
sounds like diodes are ruled out and so too the ignition units
more like valves & piston ring problem - local shop should be able to leaktest for you
you already know what cyl is the weakest its the one with least compression and doing less work
Took it to a different shop. They said spark is good on both cylinders, and compression is also good on both cylinders.
They removed the carb, and noted that on the side with the non-running cylinder, the carb was dry, and the side with the running cylinder was wet (with gas). So, they're telling me to clean/replace the carb.
I'll take a shot at cleaning it, I'll let you know how that goes.
My other major problem is a leaking tranny, I'll start a separate post for that.
For the past three weekends, I have been working to get my truck back on the road. In the process, I misplaced the Briggs carb in my garage. Took me 3 days to find it (it wasn't really hidden, just not where I expected it to be)...
So, I'll try to rebuild it this weekend. I'll let you know how it goes.
Meanwhile, I've cut the grass with a push mower. Boy, does that take forever...
I FINALLY had time to work on this yesterday. Got the carb all stripped down, and it's been soaking in B12 since last night [just the body, bowl and solenoid retainer (part that holds the main jet)]. Everything else I cleaned by hand (wire brush). A couple of questions:
I couldn't get the main jet out of the solenoid retainer. The brass (screwdriver slot in the main jet) actually started to chip when I tried to turn the screwdriver. The book says to remove the main jet when doing a rebuild, even though they don't give you a new one with the rebuild kit. I assume it will be OK to leave it in and soak it?
I'm pretty sure that I found the actual culprit for this engine running on one cylinder. One of the ports in the carb body was blocked. Hopefully the cleaner will unclog it, because it's one of the deep ones. When you take out the emulsion tube, there are two brass pipes and two ports. When I shine a light through the body, I can only see light coming through the port corresponding to the side of the engine that runs.
If this port doesn't clear itself with the cleaner (and canned air), what other options do I have, short of buying a new carb?
I also forgot to buy new intake manifold o-ring seals, but I'm not overly concerned with those.
Carb's been soaking in B12 Chemtool for 24 hours. Whatever is in that port is not coming out. I'm going to let it sit another day and see if that helps. If I have to, I'll let it sit for a week and just hope the blockage eventually dissolves.
I don't want to poke anything in there, from all I've read that will cause more harm than good (although at this point, if that blockage doesn't go away, the carb is scrap).
OK, tried the plastic broom, no luck yet. I'm going to let it soak until next week.
I do have some 36-gauge copper wire (super thin). I'm not sure if it's even strong enough to stay straight, let alone hurt anything. What do you guys think?
Carb has been soaking for a week in the B12. Took it out today, still blocked!!!
OK, so I had a scrap piece of 30-gauge (solid) thermocouple wire. Tried the copper piece, it fit through the non-blocked side. Tried it in the blocked side, it broke in place, far enough in so I couldn't get any tools on it to pull it out. Used a piece of matchstick to get it out (that wasn't much fun).
So, I took the other side of the TC wire, which was copper-nickel, and very carefully stripped a piece about 5 inches long (being sure not to nick the wire while stripping, which would make a weak point). I was able to get this into the blocked port, and it actually pushed through and opened it up!!!
I put a light through it, it was still more closed than the good side, so I took the wire and did some "flossing" (very carefully). I think they're opened up about the same now.
Ran out of time, so I now need to rebuild the carb, reinstall and see if that truly solved it. Really hoping I just saved over $100 on a new carb!
BTW, I did notice when I stripped the carb that the rubber o-ring in the bowl was deteriorated, and some black flecks were in there. Not sure if something like that got sucked into the jet and eventually clogged that port.
Put it all back together, runs great. Starts (separately) and runs on each cylinder. Runs great on both cylinders. I can take off either plug wire, it will run on the other cylinder.
If I had a complaint, it almost sounds like it's running too fast now (at least with no load, but it ran great through the tall grass). I'll have to check that out later.
Moral of the story... if you're only running on one cylinder, strip the carb and make sure all the tiny ports are free. Don't assume (like one local mechanic did) that a clogged carb will always affect both cylinders.
Mike
Status
Not open for further replies.
You have insufficient privileges to reply here.
Related Threads
?
?
?
?
?
Tech Support Forum
4.7M posts
957.9K members
Since 2002
A forum community dedicated to tech experts and enthusiasts. Come join the discussion about articles, computer security, Mac, Microsoft, Linux, hardware, networking, gaming, reviews, accessories, and more!