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Discussion Starter #1
18 HP briggs, runs fine without a load on it, doesnt have quite enough power to suit me while mowing though you can mow with it, just have to be careful not to kill it down going too fast. I thought for sure it was the carb dirty, so I took the top off and looked, was not bad dirty at all. Cleaned it up, blew air thru all the little holes, shot wd40 thru them so I could see that the holes were open, and put it back and fired it up. Seemed strong, til I tried mowing and it was the same as before. I made certain the engine was plenty warmed up and tried adjusting the carb. It only has one adjusting screw and does not matter where you put it, even screw it all the way in, makes no difference, does not change the way the engine is running.

Any ideas?
 

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model number? I had an old ariens 5 hp snowblower that lost power in snow. It was a compression issue due to lack of clearance on the exhaust valve. If you have the 28 or 31 series ohv it might be the head gasket on the way out. If an L-head could maybe be valve clearance.
 

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Discussion Starter #3
model number? I had an old ariens 5 hp snowblower that lost power in snow. It was a compression issue due to lack of clearance on the exhaust valve. If you have the 28 or 31 series ohv it might be the head gasket on the way out. If an L-head could maybe be valve clearance.
I'll go get the numbers later, right now my wife says I have to take her to the grocery store. She wont let me go in though, have to stay in the car cause I am in the group who is most succeptable to the virus, over 65 with lung issues.

Thanks for the reply!
 

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Discussion Starter #4
OK, I got them. It is model number 422437..Type 1209 01 88101912. Your first answer has prompted me to check the compression but I have a question about that too. Would you take out both plugs so the engine can spin freely, and then check each cylinder, or would you just take out 1 plug at a time while you check the cylinder that the plug came out of?

Thanks for the help!
 

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My first thought was that the governor was not opening the throttle when the load increased. Second was to ask, given it is a flathead, how hard is it to restart when warmed up? If the valve clearance is on the edge, when things warm up, the clearance generally closes up, and a marginal clearance could keep the valve(s) from seating properly, reducing effective compression at cranking speeds, making it harder to start.
If it starts well when hot, and has enough compression to 'spring back' when the crankshaft is spun the wrong way, per B&S, it should have enough compression to start. Of course, to test, you'd have to remove one spark plug at a time, and see how each reacted.
So, given all that, I'd check that the governor is adjusted properly, and see how much it wants to oppose the throttle spring pulling the butterfly wide open. The spring should open the throttle plate fully when any(ANY) throttle control is applied, even 'turtle'. When a load is sensed, the rpms drop below governed speed, and the throttle spring pulls the butterfly open to counter the increased demand. You should hear the engine start to work harder when you increase the workload. The tone of the exhaust/engine will/should change as load is applied and removed. If possible, watch the linkage while starting to cut some heavy vegetation. The throttle plate should pull open a bit to counteract the increased load. If not, check spring tension and governor adjustment.
tom
 

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Discussion Starter #7
Thanks for the reply.

I thought about the governor so with the cover off the carb I crunk it up, after having warmed the engine up, and watched the governor arm as I put the blades in gear to see if the arm moved. It does, so I know it is working some if not as much as it should be.
As for starting up when hot, it cranks like a shot. Cranks really good, hot or cold.
 

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Discussion Starter #8
WHERE are the old timers from this site? Used to be, you could ask a question and have several responses that were really helpful within a few hours. NOW you go days and days and nothing.

Thank you very much to the couple of guys, Tomw0, and 38racing who actually tried to help.
 

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Not certain responses, one on the day you posted and the other on the second day weren't fast enough. Of course that was after you supplied some of the requested information. And although you mention that you did see the governor move, did you do the simple governor adjustment ck to make sure it hadn't slipped. Also Tom had numbers of other things to ck but you didn't mention results if you did do them.
As for other members replying, I'm sure many have a lot of things on their mind as a result of what's going on these days. And yes, that can be seen in the fewer numbers of new daily posts.
MikeC
 

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homefried1...you can always "bump" your post if you have not gotten a reply...and bring it back to the forefront.....but I am actually pretty impressed with the free service on this site..I have gotten a LOT of help on here...just need a little patience...how did the advice that you received work out?....are you "back in action"?...or still experiencing problems?
 

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Discussion Starter #11
Thanks for the replies! I did check the governor, made sure it was still where it was supposed to be, seemed to be OK, didnt help any.What I dont get is, as the title implies, the carb doesnt adjust. You can screw the adjustment screw all the way in, or so far out it seems like it could fall out, and it doesnt change the way the motor runs. BUT.....The motor runs good, cranks good hot or cold, but it bogs down when you climb hills or when you turn on the blades.

As far as the other things Tom mentioned, I am not a good enough mechanic to check them out. I could check compression, but I dont have a tester. I believe it has good compression though.

Again, thanks for the replies.
 

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Have you taken the needle out completely to check it? Sometimes the tip can break off, resulting in no adjustment possible.
FWIW we "old-timers" try our best but we are volunteers, and in most cases contribute our time as well as toss in some coin to help keep the ship afloat.
Spring especially is a busy time... fields to prepare, crops to plant and everything else that comes with the Season.
🍻
 

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Discussion Starter #13
Yeah, I took it completely out and looked at it, it does not look like it has been broken off or anything. I thought about replacing it with the one from the carb in the old motor.

I'm wondering if it may be sucking air somewhere, I'm gonna try shooting some WD40 on it at certain spots and see if I can make the engine change in how its running.

Thanks for thew reply!
 

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Sounds like you're running on one cylinder. With engine off, pull one spark plug boot. Start engine and see if there's any change. Shut off engine. Put boot back on and remove the other spark plug boot. Start engine. Any change in how it runs?
 

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Discussion Starter #15
DING DING DING!! I hate to admit it, but I found that to be the problem yesterday. While I was squirting WD40 everywhere trying to find a leak, it occured to me to try taking the plug wires off while the engine was running so I switched it off, pulled both wires loose and laid them back on where it would get fire, and crunk it back up. I then took a screwdriver with a plastic handle and lifted the wire up off the first plug, and it died. Then I tried the other one the same way, and nothing changed. I thought possibly the plug was bad, so I went to remove the non firing plug and noticed it wasnt hot. I replaced it and tried again, and it stayed the same.

I looked real hard and found that the plug wire going to that plug was pinched,shorting it out. Fixed that and once again, have gobs of power!

I havent tried to see if the carb will adjust now, the engine runs so good and has so much power, I dont need to. I will try it though later.

Thanks to all for the help!
 

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This is not same situation, but I'm just throwing it in. I have a Briggs 18hp that ran OK, but was hard to restart when warm. I went thru carb several times and finally decided to take out main jet. It's under the hex bolt on side of carb. I unscrewed main jet and it looked OK too, but there was a passage way right above the main jet that was almost entirely clogged. I final punched thru the crud and the carb has been fine since.
 

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Discussion Starter #17
This is not same situation, but I'm just throwing it in. I have a Briggs 18hp that ran OK, but was hard to restart when warm. I went thru carb several times and finally decided to take out main jet. It's under the hex bolt on side of carb. I unscrewed main jet and it looked OK too, but there was a passage way right above the main jet that was almost entirely clogged. I final punched thru the crud and the carb has been fine since.
Good info. I pulled that one out of my carb too and it looked OK but I didnt know about another hole in there. I guess I got lucky on that one.
 

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pinched stuff can be tricky. I worked on one guy's which would run and then shutoff. Then no start. My first try it started fine but eventually was same for me. Run and stop and maybe hard start. Turned out someone had routed kill wire behind starter and pinched it. Glad you have it running again.
 
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