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Hillmann 
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 Topic: Allis B runaway engine
Posted: 02 Nov 2022 at 7:12pm |
This is the same engine that I melted the bearings out of a month ago, rebuilt with help of those here and found it had 3 large cracks in the block.
I am still trying to get it running so I can use it before I take the time and swap engines.
The problem I am having is when I start the engine it wants to runaway and the only way to slow it down is to choke it almost completely out.
When it is running away the governor is fully closing the butterfly valve. I even disconnected the governor linkage from the carburetor and controlled the butterfly valve directly with my fingers, it still did it and could only be kept at a semi reasonable RPM by choking it almost completely.
I originally thought it was a carburetor problem. I rebuilt the original carburetor. It still did it. (both with and without the governor connected)
I put a different carburetor, from a non running tractor on it, it behaved the same.
Then tonight I put a known good carburetor from a good running tractor on it and it still would run away with or without the governor connected.
Does anyone have any guesses on what is going on with this engine?
Is it possible for a cold gasoline engine to be running on blow by motor oil like a diesel? Without producing a ton of smoke?
I realize that the obvious next step is to just swap the engines but this is really bugging me and I want to see this engine run at least close to how it did(and I have a bit of work for it yet to do)
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steve(ill)
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Posted: 02 Nov 2022 at 7:30pm |
an engine needs fuel to run.. If you have the throttle plate closed, the motor can not speed up unless it is sucking oil out of the crank case... You would see blue smoke and level drop if that happened.. I dont see HOW that could happen when setting level on the ground..
Something just dont add up... You have to have the throttle plate open to get air, unless there is a hole in the intake manifold... but where is the fuel coming from ?
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steve(ill)
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Posted: 02 Nov 2022 at 7:36pm |
is the air cleaner connected ? what is in the air cleaner Bowl ? ........... but still the THROTTLE plate should control engine speed.
I have two different carbs... One you PULL the throttle rod to OPEN the throttle.. One you PUSH the throttle rod to OPEN the throttle.. Are you sure the rod is CLOSING the throttle plate ? Cant really speed up if that is happening...
Edited by steve(ill) - 02 Nov 2022 at 7:42pm
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Stan R
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Posted: 02 Nov 2022 at 8:06pm |
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I’d make sure the carb springs/ linkages are installed correctly and not binding. Then the governor.
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steve(ill)
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Posted: 02 Nov 2022 at 8:10pm |
if you disconnect the carburetor throttle rod at the back left corner of the radiator, where it connects to the governor cross arm..... you should PULL the rod to get speed, and Push back toward the carburetor to get to idle... If the shaft and throttle plate are correct in the carb...
If yours SPEEDS UP when you think the plate is CLOSED... what does it do when you push the rod the OTHER WAY ?
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Hillmann
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Posted: 02 Nov 2022 at 8:17pm |
 steve(ill) wrote:
is the air cleaner connected ? what is in the air cleaner Bowl ? ........... but still the THROTTLE plate should control engine speed.
I have two different carbs... One you PULL the throttle rod to OPEN the throttle.. One you PUSH the throttle rod to OPEN the throttle.. Are you sure the rod is CLOSING the throttle plate ? Cant really speed up if that is happening...
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It happens with the air cleaner connected. I don't know if I tried it with it completely disconnected. I have tried it with the lower bowl removed and it behaves the same way..The cleaner has fresh oil in it. I did clean the mesh with gasoline a month ago. Is there any place where gasoline can pool up in the upper half of the cleaner? That could be the problem. I will have to try running it with it completely removed and see if that is where it is getting fuel.
I have tried the butterfly valve it both positions on all 3 carburetors so even if one is backwards I have tried both ways.
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KMAG
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Posted: 02 Nov 2022 at 8:19pm |
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Be logical.
Rpms up when carb butterfly (not choke plate) is closed?
Yes - then there is an air source into intake manifold between butterfly and cylinders and fuel getting there as well.
Not likely.
You sure your not confusing butterfly with choke plate?
When logical fails, check absurity...
Anyone fill air cleaner with fuel instead of oil?
Edited by KMAG - 02 Nov 2022 at 8:21pm
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Hillmann
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Posted: 02 Nov 2022 at 8:27pm |
steve(ill) wrote:
an engine needs fuel to run.. If you have the throttle plate closed, the motor can not speed up unless it is sucking oil out of the crank case... You would see blue smoke and level drop if that happened.. I dont see HOW that could happen when setting level on the ground..
Something just dont add up... You have to have the throttle plate open to get air, unless there is a hole in the intake manifold... but where is the fuel coming from ? |
I assume it isn't sucking oil from blow by(or some other way) The engine is cold and the exhaust is coming out clean. It only smokes when I FULLY choke it with the carburetor that doesn't have the extra spring loaded valve on the choke plate and it starts to sputter and dies. I don't think it could run on oil when when not up to operating temp at all and if it did was I think it would be pouring out smoke.
From your other post I am thinking there may be fuel trapped in the air cleaner somewhere. I have only ran it for a few minutes total since I put the engine back together so it hasn't had time to use it up if it is trapped there. And since it would be trapped between the carburetor and oil bath it wouldn't have had a chance to evaporate in the last month of just sitting there.
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steve(ill)
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Posted: 02 Nov 2022 at 8:33pm |
I just dont see how this can happen if you are CLOSING the throttle plate.. That shuts off the air and no amount of fuel will make it RUN AWAY without having air supply.
The carburetor internal rod and plate must not be the problem, since you have tried 3 carburetors.. I still question the throttle rod from the carb to the governor cross arm.
I have tried the butterfly valve it both positions on all 3 carburetors so even if one is backwards I have tried both ways. --- I dont see how that can happen.
Edited by steve(ill) - 02 Nov 2022 at 8:36pm
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Hillmann
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Posted: 02 Nov 2022 at 8:34pm |
KMAG wrote:
Be logical.
Rpms up when carb butterfly (not choke plate) is closed?
Yes - then there is an air source into intake manifold between butterfly and cylinders and fuel getting there as well.
Not likely.
You sure your not confusing butterfly with choke plate?
When logical fails, check absurity...
Anyone fill air cleaner with fuel instead of oil?
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The engine want's to rev up out of control no matter which position the butterfly valve is in.
I am 99% sure I am not confusing the choke with the throttle plate. I just now looked up a diagram and I am for sure not confusing the two. And they connect to the operator controls in different ways so it would be very difficult to connect them wrong.
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Hillmann
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Posted: 02 Nov 2022 at 8:36pm |
steve(ill) wrote:
I just dont see how this can happen if you are CLOSING the throttle plate.. That shuts off the air and no amount of fuel will make it RUN AWAY without having air supply.
The carburetor internal rod and plate must not be the problem, since you have tried 3 carburetors.. I still question the throttle rod from the carb to the governor cross arm. |
It does it even when the carburetor isn't connected to the governor at all and I am just adjusting the throttle in every position possible with my fingers while also playing with the choke at the same time to try and keep the rpm from getting out of control.
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Hillmann
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Posted: 02 Nov 2022 at 8:47pm |
KMAG wrote:
Anyone fill air cleaner with fuel instead of oil?
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I think that may be the problem. Fuel trapped somewhere in the air cleaner from cleaning it a month ago.
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kenbow56
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Posted: 02 Nov 2022 at 8:56pm |
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You have a Haunted B . does not seem logical at all to what I have read above, and you have checked and re-checked. Can you pinch off the fuel line when this is happening? Does it die out then? Does it rev up so fast you have to kill it to prevent engine damage? Spark advancing out of control? Hope you find the issue soon, I know these things can drive a man nutty.
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MACK
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Posted: 02 Nov 2022 at 9:06pm |
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Back the ideal screw all the way out, MACK
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Hillmann
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Posted: 02 Nov 2022 at 9:09pm |
kenbow56 wrote:
You have a Haunted B . does not seem logical at all to what I have read above, and you have checked and re-checked. Can you pinch off the fuel line when this is happening? Does it die out then? Does it rev up so fast you have to kill it to prevent engine damage? Spark advancing out of control? Hope you find the issue soon, I know these things can drive a man nutty. |
I only tried shutting of fuel at the petcock once(with the original not rebuilt carburetor)while it was running the engine died within 30 seconds.
It is reeving up instantly when I open the choke just a tiny bit, I think if I let it run at that speed for any length of time the engine would be damaged.
One of the carburetors has a little spring loaded "flap" on the choke plate. When that one is fully choked the engine is still probably running too fast. The carburetor I have on it now doesn't have the flap and I can choke it out enough that the engine will slow down enough the governor will stop trying to fully close the throttle.
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Hillmann
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Posted: 02 Nov 2022 at 9:13pm |
MACK wrote:
Back the ideal screw all the way out, MACK |
Is the idle screw the needle valve coming out of the top of the carburetor at a 45 degree angle?
Or are you talking about the screw that limits how far the throttle can open or close on the throttle lever?
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kenbow56
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Posted: 02 Nov 2022 at 9:18pm |
Or are you talking about the screw that limits how far the throttle can open or close on the throttle lever?Do you have a throttle idle adjust screw? Maybe this is screwed in too far, making it rev up to that screw setting on throttle plate?
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MACK
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Posted: 03 Nov 2022 at 7:22am |
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The screw that limets how far closed the throttle plate can go. MACK
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Phil48ACWC
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Posted: 03 Nov 2022 at 7:37am |
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Steve in NJ
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Posted: 03 Nov 2022 at 8:17am |
Wow, this is crazy. I'm just coming in on this and it doesn't make any sense. This may seem like a dumb question but you don't have Carburetor on backwards and you're thinking the throttle should be closed when in fact it's wide open? LIke Steve says, the throttle blade has to be open in order for the engine to "run away". Three different Carbs and it does the same thing? Somethin' is screwy here. With the idle screw backed off all the way, and the throttle blade slammed completely closed, that engine should have a hard time starting because there shouldn't be any air getting by the throttle blade. If you crack the blade just a fuzz, the engine should start and then die not run away. Throttle linkage connected wrong. Throttle lever at the driver seat alll the way back toward the driver is low idle on a B. Throttle lever at the driver, all the way forward is full throttle. Linkage backward somehow? Steve@B&B
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39'RC, 43'WC, 48'B, 49'G, 50'WF, 65 Big 10, 67'B-110, 75'716H, 2-620's, & a Motorhead wife
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steve(ill)
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Posted: 03 Nov 2022 at 8:39am |
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YEP... hard to believe it has anything to do with carburetor internals / screws/ adjustment , since he has tried 3 carburetors... It has something to do with the linkage moving the carburetor throttle plate.... thats the only way to get AIR to the motor.... If you had a big manifold leak, you would get air, but not the PULL of fuel from the carburetor ?
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Like them all, but love the "B"s.
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Hillmann
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Posted: 03 Nov 2022 at 9:42am |
The linkage has nothing to do with it. It does it when everything is connected, and it does it when the linkages are not connected and I am controlling the throttle and choke directly with my fingers.
I am heading out to the farm around noon.
I will try running it with the air cleaner completely removed in case there if fuel trapped in that.
I will try backing off the idle screw on the throttle lever as far as possible.
And I will check for air leaks.
I will keep everyone updated once I do all that.
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Hillmann
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Posted: 03 Nov 2022 at 9:45am |
Steve in NJ wrote:
Wow, this is crazy. I'm just coming in on this and it doesn't make any sense. This may seem like a dumb question but you don't have Carburetor on backwards and you're thinking the throttle should be closed when in fact it's wide open? LIke Steve says, the throttle blade has to be open in order for the engine to "run away". Three different Carbs and it does the same thing? Somethin' is screwy here. With the idle screw backed off all the way, and the throttle blade slammed completely closed, that engine should have a hard time starting because there shouldn't be any air getting by the throttle blade. If you crack the blade just a fuzz, the engine should start and then die not run away. Throttle linkage connected wrong. Throttle lever at the driver seat alll the way back toward the driver is low idle on a B. Throttle lever at the driver, all the way forward is full throttle. Linkage backward somehow? Steve@B&B
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The idle screw on all the carburetors hasn't been touched. They are all in the same position as when the tractors they were on last ran. Even if I am wrong on the which way the choke and throttle should be I am trying both in every position and the results are the same.
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55allis
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Posted: 03 Nov 2022 at 12:11pm |
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I had a 1970s jd garden tractor that I put a new carb on and it would run away within a few seconds of starting, ended up being the float had a pin hole and filled up with fuel, replaced the float and what a happy camper I was, it fixed it.
But being you swapped 3 different carbs that would cancel that out…
It would do it no matter what the throttle was.
Hopefully this helps…
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1955 AC WD45 diesel with D262 repower, 1949 AC WD45
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Hillmann
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Posted: 03 Nov 2022 at 12:37pm |
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I figured it out!!!!!
The intake manifold was cracked and repaired at some point in its history.
The repair was crooked and caused the throttle lever on the carb to rub on the block. The person who fixed it simply filed out the rear hole where the carburator bolts to the intake to make it a slot instead of a round hole. By simply making sure the carburator was pulled as far from the engine as possible it no longer binds.
But the air filter forces the carburator towards the engine so any time I put the carb on without removing the air filter as well it would bind.
The throttle still moved through half of its motion so I thought it was closing as it should. It wasnt until I had the air filter off and was playing with the idle set screw that I noticed the problem.
Thank you! To everyone who helped me out. Without your suggestions I would not have figured it out.
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steve(ill)
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Posted: 03 Nov 2022 at 1:29pm |
 CONGRATS !
about the only way to REV UP a motor is to OPEN the throttle plate .... sure was a STRANGE PROBLEM...... got everyone thinking !!
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Like them all, but love the "B"s.
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Steve in NJ
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Posted: 04 Nov 2022 at 9:14pm |
Sure had me scratchin' ma' head!............. Glad to hear you figgered it out. Good job! Steve@B&B
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39'RC, 43'WC, 48'B, 49'G, 50'WF, 65 Big 10, 67'B-110, 75'716H, 2-620's, & a Motorhead wife
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