# troy bilt



## mrtjet (Dec 3, 2013)

I just got this Troy bilt snowblower with an eight horse engine. It doesn't run steady, it surges. More than likely a fuel system cleaning and a carb overhaul. And new fuel. My question is, I happened to look in the muffler when it was running and it was red hot inside. I never noticed that on any small engine before. I never looked inside a muffler before either, but is that normal or is that probably related to the way the engine is running? Other then that it works fine and shoots the snow a mile. Thanks for any info in advance. Ed


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## Sir Thomas (Dec 7, 2013)

*Surging*

Usually surging IMO indicates issues between the governor and the throttle. The governor gives the carburetor command that the motor is under load to give it more gas and also keeps the motor from over revving when it's not. In most 4 cycle engines there is a spring connecting the governor lever to the throttle and then the end of the governor lever the rod connect to the throttle assembly on the carb. If the spring is weak then the governor level is not kept steady thus the surging. If you watch the throttle plate on the carb while it is running and surging you'll see it moving back and forth. Hopefully it is not as difficult to get to and replace as the old Brigg and Stratton I rebuilt. A neighbor had one that had two springs in the throttle assembly. I could hear it when she was cutting the grass. I replace both springs and she was fine.


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## mrtjet (Dec 3, 2013)

Thank you Sir T. I forgot about the governor. Could be low oil also?


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## Sir Thomas (Dec 7, 2013)

mrtjet said:


> Thank you Sir T. I forgot about the governor. Could be low oil also?


You can check it because the Oil level can affect the governor. I usually check the oil level before I start up any 4 cycle engine especially if it's an older one. Lack of oil can make for expensive repairs.
While it's running after you check the oil, watch the governor lever. If it's moving up and down in the same rhythm as the surge, it's either the spring or, heaven forbids, internal problems. Some 4 cycle engines has two springs involved with the throttle linkage. Get me the model number of the engine. Make sure it's on the engine itself not the blower. Click on this LINK and it will show you the placement and format of the model number


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## 30yearTech (Sep 14, 2006)

mrtjet said:


> My question is, I happened to look in the muffler when it was running and it was red hot inside. I never noticed that on any small engine before. I never looked inside a muffler before either, but is that normal or is that probably related to the way the engine is running? Other then that it works fine and shoots the snow a mile. Thanks for any info in advance. Ed


Yes, it's normal for the muffler to get red hot and is particularly noticeable in subdued lighting. The proximity of the muffler to the exhaust is why the mufflers gets so hot and glow, this does not indicate there is any issue with the engine.



Sir Thomas said:


> If it's moving up and down in the same rhythm as the surge, it's either the spring or, heaven forbids, internal problems.


Surging on an engine with a governor is rarely an issue with the governor springs (unless the springs have been replaced with the incorrect spring(s)). In the case of a mechanical governor setup, the governor may be out of adjustment or the top no load speed may be set too high. In the case of an air vane governor, debris restricting air flow or top speed set too high.

Most often, surging is a result of a fuel delivery problem with the carburetor, and on a float type carburetor is usually caused by a restriction in the low speed or idle circuit of the carburetor.

When an engine is run under no load, even at top governed speed, most of the fuel delivered to the engine is directed through the low speed circuit of the carburetor. Any restriction in this circuit results in too lean a mixture of fuel being delivered to the engine, the engine therefore begins to stall and slows down. The very nature of the governor tries to correct the engine speed and opens the throttle, fuel is then drawn up the main jet and the engine recovers. As the engine builds rpm's and recovers, the governor once again adjusts the throttle to bring the engines rpm's back down. As the throttle closes back, fuel stops flowing through the main jet and is diverted back through the low speed circuit, and the process repeats and you have a constant engine surge. Many times, just applying a load to an engine that causes the throttle to open will smooth the operation out. 

If the carburetor has adjustments, open the low speed adjustment a little and see if operation smooths out, if the surge continues under a load then the high speed adjustment may need a little adjustment as well.

A carburetor with no adjustments will need the carburetor to be cleaned to correct this issue, paying special attention to make sure the low speed/idle circuit is clear.


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## Sir Thomas (Dec 7, 2013)

30yearTech said:


> Yes, it's normal for the muffler to get red hot and is particularly noticeable in subdued lighting. The proximity of the muffler to the exhaust is why the mufflers gets so hot and glow, this does not indicate there is any issue with the engine.
> 
> 
> 
> ...


All I know is that I have a 5 horse Brigg and Stratton that I rebuilt on a Tiller. It had a Pulse Jet Carb (which I put a rebuild kit on) but I didn't replace the spring. It ran but started surging. I adjusted the jet and it still surged. I adjusted the governor lever and checked that the lever was not bent wrong. I ordered a new spring and it has been running good since.
I was outside last year and I could hear my neighbor mower surging. It was a little cheapy. It had two springs and a vane type governor. I ordered two new springs because hers were rusty and stretched. I hooked them up and it ran fine until she broke the starter and didn't want to fool with it.
It may not be the issue on this one but I wouldn't rule it out. Springs are not that expensive.


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## 30yearTech (Sep 14, 2006)

Sir Thomas said:


> It may not be the issue on this one but I wouldn't rule it out. Springs are not that expensive.


I am not saying that in your experiences the springs were not bad, I am just saying it's rare. Damage on the governor spring is not a natural occurrence from wear or use. If they are stretched out, someone did it. Even damaged springs will not necessarily cause an engine to surge, but would be more common on a non float type carburetor setup (Pulsa Jet), and air vane governors. Pulsa jet/prime carburetors do not have a separate low speed circuit, like most float carburetors.

I repair hundreds of engines every year, I can say without any doubt " governor springs are rarely an issue" with surging. You can chase your tail replacing parts until you fix an issue, but this type of approach is time consuming and in the end can cost more, and you may not fully understand what you actually did that fixed the problem. That is why I tried to explain what the most common cause of surging is, so it may help anyone with this issue understand why their engine is acting up and what needs to be done to correct it. That's what I mean by knowing how it works, before understanding why it won't work.


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## Sir Thomas (Dec 7, 2013)

30yearTech said:


> I am not saying that in your experiences the springs were not bad, I am just saying it's rare. Damage on the governor spring is not a natural occurrence from wear or use. If they are stretched out, someone did it. Even damaged springs will not necessarily cause an engine to surge, but would be more common on a non float type carburetor setup (Pulsa Jet), and air vane governors. Pulsa jet/prime carburetors do not have a separate low speed circuit, like most float carburetors.
> 
> I repair hundreds of engines every year, I can say without any doubt " governor springs are rarely an issue" with surging. You can chase your tail replacing parts until you fix an issue, but this type of approach is time consuming and in the end can cost more, and you may not fully understand what you actually did that fixed the problem. That is why I tried to explain what the most common cause of surging is, so it may help anyone with this issue understand why their engine is acting up and what needs to be done to correct it. That's what I mean by knowing how it works, before understanding why it won't work.


I'm not questioning your expertise. You probably had more training and experience that I ever had. My "training" is trial and error. I'm 64 years old and have tinkered with and rebuilt 4 cycle engines since I was 12. I'll PM you if possible.


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## 30yearTech (Sep 14, 2006)

Sir Thomas said:


> I'll PM you if possible.


I received your PM, but when I tried to reply I got a message that your account was not set up to receive messages.


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