[volvo4fun]

Just fixed a PTO side oil leak caused by a loose bearing support plate.
Now the engine sounds great, the compression is decent at 125 psig, and I was able to drive it around in the yard.
It takes a second or two for the engine rpm to level out after a speed change, but when I go up in throttle in the higher rpms the engine starts to surge violently. Almost sounds like it is running away then the speed drops and that repeats itself.

What is interesting is that the battery light comes on when the rpm goes really high.

Did a search on high rpm surge and did not find anything.

 

[boomers_influence]

robert
i stated this on the end of your last thread
about the brg. plate.
you most likely have a broken PLASTIC flyball
spacer.
OF course, i do have a cure for that also.
thank you. boomer

 

[mikeduwe]

What tractor?

 

[Hammerdown-7]

Hello Robert
I looked in your profile and saw where you have a John Deere 318. If this is the same Tractor that you speak of with a surge they are common on the Nnan engine. The first thing I would suggest is that you locate the surge. To do so get a can of Gum-Out carburetor cleaner. Start the engine and spray the gum out Carburetor cleaner along the seam of the two Piece intake. If the engine smooth's out then the Intake need's to be re-sealed. It will have to be removed from the engine to do so and you would need to drill out the factory staking rivet's that hold the two Pieces together. Once it is split use Permatex Moto-sel where the two half's met to seal it and place machine screw's where you drilled out the factory staking rivet's. if it is Not the Intake next spray the Gum-out at the area where the intake bolt's to the engine block. If it smooth's out then your Intake Gasket's are leaking and need to be replaced. If those two Places did not show any difference in the surge issue the next spot to look would be inside the Carburetor.




Take the top off of the carburetor and look toward's the front area of it for the Idle Mixture tube. It is brass and has a straight screwdriver slot in it. Unscrew it from the carburetor base and take it out of the carburetor. There will be a series of very small hole's down the side of this mixture tube they must all be clear so that you can se light through them. Use a small sewing needle to clear them or a set of Gas Torch tip cleaner's will work for this. If the holes are all clear check the Main hole of the Mixture tube that run's from the straight screw slot on the top of the tube to the bottom chamfered area of the Idle Mixture tube. Mine was Plugged there with old Gas line rubber and my engine surged wildly where I had to run it full choke just to keep it running. Once I made sure that all of the holes in the Idle mixture tube were clear it Purred like a Kitten and quit surging. I hope this helps, Kurt

 

[volvo4fun]

1988 318 with the P218G engine.
There is no surge at lower speeds. Don't need a choke.
Beyond 3/4 of throttle it starts to surge violently.

 

[inspired_metal]

Robert,
Boomer suggested that the plastic flyball spacer was broken. Did you check that? I think thats where I'd start.
Dom

 

[volvo4fun]

Yes, I will take the engine out to check on the spacer.
Need to get some work done first.

 

[oldeerethanme]

Sounds to me to like a mis adjusted governor linkage. I had the surging issue after changing the stator pickup on my p218 and it ended up that I didn't get the spring in the right hole. my sounded like it was going to run away also..

 

[jimmy]

Most likely its the plastic spacer.

 

[volvo4fun]

Yup, broken spacer.

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