Oil & Fuel John Deere - ONE exhaust glows orange on full throttle

[glassmanmike]

I have never done a valve clearance or compression check before...I would need to figure out what is involved and understand the step by step process. What is the best way to learn about this? I am dangerously close to my limits of DIY engine repair...

Good feedback on the single cylinder idea as well. Starting to think I may need some professional assistance

 

[SPYDERLK]

OK, I found a picture of your engine ... is it a V twin :confused2: It looks like there is a black cover above the spark plug I can see. Removal of that cover would get you to the rocker arms controlling the valves for that cylinder. If you know where the timing marks to gauge crank position are thats great. If not it is rather unimportant because you can set the valves by watching for place where both valves are closed at the same time. -- Rotate the engine slowly in the correct direction and watch the valves cycle. By placement of the valves you should be able to tell which is for intake and which for exhaust. The intake is a down stroke of the piston. The valve then closes and the piston goes up for compression and then down for power then up for exhaust -- repeat. So all you have to do is watch the intake close and then turn the engine about 45 degrees further. This will be somewhere in the compression or power part of the cycle and both valves will/should be closed. You should be able to feel clearnce in the rocker arms. We are concerned that one of your exhaust valves is out of adjustment and not closing fully. If you find this adjust the threaded tappet to give about 0.010" clearance. That is safe, but youll want to find out the real spec eventually. Be sure all valves have clearance. ... ... However, before you go to this unfamiliar mechanical work, perhaps you should do the compression check 1st. It is done thru the spark plug hole. You may have a friend who has a gauge, or you can buy an inexpensive one at auto parts. Connect it to the subject spark plug hole, disable spark and crank the engine thru several revolutions. Compression should be 120+PSI on both cyls. If they are low check those valve clearances next.
larry

 

[glassmanmike]

Larry- you have encouraged me...I will take a look at this tomorrow night and report back. In the mean time I will find a gauge.

 

[glassmanmike]

And yes it is a v-twin engine

 

[buickanddeere]

A lean mixture is more prone to knock/detonation than a rich mixture. For the little bit of fuel small engines use. I can afford to spend the few extra $$$ for premium rather than regular, for air cooled engines in particular. This may have been a case of, if it isn't broke, don't fix it. Gasser stack temps while under load normally run in the glowing temps of 1000+F .Check the lash , compression and re-fix the carb.

 

[Ty Parent]

I would definitly check the valves on that cylinder as well as look for any air leaks on the fuel and intake system. If you have an infarred thermometer this is the best way to check actual temps. It may not be that much hotter than the other cylinders. The exaust manifold could be thinner on that cylinder.

 

[glassmanmike]

Ok- I bought a compression gauge and just ran the test on both sides. Results:
Left:
on initial start - 140 & 145
Release compression and got 60-70

Right:
On initial start -95 &100
Release compression and got 95 & 95

 

[SPYDERLK]

Ok- I bought a compression gauge and just ran the test on both sides. Results:
Left:
on initial start - 140 & 145
Release compression and got 60-70

Right:
On initial start -95 &100
Release compression and got 95 & 95

The right side is acting normal altho the pressures are low. Did you open the throttle as you cranked? That should give a higher figure. ... The huge change on the left side is a puzzler, but may indicate that there was some liquid in the cylinder that got flushed during the initial reading. Is it the left side glowing the pipe? Those numbers are way low. Hopefully its just a valve clearance issue. Pls repeat tests with the throttle open a bit. After getting those #s itll give an idea whether we need to experiment more to home in on the issue.
larry

 

[glassmanmike]

Yes the left side was (is) the glowing side. When I give more throttle to start up, it cranks for 4-5 seconds and eventually catches. When I do this the compression hoovers at 150 for the crank but as soon as it starts, the compression goes to 95-100 on the right side.

Same on the left now ( with throttle up). On both sides the compression doesn't get over 100 while running....it will get to 150 on crank but goes back down to 100 after it starts.

 

[greg_g]

Yeah, I think 5030 was earliest to have a glimmer here, and now I'm pretty sure your glowing on the left side is (close to) normal. The compression test does reveal a problem on the right side, and low compression is preventing the cylinder from achieving or maintaining operating temperature. The left side is doing all the work - seemingly dragging the right side along for the ride, similar to my 317 experience. That's possibly causing it to run a bit warmer. Once the load is equalized, the temperature will equalize as well. In low light however, you still may see a glowing exhaust. But this time the same on both sides.

Unless I missed it, I never read the result of the suggestion to swap the plugs and wires. So was the right spark plug tip wet when you removed it? If yes, that suggests no spark. If no, I see little alternative but to pull the right cylinder head for further analysis. I suggest buying a head gasket first however.

But I'm curious about the technique. I've never performed compression tests on a running engine before. All mine were done with the ignition disabled on purpose, so the engine DIDN'T start during the test. What sort of operating instructions came with that tester?

//greg//