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

[SPYDERLK]

I recently purchased a 1999 John Deere 425 with 800 hours. I noticed that when the engine was at full throttle, both exhaust manifolds were glowing orange. This freaked me out so I have been trying to figure out why. I pulled the spark plugs and they had a tan chalky appearance on the tip. I was told this is running too lean.

I took apart the carb and gave it a good cleaning, replaced spark plugs, replaced the air and gas filter, replaced the time delay module, changed the oil/filter and.... Now when I start it up and run at full throttle, ONE exhaust glows red, on the left side. One more thing...it also sounds like there is a pinging noise coming from the same side as the glowing exhaust.

Now, at idle or even half throttle there is NO glowing (but the pinging is definitely there on the left side).

Any insight as to what is going on here? I am just hoping the decision to buy this tractor is not an expensive debacle! Thanks in advance.

If you are talking full load and rpm [as opposed to hi idle], Id say what you saw would be normal to see in dim light - tho orange is on the hot side. A dull red visible in twilight is normal for full power. What you have now tho shows an imbalance. Take a hard look at your exhaust clearances. After you set them check compression. You may have a burnt valve. Conceivably that could run very hot and cause preignition/ping.
larry

 

[tcartwri]

You're quite possibly correct, especially if this was an air-cooled engine. But it's not. So isn't it a bit impulsive to wade into an overheating issue without first eliminating all cooling system issues?

//greg//

It's not an overheating issue, it's a timing / fuel ratio issue.

 

[SPYDERLK]

It's not an overheating issue, it's a timing / fuel ratio issue.

?single carb and a distributor right? Timing and fuel should then be the same yet 1 cyl glows and pings. Timing and fuel ratio doesnt quite fit.
larry

 

[5030]

Most exhaust manifolds glow a bit when the engine is loaded and working. If you could see under the hood of your car going down the freeway, you'd be amazed. Your manifolds (exhaust are) glowing. Very normal Actually, for the lambda sensor (02 sensor to clean off, it has to be (exhaust gas flow) above 1000 degrees (f).

Even diesels glow when worked. It's very common for us to have a truck on the dyno doing a horsepower/torque rise check and have the manifold, turbo and exhaust pipe glowing red.

great spot to light a cigarette.

 

[tcartwri]

?single carb and a distributor right? Timing and fuel should then be the same yet 1 cyl glows and pings. Timing and fuel ratio doesnt quite fit.
larry

I'm saying it is NOT an overheating issue. More than likely a bad exhaust valve. It's also possible that this intake runner has a vacuum fitting that is cracked or leaking upstream.

 

[SPYDERLK]

Most exhaust manifolds glow a bit when the engine is loaded and working. If you could see under the hood of your car going down the freeway, you'd be amazed. Your manifolds (exhaust are) glowing. Very normal Actually, for the lambda sensor (02 sensor to clean off, it has to be (exhaust gas flow) above 1000 degrees (f).

Even diesels glow when worked. It's very common for us to have a truck on the dyno doing a horsepower/torque rise check and have the manifold, turbo and exhaust pipe glowing red.

great spot to light a cigarette.

Yeah ... I think the OP is talking about it happening at hi idle, altho I havnt gotten an answer on that yet.:confused3:
larry

 

[glassmanmike]

Thanks for all the comments and questions! Let me see if I can answer and decipher it all...

-Yes to single carb on the 425. Regarding cleaning carb I mentioned...I took the top o the carb out and cleaned it out along with jets and float mech. However I couldn't figure out how to get the lower housing of the carb OFF as it was connected to the throttle and choke and was reluctant to screw something up by disconnecting more than I was comfort with (newbie here!). So I cleaned it out best I could with carb cleaner... Looked pretty clean to me.

The one thing I DID notice was the gasket/seal under the carb unit was not in great shape...warped a bit when I lifted the carb up...just didn't seem like a good seal. Maybe that would account for the extra air intake on the carb side ( accounting for the LEAN burn as indicated by the tan white on the plugs).

-Yes I was talking about the glow and ping at high idle (vs load...mowing grass on a hillside)...

- I did add some sea foam additive to the gas tank hoping it may clean any carb buildup I may have missed

- the only thing I have done on the coolant side is add a little 50/50 to top it off.

Today, I ran it for a little while again just to see if anything changed from yesterday. Everything is still the same... And the ping at high idle is enough to make me quickly reduce throttle cause it sounds "rough". Based on comments above I Don't want to make this issue worse!

I also took it for a spin around the yard (because i haven't driven it since changing everything out yesterday) and noticed the following:
- at medium and high throttle when I go up a hill (35-45 degree incline) I lose considerable power ... Not enough that it cuts out or stops on the incline but it just goes WAY down
- at medium and high throttle, when I engage the 48" mower deck it almost cuts out...it doesn't, but the power is reduced. When I turn the blades off..lots of power returns.

I realize there may be multiple issues in play here, so I want to mention all I see happening with the hope these symptoms may be able to more accurately pinpoint diagnosis...or, set me on the right path to fix.

Does any of the most recent info help paint a clearer picture or relate to the debate as to what may be the culprit?

I really do appreciate your input and suggestions! Thanks- Mike

 

[SPYDERLK]

Could you check all your valve clearances and correct them if wrong? Then do a compression check. I think its your valves, particularly the exhausts. The pinging cyl could have a burnt valve, and if so would show low compression even after you set correct clearance. I wouldnt run it anymore until you do these adjustments and check compression. Then well know more.
larry

 

[greg_g]

- at medium and high throttle when I go up a hill (35-45 degree incline) I lose considerable power ... Not enough that it cuts out or stops on the incline but it just goes WAY down
- at medium and high throttle, when I engage the 48" mower deck it almost cuts out...it doesn't, but the power is reduced. When I turn the blades off..lots of power returns.

That kind of reduced power scenario typically indicates 1 cylinder operation. When it happened to my 317, it was a broken connecting rod. Ran fine on one cylinder, but couldn't do much more than move itself with only half the horsepower. Not saying you have a broken conn rod, but am saying that you've got a situation that reduces (or has reduced) you to a one cylinder engine.

In that light, the symptoms you're describing could also suggest that what you currently consider to be the "hot" cylinder - is actually running normally, and that other cylinder is simply not heating up enough to match.

//greg//

 

[Egon]

- at medium and high throttle when I go up a hill (35-45 degree incline) I lose considerable power ... Not enough that it cuts out or stops on the incline but it just goes WAY down

Check the timing and ignition wires for proper spark.