Engine stuck on high RPMs- 2005 JD 4720 Diesel

[EdAvilaSr]

The RPMs suddenly went to the max and the speed lever would not slow it down no matter what I did. Could only shut it off by clamping the fuel hose

The tractor would not go off by turning the start key and the tractor would not go forward or in reverse

I was told it is most likely a frozen/stuck fuel injection pump.

Any other ideas of what could cause that?


thanks

 

[Spanner]

yes. It happened to a 4720 we had in the shop once. Originally the engine wouldn't maintain goverened revs. The workshop stripped it and found nothing then after reassembly the same max-revs occurred. A runaway condition which can prove catastrophic. I happened to be collecting parts for field-work and ran, like others, to assist the tech. Leatherman pliers used to clamp the fuel hose and someone grabbed a screwdriver and punctured the fuel filter - It was chaos!
Eventually the fault was found to be a loose-fitting lever on the throttle or governor arm behind the cover plate on the timing cover.
I can't recall exactly which it was (Throttle or governor) as I left the workshop to clear it up and ventilate the smoke!!
It was one of the un-numbered items like on the shaft assemblies shown in this pic:

Item #27 or #38 I think. It's a 'press fit' and had come loose so it could rotate, occasionally 'sticking' and making goverened idle speed setting intermittently impossible.
The pic may not be of your engine. It is from the 4024TLV08-RE530181 Parts List here: John Deere Parts Catalog

Hope that helps.

 

[EdAvilaSr]

Wow, that could have ended in disaster for the engine :shocked:. I hope it doesn't happen to mine when the shop takes it in and tries to fix it

I will let them know about your experience so they check for loose fitting parts on the governor and throttle

Thank you very much for sharing! :thumbsup:

 

[Spanner]

If you're going to a JD Dealership ask them to search DTAC for you (Dealer Tech Assist..) and they should find some reference to the upgraded parts. From lunch-room chat I believe it wasn't an easy 'find' as the parts looked and felt ok. Engine was stripped and ran twice before they found it. Glad it wasn't on my time-card.

A run-away diesel is a frightening spectacle!

 

[Rara Avis]

If you're going to a JD Dealership ask them to search DTAC for you (Dealer Tech Assist..) and they should find some reference to the upgraded parts. From lunch-room chat I believe it wasn't an easy 'find' as the parts looked and felt ok. Engine was stripped and ran twice before they found it. Glad it wasn't on my time-card.

A run-away diesel is a frightening spectacle!

One can stop a Diesel engine runaway by directing a CO2 fire extinguisher into the air intake to smother the engine...

 

[Spanner]

Correct. If you have one handy...

 

[Rara Avis]

Correct. If you have one handy...

I have one in my shop after i saw it demonstrated on a fire call...

 

[Deere Dude]

I have one in my shop after i saw it demonstrated on a fire call...

I'll have to get one to strap to the tractor. Good idea.

 

[EdAvilaSr]

Will it be easy to start it again after using the extinguisher?

 

[finn1]

CO2, not dry chemical.

You don't want to try to restart the engine until the injection pump is repaired.

A runaway usually won't hurt an na engine because the volumetric efficiency nose dives at high speeds and friction overcomes airflow limited power.

A turbo engine is another story.

 

[Rara Avis]

CO2, not dry chemical.

You don't want to try to restart the engine until the injection pump is repaired.

A runaway usually won't hurt an na engine because the volumetric efficiency nose dives at high speeds and friction overcomes airflow limited power.

A turbo engine is another story.

Correct...especially the turbos on John Deeres from India...

from the operator's manual...

Engines with Turbocharger

IMPORTANT: If the engine stalls when in operation, restart it IMMEDIATELY. This will prevent the turbocharger from overheating.

Most damage to the turbocharger is caused by not following the correct procedure when starting and shutting off the engine. After starting and before shutting off, idle the engine without load for at least 30 seconds.

But in a run-away state...I'd rather sacrifice the turbo than the whole engine...

 

[Spanner]

Just an aside:

The India assembly plant has the lowest % of warranty claims per unit produced of any JD assembly line. ie. It is the highest level of Quality Control. That statistic was delivered to us direct from JD USA via the "What's New" webpage a couple of years ago. I recall showing it to a salesman who was 'embarrassed' to have Indian tractors on the sales yard. He suddenly used that stat to great effect in his sales pitch. Do not be afraid of Indian-made JD CUT's.

The 4720 subject of this thread is "Made in USA".

 

[CincyFlyer]

Just an aside:

The India assembly plant has the lowest % of warranty claims per unit produced of any JD assembly line. ie. It is the highest level of Quality Control. That statistic was delivered to us direct from JD USA via the "What's New" webpage a couple of years ago. I recall showing it to a salesman who was 'embarrassed' to have Indian tractors on the sales yard. He suddenly used that stat to great effect in his sales pitch. Do not be afraid of Indian-made JD CUT's.

The 4720 subject of this thread is "Made in USA".

Was all of it "made in USA", including the engine castings? For almost all manufacturers, stuff has come from all over for several decades (we used to love to point out to Harley riders that their front forks were Japanese!)
I'm all for USA-made, if it's either better built or no more expensive than an import.
And I'd also sacrifice a turbo to save an engine! (Mine's NA, so it simply gets sluggish around redline, even at full throttle / no load.) But it would be best to do neither. What I have seen in some large (and rather old) diesel machinery is an air cutoff valve on the intake. It wouldn't be too difficult to rig a butterfly valve or something (provided there wasn't too much emission control stuff in the way!) Pull the red handle on a runaway!

 

[Spanner]

These days, I think the only time "All" of anything is made "Anywhere" is when the label says 'China'...
Yes, with modern engines, the only engine-stop device is the key-switch. An emergency manual-stop would seem a useful feature, even if it is never used.

 

[CincyFlyer]

These days, I think the only time "All" of anything is made "Anywhere" is when the label says 'China'...
Yes, with modern engines, the only engine-stop device is the key-switch. An emergency manual-stop would seem a useful feature, even if it is never used.

I have a Mahindra hat (came with the tractor) that has a USA flag on it. It also has a tag that says "Made in Vietnam".