Perplexed - loss of power during day, more power at night.

[RancherGuy]

I have a 4 cylinder JD 5425 - 65 PTO hp utility tractor by definition.

For two years, this has demonstrated power loss when I use it at full power when cutting hay. The crop is consistent density and I cut for hours. Power starts off great but can start to decline after 20 to 30 minutes. I shift gears when power declines to keep the PTO RPM up. I might downshift from gears 9 to 8, 7, or 6. My intuition is that the decline is fuel related.

I've changed the fuel filter twice, but I think the power revival is because the tractor was off for a while when changing. I've cleaned out the air filter, but again I think revival was because of the time while cleaning. Power losses resumed within 30 minutes after those rest periods.

This year I found something peculiar one day - started in 9th gear but had to slow down to 7th. Air temp at start was 94 degrees, but after sunset, temp was 88 degrees and power loss seemed to stop declining. Air temp kept dropping and I found that I could kick back up to 8th gear. What a revelation!

Today it got down to 7th gear, but a thunderhead appeared and there was a cool air blast. The engine was power revitalized! I bumped it up to 8th.

Here's the big question: there has to be a means to meter the fuel based on air density, right? To compensate for temperature and turbo pressure? Is there a Mass Airflow Sensor? I've looked at JD parts and can't find something that seems to fit the bill. I'm thinking that whatever the sensor is, it has become temperature sensitive. And at 16 years old, needs to be replaced. Any information? Any ideas?

 

[jdinfo]

If it is a fuel temperature issue, we have had good luck purchasing an automotive transmission cooler from an auto parts store and running the return fuel through the cooler in front of the tractor cooling package, then back to the fuel tank. The transmission coolers are small enough that you can attach it in front of the radiator with zip ties.

Just reroute the hot fuel coming off of the injectors & fuel pump to the cooler and then to the fuel tank. It should drop the return fuel temps by 30°F going back to the fuel tank.

 

[5030]

Turbocharged? Could be the compressor side of the turbo is failing. Air is denser in the evening than during the heat of the day.

 

[workinonit]

Check your fuel tank screen/strainer. I bet it is getting clogged. I just had to do it on my 5090. I actually just removed mine.

 

[workinonit]

I'm not sure the 5425 was a turbo. I know th 5420 was not.

 

[RancherGuy]

Turbocharged? Could be the compressor side of the turbo is failing. Air is denser in the evening than during the heat of the day.

Yes, turbo. Can you explain more about what you know of failure? In my mind, I'm thinking the thing is spinning or it is not. I have read that turbo failure is a thing.

 

[RancherGuy]

Check your fuel tank screen/strainer. I bet it is getting clogged. I just had to do it on my 5090. I actually just removed mine.

Maybe ... but I'm not inclined to take any action to find out. Very clearly, my issue seems to change with either ambient air temp or "final" engine operating teimp. Clogging would not tend to improve if running constant but the air temp drops.

 

[RancherGuy]

If it is a fuel temperature issue, we have had good luck purchasing an automotive transmission cooler from an auto parts store and running the return fuel through the cooler in front of the tractor cooling package, then back to the fuel tank. The transmission coolers are small enough that you can attach it in front of the radiator with zip ties.

Just reroute the hot fuel coming off of the injectors & fuel pump to the cooler and then to the fuel tank. It should drop the return fuel temps by 30°F going back to the fuel tank.

Good point. I'll have to check out my setup to see if it has a cooler already. If so, I'll try to ensure it is cleaned.

Related to that, the other day I got down to 1/4 tank and was thinking that the entire volume was circulating too often to allow time to cool. I stopped and filled fuel to full. Because of the rest period, power was revitalized, but after 30-40 minutes, it was loosing power again even with a full tank.

 

[LouNY]

If your tractor is a common rail injected unit it will have numerous sensors that feed info to the computer for the fuel injection.
I have not researched it but do you have an intercooler on that unit. Some of the sensors will be looking at intercooler temp, water temp, possibly oil temp as well as intake air temp and barometric pressure and boost pressure.

If your tractor is mechanically injected it will not have all those sensors.
I wouldn't be that concerned with fuel temp.

 

[5030]

Like Lou says, ot all depends on age and emissions level. If it's a pre 4 tractor, it's much less complex but either way it's easy to determine if the turbo os the issue. Take the intake off the turbo so you can see inside and grab and spin the compressor wheel. If it rotates freely with no radial slop or back and forth slop (play), then it's fine. If there is play in either direction it needs replaced. Conversely, if you can see where the compressor wheel is cutting onto housing (scroll), it needs replaced. The bearings on the hot side (the side you cannot see, exhaust side) are ceramic and they can wear out. If the turbo has radial or end play, the compressor wheel is hanging up and you aren't getting proper boost. time to renew it.


Rule of thumb with any turbocharged engine is, after working it (up on boost), you should always idle the engine for a couple minutes prior to shutting it off to allow the hot side ceramic bearings to cool off and allow the lubrication oil (they are lubricated with engine oil) to circulate in the turbo tp aid that cooling off.

If it's charge air cooled, rarely would there be an issue with the inter cooler so long as the air filter was doing it's job.

 

[Tx Jim]

Depending on yr model JD 5425 could have a fuel cooler. If a fuel cooler is present check to be sure there's good air flow through the cooler fins

 

[workinonit]

Maybe ... but I'm not inclined to take any action to find out. Very clearly, my issue seems to change with either ambient air temp or "final" engine operating teimp. Clogging would not tend to improve if running constant but the air temp drops.

OK. Just letting you know that this will cause exactly what you are seeing, I know. I'm guessing that fuel requirements change as the machine heats up and if you are partially starving the engine for fuel it won't manifest itself until temps come up. Just my theory, that's what mine was doing. Doesn't m,atter to me if you check iot or not. Out of all the things to try that I've read it's the simplist and doesn't cost anything to do it. So try everything else first. You would probably be surprised how much crap is in your fuel tank.

If the strainer gets clogged badly enough it will start to pull the priming plunger down on your fuel filter...if you have one.

 

[JimRB]

You also cleaned the water separator? My baby Deere tractor has a separator near the fuel tank that gets clogged up. Another fuel filter closer to the fuel pump. That does not explain liking cooler weather. I replaced my air filter after blowing out a few times. I could see a good bit of bright light through the new filter that I did not see with the old filter.

Google research show some people talk about fuel lines need to be replaced, tank cleaning and fuel filter housing cleaning "Memory, have you ever taken apart the top of the spin on filter housing and cleaned it out? I have seen them plug up with all kinds of nasty #### up there. If you are really plugging that inline filter a lot you may have crap in your tank or be getting bad fuel. If it is fungus get some biocides treatment and use about twice what it calls for for a couple tanks of fuel and treat your storage tank with it also."

By the way I got fuel lines from McMaster Carr for my diesel car. They were for return lines and were silicone based I think. One of my friends was commenting that he had a hard time getting lines from regular car parts places like Advanced or OReilly's.

None of that really explains lower power when hot and better power when the temp drops 10-20 degrees. Well maybe bad fuel lines and they might be expanding internally and choking off fuel supply.

I do know on my car and tractor that the fuel return line has some warm fuel in it. My transmission gets plenty warm brush cutting or finish mowing. Other tasks never generate much heat.

All the radiators have been blown clean? My tractor just has an engine radiator. My Dodge truck has an intercooler, a power steering cooler, or maybe a transmission cooler, a AC condenser and the radiator.

Turbo failure is an off in the weeds thought to my mind.

I cannot find any temperature sensors at the JD parts website.

 

[5030]

Turbo failure is an off in the weeds thought to my mind.

Turbo failure is way more common that you think and most times it will be the failure of the ceramic bearings and seals on the hot (exhaust) side of the turbo. Once the radial play allows the compressor wheel to contact the scroll, it on the way out. I check mine for end and radial play regularly. Only takes a few minutes and a tool to loosen the clamp on the intake side.

With big trucks, you always will have a boost gage to determine if the hairdryer is providing required boost. Not something that is on most tractors however.

 

[Egon]

Cooler denser air at night. Perhaps higher moisture content too.

 

[5030]

OK. Just letting you know that this will cause exactly what you are seeing, I know. I'm guessing that fuel requirements change as the machine heats up and if you are partially starving the engine for fuel it won't manifest itself until temps come up. Just my theory, that's what mine was doing. Doesn't m,atter to me if you check iot or not. Out of all the things to try that I've read it's the simplist and doesn't cost anything to do it. So try everything else first. You would probably be surprised how much crap is in your fuel tank.

If the strainer gets clogged badly enough it will start to pull the priming plunger down on your fuel filter...if you have one.

I will say, between my filler neck strainer I installed last year on both mine plus the Racor style fuel polishing unit and water separator I've installed between the fuel tank feed and the primary fuel filter, nothing get's past it and I can see (at a glance) what, if anything it's collecting, in it's clear bottom bowl and I can easily drain it off.

All diesel fuel is questionable today so why take a chance?

 

[5030]

Cooler denser air at night. Perhaps higher moisture content too.

That kind of lends itself to a failing turbo charger.

 

[workinonit]

I will say, between my filler neck strainer I installed last year on both mine plus the Racor style fuel polishing unit and water separator I've installed between the fuel tank feed and the primary fuel filter, nothing get's past it and I can see (at a glance) what, if anything it's collecting, in it's clear bottom bowl and I can easily drain it off.

All diesel fuel is questionable today so why take a chance?

My point is that if he hasn't checked the tank strainer and at least cleaned it or at best removed it, that could be causing his power loss. I've had it happen on 2 tractors. And the hotter and longer you run it the more power loss. These strainers get completely covered with tank crap.

I removed mine because I have double filters with a water seperator as well. Mine started throwing a low fuel pressure alarm with power loss and turned out that was the issue.

 

[RancherGuy]

OK, I'm back. Great comments. Thank you all.

I'm into raking now, so I'm not running at the edge of available power, but although my autumn is fully loaded, it is an issue I will work on as time permits.

Some questions answered: this tractor is 2006 and simple, but with turbo. Air filter, then turbo, then intake manifold. No intercooler.

Fuel injection comes from the injection pump, straight into the cylinders - no fuel rail.

Metal fuel supply line runs along the engine block, seemingly as much as possible, then comes out to feed the injector. I can't help but imagine the heat it picks up. There is no fuel cooler. Replacing flexible hoses is a great idea - they are original.

I have not checked for water in the fuel filter - good idea. In the 15 years since the enclosed barn was built and tractor stored there, I have never run into water issues with any equipment. It's just not present.

The tank cleaning is a good idea, but a hated task. Did that once - tank is 2 parts and it takes hours just to check.

Thanks for the recommendation on how to check turbo. Seems like a very easy task to accomplish.