NH LX665 won't maintain high rpms (drops even with throttle full on)

[bengarland]

Hey everyone, I'm a skid steer and construction equipment newbie. Just got a '99 NH LX665 that appears to be in pretty good shape. It has about 1600 hours and the guy I bought it from said he just had all fluids serviced a month ago. He said the only thing he didn't do was change the air filter (looks pretty clean to me) and the fuel filter (not sure of the status). He had it for 14 months, I just bought it from him a week ago. When I got it home, it worked fine for a couple days. I took down a few small (4-6") trees with it and moved some dirt around. It seemed to have good power most of the time. A few times it would cut itself off when under a big load (such as when lifting tree roots out of the ground with the bucket and moving forward at the same time) -- I've never used a skid steer so I'm not sure if this is normal or not. I just cranked it back up and kept on going, no problem. Then I left it sitting out in the woods overnight and it got rained on. I figured this isn't any big deal, since I thought construction equipment is built for outdoor use. But I thought I'd mention it since the problem started after getting rained on. Not sure if it's a coincidence or? Anyhow, the problem is this: When I start it (at 1/3 to 1/2 throttle) and then bring it up to full throttle, it sounds "fine" (like it did prior to the problem) for about 10 seconds, then the rpms begin to fall so that it sounds like I moved the throttle down but I didn't touch anything. I checked the digital display and it shows 3170 rpm at full throttle, then 10 seconds later it slowly winds itself down to about 2560 and stays there. I can get it to go back up to 3170 ONLY if I bring it down to idle, wait 3 seconds, then jam it back to full. But then it does the same thing, ramping itself down after 10 seconds or so. I tried leaving it idling for 10 minutes to warm it up more, but it had no effect. What could be wrong? It was 60 F outside when I tried this so I don't think temp is the problem (it was the same temp a few days before it got rained on and it worked fine). I ordered a manual from NH but it's not here yet. I'm not really sure what to check. The engine oil and hydraulic oil are at a good level. No warning lights are coming on. The only thing that looks kinda empty is the coolant reservoir located on the inside of the back door. It just has maybe 1/2 cup in the bottom of it. What goes in here? Regular antifreeze like I use in a car? What is the antifreeze/water ratio? How much do I fill it? I don't think this is related to the problem but I thought I'd mention it. I called the local dealer and he said "Check that the throttle cable isn't stretched" then suggested that I bring it in (of course) for them to look at. I checked the cable and it looks fine. When the rpms drop, the throttle is at the same position in the engine compartment and at the lever in the cabin so the cable is not actually moving (at least that's what it looks like to me). Any suggestions? Thanks!!! Ben

 

[bengarland]

I don't know why the forum ate my line breaks, making it hard to read. I think the admins need to change a setting or something. Sorry it ended up all as one squished paragraph, I originally had it as 4 or 5 separate paragraphs to make it easy to read. Ben

 

[jerry]

I don't know why the forum ate my line breaks, making it hard to read. I think the admins need to change a setting or something. Sorry it ended up all as one squished paragraph, I originally had it as 4 or 5 separate paragraphs to make it easy to read. Ben

I reread the post and now I see it is 60 degrees there, the book says 50/50 mixture of permanent antifreeze and water, mine has green ethylene glycol in it.

 

[jerry]

I reread the post and now I see it is 60 degrees there, the book says 50/50 mixture of permanent antifreeze and water, mine has green ethylene glycol in it.

Make sure that the fuel tank cap is venting and there is a water drop on the bottom of the water separator filter by the fuel filler cap. unscrew it and drain a small amount into a clean container then close.

 

[bengarland]

Make sure that the fuel tank cap is venting and there is a water drop on the bottom of the water separator filter by the fuel filler cap. unscrew it and drain a small amount into a clean container then close.

I don't quite understand these instructions at the moment, but I will take a look tomorrow and see if it makes sense when I'm looking at it. I don't know what the water separator filter is.

 

[skidsteer.ca]

I don't quite understand these instructions at the moment, but I will take a look tomorrow and see if it makes sense when I'm looking at it. I don't know what the water separator filter is.

Change your fuel/water separator filter inside the rear door on the lower left and the inline fuel filter in the hose going to the electric pump just inside the left engine side panel and see what happens.
Ken

 

[bengarland]

Change your fuel/water separator filter inside the rear door on the lower left and the inline fuel filter in the hose going to the electric pump just inside the left engine side panel and see what happens.
Ken

I got a fuel/water separator filter today but wasn't able to get the old one off, so I'm still not sure if this will make a difference... will have to wait until I can get a filter wrench. The NH dealer didn't show a part in their computer for the smaller inline filter, so I guess I'll have to take it off and show it to them next week. I checked the air filter(s) and it looks fairly clean but I'm going to replace it next week, too, just to be sure it's not the problem. Today I did a few tests. I cranked up the skid steer and let it idle for 15 minutes to warm up. Then I tried moving the throttle to full and it still had the same problem. I pulled the throttle back down and then slowly inched it up. First I let it sit at 2000 rpm for 5 minutes, no problem. Then 2200 rpm for 5 mins, no problem. Kept going in 200 rpm increments for 5 minutes and got all the way up to 2800 rpm. Once I tried to go past that, up only 100 rpm to 2900 rpm, then after about 20 seconds it ramped itself back down to 2400 rpm. So it seems like the problem is somewhere in the 2800+ rpm range. It's showing 1000 rpm when all the way down to idle, and 3190 rpm when full on (before it ramps itself down). Does anyone know if this is within specs? Not sure if that helps narrow it down, but I figure if it was a fuel problem or air filter problem it would show up at the lower rpms, too. Could it have something to do with the turbo? Thanks, Ben

 

[bengarland]

I got a fuel/water separator filter today but wasn't able to get the old one off, so I'm still not sure if this will make a difference... will have to wait until I can get a filter wrench. The NH dealer didn't show a part in their computer for the smaller inline filter, so I guess I'll have to take it off and show it to them next week. I checked the air filter(s) and it looks fairly clean but I'm going to replace it next week, too, just to be sure it's not the problem. Today I did a few tests. I cranked up the skid steer and let it idle for 15 minutes to warm up. Then I tried moving the throttle to full and it still had the same problem. I pulled the throttle back down and then slowly inched it up. First I let it sit at 2000 rpm for 5 minutes, no problem. Then 2200 rpm for 5 mins, no problem. Kept going in 200 rpm increments for 5 minutes and got all the way up to 2800 rpm. Once I tried to go past that, up only 100 rpm to 2900 rpm, then after about 20 seconds it ramped itself back down to 2400 rpm. So it seems like the problem is somewhere in the 2800+ rpm range. It's showing 1000 rpm when all the way down to idle, and 3190 rpm when full on (before it ramps itself down). Does anyone know if this is within specs? Not sure if that helps narrow it down, but I figure if it was a fuel problem or air filter problem it would show up at the lower rpms, too. Could it have something to do with the turbo? Thanks, Ben

Also, how are you getting paragraph breaks to show up? I tried Firefox and Internet Explorer and no matter what I do my paragraphs get smashed together with no space in between when it is posted.

 

[jerry]

Also, how are you getting paragraph breaks to show up? I tried Firefox and Internet Explorer and no matter what I do my paragraphs get smashed together with no space in between when it is posted.

did you find the drain on the bottom of the water separator filter? It is in the center looks like a black wing nut. I think you can only do paragraphs from internet explorer and you have to check the html box on your profile page.

 

[bengarland]

did you find the drain on the bottom of the water separator filter? It is in the center looks like a black wing nut. I think you can only do paragraphs from internet explorer and you have to check the html box on your profile page.

Yes, I drained the fuel filter twice. Didn't see any water coming out, only fuel. I wish the fix was that easy! *sigh*

 

[skidsteer.ca]

Also, how are you getting paragraph breaks to show up? I tried Firefox and Internet Explorer and no matter what I do my paragraphs get smashed together with no space in between when it is posted.

Go into the "profile"link,(1/2 way down, in the middle) and put a check in "use free html editor"
Draining your filter won't always help, you need to change it,
The small inline filter is a common filter, it is just there to keep trash out of the pump. Any inline will work.
Problem sounds like typical fuel starvation.
Ken

 

[bengarland]

Go into the "profile"link,(1/2 way down, in the middle) and put a check in "use free html editor"
Draining your filter won't always help, you need to change it,
The small inline filter is a common filter, it is just there to keep trash out of the pump. Any inline will work.
Problem sounds like typical fuel starvation.
Ken

Thanks again. I'll get a filter wrench at autozone later today and change it. I'm keeping my fingers crossed that it works! Ben PS: I tried the html editor, but I couldn't type anything into the box (maybe it only works with IE).

 

[Chummins]

Thanks again. I'll get a filter wrench at autozone later today and change it. I'm keeping my fingers crossed that it works! Ben PS: I tried the html editor, but I couldn't type anything into the box (maybe it only works with IE).

Cut your filters apart, if you see any black slime in them or something that almost looks like roots growing you have an algae in there. If it is present you will need to drain your tank and try to flush them out and then put an additive in it. Its kind of a common problem when you get some contaminated fuel and can cause the problems your experiencing.

 

[bengarland]

Go into the "profile"link,(1/2 way down, in the middle) and put a check in "use free html editor"
Draining your filter won't always help, you need to change it,
The small inline filter is a common filter, it is just there to keep trash out of the pump. Any inline will work.
Problem sounds like typical fuel starvation.
Ken

Ken had it. Turned out to be the small fuel filter in the engine compartment. I replaced the outside fuel/water filter first and that didn't solve the problem (but still good for it). Then I figured out that the side panel slides off the engine compartment making it easy to access the in-line filter. Whew! It was the clear plastic see-thru kind. There was a bunch of sand and dirt and junk in it. I replaced it with a metal one (same thing I guess just not see-thru). Works like a charm now. Lots of power. Thanks SO much! I called the guys down at the NH dealer and asked if they thought it might be the fuel filters and they said NO. Guess I won't be taking it to them for service in the future!!!

 

[jerry]

Ken had it. Turned out to be the small fuel filter in the engine compartment. I replaced the outside fuel/water filter first and that didn't solve the problem (but still good for it). Then I figured out that the side panel slides off the engine compartment making it easy to access the in-line filter. Whew! It was the clear plastic see-thru kind. There was a bunch of sand and dirt and junk in it. I replaced it with a metal one (same thing I guess just not see-thru). Works like a charm now. Lots of power. Thanks SO much! I called the guys down at the NH dealer and asked if they thought it might be the fuel filters and they said NO. Guess I won't be taking it to them for service in the future!!!

Just for comparison I just bought the little plastic fuel filter from NH dealer, it was $6.48 but with winter here you never know when you will need one and it is a long way to the dealer.

 

[skidsteer.ca]

Just for comparison I just bought the little plastic fuel filter from NH dealer, it was $6.48 but with winter here you never know when you will need one and it is a long way to the dealer.

Should always have spare filters. Especially in winter. Once they get so plugged themotor either won't run or has no power, either way your hooped.
Ken

 

[Hilltop NH]

Should always have spare filters. Especially in winter. Once they get so plugged themotor either won't run or has no power, either way your hooped.
Ken

I had the same problem maintaining high RPM's with my 99 LX665 when the temperature was below 30°F. I used this and a few other threads on the internet to trouble shoot the problem for three winters. Changing the filters the first winter seemed to help a little but didn't solve the problem. The weather got warm and I used the machine w/out incident. The second winter I replaced the rubber fuel lines, drained the fuel tank of old fuel and the replaced the filters again. The problem came back once the temperature dropped below 30°F and got worse the colder it got. Because of this I didn't use the machine much and missed out on making quite a bit of money due to the historic snowfall last year. So this year I was determined to find the problem. I moved upstream in the fuel system and had the still painted-in original injectors bench tested at the local D&W Diesel shop, turns out one injector was leaking and the other three were sticking shut. They rebuilt the injectors the same day for $340. I reinstalled them and noticed an immediate difference in starting and power but still had a slight stumble and loss of power at high RPM's. As it turns out I'd come full circle on the loss of power problem, the plastic in-line was clogged again. With a chuckle I put a new one in and now the machine runs excellent at any temperature. John

 

[Tazza]

I had the same problem maintaining high RPM's with my 99 LX665 when the temperature was below 30°F. I used this and a few other threads on the internet to trouble shoot the problem for three winters. Changing the filters the first winter seemed to help a little but didn't solve the problem. The weather got warm and I used the machine w/out incident. The second winter I replaced the rubber fuel lines, drained the fuel tank of old fuel and the replaced the filters again. The problem came back once the temperature dropped below 30°F and got worse the colder it got. Because of this I didn't use the machine much and missed out on making quite a bit of money due to the historic snowfall last year. So this year I was determined to find the problem. I moved upstream in the fuel system and had the still painted-in original injectors bench tested at the local D&W Diesel shop, turns out one injector was leaking and the other three were sticking shut. They rebuilt the injectors the same day for $340. I reinstalled them and noticed an immediate difference in starting and power but still had a slight stumble and loss of power at high RPM's. As it turns out I'd come full circle on the loss of power problem, the plastic in-line was clogged again. With a chuckle I put a new one in and now the machine runs excellent at any temperature. John

Well done working out the issue, i have seen injectors stick closed when they have sat for some time.
Glad you got the leaky injector fixed, i pulled down an engine that had a leaky injector, there was a sizable divot burnt into the top of the piston.