Howdy all, I've got a developing issue with our CAT 420D that I'd like to ask the board about. We've been moving some utility poles recently up one of our skid roads. Everything seems fine until we hit the steeper grades on the road, at which time the engine is unresponsive to the throttle pedal. This loss of power is not drastic or sudden; it just sort of comes on gradually and seems to clear up once the road levels out. Having some experience with diesel engines, I was thinking that this problem might be related to moisture accumulating. Specifically, I was thinking that a separator might be passing a bit of water when the machine is pointing upward. The problem with this is that I'm not aware of where the water separator is on this machine: if it has one at all. The machine is over five years old, but has low hours. This being the case, we've never really had to deal with many issues other than normal fluid maintenance, greasing and filters. We have no way of our own to move the machine to the CAT dealer -- which is quite a few miles down the road -- so anything we might be able to do on-site would be a Godsend to us. Thank you for your time...
Does it lose power in all applications requiring more power like digging into a pile or using the backhoe or is it only while roading?
The hydraulics seem fine... ...and I've only noticed this "phenomenon" when I'm driving uphill on our skid roads. I'll go to add a bit more fuel to the engine with the throttle pedal and it doesn't respond. It doesn't sputter or shudder when I do this, it just sort of doesn't respond normally. In short, I've never noticed this lack of power when I'm stationary -- as one would normally be when lifting or digging. Thanks for the reply...
Handlogger, as I mentioned in the email you sent me, get me the serial No. off the side of the machine, I'll do the research tomorrow with Cat and get the filter(s) for it. I'd tend to say that you've refueled it with untreated fuel recently, and with the changes in temps. we've had lately, freezing and thawing has produced condensation. Just a small dose of water in the bottom of the fuel filter will cause that symptom, had it many, many times.
Sounds like you have a restrication in the fuel tank or line somewhere that allows the fuel to flow enough normally but under a harder load it needs more fuel. I have seen a lot of small rocks stuck in fuel line elbows coming out of the fuel and the only indication was lack of power on hills. Just because fuel runs out when you crack a line doesn't mean enough flows under load. Fuel tank pickup tube is another place to look. Air filter is ok right?
Thanks for the reply, LowBoy. I posted this prior to hearing from you. I will definitely get back to you with that number...I'm just trying to clear some work off of my desk right now.
Fuel tank.... Sounds like the stand pipe in your fuel tank has a crack in it near the fuel level in the tank. Either that or you don't have enough fuel in the tank. Remember that this tank is mounted on the side, not in the rear like most machines. My guess is that the pipe is cracked near to the bottom .
Are you in 4th gear? If you are its your torque converter. Its normal these machines. They are not high speed road machines. If you have a trans temp gauge watch it and your trans might be heating up. I have had customers complain about this very same problem and it has always came out to be the torque converter slipping at high speeds. The fuel water sperator is located on the left side engine. On the D there could be one two or three of them. In the engine compartment around the fuel injection pump might be one. Down next to the oilfilter and I have actually seen one under the cab on the left side behind the fuel tank. Also make sure the air filters are clean. What are the machine hours?
Thanks for the replies, fellas. First, I haven't had the time recently to actually work on correcting this issue. Regular work, limited daylight and too many any other fires to put out recently, I'm afraid...I have, on the other hand, had to use the machine a few times to move snow around (winter hit early in the Berkshires this year). I was on the machine yesterday (12/21/08), for example, and I'm noticing that the problem is getting worse. The fuel level is high, so that should eliminate the cracked standpipe as a possibility. Perhaps the cold weather is making things worse somehow? LowBoy : I finally got the time to get the filters, so I will try them first. I sure hope that's the solution because those drives up our now icy access road are surely getting interesting -- especially when we suddenly lose power at the start of the steepest sections. The final climb, as you know, is somewhat hairy even in the best of conditions. KSSS : Yes, the machine is now losing power when the hydraulics are operated as well. It wasn't always like this, however. Like I just wrote, this issue seems to be getting worse. khp-mech : I've now got fuel filters for the machine, which I will try first. Nevertheless, your diagnosis is an interesting one. I will get back to you after I change the fuel filters. cpfrank : As I already mentioned, this problem rears its head now even when the tank is full. I'm thinking this should eliminate the stand pipe. cread : The terrain this machine is typically operated on does not call for 4th gear. In fact, I don't recall ever using it. The machine is normally operated in 1st or 2nd, and this problem occurs in either gear. Wouldn't the engine RPM be maintained (or increased) if the transmission was slipping? By the way, the machine has less than 600 hours on it. Does anyone with a CAT 420D know where (and how many) fuel filter/separators there are on this machine? It would also be great to read information about where they're all located as well. Once again, thanks for the replies and your time...
At 600 hours what does you warranty cover??? Read your Operations and maintenance manual for fuel filter placement they are under the machine on the left side!!! Has the machine had its recomended services since owning? I think cat wants you to change all filters at 500 hours and the first one is the most important. Your dealer should be notifed of your problem since it only has 600 hours on it.
Well How about the lift pump? Meh ..... I agree. Warranty Job.
I have the same problem with my 2001 416 cat backhoe. all i can tell you is thats how mine start out and now 6 mo later it will only idle. if you give it any "gas" it will die.thats how i found this site. as i am broke and out of work. i cant afford to take it to caterpiller
Thanks for the reply, CCGC. I'm not sure about the design of the 416 fuel system, but I replaced one fuel filter on our 420D: and it made a major improvement. I haven't operated the machine enough to judge whether or not it's totally cured yet -- we're having an icy winter here in the mountains -- but I can tell you that I moved the machine up the same hill that's been giving us fits lately and it motored right up it. I'll get back to this thread once I've had a chance to put some real time on the machine. By the way, if you haven't changed your own fuel filter(s), perhaps I could guide you through it (bearing in mind that we have different machines). Have a good one...
thanks for offer on the fuel filters but i did that.i wish it was that!
I'm sorry to read that, CCGC. Perhaps you could post a thread of your own and describe the issue in detail. There are some pretty knowledgeable techs and operators on this site. Good luck to you in the new year...
yeah we have a 420dit that had the same problem last winter,,,draining the separator didnt help. once the water froze in side it was all over. replaced the filter/separator and it was fine. its located under the machine between the front left tire and the fuel tank. kinda trickey to get at it . but yeah we couldnt even load it onto the trailer. no power and it got worse with time . try the separator/filter and drain the tank for good measure.
We had a 416C with about the same problems. We changed the filters on it and it did not help. The transfer pump was removed and checked, and it was good. Finally, I decided to change both filter bases and that fixed the problem. Dont know to this day which one was bad, and they both had no visible cracks. Be careful, on ours the filters look the same, but they are different. The lugs that slide into the base are slightly different, and if mismatched it will let air into the fuel system.:Banghead
The 420D is not signifcantly different from the 416 it replaces. I suspect that the filters are your problem and the only filters I'm aware of are close to the injection pump and should be changed at least twice a year under light use and every 500 hours of normal use. You can not really drain sediment or condensation easily from the fuel tank, so need to watch the filters closely. You can look into the tank somewhat thorough the filler opening and if you see water rolling around the bottom, either use some fuel conditioner, or try to suck it out. These little engines do not like water in the injection system at all, particularly in winter. These machines are not strong pullers in 3rd or 4th gear. Expect some drop off in speed on hills or on soft ground. I might also suggest that if you road the machine much, change the differential oil (5 gallons) every engine oil change. (250 hrs) The disc brakes in these machines are of very poor quality and wear quickly when the differential gets hot as it does roading. The debris off the brake discs and plates wears them and the planetaries out very quickly. (Cat has no filter on these differentials) I kept a spare axle assembly built up ready to go and when we lost an axle, my best mechanic could change one out in about 2 1/2 hours by himself, less with a helper. The brake parts are the same as Ford/New Holland uses in their backhoes. But there are also better quality discs with a different lining available from an aftermarket source here in the states. Now it's possible that the latest production Cats have been upgraded or improved, lord knows I beat the dealer and Cat both about the head and shoulders on the need. But Cat moves slowly, and it seems, we were among only a very few contractors having this problem, or so Cat told us. Anyway, changing the diff oil regularly practically eliminated the problem. Good Luck!
Private Message Please log in and click on the Private Messages link, Brian . I sent you a PM. In case you haven't used it yet, the link is located in the upper-right portion of this window -- just below the McLaren tire advertisement.
axle problem Interesting to read this post as I have just purchased a 2004 420it with only 1700 hours but it has a rear axle problem. It won't move in 2wd until I step on the diff lock and them the rh axle only drives the machine. Any Ideas what it could be? I plan to fix it myself and have removed the rear end from the machine but have not started disassembly.
I had a similar problem with my 420, just not as severe. I got by with running about 1 gallon of kerosene and 4 gallons of diesel thru mine when the tank got low. Runs like new now. Sounds like your problem is more with a filter though.
Promod1973, I suspect that when you drain the Diff housing, you will get a bunch of debris along with the oil. The debris will consist of brake material, friction plate material (steel) and larger chunks of gears and planet housing. Also bearings of course. You will likely need all the planets, the housings, bearings, the brake housings, friction and brake discs, lets see, springs I think, and I can't remember what else. You will also need both sides as it's common oil and if one side goes, the other isn't far behind. If you are lucky, the splines on the axles will still be intact. I don't remember having to replace many of those. What happens is the brakes put out so much debris that they rapidly wear the planetary gears and housings out to the point the housings actually break once the wear widens the spider bores to the point there isn't much left. Of course, once the housing breaks, big metal chunks get into the gears and tears them all to hell. One reason why only one wheel will pull. Both the planetary and brake housings are expensive, and it's doubtful you will find any good used ones. When these puppies let go, it's usually 100% destruction. You will have to clean the interior of the Diff housings very carefully, and if the destruction is real bad, as it sounds like it might be, the differential ring gear and pinion may need to be replaced as well due to the intensive wear. It's a good idea to replace the pinion bearings and seals in any case as they have been contaminated. Also the outer axle seals. I have had to replace a couple axle housings because the contamination ate the outer bearing and seal bores so badly they could not be reused. These can be sometimes be found used in good condition at reasonable prices. I'm trying to remember the cost, seems like it was around 1800 bucks to rebuild an complete axle assembly if we didn't have to replace the ring, pinion, and axles, and used our own labor. That was in 2004 dollars. The brake discs and plates were a little cheaper from Ford/New Holland at the time. The other aftermarket brake discs were about 20% more expensive than the Cat OEM parts, but lasted far longer, and the debris that came off them was about 98% less abrasive, meaning everything in the compartment lasted much longer. Total rebuild labor with a good mechanic was about 6-8 hours. Hope this missive helps you. A good PM schedule will help as well. Too many folks just ignore or forget the Diff till it breaks. Good Luck!
420d issues Handlogger: Did you solve the fuel problem? If the fuel system is the same as the416 there is a water seperator so to speak of on the right side. Remove the right side engine cover take a light and look toward the transmission there should be a glass and or plastic cup on the fuel line it also has a primer pump there try cleaning this out too. mailtrain
I'm also curious whether you found the issue... I know of another 430D that is experiencing similar problems.
Back to the issue at hand ... Yes, Tiger , I did solve the issue. As this thread started to go in a very general direction, I sort of thought that the issue at hand was lost. In fact, I'm pleasantly surprised to see that some of you stuck with me on this. The issue was fixed fairly easily -- after I got a bit of an education, that is. In short, I replaced the Fuel Filter/Water Separator and haven't had the power loss issue since. I also replaced the air filters shortly thereafter, but I'm convinced that the filter/separator was the actual culprit. By the way, and once and for all, our CAT 420D has only one fuel filter/water separator on it, so don't be shocked if your parts dealer gives you two different part numbers. We were at first, but everything worked out in the end. Have a good one ...
Interesting. There was another thread (that I guess I'll have to poke my head in) that referred to a "lift pump," so now I'm curious what symptoms each BHL had before going through the power loss. Either way, glad things got worked out and thanks for the confirmation on the F-W separator!