97 Cat 311B 8GR00134 I finally got a service manual and pressure gauges for my machine to hopefully figure out what's going on with the weak hydraulics. Cycle times for all implement functions were well within specs. Relief valves seem to have been turned up previously. Spec is 4350 Psi for all implement line circuits and they were set around 4700 Psi. The pumps had no problems building and maintaining pressure, but the hydraulics still didn't have as much power as when I first bought the machine last year. Ambient temps were in the high 50°s F so we could only get the oil up to around 140°F . The lack of power is a lot worse when the oil gets hotter than that, which it does fairly easily on hot days. We didn't have the right gauges to test fuel pressure or intake manifold pressure. Does anyone know what the manifold pressure is supposed to be? I've read the manual a couple times and haven't found that spec. Also, I've read that there's a screen in one of the banjo bolts in the fuel system, can someone tell me which one? My manual said there was a filter on the suction line of the lift pump, so I took that hose off but didn't find a screen. I didn't dare take apart any of the banjo bolt connections since I didn't have any new copper washers to replace any worn ones with. The suction line I checked was just a hose clamp over a metal nipple type of fitting. I'd love any tips or ideas anyone could give me.
If there is a screen it will be in the banjo fitting on the pump and check the fittings on the water separator if you have one . Bob
The banjo on the main injection pump coming from the filter? Or the banjo on the lift pump going to the filter? The parts manual seems to list different washers for those 2 bolts so I want to make sure I pick up the right ones.
Is the problem engine bogging down? Those pressures don’t look too bad.
The fitting on the transfer pump Hose from the tank. Bob
Yes, but it wasn't bogging down all that much last weekend when I took those pressures. Last time it was on a job and it was really hot it was bogging down a whole lot more. At one point I was almost positive the engine was about to stall out trying to track up an incline. Not an insanely steep incline either. The tri axle went up and down that same incline a bunch of times without any problems. Hmm, that's the hose I already checked but it wasn't a banjo fitting. It was just a rubber hose pushed onto a metal nipple with a hose clamp holding it. This machine doesn't have the water separator. Could that be why it's different?
Is it black smoking when it is bogging down
Just a thought! Check PRV on account of hydraulic part leaking ( since it temperature dependent), engine speed sensor and boost pressure. Just a thought!
There is something leaking in the pump compartment, and I thought it looked like there was some fresh oil on the top of that valve one time a couple weeks ago. How would I need to go about checking it? Still haven't found out what I'm supposed to be getting for boost in that thing.
Another thought - do you have oil leak between engine and main pump?
I just posted the question moment ago, if it between engine and pump - check for excessive case pressure.
Or it could be bleed plugs on top of the pump - same thing.
Are you referring to an internal leak? Or actually leaking out of the housing?
I guess I could clean out the whole pump compartment and check it again after running it for a little bit. Right now there's so much nastiness in there that it impossible to trace any leaks.
No, it's not really throwing any black smoke to speak of.
On these ( as far as I know ) there’s no case drain, if pump leaks internally it will result in high case pressure, the hotter it gets the more load it will put on engine! Usually high case pressure pushes the seals out, but if it found weaker spot at plugs then that’s where it’ll go.
sounds like a fuel problem then
Fuel problem not out of equation yet that’s for sure!
Is your hydraulic tank and suction hose looks normal or bloated? Does sight glass leak oil? Did you measured your oil temp in the tank? How hot was your pump?
Actually this guessing game is all wrong! You need to really find out what is your fuel and boost pressure is, possibly compression too! Until then you and us will be on the wild goose chase!
Look under the fitting that the hose is hooked on there should be a 22mm bolt head .Take the bolt out should be a filter in it. If you haven't done so already blow hose out. Bob
True what they say - don’t text and drive! And why in the hell im stuck in 325b??? Maybe because I’m looking at ones parts manual and trying to comment on 311b?! Sorry! Forget about all I said earlier!!! Except fuel and boost, Got to get some sleep!!!
Unless by some miracle there’s K3V63DP instead K3V63DT!
As i finally stopped trying to do three things at the same time, ( the con. of working alone ), I re read this conversation and understood that I made fool of myself! I didn’t really paid attention to what I was reading. My train of thoughts was that PRV leaking internally could drop the powershift pressure when it was not supposed to and load up the engine, and when it was heating up it was leaking even more. Then my overloaded brain switched for some reason to problem of leaking seals and overfilled gear drives, which when overfilled get hot and the hotter they get the more load they put on engine. Then I thought that we are talking about CAT excavator and it supposed to have Rexroth pump which is bent axis and don’t really have the case drain, so my overtaxed brain just turned auto pilot “on” and carried on this gibberish! Until I finally finished what I was doing, look at what I wrote and realized that I screwed up! I apologize! I’ll try not do it again. You should have K3V63DT in that machine laying on its side. Unless someone installed something different before you bought it. So the fact that you don’t really have the black smoke kinda throws the pump overload and air deficiency out of window. The correlation of the ambient temperature and severity of the problem is the interesting one, though! But at this point,if I don’t get some sleep - I am bound to make even bigger fool of my self! Good night!
If you can plumb a gauge in the fuel system and see what kind of pressure you have and see if it dropping under a load. First find out what the fuel is supposed to be I would think 20-30 lbs but not sure
Boost pressure in the intake manifold is usually measured in inches of mercury. It's been a long time since I've done it but I remember most engines in this application running around thirty inches of mercury which is about 15 PSI. The trick will tell you whether or not your engine is putting out the horse power. If you load the engine up and can maintain that boost at around 15PSI, the engine is likely working as it should. If you load up though and the engine maintains the boost and the machine is still slow you know the issue is in the hydraulic system. If you have a fuel or air induction problem it will show up right away on boost pressure.
Ok, I see what you're talking about now. That nipple is actually the banjo fitting I'd read about.
#9 should be the filter ,don't leave it out. Bob
The manual specs 11.0 to 35.5 psi for the pressure out of the transfer pump. I'm planning on measuring this through the bleeder port on top of the fuel filter housing. That should give me the pressure after the filter, right?
yes
Where would I have to hook a gauge into if I wanted to check the pressure of the main fuel injection pump?
Never heard of checking injection pressure as the injectors have a set pressure pop off pressure. if it pops the injectors it should be OK If it cranks good you have enough pressure
He probably meant pressure inside pumps cavity.
I wasn't able to find the right fitting to hook my gauges up to read lift pump pressure or intake manifold pressure but here's an update. The machine was run another couple times in high 40s F to low 50s F ambient temps and it ran awesome. Hydraulics had all kinds of power and there were no overheating issues. Yesterday we pulled it inside, drained and flushed the fuel tank, blew out the line from the lift pump to the tank, and cleaned out the banjo fitting on the lift pump. Attached are some pictures of the screen in the funnel showing some of the gunk and water that was drained along with some shots of what was inside the banjo fitting. We took the intake hose off the turbo to have a look and the turbo is shot. Quite a bit of play on the shaft, the blades have started rubbing against the housing, and the leading edge of the blades (not the edge rubbing against the housing, but the part facing the incoming air) have a bunch of wear. So looks like we'll be putting in a new one before we get too carried away next year. We also took samples of the coolant, engine oil, and hydraulic fluid. We have no idea how long the hydraulic fluid has been in there or what the previous owner put in so it very well could be the wrong oil for the temperatures we have during the summer. A bunch of the foam around the radiators is deteriorated to the point where it's clearly letting air move around the coolers so we'll have to address that issue as well. Hopefully we can get her ready to hit the ground running next season. Thanks for all the help!