My L4630, four cylinder diesel started knocking real loud today and emitted blue smoke under power. I only have 880 hrs on the engine and this happened once before. I am guessing it is an injector that is the problem but I can't remember how to test to see which one it is? I let it cool off for several hours and also put additive in the fuel tank to dry up any water that might have formed in the tank. After I restarted the tractor I took it out to put a load on it as before and it was fine for the first few minutes and then after it warmed up it started knocking again. When it is knocking I experience a lack of power.Any help on diagnosing this problem would be greatly appreciated. Thanks......
Knocking in engine
- Thread starter Rlandrum
- Start date
I would think if it was an injector it would run rough 100% of the time. If it were mine, I would get it to a diesel mechanic ASAP before some major event took place. Hopefully it is nothing major but I wouldn't take any chances.
You can isolate which cylinder the knocking is occurring in by loosening one injector line at a time. This is just like pulling a spark plug wire on a gas engine. Sounds like a stuck injector. Don't run it longer then you need to to diagnose the problem. You will need to change oil and filter after the repair in case you have fuel in the oil.
Thanks for your reply and assistance. I changed the fuel filter and then checked each line as you suggested. When I disconnected the fuel line one at a time on each cylinder they all sounded the same and the tractor just idled rough. When you first start the tractor it doesn't start knocking until it warms up and a load is placed on it. Once I quit putting a load on it the knocking stops. Do you have any other suggestions?
Thanks...........Rod
Rod, Did you try the cylinder isolation once it was hot? I see that you say it doesn't knock without a load but do you think you might hear even a subtle difference?
This is something I might try if I was still trying to find the noise but had the "No knock without a load"
I would, EVER SO CAUTIOUSLY, get the tractor to the temperature that it knocks. I would stop it, loosen ONE injector line, SECURELY wrap an absorbent towel around the loosened union to catch the fuel and then start and load the engine, running just long enough to hear if it knocks. Repeat with each cylinder to see if it isolates the noisy cylinder. Diesel fuel while flammable is a lot less volatile than gasoline. Wash off the engine after.
This is something I might try if I was still trying to find the noise but had the "No knock without a load"
I would, EVER SO CAUTIOUSLY, get the tractor to the temperature that it knocks. I would stop it, loosen ONE injector line, SECURELY wrap an absorbent towel around the loosened union to catch the fuel and then start and load the engine, running just long enough to hear if it knocks. Repeat with each cylinder to see if it isolates the noisy cylinder. Diesel fuel while flammable is a lot less volatile than gasoline. Wash off the engine after.
have you pulled off the valve cover check the valves see if a rocker is loose I have seen actually 1 fall off. if you never adjusted the valves. I would try that if that still don't work it almost sounds like you have a collapsed lifter what kinda oil you using?
Re: Knocking in engine and power loss
I have an L4630 HST. I have been having major power loss and knocking. When using the hydraulics the power is really bad, so working the bucket and moving at the same time is an issue. I have changed fuel filter, checked all fuel lines and bleed the system for air all the way down to the injectors. The engine will idle fine and rev just fine but bogs down with any type of load (i.e. driving or pulling implements / working). I have stopped short of pulling fuel injectors to see if there is a clogged injector. I do smell a lot of diesel and seems to be getting worse hours to the gallon.
I have an L4630 HST. I have been having major power loss and knocking. When using the hydraulics the power is really bad, so working the bucket and moving at the same time is an issue. I have changed fuel filter, checked all fuel lines and bleed the system for air all the way down to the injectors. The engine will idle fine and rev just fine but bogs down with any type of load (i.e. driving or pulling implements / working). I have stopped short of pulling fuel injectors to see if there is a clogged injector. I do smell a lot of diesel and seems to be getting worse hours to the gallon.
North Idaho Wolfman
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L3450DT-GST, Woods FEL, B7100 HSD, FEL, 60" SB, 743 Bobcat with V2203, and more
Marshall, you problem would have been better posted on it's own thread.
Have you checked / changed / cleaned the hydraulic filter and pick-up screen? HST's loose power when the hydraulic system is restricted or clogged.
Does the motor bog down some when using just the loader?
If it does I'm betting on a hydraulic problem.
Have you checked / changed / cleaned the hydraulic filter and pick-up screen? HST's loose power when the hydraulic system is restricted or clogged.
Does the motor bog down some when using just the loader?
If it does I'm betting on a hydraulic problem.
Yes it does bog when using hydraulics. It also has issues when pulling or going up hills with nothing attached.
I changed the two filter and the hydraulic fluid. I am not failure with a screen. I did not see one on parts list or schematics for L4630. Where is it located?
I tried to start new thread but did not have any luck. Sorry.
I changed the two filter and the hydraulic fluid. I am not failure with a screen. I did not see one on parts list or schematics for L4630. Where is it located?
I tried to start new thread but did not have any luck. Sorry.
North Idaho Wolfman
Moderator
Staff member
Lifetime Member
Equipment
L3450DT-GST, Woods FEL, B7100 HSD, FEL, 60" SB, 743 Bobcat with V2203, and more
Sorry, there is no pick-up screen on your model. Did you use Kubota filters and Kubota fluid?
These high tech tractors need things to be just so for them to work right, heard many a story about things not working right due to bad filters and fluids.
It sounding like this might be a problem for a service tech to troubleshoot, it requires measuring pressures at different point to determine what is wrong with the system. It could be as simple as a bad relief valve or as complicated as a HST system failure.
If you truly want to find out what's wrong and your not afraid to get into it, you'll need to get the service manual for it. It will tell you where, and what to check to get it fixed.
You will also need to get a set of test gauges to test everything out, you can get them On EBay when you figure out what pressures you need to be looking for.
I have a set of 2, one low (0-100psi) for the GST and one high (0-5000psi) for the other hydraulic systems. Also have flex hoses to connect to 1/8"-1/2" lines and fittings.
These high tech tractors need things to be just so for them to work right, heard many a story about things not working right due to bad filters and fluids.
It sounding like this might be a problem for a service tech to troubleshoot, it requires measuring pressures at different point to determine what is wrong with the system. It could be as simple as a bad relief valve or as complicated as a HST system failure.
If you truly want to find out what's wrong and your not afraid to get into it, you'll need to get the service manual for it. It will tell you where, and what to check to get it fixed.
You will also need to get a set of test gauges to test everything out, you can get them On EBay when you figure out what pressures you need to be looking for.
I have a set of 2, one low (0-100psi) for the GST and one high (0-5000psi) for the other hydraulic systems. Also have flex hoses to connect to 1/8"-1/2" lines and fittings.