RedMcC
Member
I got some fantastic advice on here the last time... so here goes.
Machine: Hitachi EX200-2
Vintage: 1991, 18000hrs+
Modifications: New Engine (6BG1-T, ie. the next generation of 6BD1-T), done 6 months ago and it was working like a dream.
Recent replacements: I replaced the A-sensor this morning, it is at maximum clockwise setting and not helping the situation described below (although I still suspect the previous A-sensor was a little faulty)
Symptoms:
1. The Engine overheats (95-100degs C) after 10-15 mins of use - this is obviously a big problem. The Radiator still has fluid movement and air going through it - the temperature does vary horizontally and vertically across the radiator (I'll get some figures next time I'm on the machine). I think the variation is a bit excessive and there is possibly some internal radiator obstruction, but it not the main problem (I think).
2. I hear a pressure relief valve (at least I assume it is) whenever the machine isn't actually in operation. This is particularly noticable at Low Revs as it isn't drowned out by engine noise. The pressure relief 'hiss' stops whenever I move the boom/stick/swing etc. I think this is part of the main problem...
3. As part of my diagnostics, I electrically disconnected the pump solenoid that increases pump swash / load - the pressure relief noise was still there even when it is supposedly at minimum / very-low swash. The machine was, as expected, very slow moving, but interestingly I was able to stall the engine by continuing to order "stick-out" when already at maximum extension (this is a new symptom and repeated when the solenoid was connected as well).
4. The pump solenoid electrical resistance is a little out of tolerance (should be 16 Ohms+/-1; and is at 18 Ohms). I don't think this is a source of the problems, even when electrically isolated the pressure relief noise is still there.
5. The main pump Pressure sensor plug is a little broken - I have a replacement for that, but don't think it is part of the problem.
6. I have done wiring harness continuity checks from the PVC / ECP computers to the: A-sensor / pump solenoids / P-sensor / ECM (all were good). I haven't done anything with the DP sensor, it is on the list but I'm starting to feel like I'm missing something and my fault finding is getting random...
7. When changing revs (I,L,E,P), the actual revs change much slower than they used to (take around 4 secs to go from L to P, used to be under 0.5 secs). The Engine Control Motor is moving slowly, suggesting it is an electrical control issue not a motor issue (I'll need to triple check this.)
8. With the A-sensor mechanically disconnected (but still electrically connected), I can tweak the A-sensor so there is no pressure relief hiss. Unfortunately, at this point there is not enough hydraulic pressure to lift the bucket, let alone do any work.
Anyone have any ideas, or seen anything like this before?
Machine: Hitachi EX200-2
Vintage: 1991, 18000hrs+
Modifications: New Engine (6BG1-T, ie. the next generation of 6BD1-T), done 6 months ago and it was working like a dream.
Recent replacements: I replaced the A-sensor this morning, it is at maximum clockwise setting and not helping the situation described below (although I still suspect the previous A-sensor was a little faulty)
Symptoms:
1. The Engine overheats (95-100degs C) after 10-15 mins of use - this is obviously a big problem. The Radiator still has fluid movement and air going through it - the temperature does vary horizontally and vertically across the radiator (I'll get some figures next time I'm on the machine). I think the variation is a bit excessive and there is possibly some internal radiator obstruction, but it not the main problem (I think).
2. I hear a pressure relief valve (at least I assume it is) whenever the machine isn't actually in operation. This is particularly noticable at Low Revs as it isn't drowned out by engine noise. The pressure relief 'hiss' stops whenever I move the boom/stick/swing etc. I think this is part of the main problem...
3. As part of my diagnostics, I electrically disconnected the pump solenoid that increases pump swash / load - the pressure relief noise was still there even when it is supposedly at minimum / very-low swash. The machine was, as expected, very slow moving, but interestingly I was able to stall the engine by continuing to order "stick-out" when already at maximum extension (this is a new symptom and repeated when the solenoid was connected as well).
4. The pump solenoid electrical resistance is a little out of tolerance (should be 16 Ohms+/-1; and is at 18 Ohms). I don't think this is a source of the problems, even when electrically isolated the pressure relief noise is still there.
5. The main pump Pressure sensor plug is a little broken - I have a replacement for that, but don't think it is part of the problem.
6. I have done wiring harness continuity checks from the PVC / ECP computers to the: A-sensor / pump solenoids / P-sensor / ECM (all were good). I haven't done anything with the DP sensor, it is on the list but I'm starting to feel like I'm missing something and my fault finding is getting random...
7. When changing revs (I,L,E,P), the actual revs change much slower than they used to (take around 4 secs to go from L to P, used to be under 0.5 secs). The Engine Control Motor is moving slowly, suggesting it is an electrical control issue not a motor issue (I'll need to triple check this.)
8. With the A-sensor mechanically disconnected (but still electrically connected), I can tweak the A-sensor so there is no pressure relief hiss. Unfortunately, at this point there is not enough hydraulic pressure to lift the bucket, let alone do any work.
Anyone have any ideas, or seen anything like this before?
