jpx 260p rebuilding tips
10-26-2005, 03:40 PM
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jpx 260p rebuilding tips
Hello, I am fairly new to this forum, and have reviewed all past discussions on JPX turbines. I have a 260P engine that requires a rebuild/bearing replacement. I have aquired new factory bearings for it, and was wondering if you guys have any tips on rebuilding it. Thanks, Lloyd
10-31-2005, 11:43 AM
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RE: jpx 260p rebuilding tips
Alright guys, Due to the overwhelming response to my first posting, or lack of, I'd like to ask a couple more specific questions if I may.
Scenario: I bought this 260P used Off of Ebay. My first bench run (with help) went very well. Although I could only obtain 0.8 bar pressure no matter what adjusting I did to the GRU. After replacing the fuel line I attempted a second run(by myself). Mistake I know, too many things to keep an eye on. Before I knew it the tailpipe was glowing red hot. I immediately shut the fuel off and the turbine quickly ground to a halt. After alot of cooling air was blown through the turbine it would spin once again, but was rubbing on something. After carefully tearing it apart, marking everything, I found the rear bearing black and clicky and the the turbine wheel was rubbing on the NGV. I had thought about having the turbine shaft ground to 10mm to accept a more standard bearing. I have since then obtained 2 new sets of factory bearings and other rebuild items.
Question 1) The parts that I obtained included 2 springs and seats. These appear to be used to push/hold the rear bearing and assembly back towards the NGV. Is this correct? Is it needed? The original engine did not have it in it. I also have a number of what is called bearing o-rings. Where are these placed? Are they again needed?
Question 2) Is it necessary to have the assembly rebalanced if all parts were marked as to their original position?
Thanks again, Lloyd
Scenario: I bought this 260P used Off of Ebay. My first bench run (with help) went very well. Although I could only obtain 0.8 bar pressure no matter what adjusting I did to the GRU. After replacing the fuel line I attempted a second run(by myself). Mistake I know, too many things to keep an eye on. Before I knew it the tailpipe was glowing red hot. I immediately shut the fuel off and the turbine quickly ground to a halt. After alot of cooling air was blown through the turbine it would spin once again, but was rubbing on something. After carefully tearing it apart, marking everything, I found the rear bearing black and clicky and the the turbine wheel was rubbing on the NGV. I had thought about having the turbine shaft ground to 10mm to accept a more standard bearing. I have since then obtained 2 new sets of factory bearings and other rebuild items.
Question 1) The parts that I obtained included 2 springs and seats. These appear to be used to push/hold the rear bearing and assembly back towards the NGV. Is this correct? Is it needed? The original engine did not have it in it. I also have a number of what is called bearing o-rings. Where are these placed? Are they again needed?
Question 2) Is it necessary to have the assembly rebalanced if all parts were marked as to their original position?
Thanks again, Lloyd
10-31-2005, 12:53 PM
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RE: jpx 260p rebuilding tips
Well the pre-load spring is needed yes. it reduces the axial load in the BB while the engine is running.
I have assembled/disassembled a engine or two (not a JPX) , and balanced the parts individually..(shaft, compressor and turbine wheel) and they seemed to work ok after that.. you should run it at a lower RPM initially, and slowly increase the RPM´s paying attention if any abnormal vibration or bearing noise starts... throttle down immediately if this happens.
If the engine runs ok, remember to stay most time at above idle RPM. this helps to keep the engine temp down.
It is quite difficult to learn to run a turbine at the same time you are fixing it...all I can say is that
you should be aware of small things and fuel lines being sucked by it, have also a big fire extinguisher and to wear eye and ear protection. also keep always in front of it as far you can turn it´s switches...
Enrique
I have assembled/disassembled a engine or two (not a JPX) , and balanced the parts individually..(shaft, compressor and turbine wheel) and they seemed to work ok after that.. you should run it at a lower RPM initially, and slowly increase the RPM´s paying attention if any abnormal vibration or bearing noise starts... throttle down immediately if this happens.
If the engine runs ok, remember to stay most time at above idle RPM. this helps to keep the engine temp down.
It is quite difficult to learn to run a turbine at the same time you are fixing it...all I can say is that
you should be aware of small things and fuel lines being sucked by it, have also a big fire extinguisher and to wear eye and ear protection. also keep always in front of it as far you can turn it´s switches...
Enrique
10-31-2005, 01:44 PM
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RE: jpx 260p rebuilding tips
