Need Help with Komatsu PC55 **Possible Hydraulic Issue**

[Amjad.kamal]

The most unique thing about Komatsu is Komatsu threads. They use 30-degree metric threads, which are inappropriately expensive IMHO. They can't use 37-degree JIC & SAE like the rest of the world. Even BSPP fittings on Takeuchi are tolerable (price and availability wise).

You don't need to by a high-end Komatsu test gauge with quick disconnects. Recommend getting the items below. These are surpluscenter.com part numbers. Note: the 6-foot 1/4" hose might be overkill, but it will last a lifetime, and you can put the gauge within eyesight when you're in the cab troubleshooting.

Gauge, 600 PSI 2.5" ITEM NUMBER: 21-1246-G
Gauge, 5000 PSI 2.5" ITEM NUMBER: 21-1246-L
Hose, 1/4" x 72" JIC 4F Assy 5800 PSI, ITEM NUMBER: 920-2272
Adapter, JIC 4 Male x 1/4" NPT Female Straight, ITEM NUMBER: 9-2405-4-4 (x2 - one for each gauge)

For the other end of the hose, Surplus Center (link below) offers adapter fittings for JIC-4 male to various other threads (NPT, SAE, BSPP, ORFS) - unfortunately they do not sell 30-degree Komatsu adapters (you must shop elsewhere for those). Looking at your picture above, those fittings appear to be straight thread with o-ring seal, not 30-degree Komatsu - presumably metric. Get yourself a set of SAE & Metric thread pitch gauges, and also a dial-caliper (if you don't already have them). Use these to positively identify the threads required to construct your tee. Find a suitable tee through Parker (bottom link) - the hardest part will be adapting the tee to JIC-4 Male on one end (to connect your gauge hose).

Hydraulic Adapters & Fittings | Hydraulics | www.surpluscenter.com

Hydraulic Adapters , Fittings,NPT to NPT,SAE O-ring to NPT,JIC to NPT,SAE O-ring to SAE O-ring,JIC to SAE O-ring,JIC to JIC,BSPP,ORFS Face Seal,Plugs

www.surpluscenter.com

https://www.parker.com/content/dam/Parker-com/Literature/Tube-Fittings-Division/4300_Catalog_Cover.pdf

Additional notes: If you are unable to find an adapter thread-combination that works (without spending 500 dollars) - you can TIG weld fittings together to "force" them to adapt. If you end up doing this, recommend you stick with 300 stainless fittings only. The steel adapters sold through Surplus Center are made from free-machining carbon steel and are not suitable for welding (high risk of cracking when welded). If you buy 300 series stainless fittings through Parker, they will weld together just fine when welded with 308 filler rod.

All this info is very helpful. I'll work on a T setup to be able to test. Really appreciate your help and guidance. Thanks!

 

[Entropy1]

I too have pulled my hair - in trying to troubleshoot an intermittent Komatsu hydraulic fault. You're not alone.

 

[Doug Blair]

Wow this is spooky. I just had the same problem with my IHI 15NX. Used it one day no problem, next day backed it out of the carport, put the blade down to lift machine to wash it and swung the house around to lift the other end and lost all control of the boom and forward and reverse on the tracks. Blade, swing, and moving tracks (expanding width) still work but no boom. Checked the usual oil, filter, switch under arm rest and then because of limited knowledge stated looking on the web. And this is the 1st site i found and the same problem as Amjad and a idea on what to look for from Entropy. And now the spooky part Amjad, i moved from Edmonton (180 miles north of Amjads home Calgary) to Panama 16 years ago and bought my machine used imported from the USA.
Some things i have noted on my machine, if like the diagram that Amjad posted showing the ppc valve also included the high speed pedal switch i have found i have to keep hitting it until it finally catches? Could this mean maybe the same electrical problem Entropy? Also Amjad where is this stated solenoid on your machine as i have not found it yet on mine as i am just starting this adventure and do not own a repair manual yet. Just talked to a friend here and he has test gauges. And Amjad what was the final outcome on your prolbem? And and all options are more than welcome as i was a welder not a heavy duty mechanic. And Amjad, Entropy mentioned the Surplus Center for hyd parts. That is where i got my cylinder and pressure relief valve for my thumb, if you have a unused hydraulic circuit out on your boom put a thumb on your machine. It makes the machine twice as useful. Thanks and hope to hear from you.