Hello. We are currently dealing with a problem on a cylinder head of a Mitsu 4G63 engine on a CAT GP25. We are ready to rebuild the head but cannot find the part number for a 3rd valve and it's seal that works alongside the exhaust valve. Apparently this 3rd valve is for gas recirculation, but CAT dealer cannot identify it. Does anyone know the part number for this valve and its seal?
Thanks,
OB1
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Thanks again guys for the valuable information. Customer agreed to use plugs in the head were the jet valves work, just to get the truck back to work. He will prepare budget for a new head in coming months.
Best regards,
OB1
yeah i suppose he could just do what you say and remove all the 3rd valves and weld up the port for them.
or he could try and find a used head and put the (correct one) back on the engine to eliminate the headaches in the future just in case someone else works on this engine.
or considering the time and labor costs to do this versus just getting another head
i'd weigh out the differences and see what would be the most efficent route to take. Of course if it were my engine i'd want it right, i'd put it back like factory like it was designed to be in the first place ;o)
The head most likely went bad and was replaced with an automotive equivalent. I have sen many of them but never on a forklift. 15 year cat tech. The head will work but the jet valve was always the weak link in an automotive setup. I have bought and sold many D50 doge trucks that smoked or used oil that was the direct cause of the jet valve. Never had an ill effect bypassing them. The additional jet valves to improve emissions (MCA-Jet system). On the intake stroke, air rushing out of jet valve opening scavenges gases from around the spark plug and produces a strong swirl in combustion chamber promoting high combustion and minimizing exhaust emissions. Not so important for a low rpm forklift engine.
you got a complete model and serial number of the truck this engine is in?
dumb question but i'm sure you have looked and made sure of the engine model by looking on the side of the block on the flat surface where they stamp the engine number? Maybe there are other numbers there indicating a special application or something?
I've looked through every engine manual cat has on their GP25 series trucks and they all show a standard 2 valve per cylinder setup. Nothing to indicate a 3rd valve.
This is rather odd setup,unique apparently and may not be factory OEM setup. I've worked for cat for years and never seen a 4G63 or 4G64 with this head setup you speak of.
Thanks for the information. We'll go ahead and eliminate it just as you've done.
best regards!
OB1
I t is called a jet valve. Used on many Mitsubishi engines from the D50 to the Colt Vista. There used to be a kit to eliminate them but we always just pulled them out and removed the valve. Then braze up the guide. May be able to find seals for them on line.
It does sound like an automotive cyl head. I was researching high performance head gaskets for a 4G63 a while back & remember that there were 3 valves on high performance mitsubishi's. If I remember corectly it was a turbo model.
It is supposed to be an Exhaust Recirculation Valve. It opens right befor Exhaust valve completeley closes and it sends unburned gases back to admisions so they can be thoroughly burned.
Customer does not want to buy a new STD head with only the 2 exhaust and intake valves, so I need to look for these 3rd valves which are bent. Tried automotive parts dealers, but they can't identify it either.
Yes , i have not seen ever a third valve in a 4g63
It sounds like someone has put a aftermarket head on the truck. I have seen a few new cylinder heads coming out of China and Taiwan that have a 3 valve set up.
Original only came with 2.
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