Miller Trailblazer 300D?

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I just acquired a Trailblazer 300D from work. I do purchasing and we had one that had too many hours for the company to rebuild. It has 4037 hours on the meter. I had sent it to a repair service for a quote and it came back really high. I'm talking $4400.00 They started the welder and it welded fine and the output voltage was fine. The main problem is the blowby / lack of compression. I bought it from the owner for $250.00 I was wondering if any body has ever rebuilt a Kubota D722 engine. I have a friend that's going to rebuild it for me. I was going to get a piston, ring and gasket kit, but he told me to wait till we tear it down to see for sure. He said we may only need rings and bearings. I only gave $250.00 for it, so I don't really want to get carried away on a bunch of parts I do not need. Any body ever have one or work on one? I think I got a really good deal.
Reply:could be head to maybe a dropped valve seat but yea id for sure wait till you have it torn down befor ordering any partsHigh Octane Welding
Reply:If it runs good with no funny noises... Work it hard for a while and see if things improve. If its never run anything larger than 1/8" rod it needs to be worked hard to "clean it out". I've seen this many times when somebody buys twice as much welder than they need. Ten lbs of 3/16" or 1/4" rod should show some improvement if that's the issue. Gouging would really be a good test. 4000 hours on a Kubota is not much. JMO.
Reply:I don't think I'd gouge with it but burned a dozen 1/4" 7018 would be a good load. See if the exhaust has been slobbering a lot. That's an easy indication its done a lot of idling and not worked very hard. The other thing that is a BIG, BIG NO NO with a Kubota is using starting fluid. My skid steer has a Kubota and I remember the mechanic at the shop saying that Kubota's have really tight tolerances and starting fluid should never be used on them. They have glow plugs and if they don't work plug it in or warm it up under a tarp or something. I don't think Kubota's use sleeves but are bored out if required. Try burning some big rods first. If it doesn't clear up, take it apart and see what you find. It might not need a complete rebuild.
Reply:The guys at the shop we took it to had to use WD40 in the cylinders and starting fluid to start it. When started it ran well, except the blowby. They actually welded with it and load tested it and said everything was good except for the compression. I know the machine hasn't burnt any 1/4" rods. The biggest I've ordered here in 7 years is 1/8" 7018 Lincoln Excalibur. We do strip mining and all our welders use Big Blue Turbo welders with LN25 mig boxes running 1/16" Elite Outershield wire. I know this is too much welder for me but, as I'm just a beginner / hobby welder,  I couldn't turn it down for the price. I'll wait till we tear it apart and find out what we need. Anybody else run one? Anything else I should know? This will be my first engine driven welder.
Reply:It probably needs rings among other things if they were using anything other than the glow plugs to start it. Possibly the glow plugs aren't working and they caused damage by using starting fluid instead of checking/fixing the glow plugs.
Reply:I was thinking the same thing about the rings. I'll keep you guys posted as I get to working on it.