We just acquired a very tidy, 5,900 hour 2007 year Hyundai HL760-7 wheel loader It is fitted with a Cummins QSB5.9C engine. The engine starts and runs well, plenty of power and no excess exhaust smoke. But blowby, never seen anything like it. (venting pipe comes from the side of the block, above crankshaft and exits under the engine) Puffs pretty hard on idle but actually pumps out a spray of oil when you rev it up. It looks like the previous owners have tried to remedy it, new rocker cover ( assume valve clearence set) and looks like injector pump overhaul. Some major compression getting into the crankcase by the look of it. I guess we start with a compression check, but it looks like it may need a rebuild. It is inconsistent that a worn out engine runs so smoothly and appears to have full power. Any other ideas to diagnose this issue would be much appreciated. cheers Michael. PS it has spent its life in a concrete batching plant, lots of fine particles, could have been dusted I suppose.
I guess the first thing I would do would be to pop off the valve covers and see what your oil return looks like. Well you have those valve covers off I would so go ahead and adjust the valves. I believe the qsb engine uses fuel control to Monitor and adjust boost but if your turbo charger has a wastegate make sure that it is not stuck. And while you're there it would not hurt to pull the intake boots off the turbocharger and look at the condition of the impeller blades. Good luck Happy Hunting
I have PERSONALLY SEEN so many of those engines "dusted" from concrete plant use.. The turbos are usually seized or the impellers are ground down to nuthin.. & the oil rings on the pistons are usually the first to go.. Lost several customers over the exact same scenario.. THEY just couldn't understand the need to change air filters.. "weekly".. THEY felt it was Cummins duty to install proper air cleaning systems.?? WE ate the 1st one & toldm to shove the 2nd one.. 2 engines in 1 year.!!!
If’n I was a betting man I would say #6 cylinder is TOAST. Probably 2-3 others as well with a couple that are ok. I’ve seen a bunch of the little Cummins with dusted cylinders that ran great but had horrible blowby. Some you couldn’t hardly hold the filler cap if you removed while running. It could be dusted but on the automotive side of that particular engine I’ve also see cooling issues hurt #6 as well as less than satisfactory injectors used in a repair which washes cylinders down and smokes them just as bad as dusting. I don’t know if the industrial application of that motor uses sleeves or not. Automotive doesn’t so it’s bore and sleeve to stay standard or if a overbore cleans it up then oversize pistons. Reman is also an option.
It is usually not puffing and usually much more pronounced at boost but do not count out a turbocharger problem.
I have no idea if you have a air compressor but if you do check that. Bob
Hello to you all and thanks very much for your suggestions here regarding the Cummins. I will follow up on your suggestions and report back when we know whats going on. Cheers Michael.
Well we have solved the problem, and it was quite inexpensive. The turbocharger shaft was worn, the seal was kaput and exhaust gas was blowing down the oil tube straight into the sump. New turbo fitted and its like a 6,000 hour engine should be. thanks to all for your input, and Birken you nailed it ! great forum, much appreciated.
YUP.. the turbo is the 1st to go.. just watch that air filter.. Whoever is in-charge of maintenance, have them take it & tap it on the ground every other FRIDAY.. Just remember, no warranty on a dusted turbo..
Blind squirrel finds a nut!