So engine 6076T in a 644 wheel loader. this engine had what we guessed was a liner seal failure at 12k-14k hours, we pulled it out and did a complete overhaul, Head checked for cracks, crank checked and polished. New liners and pistons, followed all the steps, Engine was fine for six years I'd have to guess, there was a crack in the radiator and it would loose a little coolant, maybe half a gallon twice a year. I did find some time to track down the leak, the neck was never attached to the top tank, sliver soldered that in place and fitted a new cap and expansion tank. The other day after a run, operator says the heater isn't working, checked it out the next week, it was almost 5 gallons low on coolant, added coolant, everything seemed normal, oil level normal, no foamy junk, thinking a nicked line or leaking hose. Finish for the day and shut down with a note to investigate. Oil hasn't ever gotten milky yet, checked oil to find its way above full, pull oil drain plug and after a few seconds of oil from the drain line its a stream of coolant, a little more than a gallon, still not mixed with oil. Oil is black and not gray or beige. No idea what's leaking, I was careful with the liner oring install and liner install everything cleaned and deburred and soaped up, it went together smoothly. On a hunch we pulled the oil cooler, a little soapy water and pressure from the oil side shows no leaks. My next hope is to pull the water pump.. Any suggestions or likely culprits? When we did the rebuild we didn't change the water pump, it seemed tight, Also didn't change the cooler as it was leak free, not full of junk. Being a loader the pan won't clear the rear axle for taking a peek. Hopefully I didn't screw up too bad! Glad we didn't start it with a pan full of coolant. I'm still at a loss where 5 gallons wandered off to without a trace.
644E ? A gear driven water pump so very likely the issue .There is a 1/4 inch weep hole to allow coolant to leak externally if the water pump shaft seals fail but after 15000 + hours the weep hole will be plugged solid. A leaking water pump would account for the 1 gallon of coolant found in the pan but the missing other 4 gallons must be an external leak of some kind.
Second the waterpump
Thanks, looks like reliable aftermarket has the pump. Imagine its a safe bet to replace the cooler as well, seeing its out and needs all new gaskets and o-rings. Not that I object to pulling the engine out but I'd really rather not! Though the paint job could use a touch up! Rebuilding it was a fun experience, even got to make a driver for the liners and cam bearings. Also found that the prior rebuild/swap lost 1 pulley from the crankshaft and never tightened the cam gear allowing 1/4 inch end play, slightly more than the suggested 0.005
Recommended Next Steps Clear the Water Pump Weep Hole: Use a small wire to ensure it isn't blocked. If it's plugged and you see coolant behind the plug, you've found your leak. Pan-Off Pressure Test: This is the most definitive "old school" method. Drop the oil pan, fill the radiator, and use a Cooling System Pressure Tester to pump the system to ~10-15 psi. and too recomend check John Deere 6076T Coolant in Oil: Static Leak Diagnosis & Fixes Watch for drips from the bottom of specific liners (confirms O-rings). Watch for a stream coming from the front cover area (confirms water pump). if you like repair guide
Going for the weep hole, ordered a water pump and cooler anyway, good to have it. Would love a pan-off option but the loader's rear axle is just a couple inches below the pan, the oil drain is a 3/4 inch hose that exits the side of the chassis. More in-depth will be removing the engine from the chassis, that takes a few hours. I'm not sure if there is a good way to get a scope into the pan, the oil fill is right close to the gears. Maybe from the top down via the valve cover if its a small camera. It might be possible to remove the oil drain hose and get in that way but it'll be a heck of a job getting in there, maybe pull a tire and teeter the axle.
Understood. Since the axle makes a pan-off inspection difficult, let's proceed with the weep hole check and have the new water pump and cooler ready as a precaution. Regarding the scope, we can try the valve cover approach first; if that doesn't work, we'll evaluate if pulling the tire to access the drain hose is worth the extra labor. Let's aim for the least invasive path before considering an engine removal.
Guess its better than filling the cooling system with 5-40 and refilling the radiator from the oil drain.
Be careful, mixing oil with antifreeze destroys engine metals (bearings) and ruins rubber hoses.
Looking at the replacement water pump, the weep hole certainly isn't really obvious! going to need a mirror to try and hit it with the crank pulley being right there, I'll try a pick and see what happens.
Will be looking into the water pump this Sunday, tarp the machine and toss a big heater down under. I'm thinking on the engine oil, it had to have some contamination. My thoughts are blowing out the galleries with compressed air from the oil cooler pipes, with the drain plug out, let it all run and give the pan a gallon of diesel for a rinse. Add in a couple gallons of fresh oil and let it get to the cooler up-pipe before putting on the new cooler, crank that oil through the system without letting it start, then drain that off and refill with a fresh 5 gallon pail. Just wanting to dilute the nasty oil
Check the end of the rocker cover breather hose for signs of oil/coolant sludge. If you find a lot, remove the rocker cover for cleaning.
Heh, rocker cover, well that's always fun!! Will do.
So update, start working, its -3f , tossed a big heater underneath to get things warmed up, tarp the back of the machine, let it cook for a while, remove fan guard, alternator, battery grounds, rear grille, move the big radiator cover back just enough to get to the fan bolts, coax fan out of the way. Belts and alternator out the weep hole is solid plugged, no easy way to dig it out. Pull the thermostat housing and fan support, remove housing, remove fan, remove water pump. On the bench was able to run a drill up the weep hole, solid solid, right at the very end the drill comes out all goopy and about half a cc of rust/coolant dribbles out. Had ordered a new oil cooler, the JD parts book says the T model engine takes the larger oil cooler, nope, block tag says 6076T but it needs the short cooler. Order correct cooler and thermostat gasket, orings and the like
Looks like you got caught in an engine serial # break. See screenshot below.
AR55394: Oil Cooler looks like the shorter unit for certain.
After exploring online for obtaining gaskets, opted to just call deere and order the thermostat neck gasket, all the orings, all the cooler gaskets. Most were in stock and the rest getting ordered including a rocker cover gasket, can check the clearances while I'm up there. Hasn't been checked since the rebuild, maybe 800 hours or so.
Perfect timing as the valves will have set by this time. Simon C
Drained the oil and checked things out, put a gallon of diesel in the oil pan to let it sit, drained it out and there wasn't any chunks or ice, had the tail under a tarp with a big heater going, it was almost too hot to work on it under there. New water pump fitted, old water pump was leaking a lot when tested with air. New oil cooler fitted, pulled the filter and dumped some fresh oil in the crankcase. Cranked it over until clean oil came out of the filter mount. Ran the engine about 30 minutes with a little light work and the new oil still looks new, I'm thinking a good plan is to run the fresh oil for about 10 hours and give it another oil change. The oil in the engine was black black, didn't feel like it had much water in it, not the usual foamy grey or brown goop. I bet there's a bunch of condensation that has to get chased out, luckily we're having an honest blizzard so it'll get some hours tonight.
Attempted to start the first run while under the tarp tent, the exhaust was getting sucked into the air filter and it ran terrible. proof that egr is bad.
So did a couple test runs, first one was 5 or 6 hours moving a blizzard, had the oil right at the add oil line to keep an eye on it. No rise in oil level or drop in coolant with the new water pump. Oil was quite clean, looking in the timing cover there was a blackish film beneath the film of clean oil that wasn't getting into solution. Added a couple quarts of ATF to the clean looking oil and ran again removing a couple hundred yards of snow. After another six hour run now the previously clean oil was far far from it. no moisture seen under the fill cap or top of dipstick. The residue in the timing cover still had a little residue stuck to the metal beneath the hot and somewhat dirty oil. New oil and filter at the end of that day while it was hot. Is there an good wonder substance to help clean off any residue in the corners and crevices or is a shot of ATF before doing an oil change acceptable.
You will have to change oil another time after one hours run or within a day or two. I have done the exact same many times before shutting down an engine for overhaul, helps to get cleaner inside. Only thing is that some oil always stays behind in the oil cooler and in the crank journals and around camshaft pockets and other places. It is usually about 10 percent of capacity but still better to have pure motor oil for next couple hundred hour run. Simon C
So I pulled the filter for a couple days to let it dribble out, also drain plug out for a couple days, gallon of diesel in the crankcase disloged some stuff, drained that for another day. Added fresh oil and held a bucket on the oil filter mount cranked it over to push oil from the pump, pipes, cooler,more pipes and then over to the oil filter mount, gave it another long crank to build oil pressure before starting. The first run left pretty clean oil behind, adding ATF really did some scrubbing. I'll plan on another flush after a bit of run time, maybe being hotter weather would be better.