Um, yep....looking for #1 TDC also requires using inj pump timing pin.
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Cat D6H bulldozer engine problems
- Thread starter Crock
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- black smoke cat d6h engine problem
Um, yep....looking for #1 TDC also requires using inj pump timing pin.
R.D.G013
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Thats what I reckon 379Pete, that why I reckon its a broken crankshaft but there is enough grip on the broken ends to still turn over but slightly out of time, will be interesting to see the post mortem results.
R.D.G013
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Broken crank would do it Nige, might be enough drive across the fracture to still turn over but some cylinders will be out of time, Seen a 6/71 GM in a Champion grader brake a crank, it still ran but not very well was knocking pretty well.
John C.
Senior Member
I've seen the broken crank as well on a 950B a lot of years ago. The engine just sounded funny and lost power. We didn't find the problem until my helper and I tore down the engine. He was on one side and I the other to pick out the crank. It folded in two and both of us couldn't stop laughing for some time.
R.D.G013
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Should put some money on this as to who can get the right answer. LOL. I am going for a broken crankshaft.
If it is a broken crank, they could put the timing bolt in the flywheel and rock the vibration damper back and forth and probably know for sure
R.D.G013
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That would do it for sure, seems like everything else has been tried and the easy fixes have been ruled out, might as well get serious, just glad its not my machine, but these things happen at times unfortunately.
Nige
Senior Member
I like the idea of installing the timing pin and rocking the damper.
kshansen
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Just to be sure I believe Nige is meaning to install the timing BOLT that threads into the flywheel, not the pin that goes in the fuel pump. Please feel free to correct me if I'm wrong.
As a former boss like to say "I thought I was wrong once but turns out I was mistaken!"
Only know of one Cat with a broken crankshaft, it was in a 992 loader at another quarry for the company. The boss at that plant did not want to believe the Cat mechanic so had be come over for a second opinion. I had one guy watch the flywheel and one guy watching the damper. Sure enough the damper end moved several degrees back and forth with no movement of flywheel.
Also had broken cranks in a couple 8-V71 Detroits. One was in a IR Drillmaster and we ran that one enough to remove drill rod lower mast then after driving truck out of pit raise mast back up to pull engine. Both of those did crack the blocks at one of the main bearing bolt holes.
Nige
Senior Member
Ken, you're right. I should have said bolt.
I suppose the other way would be to pull the starter motor and have someone watch the flywheel while the damper was rotated.
I suppose the other way would be to pull the starter motor and have someone watch the flywheel while the damper was rotated.
R.D.G013
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Its not sounding good.
Dave Neubert
Senior Member
If it is blowing smoke out of all cylinders even it must be broke toward the front I have had them break in the front before interested to see how this turns out please keep us posted Crock
Crank Arm breakage @ 1 is very common on in-line 6 engines, usually caused by vibration damper deterioration. On-highway engines you can used a pry bar to quickly determine if the crank is broken; 1/8" to 1/4" movement...also there will be a slight 'clack' @ engine start and 'bang-clack' @ engine shut down.
Cat scrapers; engine downgrade over-revs guaranteed to crack-break crankshafts or drop valves (current and older engines). When we were still using D346s, cracked-broken cranks were stacked up like logs along side of the engine shop awaiting Cat's OR for new crank deal. Mechanical tack with tattletale...operators had their own key to set the needle back. ECM stopped that BS.
Diagnostics via the internet
can't hear it, can't feel itR.D.G013
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So what was the out come, we are all awaiting the postmortem results.????
tctractors
Senior Member
I would tend to think it's Valves failed on 1 cylinder resulting in nozzle damage, by failed I mean snapped off and whacked well into piston top possibly holed, the valve lift on the 3306 is 330 thou, the crank snapping usually only makes vibration and some clatter, it's not common to happen on the 3306 P.C. or D.I. engines as the crank has a strong shape and form with more chance of snapping a rod than cracking into 2 parts, the black smoke being caused by open inlet valve port/s tctractors
Dave Neubert
Senior Member
But he said he has black smoke coming out off all cylinders evenly
tctractors
Senior Member
I did read that comment that is why I tend to think it's a snapped off valve head and damaged nozzle, this would blow crap into the inlet? it's not going to be dirt trapped in the fuel line it's going to be $$$$ costly. tctractors.
OP stated they tested each injector nozzle's spray pattern by hooking up the removed injector to the injection pump with a jumper line, one-by-one. (spray pattern was okay for each injector) Engine would still start and run at that stage. After fricken around with testing etc engine would no longer start.
3306 breaking cranks is rare, breaking rods and holing the cyl block common.
Dave Neubert
Senior Member
Any word on this problem