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Engine Specific Info and Questions => IDI Engine => Topic started by: libbydiesel on February 08, 2014, 11:23:55 pm
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A few weeks ago I went through a spare 1.6TD injection pump of mine. I cleaned and lubed all the internal bits and replaced all the seals and o-rings. I installed the pump in order to test and tune it. It took a little bit of adjusting to get it idling and revving correctly. Once that was sorted I took the car out on the road for a test drive. I got a few blocks from my house and it suddenly stalled out. I rolled into a nearby parking lot and popped the hood. I was relieved to see that the timing belt was intact. I cranked it over and the engine spun over normally but didn't start. I went and checked the belt again and it all looked fine. I cranked it some more and it finally fired up with a cloud of smoke. It obviously wasn't running right, tho. Idle was somewhat rough and kind of pulsed, vroom, vroom, vroom... I drove it back to my house and parked it. On the return trip it ran very poorly and stalled out once but I made it without much ado.
Today was beautiful weather and I had a chance to pull it apart. I checked the belt timing and the crank to cam was correctly in time, but the pump was waaaay off. Basically 180°. I knew that I had installed the belt correctly so I was curious what else I would find. Once I got the belt off I rotated the pump sprocket using the nut and it was a fair amount harder to turn than normal. The pump sprocket was also quite a bit harder than normal to pop off the pump shaft. When I finally got it off I noticed that the woodruff key had sheared and that the shaft and sprocket had kind of smeared together... When I drained the pump, what came out was metallic liquid almost black in color. When I pulled the pump lid everything looked beautiful inside. I pulled the distributor head and again it all looked great. Camplate and rollers were beautiful. The governor gear and flyweights also looked good. I rotated the mainshaft at that point and noticed that the vane pump cover was rotating right along with the mainshaft. Hmmm... I pushed the main shaft out and lo and behond, the vane pump hub has welded itself to the vane pump cover. :o
(http://i13.photobucket.com/albums/a269/libbybapa/100_2562_zpse895f494.jpg)
The screws are sheered off flush to the pump case. My conclusion is that the vane pump did not receive enough lubrication causing the hub to seize to the cover. When that happened, the stress on the woodruff key was too much and it sheared and the sprocket gradually spun to 180° out. The thing that is most amazing to me is that it STILL RAN! I drove it home 180° out of time with the vane pump cover and outer ring just spinning around. What I am most thankful for is that the timing belt did not jump.
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OUT bolt plugged?
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holy cow. One would have thought that a few teeth would have been missing if nothing else from the TB.
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TylerD, I'm not sure about the out bolt being plugged. It probably is now after catching a lot of fine metal particulate. I'm not sure if it plugged prior and if it did I can see pump pressure going up and a seal bursting but I don't know why that would seize the vane pump. If you have a theory, I'd be interested.
Theman, I'm astounded that the timing belt did not fail and equally astounded that I drove it home. That's borderline miraculous to me.
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THe question is what timing belt was it?
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The belt is Conti and is two years old. Not many miles on it, tho. Probably less than 2,000.
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If you have a theory, I'd be interested.
Lack of cooling, perhaps.
I'll be checking mine on any reseals from now on, that's for sure.
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Any bluing of the plunger, or other signs of overheat?
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Nope. Plunger looks and feels perfect.
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WRT the out bolt I would mention a couple other things. It was a used bolt. Prior to using it I blow it out both directions with compressed air.
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Surely that can only fuse due to lack of lubrication and not down to a blocked out bolt which would not prevent regulation of oil pressure.
Having said that if the out hole did block, the pump would have no means of cooling, beyond replacing fuel used by the injectors.
If the diesel gradually thinned due to heating and so began to bind the vane pump to it's stator, it needn't have actually fused until you stopped and let it cool down.
Clearly a good belt is stronger than the soft Woodruff key...
If pulley nut not tight enough, binding plate would allow belt to rotate pulley through woody key and tighten nut for you...
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The pulley nut was torqued to spec.
I was under power when the engine stalled. If the hub seized to the plate after shutdown then what caused the stall and the sprocket woodruff key to shear? Also, if the hub seized after shutdown, it would not have sheared the screws.
The most logical sequence of events that I can see is that the vane pump seized causing the engine to stall and the pump sprocket to shear the woodruff key and move out of time. The friction of the pump shaft/sprocket interface welded the sprocket to the shaft. That weld then became stronger than the screws of the vane pump and they sheared.
The most significant question is 'why did the vane pump seize'. I agree that lack of lubrication has to be the answer.
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Was this with your vnt rabbit? so it must have spun at least a few revs after the key sheared to cause the welding??
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Yes, this was on my rabbit. The welding of the vane pump to the vane pump cover had to have been the cause of the sprocket woodruff key shearing. In looking at the sprocket and shaft, I do not think the sprocket rotated on the shaft more than the 1/2 turn before it seized.
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If you've recently serviced the pump, then maybe it's not down to any incompetance/ or fault of yours, and indeed not a fault of the pump, but something external.
Could partial restriction in the pipework upstream cause the vane pump to starve enough to allow the fuel reservoir to drop but still have enough to supply the piston? Mabe not.
Perhaps prying the fused pieces apart and using an eyeglass to determine if it is baked diesel, or metal to metal welding. Perhaps there is a series of concentric circles, or just an arc...
EDIT: OK I've just read you initial post properly. You were only a short distance into your test drive, no time for the pump to develop a fault, more likely there was something amiss from the beginning. Is this a pump created from several pumps perhaps?
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As I mentioned I was a few blocks into the initial test drive after assembling the pump. On assembly everything was well lubed. It had been running for some time in the drive as I got the idle/timing adjustments dialed in.
I initially tried to separate the vane pump hub from the cover by hammering on it. It didn't budge. It is not stuck by baked on diesel. It is welded. I'm not going to try any harder to separate the pieces as they are an interesting paperweight/conversation piece.
I was very low on fuel and it is feasible that it sloshed away from the pickup enough to momentarily starve it.
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I was very low on fuel and it is feasible that it sloshed away from the pickup enough to momentarily starve it.
I didn't think it was possible to "starve" an IP. The inlet to the HP head is higher than most of the other guts including the lift section. The engine should stall if the level of fuel drops. Otherwise, running out of fuel would kill IPs left and right.
(https://lh3.googleusercontent.com/-3Z-KKto7RPs/UvgBVOEGiWI/AAAAAAAABbc/CBYUJsjT23U/s800/Waterline1.png)
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I initially tried to separate the vane pump hub from the cover by hammering on it. It didn't budge. It is not stuck by baked on diesel. It is welded. I'm not going to try any harder to separate the pieces as they are an interesting paperweight/conversation piece.
How about slicing it in half?
Aside from lack of lube...how about something with the vanes themselves , like pulled from another pump, put in backwards, with grit or varnish...
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I'm not going to cut up the piece. I will save it on 'the wall'.
I'm quite meticulous when assembling a pump but grit/particulate is certainly possible. I don't think the issue was with the vanes, tho, as they all came free of the hub without much doing. I also try to be very careful to maintain the relative positions of the vanes, camplate rollers, flat bushings, etc. That said, it is certainly possible that I flipped one or more of the vanes. I have fumbled bits and dropped them before. My typical approach is to wipe the bits off, blow them off with compressed air and then wipe off again before lubing them up with vaseline in order to install.
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It seems really weird to me there would be enough force going that direction to stick the parts to each other. Which leaves heat...
Lightning strike from under the car hits the pulley, and in grounding through the pump-plate interface welds the two together ;D
It still looks good at the front of the pump housing right?
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I like the lightning strike theory although I didn't see a flash. The pump case looks decent. There is a bit of marking where the screws broke and from the outer ring spinning but really quite reasonable. No galling of the aluminum or any wear that can catch a fingernail on the area where the hub spins. The case side of the hub is a little shiny but really looks good. There isn't any wear on that side that I can feel with my finger or fingernail. The whole thing is weird. The internal parts of the pump all look really good except that the vane hub is welded to the cover, the bolts are sheared in the case and the shaft/sprocket are both galled. If I get the sheared bolts out I will install another vane pump, clean up the pump shaft and reassemble and have a pump that's good for another 200,000 miles or until someone over-tightens the belt...
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If the fasteners are broken, maybe they are the suspect. Imagine in previous service, something was cocked in the bore, and the plate was zipped in with an impact, stretching the screw to near breaking, and or bending the plate. You pull it out, give it a wipe, and throw it back together
???
I'm not to clear on how this scenario ends in seized parts though.