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+--- Thread: CM871 oil pressure (/showthread.php?tid=2990)
RE: CM871 oil pressure - Signature620 - 04-14-2018
If possible, you might want to prefill the oil cooler and rifle before the next startup by pumping oil into the plug halfway between the front of the oil cooler and the filter. It's done a fair bit of running without oil by now so every bit will help.
RE: CM871 oil pressure - pearce trucking - 04-14-2018
Quickserve has a priming instruction in the service manual. This link might work.
https://quickserve.cummins.com/qs3/pubsys2/xml/en/procedures/10/10-007-037-tr.html
RE: CM871 oil pressure - Signature620 - 04-15-2018
That's the one. You can even put the oil filter on dry and prime it this way if that's easier for you.
RE: CM871 oil pressure - pearce trucking - 04-16-2018
So I got everything torn down today. Couldn't get the thermostat out, but will have the 19mm allen wrench to remove it tomorrow.
Here's a couple pics of the oil cooler. Looks pretty healthy. I'll know more tomorrow.
RE: CM871 oil pressure - dhirocz - 04-17-2018
I did 6 in my 871.
Hot idle: 22psi @ 620 rpm
Hot high idle: 45 psi @ 1200 rpm
Hot 700rpm: 25 psi
Hot 800 rpm: 30 psi
Hot 1600 rpm: 47 psi
That's with half a gallon of 80-90 in a fairly worn 871 a 740k. I did roll new bearings into it and changed cooling nozzles at that time. New cam bearings, oil cooler and thermostat as well.
I too dropped mine in first, but had the pump removed and was able to verify they all dropped in and sat down flat before reinstalling the pump, since the bore was vertical with my pump in a vise with softjaws. I've shimmed a number of other pumps before, and personally, wouldn't do it unless the bore was vertical. I took note of the bore and why they need to be flat, so if I did one with the pump installed, I would think the cup is the only way to go. I also trimmed the tab on the pump shims on one side to not interfere with the gasket.
It does sound like a couple dimes slid out of the bore and got fed through the pump...if that pump is not perfect I'd consider replacing it now...but at a minimum, find those pieces!
RE: CM871 oil pressure - pearce trucking - 04-19-2018
So I figured out the oil pressure problem. The dimes initially held back the dog bone, causing the 90psi condition. The dimes were snapped then and the dog bone pushed forward past them, but was then stuck in the 0 psi position. I went through the pump thoroughly, and though my explanation may be hard to follow, it makes sense for the way the symptoms presented themselves. There were small pieces in the thermostat and the passage between the thermostat and the filter. Likely some in the filter itself also. The gasket for the oil cooler housing looked to be seeping at the bottom, so good to replace it. Got the new pump. Not installed yet.
Latest is the turbo. I removed the hot side, and found the vgt ring broken. Is it replaceable?
RE: CM871 oil pressure - dhirocz - 04-19-2018
I've seen new Cummins ones for sale. I know you can also get them at the dealer...but they would rather sell you a turbo. I had to look up the parts listing for the turbo to find that number, but I ended up sending in my spare turbo to get rebuilt instead.
I would not put that thing on in that condition. It's a disaster waiting to happen. I doubt the VG ring would allow it to work long properly, if at all.
If that turbo has alot of miles on it, you might be better off replacing it and calling it a day.
When my original 700k turbo came off and looked like that, it also damaged the compressor wheel. I'm surprised I was able to make the trip home (carefully and gently) from Baltimore to Savannah after seeing that.
RE: CM871 oil pressure - Signature620 - 04-20-2018
There is a turbine housing kit. I'll try to find the bulletin for it because 99% of parts interpreters will think you mean recon turbo.
Edit: Use this bulletin if your CPL is mentioned.
https://quickserve.cummins.com/qs3/pubsys2/xml/en/install_inst/2883516.html?q=turbine%20housing%20repair%20kit
RE: CM871 oil pressure - pearce trucking - 04-21-2018
So with the ring being broken, I assume boost is lost in a high boost condition. The imap monitors air flow so I guess at max boost commanded, my boost will be lower than its designed to be. Is fuel reduced to make up for this? Or is the engine running richer? I guess ultimately power will be reduced regardless. Just wondering what other effects follow from the broken ring. I guess on climbs, egts would be higher?
Thanks.