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Old 12-01-2020, 04:15 AM   #1
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C-9 ACERT Spewing Oil

So I drove my 2009 Allegro Bus 43, with a CAT C-9 ACERT engine, about 17 miles last night, and this happened. Oil spewed from the dipstick tube, making a huge mess. Trying to figure out what caused this. (Photo flipped sideways when uploaded.)
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Old 12-01-2020, 06:42 AM   #2
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Do you have the C9S (the Regen engine with the DPF)? A C9 "ACERT" can be the 2004-2006 (without DPF) or the 2007-2010 (with the ARD, DPF, CGI, etc.).

If you remove the dipstick, can you feel (gas) pressure coming out the dipstick tube when the engine is running?

For the oil spray, One DIY check, would be to verify that the crankcase breather is not clogged/blocked. If the blow-by pressure can't get out of the crankcase through the breather it will come out somewhere else (engine seal, dipstick, etc.)

The older C9 ACERT has a breather that needs to be cleaned periodically. I don't know if the C9S breather is different from the C9 or not. Here's a snip from the C9 engine manual:

Also, I think the ECM will set a fault code if the crankcase pressure is too high - so if your not getting a code/light, then the breather may not be the issue. But it's a starting point.
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Old 12-01-2020, 12:16 PM   #3
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Thanks for the reply.
I have the 2007-2010 engine with DPF, et al.
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Old 12-01-2020, 07:54 PM   #4
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Originally Posted by rdpricejr View Post
Thanks for the reply.
I have the 2007-2010 engine with DPF, et al.
Here’s a pic of my C9s. The breather is the rectangular shape attached to the red hose. Inside is a steel mesh. Check to see if it is clogged. I have also seen where the end that attaches to the engine gets clogged.

Here’s the post that shows the clog.

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Old 12-01-2020, 10:10 PM   #5
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Make sure your crankcase is not overfilled, with oil, oil and fuel, oil and water. If the levels are OK, Make sure that your blowby tube has not been damaged by backing over something, or it got pushed up pinching off the hose. I had one machine back into a bank and plugged the hose with dirt and it blew the dip stick out. Let us know what you find. Safe Travels
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