Black box with two hoses, what is it

Tiny
MOTORIDER323
  • MEMBER
  • 2002 ISUZU NPR
  • 4 CYL
  • TURBO
  • 2WD
  • AUTOMATIC
  • 145,000 MILES
I am a diesel mechanic and I work on a fleet of Isuzu’s, although becoming very familiar with this fleet and the trucks themselves sometimes I scratch my head at things. There is a black box that has two 1” hoses coming out of it, one hose runs to the cylinder head, the other to the bottom of the truck as a what I believe is some sort of overflow relief. This box is located behind the throttle linkage on the left side and directly under the fuel filter and its housing. I could not find anything about this box or what it does. Best I could come up with was some sort of overflow relief. One of the mechanics put way to much oil in the pan when doing a oil change and there was oil coming out of this tube that leads to that box which in return has the other hose that leads to the head. Anyone know what this is?
Saturday, November 24th, 2018 AT 10:42 PM

3 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,747 POSTS
Hi and thanks for using 2CarPros.

That is an interesting one. Can you upload a picture of it? Also, based on your description, it almost sounds like a crankcase ventilation unit. Being that is located on top, I do not think it would be an overflow.

Take a look at the picture I found online. Tell me if that looks like the part. If it does, it is for crankcase ventilation.

Let me know.

Joe
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Sunday, November 25th, 2018 AT 6:54 PM
Tiny
MOTORIDER323
  • MEMBER
  • 2 POSTS
Yeah looks similar but not exactly but having another opinion has made me confident that is what that is. Even being ASE certified and working on these trucks everyday sometimes I stumble across things I need a second opinion on. Thanks for the response.
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Sunday, November 25th, 2018 AT 8:27 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,747 POSTS
Happy to help. And you are not alone. I have the same issues all the time.

Take care,
Joe
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Sunday, November 25th, 2018 AT 10:23 PM

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