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Topic: New owner of a 94 U225 seeking grade climbing advice (Read 3385 times) previous topic - next topic

Re: New owner of a 94 U225 seeking grade climbing advice

Reply #20 –
Quote from: wolfe10 –
Note:  The back pressure any exhaust brake produces MUST be within the specs for your particular engine.
Addressing Brett's point (above) about engine specs.

Our '93 C8.3 was built in a "transition year" when Cummins was starting to upgrade the exhaust valve springs.  Researching our ESN on Cummins QuickServe, I found out our engine was built with "standard duty" 30 pound valve springs.  1994 and later 8.3 engines apparently came with 60 pound "heavy duty" valve springs.

According to the documentation that came with our U280, the exhaust brake on our coach is fitted with a pressure relief spring set to hold a maximum of 35 psi back pressure.  If our engine had been built with the heavy duty valve springs, then they could have (back in 1993) fitted the exhaust brake with a relief spring rated to hold 54 psi back pressure.  :'(

If you go into QuickServe, you can find out which valve spring was installed in your engine.  Follow the steps below:

1.  open QuickServe, sign in with your ESN
2.  click PARTS
3.  click OPTION VIEW
4.  scroll down to CYLINDER HEAD, click on it
5.  Identify the exhaust valve spring in diagram
6.  scroll down, look at designation for that part number
7.  search the valve spring part number online to find out the pressure rating.

Screen grab below from the QuickServe cylinder head parts list page for our ESN: