Join Date: Jul 2004
Location: Burlington CT.
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Re: 7.3 NO OIL PRESSURE
[ QUOTE ]
After looking at some parts from another 7.3 I am almost positive that the newer 7.3 do not have a check valve to keep the oil in the hp reservoir. It looks like there is a feed tube in the reservoir that runs almost al the way to the top, so once a small amount of oil drains back and the level is below this tube it can not drain any farther. I could be wrong but that is the way it looks in the spare housing.
[/ QUOTE ] This is the correct operation of the high pressure oil reservoir. The newer 7.3s, not sure on what year this happen, check valve does nothing except to give you unfiltered oil to the reservoir on start up and closes off the unfiltered oil when the oil pressure comes up on the filtered side from the main oil galleys. This is to give the reservoir the amount of oil it needs on cold starts as quick as possible. I have never seen a oil check valve drain a reservoir on the later 7.3s. The stand pipe in the reservoir keeps the oil from draining back to the sump. A leaking IPR could cause your problems but I think the low pressure oil pump would give you enough pressure to make the gauge move. They also changed the low pressure oil pump and pickup location slightly to prevent oil drain down.
This is one of the first posts I have seen that describes the proper operation of the oil check valve and reservoir.
If the IPR replacement took care of your problem this would not be the first time I have seen a issue like this.
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