Hey guys, been a while since I was here, but knew where to come to for the best help. I'm looking for help on a oil pressure loss problem. I've got a 7.3 idi with less than a 1000 miles on it since a complete overhaul. .040 bore, new cam and cam bearings, new rod and main bearings, new oil pump. Last week I was about 5 miles from home and the engine light came on and oil pressure hits rock bottom. I stopped checked the oil was showing just barely under the full mark. I got back in the truck and started it, no knocking and the oil pressure was showing normal again. As soon as I cracked the throttle one time, pressure hits bottom again. I changed the sending unit but still same thing. I replaced the sending unit with a mechanical gauge, and showing nothing. Any ideas or help as to what the problem may be, would be greatly appreciated. Thanks in advance.
7.3 idi lost oil pressure
- Thread starter 91flatbed
- Start date
icanfixall
Official GMM hand model
Sounds like the oil pressure regulating valve in the rear oil cooler header is stuck open. May have to remove the oil cooler to fix it. Might be able to just remove the oil filter and use a dental pick to free it up. Just not sure about the oil filter removal repair because I have never done that. Others will chime in with ideas. Where did you install the feed for the mechanical gauge.
79jasper
Chickenhawk
Like gary said.
Also could've dropped a piston squirter or two.
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Also could've dropped a piston squirter or two.
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Hydro-idi
Full Access Member
I am leaning towards the oil pressure valve in oil cooler header being stuck. Like Gary said, try removing oil filter and use a dental pick to move it back and forth. You could try cleaning area with carb cleaner and lubing valve with some pb blaster, working it back and forth with dental pick. Just make sure not to scrape up aluminum surfaces with dental pick. Header material is very soft aluminum.
icanfixall
Official GMM hand model
Our oil pumps do not have a gasket between the block and pump. The surface is nicely machined.
The mechanical gauge is teed into the oil line going to the turbo. Would you guys happen to have a couple pics on the oil regulator? If the oil cooler has to come off, how hard is it to remove from the engine? Thanks again.
79jasper
Chickenhawk
It's not bad to take off.
Just drain all oil and coolant first.
And still be prepared for a nice cold shower of coolant and oil. Lol
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Just drain all oil and coolant first.
And still be prepared for a nice cold shower of coolant and oil. Lol
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You'd think I'd remember that from a recent teardown... bad info removed
just warm the truck up a bit! a nice warm oil/coolant bath is better than a cold one!
icanfixall
Official GMM hand model
We all have made statements before that were not necessarily correct but we made them showing honest support of others. After all we are all just human. Some here may think I don't make any misquotes or mistakes.. Not so .. In my day to day life I have been known to forget things and make a list to remember them... Only to loose the list. That really sucks big time too. Depending on other things to remind you and loose it. Well I think you understand the frustration I feel.
There is NO need to remove the oil cooler, just remove the oil filter and you'll be able to see if one of the holes with a disc is stuck open. Someone on here had a good pic of it.
79jasper
Chickenhawk
There's the filter bypass valve, which is visible with the filter removed.
But the other isn't visible without taking off the cooler.
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But the other isn't visible without taking off the cooler.
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Thanks to everyone for help. I'm going to take off the oil filter, see what I can find, if nothing there, I'll pull the oil cooler off and go deeper. If the valves in the oil cooler isn't the problem, where should I look next? Thanks again guys, all help is greatly appreciated.
for future reference, when installing a new pump, would you use a slight coat of RTV on the oil pump to block?
CDX825
filtration nut
Should never need to change the oil pump in one of these engines. That combined with the fact that there have been several member who have had aftermarket oil pumps fail is why I would stick with the factory pump.
