7.3 wont start. fresh motor. no oil pressure

[barrakudaman]

I have a fresh motor i installed in a 94 international flatbed car hauler. It will not start. after several cranking sessions the oil pressure guage will not move at all. I dont see why i dont have any oil pressure. I took the lpop off and made sure it was good and lubed up, re-installed it and still not much. the oil filter had about a cup of oil in it after 2 20sec. cranking sessions. Could the new lpop be bad? the oil pressure guage was working when the truck had the previous motor in it. Where does the oil pressure guage get its reading from? Thanks

[scagle1]

Checked HPOP level ??

[barrakudaman]

I filled the hpop as full as it would go. the lpop is supposed to do the rest. I know the top end is supposed to hold 2 quarts. After a certain amount of fluid is put in the resivor, it just overflows into the oil pan.

[justinmix]

When you say a fresh motor where did it come from and what all did you have to swap over? The LPOP looking like it had fresh oil coming through it? Did you have to switch over the oil cooler from your old engine? The oil pressure regulator is in the filter part of the oil cooler housing. If something is going on with that then it won't ever build oil pressure and will just dump it back in the oil pan.

[barrakudaman]

I disassembled the motor and sent it to get rebuilt. Then re-assembles the motor with all the original parts. new lpop, timing cover, lift pump. the lpop did look lke it had fresh oil in it when i pulled it. I put more oil over everything and re-installed. The engine guy took the oil cooler apart and installed new o-rings. When i was handling the oil cooler the the oil pressure regulator assembly fell out. I wonder if i could have reinstalled it wrong. I'm gonna search for a diagram. I thought i put it back together right, you wouldnt think you could install it backwards. Thanks for the ideas.

[barrakudaman]

here is a link to a pic i found of the order for the oil pressure regulator. oil pressure relief valve - Ford Truck Enthusiasts Forums I think i will give this a shot tomorrow. It seems like the newer trucks have a retainer to keep the parts from flying out like mine did.

[justinmix]

Yeah that's definitely what I'd be looking at. What part fell out, the oil pressure regulator or the oil filter bypass valve? Both were crappy designs in the early year 7.3's. They were staked in place then but then got updated to snap ring retainers in later years.

I'd check the oil pressure regulator and make sure it's not binding up or stuck open. If you have the oil cooler back off the truck to inspect it you might try cranking it over and seeing if oil starts pumping out of the front cover where the oil cooler bolts to. This will tell you if the pick up tube and LPOP are working fine.

[barrakudaman]

Ok i will be trying this today. I believe the oil pressure regulator is the part/parts that fell out.

[barrakudaman]

well, made sure the oil pressure regulator was good. while the cooler was off i checked the lpop system and it was pumping oil out the timing cover where the cooler bolts up. Hopefully I get this thing fired up tonight.

[barrakudaman]

Alright, still not getting this thing to start after several cranking sessions. I'm dealing with some ****y battery chargers and the batteries are have not been fully charged since I had the oil cooler off. What else besides the oil pressure regulator would cause the oil pressure guage not to work. I am thinking of putting an oil pressure guage right on the top of the hpop resivor to make sure its not just a faulty wire or guage, and oil pressure isnt the issue.