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1994 7.3 Zero Oil Pressure

 
  #1  
Old 02-10-2019, 03:27 PM
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1994 7.3 Zero Oil Pressure

I loaded up an excavator to bring it home and my dump truck stalled.
Figured it was ice in the filter. Nope!
I thought my oil pressure gauge quit and I was banging the dash....nope! That was working fine! My oil pump isn't!
I only drove 1 mile but it idled for about 10 min.
The truck starts but I can hear that it's bone dry.

I added a half a gallon of oil to see if I could get it to pick up but it didn't (maybe the gauge moved a tiny bit. not sure)...and I don't dare over fill it more and cause a runaway. It's gotta have 25 quarts in it now.
Did the pickup tube fall off or something?
The truck only has about 83000mi on it.

Not looking forward to pulling the engine
Signed; Depressed!
 
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Old 02-10-2019, 04:05 PM
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You have verified physically no oil pressure?
 
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Old 02-10-2019, 04:13 PM
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Nope...walked home.
GF just showed up to drive me to my pickup
 
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Old 02-10-2019, 04:41 PM
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got my pickup.
So what happened was:
Started truck. It's a little above freezing now but it was very cold last night. Like 10 degrees.
Truck started hard and I noticed right away that the oil pressure gauge wasn't reading anything. Figured it wasn't working. Banged on the dash...nothing.
Drove 1 mile to the excavator. Truck ran like it normally does when it's cold.
Hooked up trailer and loaded machine. At some point the truck stalled. Figured it was fuel.
Started truck. Was running rough and sounded like the filter was partially blocked.
Truck stalled. Hit the starter and the engine was partially locked. Heart sank!
Waited a couple min and tried again. Truck started and ran but rough. Shut it down after a few seconds.
Did that 2-3 more times and motor spun over free and started each time but sounded like an engine does with no oil.
I had checked the oil at some point. Maybe after the starter couldn't turn the engine. It was above the add mark.
Dumped 1/2 my jug of oil (probably a gallon) in and tried it again watching the gauge. I thought it might have twitched but I shut it right down and walked home.
 
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Old 02-10-2019, 04:53 PM
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If you have no low pressure oil then I don't see it starting. Without oil pressure you can't run the injectors it won't let you.
 
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Old 02-10-2019, 04:57 PM
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Originally Posted by ford390gashog View Post
If you have no low pressure oil then I don't see it starting. Without oil pressure you can't run the injectors it won't let you.
My truck is dumb.
It doesn't know what low or high pressure oil is.
 
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Old 02-10-2019, 05:22 PM
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Originally Posted by ford390gashog View Post
If you have no low pressure oil then I don't see it starting. Without oil pressure you can't run the injectors it won't let you.
Thats true for the powerstrokes, not true at all for the IDI, the injectors are driven via fuel pressure from the pump, pump is driven off the cam gear.
 
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Old 02-10-2019, 05:42 PM
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I wonder if the oil pump shaft snapped because of cold oil.
Now wondering what it would take to swap t44e school bus engine!
No way I'm finding a good 25 year old IDI in the rust belt.
 
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Old 02-10-2019, 06:36 PM
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Originally Posted by hairyboxnoogle View Post
Thats true for the powerstrokes, not true at all for the IDI, the injectors are driven via fuel pressure from the pump, pump is driven off the cam gear.
Yup didn't see this was the IDI forum. Disregard my original statement.
 
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Old 02-10-2019, 06:37 PM
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Originally Posted by fuelhog450 View Post
I wonder if the oil pump shaft snapped because of cold oil.
Now wondering what it would take to swap t44e school bus engine!
No way I'm finding a good 25 year old IDI in the rust belt.
Oil pump is gear driven from the timing assembly.
 
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Old 02-10-2019, 07:12 PM
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Originally Posted by fuelhog450 View Post
Now wondering what it would take to swap t44e school bus engine!
A lot, lots of wiring
 
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Old 02-11-2019, 11:37 AM
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Truck lives!
I dumped another gallon of oil down the crankcase and crossed my fingers.
So basically I had to over fill by about two gallons to get the oil pump to prime.
Temp is still just below freezing.
Engine runs smooth and quiet like nothing ever happened.
Tough motor!

I've heard of this phenomenon (in small block chevys) but I've never actually seen it happen....until yesterday.
 
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Old 02-11-2019, 11:37 AM
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Curious what happened.
isn't there a pressure bypass on the pump to prevent high oil pressure on cold startup?
 
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Old 02-11-2019, 12:06 PM
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Originally Posted by parkland View Post
Curious what happened.
isn't there a pressure bypass on the pump to prevent high oil pressure on cold startup?
Yes all oil pumps that I have seen have a ball/spring "regulator" bypass.
They all work the same way.
I think mine just lost prime and because of the cold temps and thick oil, it just wouldn't pick up.
Then, because the pump was turning with no oil, the little bit that was there was scraped or slung off leaving the pump dry.
From now on, my normal oil level will be above the full line!
As much oil as there is in there now, there are no signs of windage or any kind of foaming.
I'm draining out about a gallon and I'm going to run with that.
Also I'm reconsidering my choice of Rotella 15-40 for winter oil!
 
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Old 02-11-2019, 01:24 PM
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Originally Posted by fuelhog450 View Post
Yes all oil pumps that I have seen have a ball/spring "regulator" bypass.
They all work the same way.
I think mine just lost prime and because of the cold temps and thick oil, it just wouldn't pick up.
Then, because the pump was turning with no oil, the little bit that was there was scraped or slung off leaving the pump dry.
From now on, my normal oil level will be above the full line!
As much oil as there is in there now, there are no signs of windage or any kind of foaming.
I'm draining out about a gallon and I'm going to run with that.
Also I'm reconsidering my choice of Rotella 15-40 for winter oil!
what kind of oil was in it? I currently have half 15w40 half straight 40 and its been just under or over 40 below here lately, and no issues but I do plug in the block heater.

maybe something is wrong with your filter ? Maybe change oil and filter before anything else. I'd assume just about any 15w40 would work fine
 

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