Low oil pressure

[79jasper]

If you want some top shelf oil, I can put you into contact with a guy. Just be ready to spend about $150 for 5 gallons.
Has some great fuel additives too.

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[Shawn MacAnanny]

Well i changed the oil a few hundred miles ago. With 5w40 Rotella T6 i could see hot idle temperatures as low as 4psi, but usually hung around around 6-8psi. Cruising down the highway at 2000rpm i could see pressure drop as low at 26psi but was usually 28 to 30. Now that i changed to delvac 15w40 i havent seen less than 8psi, and its usually 10-12psi hot idle. Going down the highway the lowest ive seen yet is 30psi and its usually 32-34psi.

I went ahead and had a stainless line made to replace the factory line since i had new olives leaking, i'm just done messing with their horrible deisgn. I had them make is 1/4" NPT on both ends and attached it to the tee i had, relocated my 1/8" pressure sender for aftermarket gauge to the other side of turbo block. When i removed the lower 1/4" npt line fitting i realized there is an extension adapter to go from 1/8" NPT at the block to 1/4" for the fitting. So changing this to 1/4" fittings was really pointless for it intended purpose. My guess is this small fitting ensure that everything below is kept at a higher oil pressure. I saw no change in pressure changing this line out but it looks better and won't ever leak.

So I stopped in at the machine shop today and noticed the turbo feed line and port at the back of the block on the 1994 turbo idi I'm having overhauled is actually 1/4" npt directly in the block not 1/8" like my factory turbo 1993. Unless someone has replaced the engine before.

 

[Shawn MacAnanny]

I wanted to update this since i got around to pulling my 1993 IDIT motor from my totaled truck. It had a bone stock factory turbo kit on it when i got the truck, when i replaced the turbo it appeared it had never been off to me, when i replaced the up pipes the bolts were defintiely stuck in the manifolds and i had to drill 2 out that broke despite days of soaking them so i assumed all this was a factory kit. Well i pulled the engine today and see the block has a casting number endin in C1 instead of C3 which would explain why there was a 1/8" NPT port on the back of the block instead of a 1/4" NPT

 

[IDIoit]

from what ive been told,
if the down pipe has a v-band clamp, it is indeed a factory piece.
if the DP is a slipfit, its aftermarket.

 

[Shawn MacAnanny]

It had the factory smashed down pipe with all heat shields in place and all heat shields in place on the turbo, not bent every single clip and all heat shields on the factory up pipes. I wonder if they ever used 7.3l blocks in the early turbo trucks. I'm half tempted to pull a piston out and see if it has two keystone rings.

 

[cpdenton]

This might throw another twist in it.

I have a 93 model NA engine. It has the larger oil port in the rear of the block.

The best way to tell if you have a factory turbo block is the engine is number. NA will start with 7.3D and turbo will start with 7.3T.

What was the 8th vin of the truck? That will tell you if you had the NA block with turbo added or a turbo truck with the engine replaced.

 

[Shawn MacAnanny]

It's a 1993 vin c had correct harness valve covers too. When I get transmission off it I'm going to check flywheel for number and balancer to see if it's weighted

 

[Shawn MacAnanny]

Is there a different casting number for turbo heads? I know the exhaust valves are different

 

[cpdenton]

Here is a picture of the casting number on my turbo block heads.

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[Shawn MacAnanny]

Here is a picture of the casting number on my turbo block heads.

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It looks like yours ends in a C3 just like the block number, this engine ends in C1, just like the NA block number. I also have a set of 7.3L non turbo heads and their number in C3. Weird.

 

[Shawn MacAnanny]

I have the exact same pressure as you. I have a tee coming off of my turbo block with both the factory sensor and my electric pick up in it. I am using a GlowShift gauge. When it's colder out say 30-40 i see 10-12psi at idle, now that it has warmed up 70-80if i and cruising down the highway for 10 minutes or so, it cruises at 30psi at 2000rpm, 32psi is the max i ever seat hot. When i come to a stop i can see it drop at low as 6 psi and i've even seen 4psi, but i've never see the factory low oil light come on. I am going to try to check the position of my oil pressure regulator next oil change and also switch from the rotella 5w 40 to delvac 15w40. Since temperature seems to affect it so much i am thinking the 5w 40 synthetic might actually be too thin.

Also to add to this thread with the oil pressure issues. I changed Conestoga rebuilt 093 factory turbo for a new R&D SX257 turbo and gained 10-12 oil pressure cruising 6 psi idling from what i assume was the tighter clearence of the new turbo's bearing.

 

[cpdenton]

A turbo block serial number starts at 1,116,331 and goes up from there. You have the 109,992nd turbo block made. Just looking at the oil ports and seeing they are 1/4 inch plug instead of the na 6.9 or 7.3 blocks having the 1/8th inch plugs in all the oil gally ports.. Nice find...

Looking up some serial number info seems to show some things about you factory turbo engine.

I also found this info.

Block c/n 10809000C1 was used for the entire 7.3L IDI years of production. The serial numbers for naturally aspirated applications are 500,079 through 1,116,330.


So your block, numbered 6***** would actually be early in the production run near the end of 1987 and early 1988.

Someone swapped engines....

 

[Shawn MacAnanny]

That's weird. They sure went through alot of trouble. Every heat shield on the factory turbo kit was in place, not bent and had all clips. I got them back on when I replaced the turbo the first time but they were a little bent haha. Nothing looked like it had ever been off before to me.

What I'm more amazed by is if it's a non turbo clutch/flywheel that it didn't slip with the mods I had. I mean it wasn't a race setup but it sure would have stressed the clutch towing a trailer.

 

[79jasper]

Really not that much torque difference in the clutch.
The difference is the balancing.

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