6.9 IDI Build

IDIBRONCO

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My opinion is 20 PSI. Your cooling system doesn't see that much pressure in normal operation. That should give you a good idea.
 

WarNose

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Thanks for your thoughts. That sounds reasonable. Didn't the 6.9's come with 7 psi radiator caps? I wonder if the plugs in the 7.3 heads are what allowed it to go to 13 psi radiator caps.
 

Thewespaul

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I wouldnt test pass 20 psi either, no need. Dont know about the rad caps, but I like 7 psi in all my trucks
 

ttman4

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So as I try to read these threads I gather that on my '94 IDIT engine using headbolts I could torque to say 110#, or something else?

I wish I had time to read or search stuff here on these threads. Sooo much good info!!!

Another question, maybe needs to be posted on another thread, but how do I ck my fan clutch? Yrs ago I could hear my clutch kick in & out when it heated up & cooled. Last few yrs I never hear it kick in. Just seems to be steady sound all time. Still turn it kind'a stiff by hand, but don't just spin really easy by hand. It keeps things plenty cool tho.
 

Randy Bush

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So as I try to read these threads I gather that on my '94 IDIT engine using headbolts I could torque to say 110#, or something else?

I wish I had time to read or search stuff here on these threads. Sooo much good info!!!

Another question, maybe needs to be posted on another thread, but how do I ck my fan clutch? Yrs ago I could hear my clutch kick in & out when it heated up & cooled. Last few yrs I never hear it kick in. Just seems to be steady sound all time. Still turn it kind'a stiff by hand, but don't just spin really easy by hand. It keeps things plenty cool tho.

My opinion, but one should also use the head gaskets for the factory turbo engine, heavier fire rings on them.
 

Jimmy Stewart

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So as I try to read these threads I gather that on my '94 IDIT engine using headbolts I could torque to say 110#, or something else?

I wish I had time to read or search stuff here on these threads. Sooo much good info!!!

Another question, maybe needs to be posted on another thread, but how do I ck my fan clutch? Yrs ago I could hear my clutch kick in & out when it heated up & cooled. Last few yrs I never hear it kick in. Just seems to be steady sound all time. Still turn it kind'a stiff by hand, but don't just spin really easy by hand. It keeps things plenty cool tho.
From what I’ve read, I think you’re plenty safe at 110. That’s what I torqued mine to.
 

Jimmy Stewart

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Although I used studs and it’s a 6.9. But I think on the 7.3 with bolts 110 is fine.
 

Randy Bush

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OK thanks guys. Another coming up project in my world.
EDIT: Wonder what they were torqued to at factory originally? ('94 IDIT)
Anybody got any thoughts on my fan clutch?
Factory torque on the IDIT is 100 ft lbs .

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WarNose

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I pressurized the cooling system to 30 psi and held it for 30 minutes. It dropped 1 to 2 psi in this time, but there was the tiniest leak where I blocked off the thermostat housing. Just a few drops. Everthing else was dry. I have done enough hydro-testing of pipe sysyems in oil refineries to feel confident that these few drops were the only leak with that little of pressure drop.

The key to hydro-tests are to fill from the bottom, and leave any high points open until they fill with water. When all of the air is displaced you plug the high points. That way the water pressurizes the system quick and there are no fluctuating gauge readings due to air moving around.

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Here is a picture of the gauge, regulator (not really needed), block valve, and hose connection. My tap water was good enough to take it to 30 psi. I was surprised that it could have even gone higher. I was going to stop st 20 psi, but 30 was so easy to reach. My water is pretty soft so I'm not worried about using tap water for the test.

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My oil cooler block off plates and plumbers cap.

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I had to get creative with my plug here. No time to run to the store so I had to improvise. This was where I had the slight leak.

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Top side view. No fancy paint on this one. Just a plain, clean, truck motor.
 

The_Josh_Bear

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That's cool to have that kind of testing experience in your tool bag. I like the setup, I was just wondering the other day what PSI tap water would get to...
I am surprised that plumbers cap held 30 PSI, dont know anything about them really just thought they were more gravity drains and stuff not pressure. I love the paint can!! Took me about 2 minutes to figure out what graphite lube had to do with pressure testing! :D
 

WarNose

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I am surprised that plumbers cap held 30 PSI

I've probably had more than that on them, just from the head pressure by filling drain lines to check for leaks. But I still had a 5 gallon bucket underneath it just in case it decided to pop off.
 

TahoeTom

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Nice looking engine. I painted my parts separately before assembly and regret that I didn't paint my valley pan.
 

WarNose

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Work had really got busy and I just barely got the motor running. However, the 6.9 injector lines that I installed are slightly different than the original 7.3 lines. The shape of the #2 line does not allow the ATS air filter box to bolt up. I'm hoping to be able to just swap the #2 line. I'm assuming that the 7.3 and 6.9 lines are all same length and I don't have to change all of the lines (not counting the shorter #1 line on the 7.3).
 

WarNose

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I have 55 miles on the engine now. I just went on a 50 mile round trip to hit some hills. I'm liking the power that this thing is making but it is throwing major black smoke. I'm guessing that I need to time the motor. Maybe adjust the waste gate. I think my old motor produced more boost. I have to get this thing figured out. So far I have got honked at twice, received one dirty look, and one middle finger from vehicles that were behind me.
:peelout
 

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