Head gasket build

blueshift

New member
Jan 29, 2024
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Raleigh
As mentioned above, it's part of the PCV system.

There's a little chamber with a baffle built into the large aluminum alternator bracket. Any positive crankcase pressure is routed down into this box and then out the vent tube in the bottom of the bracket (vents right next to the crank pulley, on the passenger side). There's a drain line for any liquids to drain back to the oil pan (that's the hose in your picture). There's 6 screws holding a cover on the front side of the bracket, which is where you'd access the chamber.

There's a check valve screwed into the bracket, that goes to that hose. Make sure it's not plugged. I could easily blow through mine.

Mine looked similarly messy to yours, though maybe not quite that bad. For reasons that I could not figure out, there's a ~3/8" diameter hole in the back side of the bracket, routing into the PCV chamber. This makes no sense to me, considering that there's already the vent out of the bottom. This hole was clearly the source of the oily mess on my motor. My truck has excellent compression across all 8 cylinders and no detectible blow-by, so I just chalked it up to 260k miles of neglect.

I plugged the hole, and for ~2k miles now, all is well. If you do plug it, watch for the clearance on the back side. It's a fairly tight fit between the bracket and block.
 

lb7resto

New member
Jul 19, 2023
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Well I can't even believe this but I guess I've got to cuz I'm looking right at it. This fuel return banjo bolt gave up at 11.5 ft-lbs. Add it to the list of things I didn't know I was gonna replace.
1000002869.jpg
 

blueshift

New member
Jan 29, 2024
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Raleigh
Dang. At least you felt it and stopped turning before snapping it completely off.

Also, you just reminded me of a mistake I made when installing those. So with the crush washer for those (the one going to the head), make sure the little connector tab that joins the top and bottom washers together is spun around towards the inside of the head. I didn't pay any attention to that when installing, and it was on the outside and contacting the valve cover. Wouldn't let the valve cover center over it's bolt holes correctly.
 

lb7resto

New member
Jul 19, 2023
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NC
Dang. At least you felt it and stopped turning before snapping it completely off.

Also, you just reminded me of a mistake I made when installing those. So with the crush washer for those (the one going to the head), make sure the little connector tab that joins the top and bottom washers together is spun around towards the inside of the head. I didn't pay any attention to that when installing, and it was on the outside and contacting the valve cover. Wouldn't let the valve cover center over it's bolt holes correctly.
So keep them counter-clockwise while tightening? When I was putting these on the connector was trying to rip itself off because the upper washer was spinning with the bolt head and I couldn't hold it back with my finger. Maybe with new bolts and washers won't have that problem.

Speaking of which, one section of the SM says to lubricate the washers with diesel. Others don't mention it. What do y'all do there?
 

DAVe3283

Heavy & Slow
Sep 3, 2009
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Boise, ID, USA
I lube with diesel, but I imagine motor oil would also work. It usually isn't that hard to get a couple oz of diesel to put in a small cup and dunk all the banjo washers in.
 

lb7resto

New member
Jul 19, 2023
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I did a very thin film of oil on the washers.

So, are the PCV ports in the upper valve cover supposed to be normally closed? I would think so. I can blow right through mine both directions.
 

lb7resto

New member
Jul 19, 2023
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As I'm putting this fuel system back together, is there a good method for purging it to make sure it's free from debris? I was thinking of putting everything but the injector lines on and running the starter a little bit.
 

lb7resto

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Jul 19, 2023
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Well, I got it all put back together. Started right up!

The excitement was short lived. After moving it around in the driveway and going through a few hot cold cycles over the past couple days and everything seemed good, I took it a couple miles up the road to the inspection station and back home, it drove great. When I was pulling back in I noticed it was shaking at idle and when I gave it some throttle, the idle speed was solid just shaking the cab. I checked the oil and it is very full. I don't think it was that full before. I'm pretty certain I'm filling the crankcase with diesel. I'm planning to change the oil (it's still the old crap that was in it) and observe the level closely to confirm.
 

2004LB7

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Dec 15, 2010
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Well, I got it all put back together. Started right up!

The excitement was short lived. After moving it around in the driveway and going through a few hot cold cycles over the past couple days and everything seemed good, I took it a couple miles up the road to the inspection station and back home, it drove great. When I was pulling back in I noticed it was shaking at idle and when I gave it some throttle, the idle speed was solid just shaking the cab. I checked the oil and it is very full. I don't think it was that full before. I'm pretty certain I'm filling the crankcase with diesel. I'm planning to change the oil (it's still the old crap that was in it) and observe the level closely to confirm.
Sounds like the typical leaking return line under the valve cover issue. Put a vacuum gauge, like a mityvac on each of the return ports of each head to see which one if any are leaking. Before opening it back up
 
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lb7resto

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Jul 19, 2023
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My first thought was that I reused my high pressure lines and that's where the leak is. I think that would show up if I look at the balance rates right? I do have one of those vacuum gauges so I will definitely test the return.

Right now I'm too bummed to even go look at it
 

lb7resto

New member
Jul 19, 2023
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1000002955.png
With brand new injectors do you think that Cylinder 6 looks suspect for leaking on the high pressure side?
 

2004LB7

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Dec 15, 2010
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High pressure lines leaking won't effect only one injector. Infact it doesn't really effect the balance rates until it's so bad that the CP3 can't keep up. You have to remember that all the high pressure lines are connected together through the rails. So if one is leaking it's dropping pressure for all.

#6 wouldn't bother me as long as your main rate was reasonable