Will Somebody With a Loose 6.9 Head Look At Something For Me?

[PwrSmoke]

I was given a great tip at the rally for installing the return line for my bypass system. At the front of the driver's head, near the deck, is an Allen head plug. This apparently feeds into the head oil drain passages. Before I hook my return into this, I wanted to know whether this is a place that can handle a fair bit of return oil flow from a bypass oil filter. My concerns are two: 1) can it handle the flow, and: 2) will it cause the oil to build up in the rocker area because the rocker oil flow can't drain down fast enough? I think a quick look would tell a lot but I don't have any loose heads around to check. If someone has a loose head and could look and give me a report, I'd be grateful.

This all came about after I discovered some problems with the way I had the Racor ABS bypass plumbed. I ran the oil return into the Banks CDR hose adapter under the oil filler neck. I discovered that crankcase pressure was blowing a lot of oil up the hose into the CDR and literally filling the CDR up to the brim in a short period. I went thru three quarts in a few hundred miles and when you use that much oil after an overhaul, it tends to get your sphincter spasming. I disconnected the bypass filter and no more oil consumption. After this misstep, I want to plot the next step carefully and avoid stepping on my crank yet again. Thanks!

 

[OLDBULL8]

The plug on the head would be a coolant passage. IIRC, there is no oil passages in the heads, Read how the oil gets up into the head, it's thru the push rods. I would think you would want to dump the oil back into the engine where it would free flow,like into the pan or a valve cover, but thru an orfice to control the system oil pressure. Don't know what it would do if it's returned into the oil gallery, probably upset the controlled pressure from the system oil filter.

All those holes in the heads that are plugged are for rattelling out the casting sand. The 6.9 and 7.3 heads are the same except for the coolant passages.

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[PwrSmoke]

How does the oil return to the sump from the rocker area? Supposedly, and that's why I'm double checking this, that plug goes to one of the oil return passages for the head.

The pan is the preferred spot for an oil return. The VC is not, because you are dousing the valves with oil and increasing oil consumption.. especially if the VS seals are worn. I'm trying to avoid pulling the pan to install a fitting, for obvious reasons. PSDs have a convenient return port into the sump thru the block but not the IDIs. And I though I was so clever plumbing the return into the CDR valve adapter. If I'd only figured this out when the engine was apart, it would have been so easy to put a fitting into the pan. Cranial rectitis for sure.

 

[Agnem]

I can confirm the validity of Jim's inquiry. I saw the very port he mentions being used as an oil return by another attendee, and also took interest in it. I have a set of 7.3 heads laying around, which should be the same. I can look, but won't have an opportunity to do so until Sunday or Monday.

 

[typ4]

that port handles all the oil from an air compressor drain on the uhaul engines so yes it will be fine for a bypass filter setup.

 

[icanfixall]

Every 6.9 and 7.3 head has these alen screws in each end of our heads. So we actually have 4 places where an oil return can be plumbed. Getting acess to them is a little more difficult.

 

[PwrSmoke]

Wonderful! Thanks gents. This is enough confirmation for me to give it a shot. The one that matches the current hose length is fairly accessible under the AC compressor. I even have the fitting. Anxious to get the bypass going again.

 

[subway]

i would like to see a picture of these if possible, it would make custom turbo setups a little easier to plumb in.

 

[sle2115]

I have a set of heads off sitting in my shop. I'm at work now, but can prolly get a pic tonight...not sure I can upload them though, the last couple times I've tried to put a picture up, it hasn't gone well. Are these ports in the end or in the side near the end?

 

[PwrSmoke]

The plug on the head would be a coolant passage. IIRC, there is no oil passages in the heads, Read how the oil gets up into the head, it's thru the push rods. I would think you would want to dump the oil back into the engine where it would free flow,like into the pan or a valve cover, but thru an orfice to control the system oil pressure. Don't know what it would do if it's returned into the oil gallery, probably upset the controlled pressure from the system oil filter.

All those holes in the heads that are plugged are for rattelling out the casting sand. The 6.9 and 7.3 heads are the same except for the coolant passages.

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Forgot to tell you that the bypass housing already has a 0.040 orifice built in, so OP drop is minimal. This is a Racor ABS system with a 5 um element in it for break in of the engine. At the first oil change at about 5K, I will install a 3 um filter. You can buy 3, 5 and 10 um elements. The ABS filter elements are cool in that you can inspect them and the top layers will hold all the big chunks. You can see them with the filter cover off (engine off, of course). I checked at about 1K miles after the overhaul and saw a few with the naked eye. When I applied magnification, I could see a lot more. The other thing I like about the Racor elements is that they can remove a lot of water.

 

[OLDBULL8]

Ok, So after getting back from my CT Scan, I went and checked out the six heads (7.3) I have off. Yes that 1/4" NPT plug with the Hex in it does match up with a hole in the block that goes directly into the oil pan or crankcase. Both 7.3 blocks I have on the engine stand are the same. Both ends of the heads are the same with a plug there. So you have four choices on the engine.

Basically I was correct in my answer in the first post.

 

[OLDBULL8]

i would like to see a picture of these if possible, it would make custom turbo setups a little easier to plumb in.

Ya don't need a picture, just read what's posted here. There is only one threaded plug on each end of the heads, there is a machined pad with the plug and two other drilled and tapped holes for mounting something, who knows.

 

[Dave 001]

Per a genuine IHC/Navistar 7.3L repair manual, this is the recommended place to connect a by-pass filter return.

As far as using it for a turbocharger return.....I have never done it but I would think the it would be too small. It's only 1/4" NPT. The ID of 1/4" schedule 40 pipe is only .364". The turbocharger oil drain is usually about 3/4". Beside if this location was big enough for a turbo return Banks, ATS, and Hypermax would have used it.

Dave

 

[Ataylor]

Pwrsmoke,

I have my Amsoil bypass running to the port on the front of the drivers head that you are asking about. I have not started the engine yet so I can not confirm the drain back, but other members have used this spot. Once I removed the allen plug, I looked in here with a mirror and it looks like a unpressurized oil drain for one of the push rods. I got the idea from member CDX825 who uses this port for his bypass filter return. I did have to grind some metal from the A/C bracket in order for it to fit a -6 an 90 degree fitting. I had all the accessories off the front of the engine to do the water pump and other stuff. Do a search of CDX825's posts- he has pictures. If I remember, he did not have A/C in the way. The pass side front port is inaccessible because the fuel filter bracket fits too closely to the head. I tried the rear ports on both sides, but they are too far up and too close to the firewall to put a fitting in, in my opinon. Look at the pictures I attached, I'm not sure why they didn't show up in the post.

Archie

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[Dave 001]

Pwrsmoke,

I have my Amsoil bypass running to the port on the front of the drivers head that you are asking about. I have not started the engine yet so I can not confirm the drain back, but other members have used this spot. Once I removed the allen plug, I looked in here with a mirror and it looks like a unpressurized oil drain for one of the push rods.

The passage you were looking into is the oil drain from rocker/valve cover area back to the crankcase. I have a set of heads laying around. I get a picture when I get a chance.

Dave