A list of questions while I'm into it this far

[TNBrett]

So, as you guys may have noticed in a couple other threads, I've pulled the engine and trans from my truck in order to address the leaking head gasket, and a few other issues. I figured I'd go over what I've done so far, talk about what I've found, And ask for some opinions on a few things.

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I know there's lots of opinions on which way is easiest to remove these engines. This is how I chose to do it, turbo, and oil cooler still on, and core support removed. Also, the starter was removed. As you can also see, I unbolted the motor mounts and they stayed with the truck. I kept the engine level and basically just went up enough to let the oil pan clear the cross member. I also made sure to leave the ground strap on the back of the passenger side head attached to the firewall so I could stretch it out nice and tight.

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I figured I'd include this pic to show what I did to get the transmission out. With the front up as high as I could go on jacks, and the back tires just off the ground, I was able to sneak it out without taking it off of the transmission jack. Once I had the shifter out, I tilted the bellhousing down to clear the frame.

So the primary mission is heads and studs. I had a set of heads from the original NA motor that was in my truck originally. About a month or two ago I took them to a local machine shop that had a pretty good reputation. They cleaned and inspected the heads and basically told me they were not worth the trouble. One head had been redone already, but not well. Instead of replacing the guides, the last shop reamed them out, and used valves w/ oversized stems. The guides in the other head were beyond just loose. In any event, both heads were so bad that the normal machine they use to cut out guides wouldn't work, and they would require several hours of machining on each head. They recommended a set of Reman heads from Allied cylinder head @ $350 each plus tax and shipping. So for a little over $800 I've got two heads ready to go. I managed to pick up one of the last sets of ARP studs that were available from Wes, and one of the last intake / valley pan gaskets from Napa. I also have a Fel-Pro head gasket set. My questions here are;
1) What should torque the studs to? Should I just use the factory spec? I've seen reference to 150 ft/lb.
2) What about the 6.9 cooling mod? I know a lot of you guys do it, but I wasn't having any issues cooling before. My question is, if the 6.9 design was better, why did Navistar (or maybe it was Ford) change it. what were they looking to achieve by blocking those passages? Basically I'm open to it, but I need to be sold on it a little bit.

The next big thing for me is the clutch. I've mentioned before that everything seemed normal when I would first get in the truck in the morning. The problem was that once everything got heat soaked, it was extremely "grabby" in 1st and reverse. It was a real pain trying to back up a trailer delicately. Shifting between gears was never an issue, and I never noticed any slipping or burning. Well, here's what my flywheel looks like.

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There's obviously some hot spots on it. There's hot spots on the pressure plate as well, and the clutch disk is worn. The buffer springs are a little loose in it as well.

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I'm going to go by the clutch shop tomorrow, and see about having the flywheel ground. I was also going to ask about having the flywheel drilled for a 13" PSD clutch. What do you guys think about that idea? Do you think the flywheel is too damaged to grind? I only see discoloration, no signs of heat cracks. The other thing I've noticed while looking at PSD clutch kits is that they all seem to have fewer buffer springs in the clutch disks that the IDI clutches do. Also on the subject of clutches, I'm planning on replacing the slave cylinder and using Russ's clutch hose. Mainly, this is because I broke the plastic retainer on my current slave cylinder and getting it back in without that is a real PITA.

Otherwise, everything else is pretty minor. I'm redoing the olives on the turbo feed line, and hard fuel lines. I'm also replacing the front and rear main seals, and I ordered new motor mounts. I may throw some spay paint at it too before I put her back in.

Oh, and one last thing. Does any one have a source for the inner shift boot for the ZF5? I found one on ebay, but it looks like the quality may not be so hot. Mine is torn and has made a minor mess.

TIA, I'm looking forward to everyone's input.

 

[IDIBRONCO]

Here's my take on some of your questions.
I've also seen the 150 lb/ft mentioned on the studs, but it seems to be right at the point where it may work or you may have issues like broken studs. When I do my higher power engine build, I'm going to torque mine to 120-125 lb/ft at the most. I may stay with 115.
The general consensus on the 6.9 cooling mod is that Navistar was trying to get improved emissions. By blocking off the cooling ports, it would make the heads/combustion area of the cylinders hotter so, in theory, that would make the fuel burn better/more completely. I'm not allowed to give my opinion on engineers here on this family friendly forum, but let's just say that it's less than positive. I wholeheartedly believe in the 6.9 cooling mod myself. It (most likely) won't make your engine run one degree cooler. It's to improve the cooling of the heads instead of the whole cooling system. 7.3's have more issues with cracking heads than the 6.9's seem to. This (in my opinion) will also lessen the chances of boiling the coolant in the heads which, in turn, causes the lifting of a head. Yes,you are going to be running studs, but they won't affect the coolant temperatures. You can still boil the coolant in the heads. If that happens, then you still run the risk of cracking a head even though the head will probably not lift. As easy as it is to do, I will be doing the 6.9 cooling mod to every 7.3 that I have the heads off of (assuming that it's mine). I hope that helps sell you on the idea.
The flywheel. No matter if you go with the larger PSD clutch or stay with the same as you have now, if you have the flywheel turned, you need to replace the pressure plate at the same time. Turning the flywheel gets rid of the high and low spots. If you reuse your old pressure plate, then you've only done half the job and run a higher risk of having clutch chatter. I feel that your flywheel will be fine to turn, but I'm no expert. Leave that up to the place that will be doing the turning. I also feel that if you want to have your flywheel redrilled to use the PSD clutch, then that's your decision and your money so go ahead and do it.

 

[hacked89]

1. Follow the instructions from ARP. On a 7.3 it's 125. That's the tolerence of the stud. People over torque, I wouldnt. It's past the limit on the size and thread. I've done studs about 4 times on a 7.3 and no issue. Use torque lube as well. Going to be doing it again soon on a junkyard NA performance build until I get an Idit because I have a cracked cylinder and piston on my 0.040 motor. Rip.

2. I don't do the cooling mod. I do agree it's emissions related IMO.

3. Pretty much what idibronco said about things need to be matched but I don't turn things anymore. It hasn't been cost effective. I have a new SMF kit that's going behind the junkyard T04Z build which will get destroyed. There are psd level clutch kits now for the IDI but I don't want to drop 1.2k on that until I get the Idit built.

4. Like you said doesn't matter how you pull it. I pull core support and take the trans out with it. I would recommend you consider not leaving the mounts there and bolting them back in the motor. It's much easier to drop them into the triangles. I built my run stand with the triangle drops too and take the engines on and off the stand by myself.

 

[Big Bart]

TNBrett I have done many clutches on many different vehicles over the years. I have learned if you do the following you will have success and avoid a second pull of the tranny before the clutch wears out.

1) Grind the flywheel. If out of spec replace.
2) New clutch and pressure plate. I have had luck with the LUK brand.
3) New pilot bearing and throw out bearing.
4) New rear main seal.
5) If not hard a new input shaft seal on tranny
6) If not included with new clutch a clutch alignment tool.
7) Lube the pivot point on clutch fork.
8) Torque to specs

Skimping on a clutch is like skimping on new front brakes, try to do it on the cheap (Just put on new pads.) and you will have issues and wobble in a short time. Do it right (Rotors, pads, wheel bearings, etc.) you are good till the next brake job.

 

[frankenwrench]

Once you pull the heads, look at all four corners. Every 7.3 idi I have had apart has more ring ridge on cylinders 1,2,7,and 8. Alot more. Pulled my heads off of my 89 to do studs and new gaskets to find that those particular 4 werent any worse than cylinders 3,4,5, and 6. I did the 6.9 cooling mod on that engine back in 2014 after a cheap rebuild. May just be luck, but Theres 125k on that block pulling heavy since the rebuild. I noticed about 10 degree drop in coolant temps when running empty, under load(most of the time) no change from before. I torque my studs to 125 ft lbs. Preferance related, 150 makes me think of broken or stripped studs once it gets heated up and working hard. Just my opinion. Studs have been in about a year and a half and no issues other than this damn power steering leak im too lazy to hunt down

 

[The_Josh_Bear]

What are your WHP goals for the engine? That would help determine the money and time investment into the clutch.

 

[catbird7]

Another thing to consider is the oil cooler. If it's leaking at all, now is the time to install new o-rings and gaskets. Way easier as compared to doing this job while the engine is installed.
Good time to consider adding firewall sound proofing or heat shield too.

 

[jrollf]

...
Oh, and one last thing. Does any one have a source for the inner shift boot for the ZF5? I found one on ebay, but it looks like the quality may not be so hot. Mine is torn and has made a minor mess.

TIA, I'm looking forward to everyone's input.

I believe LMC truck has what you are looking for, #6 in the diagram.

Floor Shift Components

Shop from thousands of parts and accessories to help you restore, maintain, and customize your Chevrolet, GMC, Dodge or Ford truck or SUV. Keep 'em on the road with the right part, right price, right now.

www.lmctruck.com

 

[Shadetreemechanic]

I don't know where you are in middle TN, but I would suggest you take your clutch disk and pressure plate to felton Clutch in Chattanooga. They will build your disk and match it to a pressure plate and it will be done right. I have only used them on tractor clutches, but their prices were good to boot.

 

[TNBrett]

Well, first off, thanks for all the input.

For some reason, I had myself convinced that ARP didn’t have a torque spec in their instructions. I’m not sure where that idea came from, but there it is in black and white 125 ft/lbs. I think I’ll stick with that.

As far as the cooling mod goes, I’m leaning in that direction. I guess I’ll wait until I actually get the heads off to make a final call. How big of a hole is typically added to the head gasket for this?

On the clutch, I guess I didn’t mention it, but I had no intention on reusing the old pressure plate. But, I dropped the clutch and flywheel off yesterday at a clutch shop in Nashville. Tennessee Clutch and Supply. He assured me that my flywheel would be fine with a grind, and we talked about re-drilling it for a 13” PSD clutch. He felt confident that he could do it, and that it seemed like a logical upgrade. If he’s true to his word, I shouldn’t have any more money into the clutch than if I had just bought a clutch kit from RockAuto.

I don’t have a specific HP target at this point. The truck is going to serve as my daily driver again, and be expected to tow up to 10-12k lbs on a regular basis. My goal is to make it easier to drive when towing. As it was before, I was having to back off on hills because my boost pressure was getting too high, and my EGT’s would climb. I’m taking care of my boost concerns now with the studs, and I will be intercooling soon. At some point turbo and IP upgrades will happen, but they will probably pretty mild.

I did manage to find an inner shift boot from Allstate Gear. It was about half the price of LMC, and had a decent rating. I guess we’ll see what it looks like when it shows up.

For those that were asking. I live about 15-20 minutes east of Murfreesboro, and I commute into Nashville every day. I’m about an hour from the top of Monteagle.

Hopefully I’ll make some more progress this weekend and update you guys with some pics. Thanks again.

 

[TNBrett]

Oh, and the oil cooler was done last year when I first put this motor in. It has about 15k on it. Definitely a good suggestion though.

 

[IDIBRONCO]

If you use 6.9 head gaskets, you don't have to add any extra holes. They are already there when you install the tabs. At one time, Wes was offering 7.3 head gaskets that he pit holes in for this (I believe). The holes don't need to be very big. They are fairly small in the 6.9 head gaskets. Wes cut them out larger and I think he said that it let the coolant flow through the heads too fast and actually did worse under a load. Of the top of my head, without measuring or looking, it seems like the holes in the tabs for the 6.9 are about 1/4" by 1/2" long. That may be too large since I haven't looked at 6.9 head gaskets for about 3 1/2 years.

 

[TNBrett]

Wes has the modified gaskets on his website. The pics look like maybe 1/4” or 5/16”, but that’s just a guess.

 

[IDIBRONCO]

Good. I'm not going to use them in the first 7.3 that goes into the Ex Wife, but I WILL use them in the built up 7.3. If you want to play, you've got to pay.

 

[TNBrett]

Well, I didn’t get to work on this yesterday. My son had a JROTC competition that lasted until early afternoon, and I spent the rest of the day feeling like canine yard droppings from the COVID shot I was forced to take on Friday. Anyway I finally got to tear into it today, and befitting of Halloween, it was scary and disturbing.

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This was the first scary thing. The intake valves on cylinders 1, 3, and 7 looked like this. All the other valves looked as expected.

The coolant leak that started me down this road was happening at the rear of the driver's side head. This looks to be the cause of that.

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I guess somehow, water made its way to the injector bore for 8 as well, because the #8 injector looked like this.

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Here's another shot of how the leak migrated.

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I'll continue in another post for the really scary stuff.