2.4T Rebuild - Many Questions

[frankc]

I got some time this past weekend to remove the 12 left bank studs. The double-nut method with MAP gas worked well, with only two studs putting up a fight. If I have any time left over after working on my son's MINI this weekend, I'll tackle the right side.

0396,
My plan was to send the cooler to Pacific Oil Cooler to be cleaned if I don't find any surprises when I split the case. If I do find significant metal in the case, then yes - I will replace it.

Ok, time for a couple more questions:

1. Speaking of re-using the head studs, I was originally planning to use either Supertec or Raceware, but then I read that for these lower displacement motors, the OEM steel studs are acceptable. I imagine that I will get all kinds of opinions on this, but what is the conventional wisdom on head studs for a mild 2.4L motor? (targeting ~9.2:1 CR)

2. I've ready many of the threads on the Oil Bypass modification, and now I'm trying to decide if I should include this in the list of items when I send the case the machine shop. I was planning on keeping the original 3-rib oil pump (another question, perhaps), if that factors into your opinion at all. Currently I am leaning towards having it done, as I don't see any negative consequences, only positive.

[tharbert]

I found this little quote from Tom Butler (tom1394racing) that kinda lays it out in a nutshell: "You can use the original 3 rib pump, however....... When Porsche introduced the oil bypass changes in the 1976 7R case, they also introduced the new 4 rib pump. The 4 rib pump has a reduced capacity on the scavenge side and an increased capacity on the pressure side. The oil bypass modification routes excess oil back to the pressure side of the pump rather than to the sump and is thus designed to work with the 4 rib pump. As best I know, when the oil bypass mod is performed, one also upgrades the oil pump. "

I sourced my 4 rib Mg pump from Tom and it was very reasonable. Others here offer them too.

[frankc]

Hi tharbert,
Yes, I read that post about the 4-rib pump when I was researching the oil bypass mod (and also why I mentioned that I planned to keep my 3-rip pump). Further posts in that thread seem to discount the need to have the 4-rib pump if the oil bypass is performed, hence my question.

I will watch for a 4-rib pump in the classifieds forum, and perhaps pick one up if the price is right.

[frankc]

Well, all but three of the right bank studs are out, with those last three being stubborn. I'll let them soak some more in Kroil for a few days to see if that helps. Otherwise, I'll weld a nut onto the studs and try that method.

Question - do I need to worry about the steel head studs snapping off flush with the case, or are only the Dilivar studs prone to that?

And if I do end up welding on a nut, is it best to weld the nut close the to case to prevent the stud from twisting when applying torque at the top of the stud?

Thanks,
Frank

[tom1394racing]

Frank

I have done hundreds of these and have never had a steel stud snap. The key is to heat the inside of the spigot, adjacent to the stud, to expand the case and melt the loctite. This will free up the stud.

[Ed_914]

I welded the nut 2 inches from the case so I could weld from both sides. Make sure you protect your case while welding. Heating the case is the mean trick here. It took 15 min of heating.

[frankc]

Tom,

I was heating the case at the area you mentioned, but perhaps I was not heating it long enough. Ed recommends 15 minutes, while I was heating the area for only about 3-4 minutes. Let me try this again before resorting to welding the nut.

Interestingly, I would always try backing out the studs with no heat first to see if I would get lucky and the stud would budge - four of them did come out very easily without heat.

Ed,
Thanks for the tip to weld the nut on both sides, and also the recommended heating time.

[tom1394racing]

Frank

On each case I do, most of the studs come out with no heat. The stubborn ones require 10-15 min of heat with a MAP gas torch.

[frankc]

I had a little bit of time this evening, so I tried again, this time applying heat a little over 10 minutes - but still no luck. I think the main problem is that I'm not able to apply enough torque to the studs because the double-nut starts to turn on the stud (I do have the nuts torqued against each other very tightly).

If I was doing a lot of these, I would purchase the proper Snap-On tool - but since I don't plan to be, I'll weld on a nut and move on.

[Ed_914]

Frank,

Try to find a nut that is slightly larger than the stud and has no protection on it i.e. zinc or plating. Clean the stud where you are welding. I used a sanding disk for that. Then MIG weld the nut by filling the gap between the stud and the nut with weld in one go from the top side, then fill the remainder of the gap from the bottom. To keep the loose nut in place before welding just use a clamp on the stud and let the nut rest on it. If you can find a castle nut that would be better as the weld has a greater surface to weld to. Keep the MAP torch going while removing the studs.
Mine 24 studs where all a pain, even the steel ones. Don't know what the PO used to lock the studs in place but it took over 8 hours to remove them.

[frankc]

It turns out that Sundevil64 had the proper stud removal and was kind enough to let me borrow it. So, with the proper tool in hand, a rainy and mild Saturday afternoon was the perfect opportunity to resume work on the motor.

The three remaining studs came out in about 20 minutes - what a difference the right tools make. I only had to use a few minutes of heat on each stud now that I could apply a little more torque.

After I removed all the case through bolts and nuts, I finally got a chance to see what this thing looks like inside.

Here are a couple of shots of both halves. Initial evaluation of the crank is that the main bearing journal surfaces feel smooth - obviously I'll need to take measurements. The sludge on the bottom is far less than I was expecting - mainly sitting under the oil pump at the very front. And there appears to be some rust on the #3 rod, which is the same cylinder that had the water ingress.

Anything look suspect?





Is sludge build-up in this location normal?:


From this angle you can see the Windage Screens still in place:

[jdbunda]

Good progress, Frank. It looks a lot better than I would have expected after seeing that cylinder and head, you gotta love that! Is that sludge perhaps where water collected inside the case?

[frankc]

I need to start contacting machine shops, but I have some (more) questions first.

1. Should the crank always be sent out to be cleaned and polished? That is, if the crank main journals measure to be standard size and show no signs of damage, should the crank still be polished?
2. If the answer to [1] is no, and the main journals are std, should I always remove the rods and measure those journals as well? Or, if the main journals are fine, then typically the rod journals will be ok as well? Basically, what I'm trying to determine is if I need to remove the rods from the crank now, or wait until after I measure the main journals.

Thanks,
Frank