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Turbo Bolts (and related topics)
By Donald Ward aka ProBear
For all of you who don't have an EGT (or Pyro) gauge, this is a good warning.
This gauge can tell you much information. Just recently I noticed that my
EGTs were higher than normal during acceleration or under load. The first
thing that I thought about was either the EBP valve sticking or a clogged CAT
(catalytic converter - I know, some of you do not have a CAT!) Anyway, after
talking to several people, I embarked to check the possible causes. Unfortunately, my first trip under the hood resulted in finding that I had
the turbo bolt syndrome with both rear bolts backed out. The upper bolt was
lying on the pedestal bolt and the lower bolt was backed out against the
pedestal bolt (which caused it to bind -more on this later).
My next step was to go to my local friendly Ford dealer to get the
replacement bolts. (Part Number #1C3Z-9G486-AA) Once these were in hand, now
I'm ready for the replacement. (A side note: If you use a thread sealant, it
should be a ceramic type. This is the only type that will withstand the high
exhaust temps). Using my trusty 8MM - 12-point wrench, I climbed on top of
the engine and replaced the top rear bolt. The next one to replace was the
lower rear bolt, which requires that the rear turbo pedestal bolt be removed.
It wouldn't budge. After several questions to people in the know, I found
that the backed out lower rear bolt was binding the pedestal bolt. This required screwing the backed out bolt back in enough to remove the lower
turbo bolt. This is where I discovered that an 11/32" open-end ignition wrench was thin enough to slide by the pedestal bolt and the right size to
slowly turn the turbo bolt back in. This eventually worked and the pedestal
bolt came right out. Now I just used the 8MM-12 PT to remove the original
turbo bolt. A magnet does help to remove the bolt once it is unscrewed. Putting the new bolt in is almost dumb luck. It won't go very fast, but it
will go slowly. Once this bolt is back in (torque 199 in/lbs), you can replace the turbo pedestal bolt (35 ft/lbs).
Once the rear bolts are replaced, the front bolts are easy. What ever you do,
start with replacing any missing or loose TOP bolts first. If you have one
missing/loose top bolt and one loose bottom bolt, replace the top bolt first
and then the bottom bolt. (The idea is to have as many bolts in place and
torqued at the same time. This helps prevent any shifting of the housing.) A
word of caution, do not remove both turbo pedestal bolts at the same time.
Now that the turbo bolt issue is resolved, back to the original problem. The
next step is to verify that the EBP valve is operational. This valve is very
hard to spot, but it can be seen from the passenger side of the truck, under
the exhaust housing of the turbo charging. I got my wife to start the truck
while I was under the hood watching the linkage. Since it moved smoothly, I
will at this point assume that it is not stuck.
That leaves one other possibility to consider, the catalytic converter (CAT).
A friend of mine had a kit that would measure the difference of pressure
between the pre Cat pipe and the post CAT pipe. It was simple enough; it
punctures the exhaust pipe (with the aid of an air hammer) and then uses a
self-threading bolt to tap the hole. Remove the bolt and install a nipple
with hose connected to a pressure gauge. My first connection was pre-CAT and
then I drove up the nearest hill WOT (wide open throttle) to get the pre-CAT
pressure. It came out to a little over 3 lbs pressure. Back at the shop, I
plugged the hole with the supplied bolt and then installed the nipple post-CAT. Back up the same hill with the reading only 1 1/2 lbs. This
partially confirms my theory that the CAT is partially clogged. EGTs are OK
at idle, and cruise, but under load, they climb too fast, and too high.
This could lead to a new exhaust system (or at least a CAT delete pipe). More
later.
