American Expedition Vehicles 4.0L Universal Oilpan Skid Plate - Manual (Page 2)

Installation Instructions: Oil Pan Skid - Jeep 4.0L Engines
Nth30108 v2.1.doc page 2 of 3 download @ www.nthdegreemobility.com
- 2000+ Jeeps (and ’99 WJ Grand Cherokees) use the 3/8”-16 flat-head ‘socket cap screw’
Select the appropriate bolt and install it; the metric bolt will require one or two washers under the
head of the bolt to keep it from bottoming out in the engine block. Once the installation is finished,
reposition the trans cooler lines if any were moved in step 3a. If you used the M12 bolt, the head of it
may be too tall to allow the cooler lines to be reinserted in their clips – you may need to bend the lines
slightly or re-mount the clips for clearance.
Step 5: Attach back of OPS to transmission. After the engine bolts are installed, attach the rear flange
of the skid to the lower portion of the transmission bellhousing. First remove the two bolts near the
bottom-outboard areas of your bellhousing (if you have a manual trans, you may also need to temporarily
remove the small inspection cover screw at the bottom-center). You will be able to tell which holes on the
skid to use by swinging it up into place – when the bottom of the OPS is nearly touching the bottom of
the oil pan itself, the correct holes should be roughly lined up with the holes on your bellhousing. Also,
there should be about 1/8”+/- gap between the OPS and the bellhousing itself at this time, but yours may
vary from no gap to as much as ¼”. The OPS is designed/intended to have this gap ‘filled’ with washers
(supplied) to be used as spacers – this is to avoid distortion of the thin metal ‘inspection cover’. Longer
bolts have been supplied to replace those that were in your bellhousing (4LS models include two pairs of
bolts – the smaller bolts are for 32RH/42RE autos, all others will use the ½”x2.5” bolts). Insert as many
‘spacer washers’ between the skid and bellhousing as your skid will fit, then tighten the bolts.
Step 6: Finish. You are now finished installing the oil pan skid. The oil pan skid should feel solid and
secure. Normally, the exhaust should not be touching the OPS, but there is no issue if there is light
contact because the skid and exhaust don’t move relative to each other (both are engine-mounted). If
they are touching and you prefer to have clearance, you may grind/sand the skid slightly.
Tip: If your engine/Jeep is more than a year old and/or you live where ‘things rust’, the holes in
your engine block used by the OPS are probably ‘clogged’ with rust scale. You will need to
‘chase’ the holes with a tap first to allow the bolts go in easier and with less risk of cross-threading.
If you do not have needed tap(s) or if there is not enough room for one in your application, use a
die grinder or hack saw to cut two lengthwise slits across the threads of your bolt at the tip to
create a ‘poor man’s tap’ – the cuts will clean the threads in the block as the bolt is inserted. You
may have to thread the bolt until it binds, remove it, clean the rust out the thread-cuts, and repeat
a few times to fully clear the hole.
ATTENTION: Especially on automatic transmissions, pay attention to the thin metal inspection
cover when installing the OPS. If your OPS is a ‘tight fit’ (i.e. room for only 0-1 spacer washer per
side), the OPS may ‘push’ on the raised ridges in the cover – possibly pushing it back enough that
the it could interfere with the heads of the spinning flex-plate-to-torque-converter bolts. To avoid
this possible issue, you may remove the cover and flatten the lower end of the ridges with a
hammer and a flat surface – then reinstall along with the OPS, making sure the cover is not bowed
in towards the torque converter. If you hear a loud and rapid ‘clatter’ immediately after starting
your Jeep with the OPS installed, you probably have this problem and will need to re-bend the
inspection cover. This contact and the resulting noise has NOT damaged your transmission –
once the interference is corrected, the noise will go away and everything will be fine!
Note: 2000-and-newer 4.0L engines use two separate cast iron exhaust manifolds and two
connections for the exhaust downpipe. These manifold-to-downpipe connections are poorly
designed by Jeep and the four bolts and clip-nuts tend to loosen easily and frequently (they are
often loose on brand-new vehicles!) They should be checked frequently because if they become
loose they will allow the exhaust to sag – which may result in the downpipe resting against the
OPS skid. Minor contact with the OPS is normally not a problem, but you should inspect the
exhaust connections and retighten them as needed to prolong the life of your exhaust.