74 Jp jpmagazine.com OCTOBER 2019
By Trenton McGee
[email protected]YOUR JEEP
Wobbly CJ
I was wondering if you could help me
diagnose what is causing the “death
wobble” on my 19 5 9 W illys C J - 5. It has
Rancho 1- inch lif t springs, s toc k shoc ks,
and is on 33-inch tires. Besides that, the
Jeep is s toc k. I took it around the bloc k and
once I got into Second gear it shook like I
was in an earthquake. This was after I put
the Rancho lift springs on it. Any ideas?
Ryan Hughes
Via email
Death wobble can be caused by a variety
of things, depending on the suspension
and steering design. On your CJ, the wheel
bearings or the kingpins on the front axle
are among the likely culprits, as any play
in them could cause what you describe.
Tires can also cause death wobble if they
are really old or out of balance. But since
you indicate that this started after you
installed the lift springs, the culprit is likely
in the steering. Your Jeep has a compli-
cated and problem-prone Ross steering
system that doesn’t generally like lift kits.
Though just a 1-inc h lif t shouldn’t c ause
muc h of an is sue, if there was something
in the steering that was already marginal,
the mode st increase in ride height c ould
have put it over the edge. Inspect all of
the steering components closely for any
play, including the steering box, linkage,
and bellcrank, and replace those items
as nec e s sary. If this is a Jeep you intend
to modify further in the future, you might
want to consider converting the Jeep to a
Saginaw steering box with a traditional tie
rod and drag link. There are a few differ-
ent manual and power steering conver-
sion kits out there, including a couple of
systems from Herm the Overdrive Guy
(hermtheoverdriveguy.com). Converting
the steering is a fairly big project, but in
the end you will have a durable and less
problematic steering system that can
better handle future upgrades.
4.0L Engine Compatibility
My 19 8 8 XJ engine blew a freeze plug
and overheated beyond repair, and now
I need a replacement engine. Would my
19 9 6 XJ that s till runs with 18 8,0 0 0 miles
on it, but has all rusted out floorboards
like a “Fred Flintstone” car, be a possible
long-block donor to get the 1988 back
on the road? They both have automatic
transmissions.
Mark W.
Via emailYou could absolutely use the engine
from the 1996 Cherokee in the 1988, and
there are a couple of different ways to do it.
The biggest challenge you face is that the
1988 uses a Renix fuel injection system,
while the 1996 uses a more modern multi-
port injection system. The two systems
have almost nothing in common, but the
engines themselves are basically the same.
If the EFI in the 1988 is still functioning well,
the easiest thing to do is use the Renix
system on the later engine. This would
require using the intake manifold, throttle-
body, sensors, and distributor from the old
engine, which is a simple bolt-on affair. We
can’t think of a reason why the accessory
drive system from the later engine wouldn’t
work in the earlier car, but if you do run into
a problem, the earlier accessory brackets
should bolt right to the later block.The slightly more complicated method
would involve converting the 1988 to the
later MPI system. While it’s quite a bit more
work, the advantages are a more efficient
EFI system and vastly superior diagnostics
with OBD-II. To do this, you would need
the complete MPI underhood engine
harness, computer, and power distribution
center. With a good manual, you can pare
the MPI engine harness and PDC down
to just what ’s needed to run the EFI, so all
you would need to cross-connect with the
1988 harness are three wires: switched,
constant, and start power. Transmission-
wise, we’d recommend using the one with
the later engine and retaining the transmis-
sion wiring that ’s c onnec ted to the engine
harness, as the later computer is already
set up to communicate with it. You might
run into some is sue s trying to retain the
1988 transmission, but since the trans-
missions themselves are the same, you
shouldn’t run into any issues with fitment
or compatibility with the transfer case,
crossmember, or transmission mount. All
things c onsidered, we’d probably just use
the Renix system on the later engine.Overheated TJ
I have a 19 9 8 Jeep Wrangler TJ that I
can’t seem to keep cool. It seems to do
okay in the wintertime, but as soon as the
ambient temperatures start to creep up,
so does the engine temp on the TJ. The
engine is a stone-stock 4.0L with about
140,000 miles on it, and the Jeep is only
on 3 3 s. W hen it ’s around 10 0 degrees
outside, the temp will run 230 just running
around town without driving it hard. I’ve
thought about adding an electric fan and
an aluminum radiator. Do you think that
would fix it?
Stephen E.
Via emailCooling problems can be deceptively
hard to diagnose, and it’s rare for a TJ
with a stock engine to run hot since they
actually have a pretty big radiator and the
engine compartment isn’t cramped like an
XJ’s. Before throwing modifications at it,
we’d make sure that there’s not something
wrong with the cooling system. Assuming
there aren’t any leaks and the system is
full without any air bubbles, the first thing
we’d check is the thermostat. It should
open around 190-200 degrees F and pretty
muc h stay open in the summer months.
Carefully feel the upper radiator hose as
the Jeep warms up. When it gets close to
operating temp, you should feel the hose
get warm rapidly when the thermostat
opens, and it should stay warm onc e up to
temperature. If the hose feels cool and the
gauge is showing the Jeep is warm, then
that’s a sign the thermostat isn’t function-
ing properly. Make sure the coolant in
the radiator looks good and doesn’t have
a bunch of trash in it. Rusty water and
excessive corrosion can indicate blocked
passages in the radiator. If there’s any
doubt, flush the system thoroughly, and if
there’s a lot of junk in the radiator, consider
having the radiator profe s sionally rodded
out. Some places will claim you can’t do
that with a radiator that has plastic tanks
and try to sell you a new radiator, but a
good radiator shop can rod out a modern
radiator fairly inexpensively. Though
unusual, there’s a slim chance there could
be something wrong with the impeller of
the water pump, so it’s worth having a look
if every thing else c hec ks out.