93 Expo wagon 4G64 rebuild ...

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Stewart DIBBS - 05 May 2007 22:38 GMT

Don't I just love cars ...

My wife's 93 AWD wagon's smokey 4G64 SOHC-16v needs a rebuild so I got
another engine from the local wrecker, out of 93 (or perhaps 94) wagon. Had
a machine shop strip and clean, and got back the empty block with new
balance shaft bearings, crank, rods with new pistons fitted, complete
assembled head and bucket of other bits and assorted bolts. OK, a day later
I have sorted out what bolt goes where, and do a trial assembly.

Get to the new oil pump (from Rock Auto), add some oil, stick the balance
shaft into the driven gear, and see if it turns. It does, but roughly. Put
in the driven gear bolt, and the shaft jams solid. Pulled the pump apart and
checked that the pump gears are aligned correctly: they are. The old pump is
smooth as silk. Turns out that the pump chamber is about .020 too shallow at
one end ie a manufacturing defect. Rock Auto is sending a replacement
without waiting for the defective unit to return.

The old water pump bearings are shot, so I ordered a new pump from my local
supplier. It arrives and its not the same: bigger with different bolt holes
and a 3mm different positioned coolant pipe. They order a new one from a
different supplier, and its the same as the first one. The supplier swears
black and blue (and at me) that the 92-96 4G64 SOHC-16v Expo all use the
same pump. I check the Rock Auto gasket set and there's TWO water pump
gaskets: one that fits my old pump, and one that fits the other type.

So ... there are in fact TWO incompatible water pumps used in at least the
93, and probably the 94-96 too.

I am sure glad I'm not paying someone else to do all this running (or is
that F*NG) around. Up shot is of course that the engine will be perfect once
its put in.

Let's hope the chewed up flywheel ring gear lasts until the new engine is
FINALLY ready.

And then there's the 4G63T in my Summit GTX that's got a severe ring /
piston failure (again) in #2. Its undrivable because of the smoke, and it
will take a rebore to fix.

Stewart DIBBS
www.pixcl.com/lancerproject

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mpberti - 06 May 2007 22:28 GMT

> Don't I just love cars ...
>
[quoted text clipped - 37 lines]
> Stewart DIBBS
> www.pixcl.com/lancerproject

yea man when i changed the timing belt on my montero (4g64 sohc 16v), i
also on the recommendation of a good friend (lol) changed the water
pump. When i went to buy the parts i found two pumps,and both pumps were
totally different. Both were for the 1998 montero(4g64). I just figured
one was for the timing belt driven model and one for the fan belt driven
model. I opted for the more expensive of the two and i turned out to be
the right one

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Stewart DIBBS - 09 May 2007 02:21 GMT

OK, it took a while and trolling the RockAuto website database.

Almost all 93-96 Eagle Summit wagons had the same 4G64, with a large water
pump. The Mitsu Expo LRV, essentially the same vehicle, also had a 4G64, but
this was a different 4G64 variant (Japanese made, or a different Japanese
factory?) with a smaller water pump. A few Eagle Summit wagons had the
smaller water pump engine. Some LRVs had the bigger water pump.

These engines are mostly identical, but the water pump has different
mounting holes and the front engine support casting is also unique to the
engine variant. Hence its not possible to drill and tap the small pump block
to take the large pump.

The coolant pipe along the (front) side of the engine is also positioned
differently (may be different too), and hence the thermostat housing is also
unique the engine variant.

So far as I can tell, everything else (rings, bearing, belts, tensioners)
are the same.

I checked the block and could not find a serial number. I guess its there
somewhere...

Hope this helps someone else..

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Stewart DIBBS
www.pixcl.com/lancerproject

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