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1989 Isuzu Trooper
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Discussion Starter · #1 ·
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Just bought a 1989 Trooper with 154k miles. 5 speed. A little dirty but I was surprised by how good condition it is.

This is my first Isuzu. We have a 16 month old boy and a dog and we just wanted something fun to take camping or paddling or grocery shopping.

There’s no maintenance records. It came with a shop manual, so I assume there was some DIY done to it. How should I go about inspecting this for the first time? I planned an oil change, but I’m wondering what other tasks I should perform if I can’t actually be sure that anything has been done in the past.
 

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1989 Trooper R/S
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Congrats on your Trooper. I have an 89 so I can relate some issues you will read on the forum. First, the 2.6, which I'm assuming as I don't see the V6 emblem on the side, is very sensitive to overheating. Many head gasket failures reported here are the result of engine overheating. So a check of the cooling system should be done, like check the radiator hoses and fan belts for condition. Second is the valve adjustment. It should be done every 20 thousand or so miles. It also has a belt driven overhead cam so the condition of the belt. should be checked. Third is the transmission and transfer case are serviced with 10/ 30 engine oil. Not gear oil like most. How handy are you with tools? You can do most all of the maint. issues with help here that need to be done. With the ITEC fuel injection your engine will respond poorly to vacuum leaks so replacing all the vacuum lines is probably in your future
 
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To add to the above, the stock thermostat is 180F. Don't use hotter.

Valve adjustments are critical and keep the exhaust valves from burning.

The transmission drain/fill plugs are on the passenger's side of the transmission housing. The transfer case has a different set of fill/drain plugs and they are at the rear of the case.

75W-90 gear oil in front and rear diffs. Go Wild if you wish and throw some synthetic gear oil in there for less friction. If you have the "G80" code on your firewall plate, you have a limited-slip rear differential and should use Dino oil along with LSD additive to keep the clutches happy.

Cooling-system-wise, I've had 3 Troopers blow out heater hoses, so that's definitely a maintenance item. The heater core hoses at the driver's-side firewall are Twisted Little Buggers who like to blow out with regularity. So if yours look sketchy, replace.

And Good Words above to heed, regarding the timing belt. This engine is interference-type, and valves will be crunched if the belt breaks.

Parts-wise, Jerry Lemond on this site used to work for Isuzu and has a good line on the really hard-to-find parts. JLEMOND is his username or [email protected] Use all caps to make it easy on Jerry's old eyes.

Rockauto still carries many service parts and, if anything else, is an excellent place to look up part numbers:


Hope that helps and Welcome to the Planet!............ed
 

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Just bought a 1989 Trooper with 154k miles. 5 speed. A little dirty but I was surprised by how good condition it is.

This is my first Isuzu. We have a 16 month old boy and a dog and we just wanted something fun to take camping or paddling or grocery shopping.

There’s no maintenance records. It came with a shop manual, so I assume there was some DIY done to it. How should I go about inspecting this for the first time? I planned an oil change, but I’m wondering what other tasks I should perform if I can’t actually be sure that anything has been done in the past.
 

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1989 Isuzu Trooper
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Discussion Starter · #5 ·
Thanks for the advice, guys. I’m going over my chilton manual now.

Yes, it is the 2.6.

I have found some receipts, including the original sales invoice, in the glove box. The previous owner put in a new fuel pump, distributor, clutch master and slave cylinders, and few other bits it seems.

There is also a receipt for 150 feet of 5/16” fuel line. Do you suppose that was used to replace vacuum lines?

There is also a throttle position sensor new in the box. What are the symptoms of a failed sensor? I didn’t get an explanation from the previous owner on that.
 

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Nice truck! Nothing to add to the above, Harry and Ed have covered it pretty well. I think 5/16" may work for the few larger ones, but the majority of the lines take a smaller hose. Just stepped outside and measured mine. Looks like 5/32" - 3/16". Actually a metric size, not sure which at the moment.

Mike
 

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Are you in the Asheville, NC area I've seeing one that looks much like that on FB marketplace and I notice it's no longer there. I also just recently bought a 1989 Trooper.
 
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