The Simple Utilitarian Vehicle: 1991 Trooper

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The Simple Utilitarian Vehicle: 1991 Trooper

Postby m_force » Tue Jan 03, 2017 2:48 pm

Hello All,

First of all, thank you all for you help over the years. I currently have a 1997 Rodeo that is on its last legs, and I wouldn't be squeezing the last life out of it if it weren't for all of your help and support. So, knucks to that.

I recently bought a 1991 Trooper LS to replace my ever-aging Rodeo, so I'll give you the quick rundown on it and my immediate as well as my long term plans with it.

1991 Isuzu Trooper LS
2.8 l GM V6 (179,xxx miles)
5 speed
Midnight Blue/Silver with grey interior
Power windows
Missing exhaust manifold bolt as well as bits of the gasket
Heater core blew up
One power lock on the passenger door that has been disabled

It tried to kill me. No really, it had sat for a while according to Rick, who I purchased it from, but he had been using it as a farm vehicle in central Oregon. Decently clean, it has a few dings and one semi-major dent on the front fender from when "an animal hit it in the night." I got down to pick it up late in the evening, and it fired right up. after I let it warm up, I took it out and hit the road.... then proceeded to die. I needed a jump, let it charge once more, then finally set off. after getting a bit of fresh gas, i set off for its first test- a 40 mile freeway journey home. It required a lot of mashing of the gas pedal to the floor, and a consistent loss of power in fifth gear. Long story short, it nearly died about 8 times on the way home. Once it was parked on a steep drive way, I turned off the key and just sat there for a sec as I heard (what I thought) was a loss of pressure in the radiator. I was sorta right:

That is the heater core-turned-into-violent-evil-firehose-of-death. the piece that is missing broke off as soon as I parked on the steep driveway, and (I assume) that the pressure in the hose was too great for the 25 year old plastic cover. It broke off, burned the ever loving ---- out of my leg, and filled up the cab with hot antifreeze vapor. I managed to crawl into the back seat and jump out one of the passenger doors, run inside, and play medic the rest of the night.

Leg hurt like hell, but I managed to block off the heat so the core is shut completely off right now. I pulled it down, gave it a bath, then took some glam shots:

Charged the battery, cleaned all the antifreeze off the floor, and started drying it out. Went around and checked all the fuses, bulbs, connections and was pleasantly surprised at how complete it was, I'll only need one turn signal bulb. The driver headlight has some water in it, which probably isn't ideal, so that will need to get sorted out. crawled underneath and again, was reminded that a 179,000 mile car wasn't going to look terrible from below, save the few pinhole exhaust leaks.

The Passenger door was a bit sticky, and wouldn't open without pulling the tab and either of the door handles. I took off the door panel and saw that there was a motor at the bottom of the door with an arm going to the lock cylinder. took that arm off, and what do you know, it works perfectly. So I assume that there was at one point an aftermarket alarm on it, probably.


1. New exhaust manifold/gasket on passenger side
2. Take new 265/70/16 tires and wheels off of Rodeo and put them on Trooper
3. Fix the heater core debacle
4. Fluid flushes all around
5. General tune up
6. Drive it
7. Ski
8. Install radio
9. Fab up some sleeker off road bumpers front and rear
10. Fab up ladder for small door on back

Anyway, thanks for taking the time to read through this, and I look forward to talking and getting to know the rest of this awesome community.

Last edited by m_force on Thu Apr 20, 2017 12:18 pm, edited 1 time in total.
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Re: The Simple Utilitarian Vehicle: 1991 Trooper

Postby leftarmtan » Wed Jan 04, 2017 1:12 pm

Clean looking Trooper. I've never seen a heater core do that,crazy!
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Re: The Simple Utilitarian Vehicle: 1991 Trooper

Postby RickP » Wed Jan 04, 2017 4:05 pm

Wow, I can't imagine 15 psi doing that, but you never know. Hopefully your headgasket isn't blown and pressurizing the cooling system. I did have an old van that I poured about 3 containers of stop leak in the radiator and it must have clogged the radiator and the top tank blew off the radiator.
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Re: The Simple Utilitarian Vehicle: 1991 Trooper

Postby Ed Mc. » Wed Jan 04, 2017 7:05 pm

Cool, another V6 LS Blue Trooper! Welcome to the club!

Just imagine a hot radiator and you remove the cap. It blows out of there like Old Faithful!

And at 15psi, figure out the surface area in square inches of that blown out piece. Which is CRAZY, BTW! You could have 100-150 lbs of force acting upon that piece of plastic. You're lucky the burns weren't any worse. I got it in the arm years ago and it's a very painful burn. Silvadene burn cream helps immensely.

You may be able to find a heater core in the scrapyard, otherwise they're very expensive, because they have the heater control valve & bypass built-into the core. Hook up with Jerry Lemond " JLEMOND " on this forum for a new one.

Replace all the heater hoses; the twisted ones at the firewall will be disturbed when you replace the core; they like to blow out at the worst time. The large radiator hoses are easy to source. Most of the small hoses are available aftermarket (try Rockauto), but you can make your own out of straight pieces of hose and a few plastic fittings. Easier to find replacment hose when you blow one in the Toolies. It's 3/4" off the water pump, then turns to 5/8" and connects to the bottom metal pipe at the back of the engine. The 5/8" hose coming off the intake manifold just needs a 90-deg fitting and you can run another straight piece back to the top pipe.

On the heater core side, the bottom pipe hooks to the bottom spigot on the core; top pipe to top spigot.

Use a Stant Super-Stat thermostat if you can get it. These cooling systems are particularly hard to "burp" so you'll have to point the rig uphill, or on ramps/jacks to get the air out of the cooling system. A Lisle "Spill Free" funnel helps immensely 'cause it's got a large reservoir where the coolant can safely expand and purge air out. Safe to remove, too since there's a stopper for the bottom of the funnel and you'll hardly spill a drop. ... 29&vxp=mtr

Since you're gonna do the pssgr's side exhaust manifold, you'll be pulling quite a bit of stuff out of the way. Might as well do valve cover gasket as a preventative measure. The driver's side is way easier to replace, so if it's not leaking you can leave it alone or replace.

Maybe do the distributor O-ring at the same time since things will be torn apart. This cheap part will eventually save you a lot of grief, especially if the O-Ring has never been replaced. The O-rings harden with heat & age, and when they leak they'll puke a big puddle of oil under the rig. I have a writeup for that job in case you need it, just P.M. me with your email address.

As to the loss of power, pull the air cleaner lid and check the spray pattern out of the 2 injectors. Should be an even, conical spray. No uneven sections or "dribbles". Sometimes it helps to "freeze" the injector action using a timing light.

If the spray looks dicey, you could try some fuel cleaning additive. Gumout "Regane" hi-miles cleaner is pretty good stuff and really cheap at Walmart: A double-dose probably woudn't hurt, either.

Do an inspect/clean on the EGR valve when things are apart. Leaking EGR valve can cause stalling at idle and surging underway.

Congrats on your purchase and G'luck with the repairs.............ed
'90 3.4 Troop LS;
'89 Troop RS (Exhaust Valve Challenged), now gone to a Good Home!
Yes, I am a Trooper-Holic!!!
Keep On Troopin' !
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Re: The Simple Utilitarian Vehicle: 1991 Trooper

Postby m_force » Sun Apr 16, 2017 5:06 pm

Hello All,
Finally had a chance to post and give everyone a quick update on the Troop.

After pulling everything back, I realized that the exhaust manifold bolts were missing on the passenger side, hence the loud and nasty exhaust leak. Got new bolts in it, gaskets, starter, battery, temp and O2 sensor, and who would of thought! Its an awesome little ride. Before i was finished, I found a donor Troop at a junkyard with low miles and a rolled roof to pull the heater core out of. The heater core switch will happen next week at some time, but its no longer snowing so the need isn't urgent, yet.

After putting on 100 miles this weekend, I had a few things that I came to notice. in first and second gear, during low revs, there is a whine that i am having trouble tracing out. Belt? Transmission? Bueller?

Also, not sure if it is purging air bubbles, but when I park after running for awhile it has a little blow back into the reserve reservoir....?

Also, I will be replacing that thermostat this week just for good measure. Not that I am afraid of the pressure caused by overheating cars or anything....

Tires will also be put on this week. I have a set of 265/75/16s and my aluminum rodeo rims that'll fill in the wheel well nicely. But all in all, I can say I get it now. These cars are simple, tough, and built for whatever you throw at them. Consider the Kool-Aid drunk.

Lastly, I hate the square headlamps. When I hunt down a grille and buckets for the round ones, how do I go about mounting it?

Thanks guys -- John
Last edited by m_force on Thu Apr 20, 2017 12:19 pm, edited 1 time in total.

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Re: The Simple Utilitarian Vehicle: 1991 Trooper

Postby paulevans76 » Mon Apr 17, 2017 9:28 am

The round headlamp grill is pretty much a direct replacement. You may get lucky and get all or a few of the clips with the grill, or you'll be like me and keep a grip of zip ties in the glove box to re-attach as necessary :D There are a few bolts that will hold it in place in addition to the clips (or zips). The mildly tricky part can be the wire matching, as you'll need to splice the new headlamps' harness in with the old wiring, but it's all been covered here a few times over, so a search will yield all the info you'll need.

I will warn that on my 91, and I think on a few others, not sure what the date change is, but some of us have it a little tougher getting the grill to mount because of a slight design change. Missing a tab or a cutout that the earlier models have. I think my driver's side was tougher to "rig" into place because of these issues.
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Re: The Simple Utilitarian Vehicle: 1991 Trooper

Postby wmorrisiii » Tue Apr 18, 2017 8:52 pm

Great looking Trooper and the 2.8 in it looks bone stock, wiring looks to be in good shape as well. Check your tensioner pulley, they can whine when they get older. Easy and cheap to fix. For some easy to live with updates on your 2.8, check member here geoffinbc website. Throttle body update, Fiero valve cover update, and air pump removal threads are great. At 178K, this one should treat you well for a good while. Also hard to beat that refrigerator on wheels look the first gens have. You will, of course, have to get used to all the beautiful women begging you to go for a ride...even if they are only your wife or daughter.
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Re: The Simple Utilitarian Vehicle: 1991 Trooper

Postby m_force » Wed Apr 19, 2017 1:20 pm

Got the wheel stud fixed today, had a break in the rain just long enough to give it a wash and take some pics for you.
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