2002 Trooper Thermostat DIY Notes

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2002 Trooper Thermostat DIY Notes

Postby Shackman » Mon Jan 16, 2012 1:26 pm

I replaced the thermostat in my 02 Trooper this weekend.
Let me start by saying this is NOT an easy job. The entire intake manifold and all the associated bits need to be removed to access the thermostat housing. So if you’re thinking about swapping the thermostat in your 3.5l make sure you have the entire day free, or entire weekend if you work slow.

-The fuel injector rail and all six fuel injectors need to be removed. Make sure you have new o-rings for the re-install. And make sure you oil the o-rings.
-Removing the fuel lines from the fuel rail is not easy. There are two of them squeezed between the firewall and each head. One passenger side and one drivers side.
-The two fuel lines that come from the tank are bolted to the back of the intake manifold with a bracket and two 10mm bolts.. You can’t see them, but you can feel them. The trick here is to lift the intake off the motor and balance it on the head so you can get to the bolts. Not easy but it can be done.
-Don’t forget to unscrew the big nut that holds the pipe to the bottom of the EGR valve housing on the back of the intake on the passenger side.
-The wiring harness going to all ignition coils and fuel injectors needs to be free. Take your time with this and try not to bend/stress the hard and brittle harness too much.
-Make sure you have a new intake manifold gasket (the lower one). No need to split the intake in half so you won’t need the upper gasket.
-The thermostat is under the 4 bolt pipe bracket that goes to the lower radiator hose.

Take your time.
It’s not an easy ‘no-brainer’ job.
Good Luck.

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Re: 2002 Trooper Thermostat DIY Notes

Postby CatFuzz » Mon Jan 16, 2012 5:27 pm

I disagree on removing the fuel rail and injectors. I've R&R'd my intake many times for various reasons and always left them alone. I also leave those 10mm bolts off that hold the fuel line bracket. Some extra long nose pliers are good for getting at the spring clamps. Get Fel-pro gaskets to reseal the lower intake. The metal-plastic-metal 'sandwich' gaskets are garbage. You'll be doing it over again in 20K miles with those.
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Re: 2002 Trooper Thermostat DIY Notes

Postby fstr » Mon Jul 04, 2016 5:20 pm

I did the thermostat on my '99 Trooper, same 3.5. When you finally get down to the thermo housing, you will need to remove a water pipe that lays in the valley. An O-ring
is found on the front end of the pipe. This O-ring should be replaced before putting the water pipe back in place. The O-ring may or maybe can be purchased at former
Isuzu dealers. This is the same O-ring found on the 3.2L engine and is usually responsible for an overheated engine/blown head gasket. They can start leaking and are
usually not detected, because of the location in the valley, until the engine is dry and melted down. Been there and done it!
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