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95 Trooper Repair and Improvements

58K views 152 replies 18 participants last post by  SupATro.0pA 
#1 ·
I recently acquired a 95 Trooper manual 4x4 with a 3.2 v6. The little Trooper gets a warm when idling at stops, and the mechanic for the previous owner suggested that the head gasket was blown. When I checked it for 4/5 of the tale-tale signs for a blown head gasket before acquisition, I found that it didn't have any of them.

  1. Bubbles in the radiator when running? nope[/*]
  2. Water vapor coming out of the tailpipe when running warm? nope[/*]
  3. Milky Oil? nope[/*]
  4. Copious amounts of radiator fluid spilling over the blocks from the headers? nope[/*]
  5. Spitting radiator fluid out of spark plug holes when turning over the engine? didn't check before purchase[/*]

I later pulled 5/6 of the spark plugs (the one right by the master cylinder is a real booger), and saw no fluid splashing out when I turned the engine over.

My thoughts are that it is either the radiator or the water pump (although I'm still looking to see if it's actually consuming water somewhere).

I did a heat test with the radiator by running the engine for a bit (drove thrice around the block), then turning it off, and feeling for cold spots with my hand, and found that about a third to a half of the radiator was cold. I've pulled and flushed the radiator, flushed the block, washed off the outside of the radiator and ac intercooler, installed a new thermostat, installed a new upper and lower hose, and am waiting for the sealant around the thermostat to cure before pouring in fresh fluid.

While I was waiting on the engine to dry, I pulled off the throttle body and cleaned it up a bit as well.

I'm hoping this does it. I'll try to get some pictures, or be better at taking pictures for future posts. This Trooper has plenty to work on, so I'd like to add to the knowledge bank as I go, and hopefully help somebody else out in the process.
 
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#27 ·
nasty610 said:
Have you ever checked the codes? You've said several times that the CEL is coming on telling you there's a problem but I haven't seen any codes listed. Seems more a little silly if you're just throwing parts at it hoping something gets fixed. As for your fan clutch just spin the fan by hand with the engine off. If it free spins then it's bad. If it starts to tighten up then it's good. No need to shove anything in it while the engine is running.
Excellent advice. I have not yet checked the codes. I will do so today.

I've come to the conclusion that this project has become a light restoration, so I don't mind adding new pieces here and there as needed to get it running strong.
 
#28 ·
I'm getting two codes: 21 and 44.

According to this website, http://www.troublecodes.net/isuzu/rodeo-3-2l-stylus-1-61-8l-trooper-3-2l-1991-1995/:
21 = Throttle position (TP) sensor - signal voltage
44 = Heated oxygen sensor (H02S)/oxygen -sensor (02S) - signal - mixture lean

I tested the TPS, and although the results says it's fine, maybe a new one instead of a salvage yard one will do the trick.

We'll see what a fresh fuel filter does for the fuel mixture.
 
#29 ·
SupATro.0pA said:
I'm getting two codes: 21 and 44.

According to this website, http://www.troublecodes.net/isuzu/rodeo-3-2l-stylus-1-61-8l-trooper-3-2l-1991-1995/:
21 = Throttle position (TP) sensor - signal voltage
44 = Heated oxygen sensor (H02S)/oxygen -sensor (02S) - signal - mixture lean

I tested the TPS, and although the results says it's fine, maybe a new one instead of a salvage yard one will do the trick.

We'll see what a fresh fuel filter does for the fuel mixture.
a fuel filter won't do anything for your fuel mixture, your O2 sensor is responsible for that, and since it's tripping the code change that out.
 
#30 ·
IIRC you will always get a 21 with the key off. So I would look at the other one first.
 
#31 ·
asghilo said:
SupATro.0pA said:
I'm getting two codes: 21 and 44.

According to this website, http://www.troublecodes.net/isuzu/rodeo-3-2l-stylus-1-61-8l-trooper-3-2l-1991-1995/:
21 = Throttle position (TP) sensor - signal voltage
44 = Heated oxygen sensor (H02S)/oxygen -sensor (02S) - signal - mixture lean

I tested the TPS, and although the results says it's fine, maybe a new one instead of a salvage yard one will do the trick.

We'll see what a fresh fuel filter does for the fuel mixture.
a fuel filter won't do anything for your fuel mixture, your O2 sensor is responsible for that, and since it's tripping the code change that out.
You were dead on the money. :D

I was poking around and found this on the forums http://www.planetisuzoo.com/viewtopic.php?f=4&t=67027 Disconnected my O2 sensor, and it's like I actually have a functional vehicle. It still wants to stall when I throw it into neutral when approaching a stop sign, but I've got my loss of power issue figured out. Off to buy a O2 sensor.
 
#32 ·
By disconnecting your o2 sensor you basically forced the computer into the wide open throttle map. When using that map it ignores the o2 and a couple other sensors. Basically it runs rich to get maximum power. That would cause the engine to run correctly if you're getting a lean code. You may want to actually figure out why you have a lean code. It's extremely rare that an o2 code means you have bad sensor.
 
#33 ·
nasty610 said:
By disconnecting your o2 sensor you basically forced the computer into the wide open throttle map. When using that map it ignores the o2 and a couple other sensors. Basically it runs rich to get maximum power. That would cause the engine to run correctly if you're getting a lean code. You may want to actually figure out why you have a lean code. It's extremely rare that an o2 code means you have bad sensor.
nasty610, in your experience, what have you seen as the most common cause of a lean code?
 
#34 ·
Usually a vacuum leak somewhere. If you can smoke the engine through the intake pipe. I use a machine at work to do it so you may need to get creative. Check YouTube, I'm sure someone has come up with a good way to do it without a dedicated machine.
 
#35 ·
hmmm. I replaced all but one vacuum line, but it may be worth looking into again. Thanks for the advice!
 
#36 ·
There's more then just vacuum lines that can leak. That's why I suggested smoking the engine through the intake boot. Intake manifold gaskets are a common fail point on these engines.
 
#37 ·
It's been a while. Here's an update on this project:

  • New Radiator Installed, no more cold spots[/*]
  • New O2 Sensor + New Iridium Spark plugs resolved the power loss issue[/*]
  • New Water Pump and Timing Belt resolved water pump chirp[/*]
  • Removed the thermostat - boy does it hold cool now[/*]
  • New battery terminals solved an issue where I lost all electrical at a stop light (terrible/fun story)[/*]

The Trooper runs so much better. I didn't realize how anemic is was before. Just did a two hour round trip camping trip, and it ran like a champ...

Except that it had the heat up and sudden temp drop issue again at the end of the trip. There was no water vapor coming out of the pipe when I was running it just prior to the trip. I topped off the radiator, ran it again from cold, and for the first time, I'm seeing bubbles in the radiator. I ran a compression test a few months back, and had one showing low as well, but it held with a wet tests.

(One of my door locks broke as well preventing the door from unlocking, but this seems to be a known issue with a plastic clip breaking that I can resolve after dismembering the door)

SO...

I'm going to pull the heads shortly and see if there is any warping before I order my parts, but I'm considering just buying one of the kits that has new pistons, rings, gaskets, etc. for a rebuild. $300 and change doesn't seem too bad for a refreshed engine. I'm not sure I could find a good pick and pull engine for that much, because I'd still have to go back and check all of the same things out.

Is there anything squirrely that I should be watching out for in the rebuild? Any minor improvements that can be made on these 3.2s (that still let me pass CA smog)?
 
#38 ·
I did a block test and am tearing into the engine to look at the head gasket. Let's hope nothing is warped.

While I'm doing this, I noticed that my heater doesn't seem to work, and it looks like the line in has been cut. When I pulled off the intake manifold, I found the what looks like the bypass, where you connect a hose from the intake to the output spots on the engine. Could somebody confirm that this is what I'm looking at?

 
#39 ·
Welp, I've got the heads off now. There's lovely pools of coolant in three cylinders. Definitely going to change the head gaskets. I'm contemplating buying new pistons and bearings, but am not fully on board yet.

Here's some pictures.










 
#40 ·
Some quick notes on removing the heads:

  • Tightening the bolts before loosening them seemed to work.[/*]
  • There were 8 10mm allen head bolts and 3 6mm allen head bolts on each head[/*]
  • My 3/8th drive 6mm allen head socket could not reach the top 6mm allen head bolt enough to get good torque. I had to use a normal allen key with a pair of vice grips.[/*]
  • The cams have a groove that lines up with the head bolts for use with sockets and extenders.[/*]
 
#41 ·
I got sidetracked in late march due to travels.

I've starting tearing apart the heads, but ran into problems getting the bolt of the camshaft sprockets off. It looks like there should be a specialized tool for this, but I haven't found it online.

I'm going to send the heads to the shop to get cleaned up, and then make further decisions after that is complete. I snapped one of the star head exhaust bolts right at the star tip.





 
#42 ·
Quick update:

Pulled my heads. Got them to the shop, and all of the valves were bad. Shop gave me a very large quote. Looked around the local salvage yards and found a nice set of 1995 DOHC heads. Got them pulled and at the shop. Waiting on word, but they looked much nicer, no blown headgaskets.

Looking forward to a little more power. I'm going to ask the local shops about getting custom headers done too.
 
#46 ·
DOHC Heads Progress: Pulled from a donor in the yard, and back from the shop with new valves and some welding work.




 
#47 ·
I just pulled the heads off of my 95 Trooper's SOHC donor junkyard motor last night to prepare for the machine shop. I've never broke into an Isuzu engine before but it seemed to me, especially based on the tightening specs, that every bolt in that thing was over torqued. 3 out of 6 of the little allen head bolts that hold the camshaft had to be drilled out on each head. Has anyone found a source for these? All of my searching keeps returning head bolt kits (which I already have).
 
#49 ·
Well, it took about three different timings, but I have the heads on now and everything timed. Unfortunately it still doesn't pass ca smog. Was going to the muffler shop, and my power steering belt shredded along the way, tearing my alternator belt off as well. I muscled it home, and am now dealing with the consequences of me probably stripping the bolts putting the fan bolts on.

As for the heads.
I hand cleaned and scraped the top of the block as much as I could. Wasn't as clean as I thought, but it took about a week or two to get it that clean. The timing of the heads was something that I initially missed, and then had to come back and correct on both heads. I eventually taped nails on the top of the heads to get the marks to line up. The marks have the be parallel, but on opposite sides of the cogs.

Posting pictures below.
 
#51 ·
I started with a plastic razor because I didn't want to scratch the block.

By the end of it, I was using metal razors, dry sandpaper, wet sandpaper, brass wire brushes, and green scotch pads.

 
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