1st Gen Engine Swaps

From Planetisuzoo Wiki

Replacing the 2.6L 4 cyl:

This is the hardest engine to swap out because the transmission bellhousing is unique to this engine. The GM 2.8L V6 has the common 60 deg GM bellhousing pattern so many GM engines will bolt up, but that is not the case with the 2.6L 4 cyl. If you have a 2.6L with manual trans, you'll need to replace that trans with one with the 2.8L V6 bolt pattern. If you have the 2.6L with automatic trans, you have the Aisin trans, and according to Jerry Lemond, you'll need to get the 2004 V6 Rodeo trans bellhousing (one year only deal) if you want to keep the Aisin trans (which is stronger than the GM 4L30). Or you can replace the Aisin trans with the GM 4L30 which will have the 60 deg V6 bolt pattern.

There is another difference between the 2.6 4-cyl trans and the 2.8 6-cyl trans: the input shaft diameter on the 4-cyl is larger than the 6-cyl's. Jerry L. said you could use a 4-cyl tranny in V6 application by switching front case/bellhousing assy and machining the V6 pilot bushing to fit the 4-cyl tran's input shaft.

Note also that if keeping the Aisin trans, you'll need to retain the wiring and computer controls for the Aisin along with the Throttle Pressure control cable. He notes this is not a kick down or upshift timing control cable as it controls only the line pressure and has to be connected to the TPS.

The is no difference between the 4 cyl and V6 engine frame mounts. Obviously, the wiring harness, engine computer, fuel lines, etc. are unique to the 4 cyl and would need to be replaced.

Replacing the 2.8L GM 6 cyl:

The easiest transplant is to use the 3.4L from the 93-95 GM F body (Camaro/Firebird) because it has the motor mounts in the right place, but the starter motor would have to be swapped to the other side, requiring some drilling and tapping for the starter bolts on the block. A jig is sold by http://www.rodneydickman.com/n101.html to do this. 2.8 engine mounting brackets and cushions are needed, and the oil pan is a must. Oil pan is the same as a 4x4 S10 with the 2.8L. Also, the 2.8L throttle body is a bit small for the 3.4L so most people use a throttle body from a 4.3L.

The 4.3 TBI conversion: changing out the TPS can be a little tricky. The problem is that if you have a generation 1 Trooper the connection from the Trooper won't fit the TPS on the 4.3L TBI. You need to replace the plug from the Trooper with a later round one. This means splicing the wires. Seems straight forward but it's not. The color codes on the wires from the Trooper vary alot so you can't trust them.

So, this is what you do: Take the 3 wires from the Trooper, forget the colors, except the black one, it's the ground. Take a DIGITAL Ohm meter and set it on DC volts. Turn the key on but don't start the car. Put the black probe on the black ground wire and the red probe to one of the 2 remaining wires. Test both wires until you find the wire with 5 volts. That wire is the constant. Remember that. Next turn the key off. Then switch the Omh meter to resistance, ground the black probe and touch the red probe to one of the wires coming from the TPS (not the black wire, that's the ground). While the two probes are attached open the throttle. If the resistance changes that is the sensor wire. It's probably blue but don't count on it. The other wire (probably grey) won't change when you do this and it is the reference wire. It splices to the 5 volt constant wire you found a momment ago. Black goes to black and the remaining wires go together. That's it. If you need to adjust the TPS with an Omh meter be sure to use a digital one. Varify that the throttle is closed. Turn the key on but don't start the car. Set the meter to DC volts. Put the black probe on the black wire and the red probe on the sensor wire. Meter should read .54 volts. Now prop the throttle full open. The meter should now read 4 to 5 volts. If you can't get these readings the TPS needs to be replaced, or, if you're like me you got the wires crossed when you did the splice.

For info about which oil pump to use in the 3.4L, see this link: http://forum.planetisuzoo.com/viewtopic.php?t=23846

Ed Mc. suggests to replace the 2.8L clutch with one out of a 3.1 4WD Rodeo or 3.1 4WD Pup. Note only the 4WD versions of these rigs have the correct clutch assembly. The 3.1L clutch is larger diameter and way better for use in a 3.4L compared to the stock 2.8L clutch.

The FWD 60 deg engines don't have motor mounts in the right place to match up to the Trooper mounts. Also, the Trooper TBI injection manifold won't fit with the FWD aluminum heads.

The motor mount bolt pattern on the GM 60 deg V6 block used in Troops/Rodeos/P'ups is somewhat different than the RWD block. The Trooper pattern looks like an upside-down triangle while the S-10 is an L shaped pattern. Each side uses 3 bolts on both vehicles. So when you swap in a RWD 3.4, only 2 of the 3 mounting holes on each side line up.

Red0ktober has used the SFI intake and kept the SFI system. He says the SFI intake makes a few things not fit. You have to use all the accessory brackets from the 3.4L, which means the alternator interferes with the battery (I moved mine to the back), and the AC compressor is a different style and located on the lower right (instead of upper left). Would need custom lines to hook it up. The intake/throttle body are too far forward; interferes with the mechanical fan and a 15" electric. I used dual 10" fans mounted lower, controlled from the 3.4L ECU. The ECU on the Camaro was mounted in the engine bay vs the center console on the Trooper. I met in the middle and sacrificed my glove box for the new ECU. The Trooper ECU is merely for engine functions, so that and the wiring can be completely removed. Cruise control, AC, A/T, etc have their own controllers. The tach will not take the input from the new ECU, need an MSD tach converter box in-line. Fuel lines come in on the opposite side of the engine bay, I just extended mine (not pretty, but it works). Speaking of fuel, the TBI system uses much lower fuel pressure than the SFI. The fuel pump needs changed. Luckily, the Isuzu 2.6L requires the same pressure, so you can just steal a pump from one of those. I wasn't sure if the pump itself was interchangable, so I just got the whole pickup assembly from another Trooper and dropped that in the tank. ALSO... the exhaust manifolds exit the same place, but with a different flange (the Camaro uses a flared end pipe vs the attached flange of the Trooper), plan on rebuilding the entire exhaust. OR possibly just drill and tap the Trooper manifolds to take O2 sensors and plug the air pump hole. The bosses for the O2 sensors are there. You'll at least want bigger cat-back exhaust though.

Hints for pulling/replacing the engine:

Ed Mc. says you'll also have to decide, when you're pulling the engine, whether to "peel" the wiring harness off the engine prior to pulling, or disconnecting at the plug and leaving on the motor. If the wiring harness is intact, it'd probably be easier to leave the harness in place. However, in doing that, you have one pesky wire from the O2 sensor which runs all the way from the sensor on the driver's side, up over the transmission, and directly into the engine harness. No disconnects in-between, so you have to undo at the O2 sensor then peel it back so it'll go out with the harness.

Under NO circumstances CUT this wire, it's specially shielded and virtually non-repairable!

Having done it both ways, he thinks the extra effort of undoing the sensor wire is worth it. Ed suggests peeling the wiring harness off the 2.8L and leaving it with the truck, and attaching it back onto the 3.4L. Saves a lot of hassle running wiring around the motor, and you'll really appreciate it when you get to the starter wiring!

With the manual trans, drop the front axle assembly -(4) bolts total, (2)per side hold the entire assembly to the frame. It'll drop down just enough to make enough room to clear the trans input shaft from the fingers of the clutch pressure plate without destroying the fingers. Conversely, you won't be able to get the engine mated back up to the tranny without ruining the clutch. Either that or drop the transmission first and put it back in after the engine is already in.

Jerry Lemond says you cannot pull/replace the engine/trans combo together, you need to put the engine in without the trans attached. There's not enough room to wiggle the oil pan around the front axle with the transfer case attached. With the 5 speed manual, the length makes it impossible, but with an automatic it could be done if you removed the transfer case first if the axle is dropped all the way down. He recommends dropping the engine down in front on top of the front axle and then pulling the trans off - this makes access to the top bellhousing bolts easier.

Good links to Trooper engine swaps:

http://myweb.cableone.net/bcanderson/trooper/AuroraSwap.html

Apparently this guy put a 4.3L in his '86 Trooper. http://myweb.cableone.net/bcanderson/swap.htm

I think he's mirroring this page from another swapper. http://myweb.cableone.net/bcanderson/trooper/Cadillac/cadillac.htm

2.8L to 3.4L swap writeup by 4xtoy: http://forum.planetisuzoo.com/viewtopic.php?t=17324