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Engine Modifications


Electric Fan Part I

Not long after buying my Trooper I ran into a problem with the stock engine driven fan. The fan has spit out the cage for the ball bearings causing it to seize to the shaft. This meant that is was spinning at engine speed all the time, killing my gas mileage. My solution was to install an aftermarket electric fan. When I did my S-10 the options were unlimited since there is a huge amount of space from the water pump to the radiator. The Trooper however, has only 3.5" to spare. After scouring the junkyards and coming up empty handed I was able to locate a Flex-A-Lite 110 low profile fan that was just 2 5/8" deep. So I picked up one from my local parts store and installed it to the radiator. I chose to use the through radiator mounting straps knowing they were not the best method of mounting but considering the light weight of the fan and the perimeter cushion on the fan I figured it would be ok to use. Had the fan been heavier I would have used a different method. To control the fan I used my own method and only used the wires provided in the Flex-A-Lite kit then discarded the rest of the kit. I got heavy duty relays from an S-10 in the junkyard as well as the mounting bracket. I then purchased a GM Cooling Fan switch to control the relays. There is also a manual over ride in the cab of the truck. The second relay is wired to the A/C clutch so the fan turns on with the A/C system. All the connections were made with weather pack connectors and solder.

Fiero Valve Covers

After the fan was installed there was still a problem with leaky valve covers. The leak was so bad there were little lakes forming on the intake manifold there was also oil running down the side of the block and dripping on the front axle and suspension making a horrible mess. I could have simply replaced the gaskets and straightened out the bent flanges on the valve covers. That would have solved the problem considering the previous owner had only used silicone and over tightened the valve covers. But I wanted something better. The solution was Fiero Valve covers. I had already done this same swap on my S-10 in the past with excellent results. So I found a couple sets on the internet, stripped them down to bare aluminum and painted them. I installed one set on the engine and kept the other as spares. The advantage to the Fiero valve covers is the rubber gasket and ridged cast aluminum construction. A K&N breather filter was added to the valve covers to help crank case breathing and keep any possible blow by out of the throttle body.


Remote Oil Filter

After the Valve covers were replaced and that leak had stopped I found another one. The oil cooler lines were leaking where the hose met the fitting and was crimped on. The previous owner tried to fix it with some hose clamps but that was a wasted effort. The leak was getting worse by the day. I could have ordered new lines but there was another problem bugging me. The oil filter sat sideways and was hard to reach for oil changes. So looking back at what I did with my S-10 I figured I would go the same route. I ordered a Canton racing remote oil filter adapter and a filter mount. These are serious parts and are of the best quality. There is no better way to do a remote filter. The cheep cast aluminum parts sold by Be Cool and Trans Dapt are not even a comparison. In order to get the remote filter adapter to the block I had to clearance the engine mount. The mount is made from cast iron and is very sturdy so a little grinding and cutting wasn't going to hurt it. Then turning to the filter mount I made a bracket from 3/16" aluminum and put a couple bends in it and mounted it to the fender where there was already bolt holes from the cooler lines I removed.

3.2L Engine Build

Well just over a year has gone by since I bought my Trooper. The original 2.8L had racked up well over 300,000kms. It lived a hard life. Evidence left behind by the last owner showed signs of oil leaks, poor maintenance low coolant levels and overheating. So I have to hand it to the engine for hanging in as long as it did. I had great success at stopping all the oil and coolant leaks. But even with no evidence of leaks on the floor I still lost coolant. I knew from experience that it was probably a cracked head due to overheating, or it could be a head gasket but these engines usually don’t suffer head gasket failure without underlying problems. The engine still ran great but as time went on I had to add coolant more and more frequently and a large white cloud came out of the tail pipe when I started the engine. I knew it was time for a new engine and I immediately tracked down a 91 Isuzu Rodeo with a 3.1L on craigslist and drove out with cash in hand and grabbed the complete engine and the ECM for $250. The race was on to replace my engine because by now I was adding a bottle of coolant every 2 days and sometimes I had to bump the engine over by hand with a socket because the #5 cylinder had water in it and the starter could not turn the engine over.

When I got the engine home I tore the donor engine down to the block. Before I sent it off to the machine shop I cleaned up all the casting flash in the lifter valley and front timing cover area. I also chamfered the oil passages in the block and on the rear main cap to help improve flow. The heads received the same attention and were gasket matched and bowl blended and the casting flash was removed to improve oil drain back. When I was done with all the pre machining work I sent it off to the machine shop for a .040 overbore with new pistons. All the bearings and rings were replaced and the deck was milled to help increase compression. The heads were also rebuilt with new valve guides, a valve grind, milling, new seals, springs, retainers and locks. I had the shop install the rotating assembly but I took care of the rest at home. When the engine was off at the machine shop I sand blasted all the accessory brackets, glass beaded the timing cover, and used baking soda to clean the throttle body and intake. The choice to go with baking soda on the intake and throttle body eliminated the risk of a piece of sand being stuck behind and getting into the engine during assembly or start up. After blasting the parts got a coat of semi gloss black.


When I got the engine back I gave the block and heads a coat of Chevy Orange paint and began the assembly. A new Comp Cams 252 cam was installed along with some 1.6:1 roller tip rockers and a new COMP timing set. When the block was at the shop I had a set of Small Block Chevy cam bearings installed which are wider than the stock bearings and offer a little more support for the cam. Next I installed the intake. The intake ports can stand to have about 3/16” of material removed from the port in order to be the same size as the openings in the head. So in order to get an accurate gasket match I installed it with a few dabs of RTV on the intake side and let it dry. The next day I removed the intake with the gaskets stuck to the manifold and was able to get an accurate outline for gasket matching. After the work with the carbide burr I reinstalled the intake with new gaskets. It cost me an extra $20 or so but it was worth it because it gave a very accurate outline. On this build I decided to go with a Camaro water pump like I did on my S-10 since it offers more clearance in front of the engine for an electric fan or any other device I may want to add later. I also did the same 4.3L throttle body modification on a bored out intake.


With the engine finished and ready to install I got some friends together and we pulled out the old motor and transmission. When the motor was out I used the extra room to do some cleaning and modify some wiring. I had to splice in a late model TPS plug since I went with a 4.3L throttle body with the later model TPS sensor. I also added a heated O2 sensor so I did the same modification as I did on my S-10. When the transmission was out I took the opportunity to add a vent to the transmission and extend the vent on the transfer case. More on this modification is in the drivetrain section. After all the pre installation work the engine was dropped in with the help of my friends and the transmission was muscled into place and the hard work was done. Over the next couple days I tied up the loose ends and it was all finished within a week. I could have done it faster but I took every opportunity to do some cleaning and improvements as I went along.

Electric Fan Part II

After the engine swap everything was working great. The only problem I had was heat control. I had the same issues with the old 2.8L. However the 2.8L had a lot of build up in the water jackets so I figured the 3.2L would be fine since the water jackets were clean. For the most part it was good. Driving on the road even in traffic was fine the old 12" electric fan was good. However off road in the heat was another story. Long hill climbs, on or off road, in the middle summer would make the temp gauge climb to the point I had to pull over and let it cool off. My solution was to increase the fan size to a 16" fan and now that I had the Camaro water pump it was easy to fit a bigger fan. I installed the fan right to the rad like last time. It fit tight top to bottom and worked very well. Cooling was improved and I never noticed any issues until I did another summer run this time in 30*C whether and climbed a hill into the mountains for a couple hours at about 1700m (5600 feet) and the temp started to climb again and I had to pull over. This was not such a big issue since I rarely make a climb like that. But a month later it happened again when I was towing a couple thousand pounds up a long 12% hill on the highway.

The temp never got above 3/4 on the gauge but it was obvious the fan was not cutting it. I was out of room for a bigger fan so my only solution was a shroud. I had a friend cut some sheet metal at his shop on his new HD Plasma table and bend it into shape on his brake. After that it was a simple install because the rad has built in brackets that were used to bolt on the shroud of the stock clutch fan. All I needed to do was take the rad out and lay the shroud on the rad and clamp it in place and drill four holes to mount the shroud and four holes to mount the fan on the shroud. A coat of flat back paint put the finishing touch on the install.

With the fan and shroud working great I was quite content with the cooling system everything was working great until one day the fan failed to come on and I has to use my manual override switch to turn the fan on. I suspected the temp switch screwed into the water jacket of the cylinder head. It was not even a year old so I was able to exchange it under warranty. About 8 months went by and it went out again. I changed it again with a different brand and this time it only lasted a few weeks. In my S-10 I was using the same method to control the fan and it was working fine for over 10 years. So maybe every manufacturer has shipped production over seas to a crappy facility or something but I could not risk having the fan not work the one time I am not paying attention to the gauge. So after reading good reviews on the Flex-A-Lite Pulse Width Modulation Fan Controller I decided it would be a good fit for my application. The controller reads temperature the same way the factory ECM does. I simply removed the old temp switch I was using and screwed in the sending unit. It sits at the rear of the passenger side cylinder head. The PWM controller then takes the reading from the sensor and turns the fan on at 60% when engine

temperature reaches the turn on setting. It will progressively speed up the fan to 100% if the engine temperature rises. The controller also has inputs for the A/C compressor and a manual switch.I chose to use the A/C and manual switch input. The A/C Clutch wire simply needs to hook up to the positive side of the A/C compressor clutch. Two wires were needed for the manual toggle switch in the cab You have the option to command the fan on 100%, leave it in auto mode or command it to stay off. I chose to only have the fan in auto mode or 100% on. Having the switch accidentally left in the off mode could cause an issue if someone was not aware of it. A few more connections are needed such as constant battery power, ignition power and a good ground. Flex-A-Lite includes an inline fuse for the main power wire that goes to the fan. However rather than running an external fuse I tapped into the power source that would be used for the power windows, which I don't have. This circuit is protected by a fusible link and I had been using it for power when I had my fans controlled by the temp switch and relays. I just had to run a new 10gauge wire right to the positive side of the controller. The other wire needed is an ignition power source which is located at a second pin beside the constant power source. With all the connections complete it was time to set the turn on temperature on the controller. I plugged in my laptop and used win ALDL to monitor the ECM and used the temperature is sees as the basis for my settings. I set the fan to come on at 208*F. So with the controller all set up I was happy once again.

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