3.4 swap into 91 Trooper

[Canyonero]

I talked to my old man, he said not to worry about fixing his Trooper for now - but he'll share the profit from its sale if I do. He's looking for a used Toyota Tundra, one of us in the family should have a pickup anyway.

I'm charging forward with the swap on mine. Putting all the time I can spare into it. Would have drained my transfer case and tranny today and then dropped the drive shafts, but didn't have the right size socket (25mm I think?). Something to do on Wednesday evening I suppose. Instead, I'm mounting what bits I have removed from the 2.8 onto the 3.4. Looks to be filling out. Also rigged up the mounting brackets for my electric fan, turned out very nicely.

Would you happen to have a Trooper wiring diagram you could share? I just have the generic one in the Haynes manual. The Chiltons diagram for the Camaro 3.4L is much more detailed, hoping to get something like that for the Trooper.

[Ed_Mc.]

On the EGR, there's passages that start from the rear of the intake where the EGR valve is mounted, all the way up front to a hole on the floor of the intake just inside the flange where the throttle body mounts. The hole was carboned-up on my '89 Spacecab, such that when I manually actuated the EGR valve at idle, there was no change in idle quality. Finally found the clog at the TB and after unbolting and pulling the TB out of the way was able to clean it all out. I expect the lack of EGR probably led to the exhaust valves burning up before I purchased it. They were seriously cooked too!!

The surging idle you've noted could be caused by overheating, air in the system, or a defective VSV (vaccum switching valve) atop the thermostat body. It lets more air into the intake if the engine gets too hot, in order to make it run faster and cool things down. But sometimes they malfunction and cause the "galloping" idle or are merely symptomatic of other problems.

There's an idle speed/air bleed adjustment on the throttle body, it's on the firewall side of the TB and you just turn the slotted-head screw to adjust speed. Not easy to spot unless you know it's there and are looking for it!

G'luck.......ed

[Canyonero]

Thanks, that's some good info. My dad doesn't want to fix it again (or pay to fix it), but maybe I should take a swing at it using an OEM gasket.

What would be the symptoms of a non-functioning EGR? It had a "galloping" idle that the mechanic couldn't figure out how to get rid of. It always idled low for me since we got it back.

It took us four years to put that 7000 miles on. Doesn't get driven all that much.

Well, time to grab a backpack and ride to the grocery store in the pouring rain.

[Ed_Mc.]

On the 4-cyl, the aftermarket head gaskets don't seem to hold up as well. I used an Isuzu factory gasket on my '89 Spacecab 2.6 and have had no issues as yet.

A friend of mine picked up a cheap '89 Troop 2.6 with bad head. He then installed a Pro Topline new head (under $400 with valves from www.aluminumheads.com ) but used an aftermarket gasket. In less than 2K it blew out the compression ring on #3 cyl. He replaced that with a factory gasket and had no further problems.

Surface prep on the head is extremely critical as well. Note that the 2.6 doesn't have Torque-to-Yield head bolts and they don't necessarily have to be replaced unless the bolts are stripped out. But one thing that's often missed is the need to run a metric tap down all the head bolts holes in the block. Otherwise, the holes can be full of rust/crud and you get false torque readings.

Another thing that'll kill these motors is a non-functioning EGR. #2 and #3 cyl's have siamesed exhaust ports and tend to run the hottest. If the EGR is plugged up it's all the worse and sometimes will push things over the edge and cause a burnt valve or worse.

Cooling issues are also critical, some of the older Troops had a single-row radiator which isn't the way to go on these. Later ones had 2-row as did the GM V6 models and I can attest that an aftermarket 2-row is more than enough for even a 3.4.

One more thing, stock thermostat is 180 deg and if the mechanic put a hotter one in, it could contribute to a failure.

Last but not least, when you refill coolant you've got to 'burp' entrapped air out of the system, easiest done by pointing the rig up a hill such that the radiator neck is the high point in the system. Otherwise a pocket of air may cause overheating in the head and subsequent failure.

Anyway, bad timing on the 4-cyl's breakdown; hope things work out for ya..........ed

[Canyonero]

I'm keeping the SFI system on the 3.4L, so it's ready to drop in, but there will be a little wiring to do and I'm working on the assumption that the fuel pump I picked up from a MPI Trooper will have the pressure to drive the SFI system on the 3.4L (I have faith).

[geoffinbc]

Well if you already have everything disconnected then you got alot of progress. What condition is the 3.4L in? Is it fresh and ready to drop in witht he 2.8L stuff bolted on? Or do you still have prep work to do?

[Canyonero]

Well shoooot. I was borrowing my dad's Trooper assuming that if he needed it I would take it back to him and ride my motorcycle home (we live about 7 miles apart). Well, his Trooper blew it's head gasket on me yesterday. That means either we have a sucky mechanic, or that engine has some major problems - the head gasket was just replaced 7000 miles ago (at 89,000). The head was sent off to be tested and surfaced, so it should have been fine. Block possibly cracked/warped/damaged? (I should mention that this is the Isuzu 2.6L I4, not the GM 2.8L V6.)

So we're short two cars, and my dad's Trooper may not be worth fixing. Putting my Trooper back together as-is is an option, then go back to the engine swap when it warms up in the spring. OR, I could tough it out for another month on my bike until I have some cash to buy a cheap (sub-$1000) car to drive in the meantime. I found an '86 Trooper for $750, probably a 2.3L I4 with carb. But I can't afford even that just yet. But, we're talking later November and early December. I have good riding gear and don't mind the cold, rain is fine but I'm not touching my bike when there's risk of ice and snow. I don't want to give up on my engine swap and waste time reconnecting everything, but that looks like it might be the easiest thing to do right now.

[Canyonero]

Well that said, and considering my work area - I think I'll be better off dropping the tranny. Thanks for the input, hope to have some more time to mess with it this weekend.

[Ed_Mc.]

Unless you at minimum drop the front diff/axle assy, you may be able to get the engine out but won't be able to get it back in without damaging the fingers on the clutch pressure plate. It's that tight! I've done 2 rigs, however without pulling the tranny/xfer case assy so it can be done.

There a (2) big bolts per side that hold the front assy up to the frame rails; if you can get those bolts out (one of my Troops was easy, the other required lots of time with impact wrench and 110 psi!!), the diff/axle assy will drop down enough to for the oil pan to clear. Still a tight squeeze and one of those load levelers would be a welcome addition to the engine hoist.

And it's a lot easier to get at stuff underneath if you also pull the front driveshaft.

Gearwrenches come in handy in the tight spots; unbolt the motor mount brackets from the motor when putting the motor in/out. Having these brackets out allows a more favorable angle for removal/reinstall.

G'luck...........ed

P.S. I found it easier to pull the engine's wiring harness with, but don't forget that pesky long O2 sensor wire running in one continuous length from the engine harness on the pssgr's side, over the tranny, and down the driver's side, it's lots of fun to get it out of the wire clamps on top of the trans!!!

[geoffinbc]

No you don't but it is a hell of alot easier to line up the tranny to the engine versus doing it the other way around. But if you can make it happen go for it.

[Canyonero]

Do I really need to drop the driveshafts, transfer case and tranny to swap the engine? I really don't want to, but obviously I will if I have to. If I don't have to, then I'm pretty much ready to pull. I ended up ordering a chain hoist so I wouldn't feel rushed if I rented something. The hoist should arrive on Thursday, then it's just a matter of making the time.

Also, I'm moving into a house at the end of next month (apartment living for the last five years, I'll finally have a garage!) I'll need to divert some time into prepping for moving, so the Trooper project gets pushed back even further. I should have started this project in the spring...

[geoffinbc]

Sounds like my advertures with my swap.

[Canyonero]

FINALLY. I got gloriously greasy tearing my Trooper apart today. And might I also add, draining coolant is a real pain. I got that stuff EVERYWHERE. Still have to pull the heater, A/C and power steering lines - then we should be ready to rent the hoist for the swap next weekend.

[Canyonero]

So the troop sat around for a week since I commute on my motorcycle to save on gas.

Sounds like me. My Trooper still runs fine with the 2.8L, but frequently gets left behind in favor of the 60MPG Suzuki. Gettin' cold out there though.

I have a feeling that the source of your coolant in engine oil may be a leaking intake manifold. Not uncommon; the bolts will slack up which causes leakage, or the gaskets themselves deteriorate around the water passages in the heads.

Agreed! This is the only engine work I've ever had done on my Trooper. I had a nasty oil leak from my intake manifold for quite a while. After the engine was shut off, it would leak a fair bit of oil out the back and down the bell housing. Not while running, not when sitting, only right after it was shut off.

Concerning the valve covers. I thought they were they were almost the same, but you're right, the 3.4L has everything reversed. PCV on the left, oil fill on the right. Doesn't matter for me since I'm keeping all that as-is, but for the usual Trooper swap you might want to switch them.

[Ed_Mc.]

I have a feeling that the source of your coolant in engine oil may be a leaking intake manifold. Not uncommon; the bolts will slack up which causes leakage, or the gaskets themselves deteriorate around the water passages in the heads.

Either way, leaking coolant into the lifter valley and subsequent draining into the oil pan can cause the oil "milkshake" and besides very likely wreaking havoc with the lifters, coolant is Really Really Bad on the bearings. It'll eat up camshaft, rod and main bearings for dinner! That's what finally did in the motor in my $500 3.1 'Stroker' Trooper project. With over 240K on the clock, the gaskets had been leaking for a while and finally rotted away. The bearings were wiped bad, virtually no babbitt left on the shells and very low oil pressure (besides rod knock!).

Anyhow, if you plan on running the 2.8 for a while longer, it'd probably be a good idea to pull the intake manifold and reseal. Of course other sources of water into oil could be a leaking head gasket or cracked head, but you'd likely have other nasty problems like white smoke in the tailpipe, or fouled plugs/poor running.

In the absence of other indications, my money's on the intake leak and I'd fix it soon or you may be installing that 3.4 a bit prematurely!!

BTW, pulling the intake would give you a perfect opportunity to send it off the the Friendly Local machine shop to have the TBI holes enlarged to fit the larger throats of a 4.3 TBI. 'Course if you're time-limited you could have this done while you're actually in the swap. Just a thought. All you'll need to template the holes is a TBI base gasket from a '90 Chevy S-10 4.3 (many others will fit, just an easy one to tell the parts counter dude!).

HTH & G'luck with the motor...........ed