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2001 AWD 5.7 Swap

52K views 228 replies 31 participants last post by  Big_kid 
#1 ·
Fist I want to thank all those who have posted various advise.

So I'm just about done with my 2001 AWD Astro LT swap to 5.7 Vortec. It's not a trivial amount of work but the other day I started it up and it purrs like a kitten :0) I had a bit of trouble that I initially attributed to not getting the distributor installed properly at tdc. Problem really was that after installing the v8 programmed computer, I had to have it "learn" the passlock code from the steering column. Who woulda thunk?

I'm going to elaborate over the next few days but wanted to point out a couple of things I had not read on previous posts. I was able to get a $200 Canton Racing 8qt pan to fit by beating it to submission to clear the front diff and cross tube with a reasonably heavy hammer. I don't have the part number on hand but I ordered it from Summit Racing and made sure it had a passenger side dipstick provision and was "4 x4". Again, beating it with a hammer a bit and packing three washers behind the tops of the JTR mounts to raise the motor just a tad gives me enough clearance (just). Also prevents the need for clearancing the frame around the RHS manifold (just).

I did all the work solo with no assistance really needed, just be VERY careful lifting the van up to pull the subframe. I could not get jackstands anywhere close to helping out and I ordered 12 Tonners just for the job. They would barely reach the running boards and were only really there for redundancy should my rigged-up supports fail. I ended up using two steel bars with the subframe mounting bolts to key 'em into the chassis and relied on biasing the load to the rear wheel chocks to support the van as I wheeled out the subframe. Kinda like an A-frame i s'pose.

Bleedin' transmission electrical connectors - arg. the primary one is glued- in, don;t try and pry it off the PRNDL switch like I did, the wsitch housing will break before the connector comes out. As I learned. doing it again, I'd either heat the connector and/ or lube it up with something non corrosive to plastic of course.

Wasn't expecting the oil filter housing to be such a pita. I wound up sourcing and pulling a oil filter adapter from a 96 impalla SS which fits like a glove and allows the re-use of the 4,3;s oil cooler lines just by removing the stud from the SS oil filter housing. V6 oil filter adapter will not work.

The motor I used was allegedly from a 30k mile 2002 Express 5.7 but I'm pretty sure it's a 96-98 L31 from a pickup. I replaced the intake gaskets which were already bad and the motor other wise seems fine. I put in the SEFI update (get the newer spider assy from amazon btw) and put in the newes GM intake gaskets which will outlast the rest of the van I'm sure. new plugs dist cap /rotor of course, orig ht leads seem fine so I am using them.

So how does it drive I hear you ask? Well it doesn't, well not yet. See, I was so focused on the mods, wiring, mounts, pan etc that when I pulled the V6 off the trans, I left the torque converter attached to the flexplate. Being an idiot, I assumed it would line up with the new trans if I lined up the dog-ears on the TC in the same orientation on the 5.7 as from the 4.3. Well let's say that wasn't my best idea ever. :banghead: Take a few mins and watch a torque convert installation procedure vid on you tube… 5 mins will save you a couple of days.

So after finishing up and getting the van running, installing my new 1" core radiator and dual flex-a-lite fans, routing the dipsticks etc, I dropped the van off the stands and fired 'er up for a ride. Alas no gears were to be had. I spent yesterday pulling the trans and am facing a $1,700 rebuild to fix the buggered up pump and various other worn-out bits. Turns out if I had not fluffed up the tc installation, it would have worked, but not for long. There are several components that were on their way out so there's that. Hopefully I'll get the trans back in the next couple of days and get it back in. Good Grief. Se word to the wise: I though I had taken grat care of my trans and after having it torn down I was close to losing reverse, and had various other worn parts. Do yourself a favor and at minimum have your transmission inspected while it's easy to pull from the subframe. Going through all the work to do the swap right and then to have to R&R the xmission is regrettable. Also, I was told it's best to use a V8 TC as they differ from the V6. My drivetrain has/ had 108K on it and maybe another 6 mos optimistically looking at the transmission parts this morning.

I could not unload my torsion bars by using the keys so had to pop the front ball joints etc to get enough travel from th lower control arms to unload the bars and slide em forward to drop the crossmember. Still, droping the trans is a lot less work than pulling the subframe agian....

Couple of other things, upper radiator hose needs a coupler to relieve some twist necessary to clear the brake reservoir, cruise control "clip" from the 4.3 will not fit the 5.7 so I'll need to rig something up for that. If anyone has a solution pls advise, my cruise control cable has the black plastic screw on it but the nub on the 5.7 lever/ cam thing on for cc on th throttle body is bigger than that on the 4.3, I tried drilling the plastic clip/ adapter thing out a bit but no-go.

I ordered A/C hose barbed couplers from eBay and got a few inches of A/C hose to extend my rear A/C hose to the compressor. I need to figure out an air leaner and will likely just chuck together something from the auto-parts store for now.

I had to extend the knock wire (singular -used the one from the V8) extend the water temp sensor wires (used the water temp and oil pressure sensors from the 4.3) other than that and the inevitable harness rework for the extra injector wires, wiring was pretty uneventful. I did pick up a relevant section of harness from a 4.3 blazer to avoid extra crimping etc. Also ordered a new v8 injector connector thing. BTW there are a lot of useful links on the S10 V8 sites to help with pinounts etc...

I used my stock y-pipe, and exhaust and got an o'rieley/ kragen passenger side manifold and the alignment is fine. If you are doing this swap on a newer AWD, get all Moog stuff ang replace anything that moves in the steering assembly while you have the subframe out. Also spring for new motor mount-mounts (the bits that bolt to the subframe with the rubber inserts), this will likely help with keeping your pan clear of the diff and cross tube.
 
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#4 ·
Nice job, and thanks for the details. Most swaps are with earlier vans due to emissions, so there isn't as much info on the later models. Also the tips & tricks to get it done will be appreciated by anyone who is doing the same swap.

Only a few posts and already eligible for the V-8 Swap Club!

Welcome to the site.

-Andrew
 
#9 ·
I pulled the intake on the motor and found some pitting where the original intake gaskets were failing. Put the new GM gaskets on after having the intake hot-tanked and cleaned up a bit.

I'm going to get another cruise control clip and see if I can get it to work, maybe I didn't try hard enough to get it installed. :think:

Has anyone else in California done a L31 swap and gotten through the DMV referee? I'm wondering what to do about an air filter/ cleaner box assembly. I picked up a cheap cone filter to attach to the MAF 'till SMOG time. Aparrently non-stock air cleaners need a CARB number. Not sure yet which air intake kits could work.

All of the other emissions stuff is on the v8 motor, just doesn't seem to be room for the Express intake box i picked up with the motor. Any suggestions?
 

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#10 ·
Just a quick thought in regards to the cruise control clip; check at the dealer, the cable on the cruise control assembly is replaceable and relatively cheap ($25-35) and by changing the cable you could get the correct length and clip to attach to the throttle cam. They all use the same cruise control module.
 
#11 ·
Went for a drive today!! Got the rebuilt transmission in and it works great! Motor is running rough though and throwing P1345 Cam / Crank timing off. I will try and borrow a scanner and see if I can set the timing. Apparently the distirbutor has to be in +/- 2 degs which is tough by eye-balling.

Anyway, it runs well enough to get around town :0)

Can't wait to get it running smoothly. Also need to do something to quiet down the intake noise. I'll take some pics tomorrow.
 
#12 ·
Oh boy. So transmission shifts great. Problem I have now is that the "30,000" mile 2002 motor I bought from Regions Auto in FL will not hold oil pressure. It would hold 40 idling while stationary when my transmission had issues and I could not drive it but now oil pressure it drops into the red as it warms up and under any load i.e. moving, there's a distinct knock which I suspect is a rod knock or spun bearing.

I had bought this motor from Regions and it's under the 90 day warranty but based on some recent searches and the fact it shipped from another yard. I will have to either pull it or perhaps see if I can drop the front diff and pan and have it fixed by a local shop. I'm now into this way over what I had intended to spend in $$ and time and still don't have wheels. Needless to say I'm not impressed with Regions I hope they will warranty this thing. I have new injector spider, plugs, thermostat, cap, rotor, oil filter housing etc.

I am tempted to sell/ donate/ trade it in as I have two small kids this project is burning serious time and energy. I also just dropped $1,700 on the transmission and spent so much energy trying to do this right. The van has

all Moog steering components, I mean ALL
new steering gear,
new starter
Rancho RS 8000 adjustable shocks,
torsion bar keys from overlandvans.com to correct saggy-front syndrome,
auto adjusting ride-rite air springs in the back,
Alpine 305sbt deck w/ amp and upgraded component speakers,
Factory LT trim w/ hitch,
Factory running boards,
Rear AC (new evap valve)
Rear Heat
Custom floor mat to cover middle seat mounts for the kids to have lots of room between rear seats and front.
Of course rebuilt trans and new TC from gearmaster, san jose, CA (check out their Yelp reviews)

I am off the road now as oil pressure is into red when it's warm and it's a matter of miles 'till it seizes. :0( I have been fixing her up over the past few years to be my long-term ride and I am quite upset.

I just can't think of another vehicle with the seating flexibity, internal space, AWD and 5000 lbs + towing capacity that I want to spend any money on.

Here's my question to you fine folk. Has anyone dropped the front drive assembly to then dropped the oil pan on their latte model AWD astro or Safari? If so, how long did it take? reason I am asking is if it is a bottom-end issue, I'm wondering if it's feasible to have a shop scope it out without having to R&R the motor. At this point though I'm seriously torn. I can get a new GM longblock for $2k or so R &R it over a couple of days. Then all I need to do is deal with the intake to get it through the CA SMOG.

Tell you what though, if I had my time again, I must say would have paid the dealer $1k they were looking for to replace the intake gasket…..
:feedback:
 
#13 ·
So after a week of vitriolic exchange with the wankers who sold me this motor, The have offered to send another next week. This one they assure me (again) is a 2002 from an Express. They will send me documentation on Monday and we'll see what it looks like. At this point i'm tempted to get a full refund and get a new longblock from GM.

In the mean time I have a bit more info for anyone else doing a similar swap in California. I borrowed a scanner from a friend and seems I need to install a second 02 sensor after the cat. The PCM is showing bank 2 0xygen sensor 2 inoperative. I'm going to need to get the fitting installed by a muffler shop next to the existing one and a section of harness from an Express presumably to wire it to the PCM. Also, scanner showed coolant temp at constant -40 even though the dash temp guage shows correctly. After a bit of research, I'm also going to need to wire up a coolant temp sensor around the thermostat assembly. apparently the L31 PCM does not use the 4.3's temp sensor wiring for emissions control. I'll see about getting the harness parts for the 02 sensor and front temp sensor installed I remove and replace the motor.

I'll keep you all posted...
 
#14 ·
Unless you are worried about the boogy man not seeing a second set of O2 sensors behind the cat, do what they did on mine, piggy back the signal from the post cat O2 that is there and pin it into the proper terminal in the PCM harness. The computer will see a post 02 sensor for "both", but they will read identical numbers when you put it on a scan tool. If the rear O2 ever fails, you'll just get the code saying both rear 02 sensors are out of range.

Really sucks about the motor though, sorry to hear about that. If you plan on using the van long term and can swing it, I'd look into the long block from GM and be done with it. You already have the clean intake and everything else, though I suppose you might have issues with Regions if you send them back a motor that isn't complete. Might be worth taking a short video of the motor running for proof. I dunno, it might be worth giving them a shot at another motor, but I'd probably have something to say about getting some kind of extra guarantee with the 2nd motor that if it fails prematurely ,that they are going to compensate you somehow. This kind of work isn't something you just "do", and they should do their best to ensure that you will have a solid motor this time around.
 
#15 ·
Before you assume the engine is a high mileage dud, pull the oil pan and check the crankshaft main thrust bearing. I bet it's wiped. If you ran it with the torque converter jammed against the flexplate, it put undue pressure on the bearing wearing it out and making your oil pressure fall off at idle. The bearing can be replaced without removing the crank. Just loosen the main cap bolts and leave the rods connected. Use something soft to roll the upper shell out. Good luck on your swap.
 
#16 ·
Thanks for the info. I spoke with th yard my motor came from and they guy there said the suburban was pretty badly wrecked and generally thrashed. Lifted blown trans etc.

I apparenlty have a brand new GM long block en route to me and am in the process of getting ready to do the swap again. I'm not messing around this time, going w/ new distributor, water pump etc for the long-run.

I got another vortec 4.3 harnesss so I can run another post-cat o2 sensor. I think what I'll do is mod an o2 extension harness to couple both harness connectors to the one post cat 02. Run it for a while and will likely have a custom y-pipe made up w/ two cats a la express van etc so I can legitimately run two post cat 02 sensors and stand a better chance of getting it through SMOG.

As far as the intake goes, I think I'm going to get a 4" Sprectre or the like CARB exempt intake and mod it carefully so it looks "stock" (not modified) as to fit in the limited space I have for an air cleaner.

Also going to wire up and use the coolant temp sensor by the thermostat so the PCM knows how hot the motor is.

Anyway ETA one week for the new long block and I'll be doing the swap likely next weekend or the next. I also ordered polyeurothane motor mount inserts to help keep the oil pan away from that front dif.

Will take more pics and post them. Hopefully second time's a charm :0)
 
#17 ·
The coolant sensor by the thermostat is the sensor that the PCM uses, the one on the side of the head is the temp sensor for the gauge. I don't think you get to do this mod without playing hell at some point or another. I hope your new motor is the cats meow for you.

I finally got my van straightened out ( wrong 02 sensors ) and then the water pump gasket decided to blow on the way to work one saturday...really? WHY?! Now I've got a little lean bank code fluttering about the edge of proper fuel trim. It was on for a week, went off today on a drive, then came back on.

With any luck, the weather will be nicer this week while I don't have to drive the van and I can pop under the doghouse and fiddle some more at my leisure instead of being forced to work on the van yet again. I hate not being able to do automotive work on MY TERMS.

Good luck though, I'm really looking forward to seeing your van completed. BTW, what did you have to do as far as the computer and the wiring?
 
#18 ·
Alrighty then, got a brand new GM longblock installed! Runs great!! Started first crank. Took three days, one to remove the existing motor, another to transfer the intake, flexplate etc and another to re-install. It's throwing p0300 and p0327 random misfires and low signal from the 5.7. knock sensor. I've read on various forums that I need to perform a crank relearn even though I'm not throwing that specific code.

Other issue is the Astro's PRND321 indicator is inoperative. Seems I need to splice the four wires from the transmission range switch into the 411 PCM. Thing is, the crank relearn needs the Park signal which it's not getting. I need to fix this before I can do the crank relearn and get that SEL lamp to stop blinking at me.

http://www.thirdgen.org/techboard/tpi/3 ... ns-18.html

Is a very useful link I found it invaluable while dealing with the wiring. I elected to bridge the pins for the two post-cat signals to deal with that - seems to work just fine!

:swerve:
 
#23 ·
:0) Well, I bought 12T jack stands, the tallest I could find and they were nowhere near tall enough. Turns out after lifting the body up with the hoist I was able to screw back in the center subframe bolts and use the two poles I have on my boat trailer to support the body. Biased a bit rearward naturally against the wheel chocks. I have it a good wiggle and was sound enough to complete the swap (twice).

Did some poking around today under the van to verify my 411 PCM is hooked up properly with no broken wires/ bad connections. Seems all fine. My current assessment of the PRNDL situation is that the instrument cluster must be different on an express as I pulled mins off and there are not enough wires to correspond to the PRND321, Fuel, coolant temp, oil pressure, volts etc. there must be some multiplexing going on. I have a couple of emails into PCM programmers to see if I can have my PCM sorted out. The 2002 Express program does not seem to like the astro's PRNDL display. Without the computer seeing Park, I can't to my crank re-learn 
 
#24 ·
Here is the 411 PCM wiring for the 2001 Savanna which is the same as the Express , just a GMC , I can get the Instrument panel wiring if needed , if you don't see any help in these , If you find a library with the Michell Repair Manuals , the relearn process is in them ,
 
#25 ·
I got the PRNDL solution for you...did it on my Astro...easier than you could possibly imagine. Behind the battery is the connector that runs your PRNDL wiring to the Dash cluster, you can tap into it right there like I did on mine. Do the crank relearn, but more importantly, get the CMP retard set on the distributor. You'll need a scantool to do it, but it will eliminate most of your misfire problems, if not all of them ( it should unless you have something like vacuum leak, etc ).
 
#26 ·
Thanks for the tips guys!!

Turns out my 01 astro was factory wired with the trans range switch wires all correctly going from the switch to the PCM red and blue connectors per the 2002 express pinouts i've seen. The wht gry blk/wht and yel wires were already in the correct pins at the PCM. I've not come accross the wiring for the instument cluster, I searched a lot today but ony found what I think is the pinout for the previous gen Astro instument panel.

I'm trying to understand how the PRNDL display works. Are there wires that i'd splice from this connector behind the battery to the PRNDL leads, or from the connector to the instument panel? I'm just trying to understand how the PRNDL display function differs between the astro and savana, can't seem to get my head around it.

Thanks for the help!! :cool:
 
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