L59 fuel question

[osaltyone]

So I picked up my motor last weekend... It is a L59 from an 06 Tahoe. The guy at the salvage yard said it did not have the FlexFuel option, but the fuel rail has 2 lines. Is this normal? Do I run the 2nd line as a return if I am not doing FlexFuel?

Also there is a nylon tube with a quick disconnect on it. What is that used for?

Thinking I should pick up a book on the swap. Any recomendations?







Is there any way to get the # off the motor and track it back to a VIN? Just want to be sure I got the motor they gave me the VIN for. Verify mileage and all...

[83_shortwide]

I have the book GM LS-Series Engines: The Complete Swap Manual written by Joseph Potak. I dont know if it is any good, I have nothing to compare it too.

This book says "All oem engines are stamped with the last few digits of the VIN of the vehicle that the engine was installed in at the factory. Sometimes these numbers are useful if other identifying marks prove unreliable in engine identification.''

Looks like the numbers are on the drivers side, back corner of the block next to the flywheel.

[ls1nova71]

The black nylon line goes to the evap purge solenoid, you wont need it. Also, an 06 should be single line rail, either flex fuel or not. I belive the earlier flex fuels were double up to about 04 or 05.. might be worth checking to make sure they gave you the right engine. You'll need to run the return to the tank on a return style fuel rail.

Also if you got the PCM with it, it's got the VIN in it, but you'd have to power it up to read it.
Posted via Mobile Device

[ls1nova71]

Looks like it has a harness on it, it it hasn't been cut the harness will have a tag on it close to where the PCM plugs into it, and they have a build date for the harness. That should give you an idea on year.
Posted via Mobile Device

[osaltyone]

Thanks for all the replies!

Originally Posted by 83_shortwide

Looks like the numbers are on the drivers side, back corner of the block next to the flywheel.

The only numbers I can find on the back of the block and stamped are 12567398. Can't find anything on google and nothing close to the VIN I was given 1GNEK13T76R167608.

Originally Posted by ls1nova71

The black nylon line goes to the evap purge solenoid, you wont need it. Also, an 06 should be single line rail, either flex fuel or not. I belive the earlier flex fuels were double up to about 04 or 05.. might be worth checking to make sure they gave you the right engine. You'll need to run the return to the tank on a return style fuel rail.

Also if you got the PCM with it, it's got the VIN in it, but you'd have to power it up to read it.
Posted via Mobile Device

So if I wanted to stay emissions legal would that line run to a charcoal canister or the extra bung on the gas tank. Yea, I am thinking they might have done a swap on me or told me it was for a different vehicle. I just have to find a way to prove it.
I do have the PCM, just not sure how to power it up and read it. I plan to send it out for work. Guess they could get it at the time. The harness has no cuts (checked that before I left). It has the white label on it, but is faded and I can't read the info on it.

Originally Posted by nacho55

Does it have a cable throttle body or a drive by wire?? Your fuel rail and regulator looks identical to mine and its an 2002 motor, and they changed the regulator in 03 or 04 I think.
Posted via Mobile Device

It has a DBW throttle body the # on that is 1257080 RME75-.

Originally Posted by clinebarger

A Flex Fuel engine would have stainless fuel rails not plastic. ALL L59 engines are Flex Fuel, You have a LM7 (If its a 5.3L).

Trucks & SUVs went "returnless" in 04, I doubt thats a 06 Tahoe engine.

That is what I thought stainless. I did not want FlexFuel and the guy said it was the regular version of the L59; but the return was throwing me off since he said it was from an 06... I can run it back to the tank no problem as I have the return on my brothers tank.

[osaltyone]

Here are some of the other #'s I found on the engine.



Y3R298141 I believe

[ls1nova71]

Not all flex fuel engines have the metal fuel rail, '04's were plastic. Post a pic of your fuel injector, that would be the easiest way to tell.
Posted via Mobile Device

[nacho55]

Does it have a cable throttle body or a drive by wire?? Your fuel rail and regulator looks identical to mine and its an 2002 motor, and they changed the regulator in 03 or 04 I think.
Posted via Mobile Device

[Daaaanz67]

My 06 Tahoe motor is dbw with single fuel line but it's 4.8l
Posted via Mobile Device

[clinebarger]

A Flex Fuel engine would have stainless fuel rails not plastic. ALL L59 engines are Flex Fuel, You have a LM7 (If its a 5.3L).

Trucks & SUVs went "returnless" in 04, I doubt thats a 06 Tahoe engine.

[BR3W CITY]

Thats an 04-06 head casting (706) and those were actually the ones that were prone to failure (GM issued a TSB for it) for a 5.3l

With dual plastic rails and those heads, I'm saying its an 04 5.3L

[osaltyone]

I was thinking older too. wish I could prove it... going to try to do a compression test today. Moving forward with the install to make sure it runs in the warranty period.

[ls1nova71]

That's not a flex fuel injector. I'm guessing this is going to turn out to be an '03, an" 04 non flex would be a single line rail. Can you post a pic of the DBW throttle body? 2002 and older have two plugs.
Posted via Mobile Device

[osaltyone]

Here you go!

[gringoloco]

02 and older 5.3s weren't available with dbw, to my knowledge, this was an LQ9 only option in trucks before 03. I'm thinking 03, too, assuming these are original parts to this truck/engine...
Posted via Mobile Device

[usmcchevy]

You have a 03-04 LM7 there................or possibly even a LR4 (4.8)

[gringoloco]

Check the head gasket tab to verify displacement. It will be stamped with 4.8, 5.3, 6.0...

[osaltyone]

I can't see anything but black when I put the light in the spark plug hole. Spent a few hours putting the engine on the frame and ...

found this today

Is this is the tab you mentioned before?

Originally Posted by gringoloco

Check the head gasket tab to verify displacement. It will be stamped with 4.8, 5.3, 6.0...

I think I am going to call the guy tomorrow and talk to him. Things are not adding up. I will tell him I will be pulling the head to see if it is a 4.8 or 5.3. The computer came back as a 2006 tahoe with a 4.8 that was salvaged, which he says he just pulled off the shelf, and the vin he gave me was for a 2006 Tahoe, but the mileage did not match what he said. He said it was just under 58k and the vin says last reqistered in Ohio at 23k, nothing about a salvage.

[osaltyone]

Does this look like a windage tray from a truck that had 23 or 58k miles on it? Pulled the pan, windage and pickup to put a LS1 pan on.

[85burb]

On the back of the motor there should be 4.8 and 5.3 stamed in to it. There will be an paint mark one the displacement it is

[Jonboy]

I am pretty sure some '01's were avaliable with DBW. They do have 2 plugs on the TB, though.

[osaltyone]

What is the easiest way to tell that I don't have a 4.8? I can remove the heads if I don't have to. Not something I have done before, but can if I need to.

[usmcchevy]

Originally Posted by gringoloco

Check the head gasket tab to verify displacement. It will be stamped with 4.8, 5.3, 6.0...

Originally Posted by osaltyone

What is the easiest way to tell that I don't have a 4.8? I can remove the heads if I don't have to. Not something I have done before, but can if I need to.

There is a little tab sticking off the head gasket below the exhaust ports that will be stamped with displacement. Take a wire brush to it and hopefully you can read it.
Posted via Mobile Device

[ls1nova71]

Pretty sure that 4.8's and 5.3's use the same head gasket, so the tag doesn't always match. The easiest way to find out if it's a 4.8 or 5.3 is to pull the heads, but you can pull a spark plug and shine a flashlight in the hole to see if the top of the piston is flat or dished. Flat is 5.3, dished is 4.8.

[osaltyone]

Originally Posted by ls1nova71

Pretty sure that 4.8's and 5.3's use the same head gasket, so the tag doesn't always match. The easiest way to find out if it's a 4.8 or 5.3 is to pull the heads, but you can pull a spark plug and shine a flashlight in the hole to see if the top of the piston is flat or dished. Flat is 5.3, dished is 4.8.

So when I shine a light down the spark plug hole I am not seeing anything really. Do I need to spin the motor a bit to bring the piston down to the bottom of the stroke? Pulling the plugs I noticed the drivers side set of plugs were black and the pass were white chalky look to them. Throught that was a bit odd.
I am just a bit worried pulling the heads since I have not done it before. Seen it in videos and... well on TV. I have all the tools; just might have to do it. Can I reuse all the head bolts or do I need new ones if I pull them. I assume I would just be pulling the bolts, checking then putting everything back together, with new head gasket of course.

My PCM came back as a 4.8 from a 06 Tahoe...Makes me worried and I think I need to be absolutley sure.