how hard to install older 5.3 in 07 Tahoe...

[marionso14]

I have a 2007 Tahoe with 230k miles. Its burning oil so bad that it looks like a skeeter truck driving around. Mechanic suggests installing used 5.3 from previous body style to avoid the AFM crap in these motors... (which i have had issues with ugh)

Has anyone ever done this? The motors are way cheaper (looking between 03-06 models)

My mechanic has computer to delete the afm program from my ecu, would there be much else to do to make this work? Im under the assumption that the blocks are pretty much the same

any insight on this?

 

[iamdub]

Not worth it, IMO. I had a 31,000-mile LQ9 from an '03 Escalade that I had mildly built up for an S10. I sold the S10 and bought an '08 Tahoe. Rather than invest in hopping up the 147,000-mile 5.3, I wanted to swap in the LQ9 since I already had it. After weighing all options, it was just too much work and not worth it.

The Gen3 motor has sensors in different locations than the Gen4, but this is relatively easily resolved. The kicker is that the Gen4 uses a 58x reluctor wheel on the crankshaft instead of a 24x like the Gen3. If you were to go the other way and put a Gen4 motor in a Gen3 platform, you could use a signal converter made by Lingenfelter. BUT, this converter box has been known to have a lot of reliability issues. Even when it's working normally, the crank time when starting the engine is longer.

I agree with ditching AFM. You could get a Gen3 motor, remove the crankshaft and have the reluctor wheel replaced with a 58x wheel, then perform the rest of the modifications to make it work. Or, you can get a Gen4 that should be plug-and-play and just swap the cam and lifters before you drop it in. I'd much rather pull heads and a cam than a crankshaft! Another benefit to this is that you can get a performance cam for more power while you're at it. Have an appropriate tune performed (more power to be had here as well) and you'd have a stronger motor with AFM mechanically and electronically deleted that will be a direct-replacement for your Tahoe.

 

[retiredsparky]

If you search on the internet, there are many sources for new, used, or rebuilt GM V-8 engines. Many of the companies have been doing it for years. It is often cheaper to send your old engine in as a core, they send you back a good one. Assembly line rebuilding at a quality oriented facility can be less costly than having a local mechanic do it. And you can be assured that they know all about the AFM engines and know how to eliminate the system.

They also don't use the "706" aluminum Castech heads which are prone to cracking at the head bolts, resulting in engine coolant mixing with lube oil. Google Castech heads for more illuminating information. I don't know when GM stopped having head problems.

 

[marionso14]

Im looking at $1600 to get used Gen3 motor with installation... I am on a TIGHT budget so im going cheapest route possible. A used Gen4 motor will cost me at least 3k around here. this is with around 100k miles.

 

[iamdub]

I totally understand a tight budget. But, regardless if this motor is $1,600 or $16, incompatible is incompatible. Have the mechanic give you a price on swapping the reluctor wheel. Of course, any good mechanic would want to replace the bearings since the entire rotating assembly will be disassembled. Then it'll essentially turn into a short block rebuild, minus the piston rings, cam bearings, etc. If the mechanic doesn't know about the reluctor wheel difference or the other extra modifications needed to make the motor work in your truck, then that mechanic is not the one for the job. Where is "around here"? Are you in the U.S.? There are plenty of 50,000 to 75,000-mile Gen4 5.3 motors from yards all over the country on car-part.com for $2,000 +/-.

 

[marionso14]

This mechanic nor any around here have done this particular swap. He told me that he has not done one and would be using me as a Guinea pig... that doesnt make me feel comfortable but if thats all i can afford... but at same time i also want a working motor lol.... The whole reason I brought it in is because it is burining lots of oil and pouring white smoke from tail pipe...

 

[iamdub]

But at least it's still a running truck, which is more than can be said if you try to run a Gen3 motor with Gen4 equipment. Again- check car-part.com. Get a Gen4 motor within your budget, change the cam and lifters, delete the AFM from the tune and be done. Or, if you insist on getting a Gen3 because the initial cost is cheaper, get one and dump a couple grand into it to make it work. If paying this mechanic to attempt to do what you've already been told won't work is "all you can afford", then you SURELY can't afford to pay another mechanic to do what WILL work afterwards.

 

[marionso14]

I see what you're saying. Thanks a lot!

 

[marionso14]

I see what you're saying. Thanks a lot!

I'm also debating on tearing down current motor and fixing it if possible. Have no idea on how feasible that is though

 

[iamdub]

If it's torn down to have the piston rings replaced, it's essentially gonna be a rebuild. No one in their right mind would tear down a 230K-mile motor to replace ONLY the rings to try to solve an oil burning issue. This means honing or boring the cylinders, replacing the piston rings and maybe piston as well, new bearings all around, etc. Of course, at this time is when you'd replace the cam and lifters with standard ones (non-AFM). Even if rebuilt, it's still a 230K-mile block and it's at the mercy of whomever does the work and their knowledge, skill, expertise, etc. I have no faith in the mechanic you've mentioned based on him telling you he can swap in an older motor and then you'd be a guinea pig. Can you afford to let someone use your truck as a learning experiment? From this thread, you already know more about the swap you mentioned than he does and that it's not as easy as he thinks. I'm not bashing him, just pointing out that this is something beyond his knowledge. I still believe the cost of rebuilding your current motor would be more than a "low" mileage direct-replacement motor from a salvage yard. I'd trust a motor that was assembled in a GM factory way before one that was dug in to unless I knew of the person's previous pertinent experience. A relatively low-mile Gen4 motor can be had for around $2,000, plus or minus a few hundred and regular lifters and regular cam can be had for a few hundred more. An experienced mechanic could get up early, swap the cam while the motor is sitting on a pallet in a couple of hours (including coffee/smoke breaks), swap the motor into your truck, tune out the AFM and you can drive it home that night and be good to go for another 200K miles.