Hi!
I've just bought my first Jeep! It's a 2 door, black JK Sahara from 2009 with only 50000 miles on it. 3.8L V6 and 4-speed automatic.
Previous owner ran it pretty much dry on oil for some reason so i got a good deal on it. The engine is running but its knocking so i will rip it out and restore it if possible.
While im at it. What mods is a must when the engine is out of the car? Im thinking in terms of improving reliability and making it better and more reliable overall?

Thanks,
Jörgen from Sweden

 

While the 3.8L is out, drop an LS or hemi in it and you'll be set.

You'll be doing the typical lower intake manifold gasket in the process which is a typical issue for that 3.8L. Upper oil pan gasket is another one. I don't believe you have a tranny cooler from the factory, so you might add one. ​​​​​​

If you plan to keep that for a while and are successful in restoring the engine, you might either 1) replace the tranny pan with one that has a drain, or 2) drill that current pan and add a plug for easier servicing in the future (though that would be a long ways down the road before paying dividends considering you'd have fresh fluids in there after this).

 

All options are at the table i guess. What LS would be easiest to install and best for the money?

Good advice! Keep em coming! What are the week spots of this engine?

 

Weak spots of the 3.8 are only two;
1. Oil rings on the pistons are very narrow and after a while cause the engine to burn oil
2. Connecting rod to crankshaft bearings have a different design retaining key in them to prevent bearings from spinning. If oil gets too hot for some reason they can spin the bearings

The fix is to get forged pistons with standard 3/16" wide rings and new conrods with standard type bearing retainers. The rest of the engine is pretty stout. You could look into a different camshaft but need to seek advice on that from an engine specific knowledge source as with auto you sure don't want a lumpy cam. During engine reconfiguration cam timing offset can be advantageous for more bottom end but when you do that you lose upper power - no free ride here.
As far as V8's go they are ridiculously expensive to do a proper conversion and with a 2 door you may have an issue with real short driveshafts as the conversion usually moves the transfer case back about 3" with a Chev anyway. The new JL 8 speed auto and the later JK 5 speed will handle a 5.7 Hemi but still you need to take a long hard look inside your wallet to see if that's what you want. And buying a high mileage "cheap" engine does you no good as it may need a rebuild later. You are in Sweden - go get a 2.8 CRD / tranny and ECU and install it is my advice if you can find one.

 

So thats why they are burning oil, thanks!
When i bought the car i noticed how nice the engine ran just after it was started. After a little while like 10-15 seconds the knocking began. I thought it was going to be much worse. Ive seen a video on Youtube where a guy solves this problem with a new oil filter. Im gonna start there. Just have to find a good filter.

If i would have to change the pistons and rods. Do you know of a good kit? Quality/price?

 

There was a member on here that rebuilt his 3.8L, and was actually going to have to dig into it again. I've looked and looked for that thread as I can't recall the member and they aren't around here very often. I can just recall the avatar had a blue jeep and that he had noted the 3.8L was actually very easy to work on. Was going to try to find their ID so you could PM them and see if they have advice.....but no luck yet. I will keep looking.

 

The rods and piston upgrades used to be sold by 505Performance in the US. 505 Performance | 505 Performance

 

Is the 3.6 a direct replacement for the 3.8? It looks like 3.6 crate engines are relatively cheap.

 

My understanding is that is more effort than it is worth.

 

What Resharp said. The 3.8 and 3.6 mechanically fit either model but from there it is so different and one guy on here did it but he was a bit of a whiz kid then later he turns around and places a 392 Hemi in it.