Failed 3.7 Engine Disassembly (2003) - Interesting Finds

Hi guys,

As some of you might now I blew my engine in April. This engine has been overheated a couple of times in the past, being driven hard almost 220.000 km and eventually failed me.

Back in 2022 it had dropped a valve seat and decided to take it to a rather shady shop for inspection. Heads where surfaced and it was up and running after almost 3 months sitting inside that shop.

Since I found an engine replacement, I decided to take apart my old engine for science and figure out what went wrong. Being doing that the last couple of days and I have found some very interesting things. Since I have not taken apart this engine again I wanted to share some things with you and let me know what's normal and what's not.

What I have noticed is that 3 cylinders (passenger side) where filled with water. That's the first weird thing.



The second even weirder is that the head gaskets seem to me from another engine / block and don't fit right.



Third and even crazier is that I found this blocking a water passage way


Not the lighter, but this small pebble. It was aluminum, which made even less sense.

These are all my findings for now - I ll keep you posted on the process.

Looks like it blew the head gasket again and fill the 3 cylinders with water, the aluminium lump is probably something the machine shop dropped in by accident when they were doing the valve seat.
The gaskets are odd, sometimes you find they don't have all the cooling holes cut out, allegedly a modification to adjust coolant flow but I've not seen a set that fit that badly!
Try a straight edge on the heads to see if they are warped.
And don't throw anything away, it can usually be refurbished and used again.

In my past experiences, the water usually leaks in when you pull the head anyway. Be sure to check the heads over very closely. I have seen little chunks come off the lifter casing or even the valve keepers when it drops a valve. Check the cylinder walls as well to ensure a chuck didn't bust off from that pebble! The gaskets do cover some water jacket holes, but I think it's designed that way. I have had the best luck using the Graphite gaskets, rather than the MLS. Just make sure you don't use anything on the graphite, like copper coat spray or something like that. I have had good luck with engine rebuild kits on Ebay. Be sure to have the machine shop give you the correct piston size, in case they have to bore it out.
Best of luck!

The whole engine got disassemblied and sent to a machine shop for inspection. Final verdict was that the engine was starved from oil.

Lots of debris in the oil pan and the pickup screen. The middle cylinders 3+4 where starved and both rods where stuck on the crankshaft. Damage was terminal and the block suffered a long crack on the oil feed of the crankshaft. Definitely not repairable - on it's way to the scrap yard.

The heads are definitely machinable and fixable, so I just got a spare set of heads.

Currently in the process of removing the crankshaft sensor ring just to keep it in stock. I definitely want to get a newer 3.7 and retrofit it on my Jeep someday.

Sorry to hear about your bad luck. You can always get a junkyard engine and rebuild it. Be careful what year you get as the heads change a little bit. I have had luck finding Liberty's on Craigslist, Facebook, junkyards and even city or police auctions. Best of luck!