This is my first post so if I put in the wrong place please just let me know and I apologize in advance for any inconvenience. I have read quite a few forums on the 0331 cracked head issue (including the Cherokee John forum). However, my particular question is how to determine if my lower end is trashed or not. Unfortunately I have a single stall garage with a non-running Vette in it and I live in the Mid West and temps are beginning to drop quickly so I am looking for the best way to determine if I can put a remanufactured head on it or if I need to replace the entire engine.

I have included pictures of the valve cover cap, coolant cap, dip stick, and a video of the bubbles coming from the crack (the camera comes in to focus about half way through). I have only owned the Jeep for a month and in that month the coolant level hasn't dropped drastically. After warm-up, the factory oil pressure gauge reads between 10-15 PSI and at speed it stays right at 40 PSI for the most part (yes, I know the digital factory gauge isn't accurate. After warm-up the engine also idles a little rough and just shy of 750 rpm. The engine stays right at 210 for temp although my heat never seems to work for long. Looking through the valve cover cap you can see some milky sludge. There is also some sludge on the bottom of the cap.

I know many people have posted to drop the oil pan and plastigauge the bearings but I don't have the space or the time at the moment. I'm not mechanically incompetent but I'm definitely no a mechanic so any help would be appreciated. Thanks.

 

This much you know; the head is cracked. As far as the bottom end of the engine, it's impossible for us to accurately "guess" the condition of the rest of your engine. A guess is truly all it would be; don't let anybody tell you any differently. The fact that you have only owned this XJ for 6 weeks is a bit of a wildcard as well. Cracks can be small or they can be large; I've seen both with the 0331. It's not impossible that this head had a small crack for some time now and it may have even been the reason the former owner decided to sell it.

Some testing of bearing clearances would help you diagnose this, and although this may not be something you want to do yourself, you may be able to pay a shop to do this for you for not a lot of coin. Might be money well spent.

I've seen this type of situation go both ways. Some slap a new beefed up Clearwater cylinder head on it and live happily ever after. Others slap a new head on it and then find that the engine is wounded enough to where they eventually have to open up their checkbook again for a rebuild, salvage yard engine, or a new engine. With the latter, they wish they would have gone all the way, right away.

40 is a bit low for oil pressure at highway speeds, but as you mentioned....there can be some inaccuracy between the sending unit and the dash gauge, so you might want to rent a "mechanical" oil pressure gauge from a parts store and get more data for starters.

Continuing to drive it though will create more damage to your engine. Factor that into your decision.

Good luck and keep us updated!