Chasing down a coolant leak on my 00’ XJ. It was leaking pretty significantly, almost a gallon a week.

I overheated it in July last time I wheeled it. I’m anxious about the 0331 head cracking issue so I pulled a junkyard TUPY head to swap, so I plan on killing two birds with one stone by fixing the coolant leak while the engine is apart.

I was looking at it last night, and I suspected the water pump again (replaced about a year ago) and I noticed that I have a loose bolt on the timing cover sticking out right behind the crankshaft pulley. It’s covered in crud so I can’t really tell exactly where it’s leaking from but I’m suspecting that if this bolt goes into a water jacket, it’s gotta be where my leak is coming from. I’m not familiar with all the water jacket locations on the 4.0, does anybody know for sure?

 

I don't think so.
When I did my water pump this past year I spotted what I am guessing is that same bolt too.
I thought it was a glob of grease until I touched it and realized it was a bolt.
Kinda freaked out for a second.
I did not feel any ridges from the bolt on the back of my harmonic balancer which made me feel better.
And I got to use some of those ignition wrenches that come with the Craftsman wrench sets so they can up the count.
You know you buy the 26 piece set but 10 of the wrenches are those ignition ones so in reality it is really only a 16 piece set. LOL.
Only thing I had that could get in there to tighten that bolt.
White circle is the bolt and the black is the oil pan bolt on the driver's side corner.
Just to give some perspective.
Sorry for the crappy shot.

 

There is only 1 bolt that is directly in contact with coolant and that's the #10 head bolt...most fwd on the drivers side. All the others are sealed....unless the person before you put in too long of a bolt and cracked the dome into the coolant chamber...This is a fairly simple fix but you need to drain the coolant...try to dry the suspect thread hole and bolt the best you can...put a good amount of Permatex hi temp high performance thread sealer in the thread hole and on the bolt threads and reinstall. If you can wait overnight to let it dry...great. It works on the headbolt and that's drilled directly into the coolant chamber...If you are not leaving a big puddle on the ground then its your head like all the other 331's..Is there froth in your valve cover when you take off the oil cap. When I changed my 01 head I used the Felpro Heavy Duty head gasket...I think its a bit thicker than some of the others .051 but it has lots of sealant and did not leak

 

Why is water coming from bolt holes on drivers side of valve cover bolts ??

 

Why, indeed. Got a pic?

 

does it look like a milkshake under your oil cap?