Thanks for the responses so far. Based on those comments, I backed the bolt out and inspected; no signs of thread locking compound and no signs of galling or any other thread damage. Bolt is .375-16 x 4.25”, which is spec.

I noticed today that the bolt goes in smoothly until it hits the point in the OP, then gets much more difficult. Anything past that point and coolant seeps out in multiple places from behind the water pump.
Makes me think that it’s bottoming out on something early, perhaps a misalignment between the pump & timing cover and the block, which pries away the water pump just enough to cause it to leak.

I fully acknowledge that this theory may be an elbow-deep orifice extraction, but without experience in water pump replacement, it’s kinda where my mind is stuck.

Thoughts?

 

Thread it in as far as it wants to go. Then mark the bolt exposed. Remove it and measure how far it goes in. Get something thinner, like a pencil, and see how far THAT goes in. If it goes in farther, something has slipped and is stopping progress. If it bottoms out the same depth, you may have the wrong bolt you're trying to thread in.

 

Honestly I'm a bit baffled. Doesn't make a lot of sense.

That bolt sure looks long to me but due to my failing memory I can't say it's incorrect, esp if you were able to find specs for the timing cover bolts. That seems like one that should also pass thru the pump at the coolant passages

Did it back out hard? Do you remember?

 

I think that's it. The bolt is hitting the cover and prying the pump away. Might be in for a pump job.

 

Well AFAIK the bolt should only be threading into the block or the head (ie "the engine")

It shouldn't *thread* into the pump or the timing cover, merely pass through them. This is why I'm confused. If it's hitting the end of a blind hole it should just STOP, and there's really no way it should be able to act as a jackshaft and *pull* the timing cover away.

Clearly something is going on, we need someone really strong in these Magnums

 

Yeah, that makes more sense. I was having too many beers. Hmm, maybe there's just some coolant in the hole and the bolt is hitting a hydraulic resistance.

 

From the 1st photo that was posted, it looks like this bolt has something else other than the timing cover its going through. I suspect that the other bolts that's supporting this accessory need to also be loosened to help the bolt you're having trouble with get into better alignment, which should take some of the side load off of it and allow it to thread in more smoothly.

 

The pic shows no brackets so it may bottom out because of that. The long water pump bolts are up top by the water jacket(water that flows in/out of the pump). Put the pump and bracket back on and see if it tightens it down. Are you trying to run it without the ps pump?

 

Yeah I think that's an accessory bracket bolt? Every time I try to compare to another photo or video I just can't quite make it out because the angle of the photo in this thread is just wrong.

 

Now that I zoomed in i think you are right.