08 780 D13 water pump and pump housing removal?

Anyone have any insight into this? We're looking at driving upstate and trying to remove all the junk in the way of the water pump and housing, taking both of these off, and replacing all the seals and gaskets involved because there is a huge catastrophic leak in this area. How difficult is this? How do we lessen tension on the belt, etc? The owner paid for some sort of service manual (turns out to be a collection of pdfs) but it looks like it omits anything about this job.

And does anyone know anything about a coolant filter in this general area?

This started as diesel in the coolant. Suspected water separator, so bypassed it since it's been warming up. (coolant lines serve to warm it, figured that might be where the mix was happening.) Flushed coolant system and days later had a liiittle bit of diesel in the coolant, which could just been pockets that didn't get flushed or something. Was a tiny amount, so we weren't worried.

Then on an overnight run the engine started bleeding water from the front right corner, turned out that the water pump housing was leaking like a sieve - add water to the overflow tank and it would immediately drain out of the water pump housing. Paid roughly $1000 in Atlanta to have the seals replaced. Mechanic/owner wouldn't/couldn't give part numbers for seals after the job was done, saying "Oh, these were just seals that Volvo had on hand." Well obviously, and if that were true, they'd have !@#$!@$ part numbers.

So at least it was holding water, but that didn't last. Two nights later it's leaking again from the same place, but the owner drove it hot (up to 260F oil temp, something I never would have done) and now the EGR cooler is leaking too. He bought a new one, so we have that, but the water pump housing is a problem since it was allegedly fixed once and started leaking again. There is also now a little bit of what might be oil in the coolant.

He saw a coolant filter in that area around the water pump in his new manual too, does anyone know anything about that? He's wondering if it could be clogged and creating back-pressure sufficient to blow gaskets/seals in the area.



Do these look familiar?

 

I should have mentioned cups is a suspicion but there are a lot of other areas it could be getting in, so he's a little unwilling to spend another $1500-$2000 minimum on cups when it might not be the cause. Thanks for the response, though.

Also I guess I wasn't clear - it doesn't really appear to be pumping much or any fuel into the coolant now, compared to how bad it was at first. If it was cups, that would be pretty constant, right?

 

I've spoken to two mechanics about inding out if it's cups, and they both said the only way to tell is to really do the job and see, which sounds like bs to me. Is there any inexpensive way to tell if the cups need to be replaced? And is there a compression test for coolant system or something?