Okay, so I do not have an Aurora, but my 97 Cadillac STS uses the same water pump and thermostat setup (through my research at least.)

When I got back from vacation, coolant was leaking from the water outlet gasket, so that needs to be replaced. Why I did not do this when replacing the hoses 4 months ago, I do not know.

Any tips, tricks, or recommendations to doing this? The service manual just says to disassemble, replace thermostat and gasket, and reassemble. Who needed the manual? Bolt specs maybe

Sounds too easy. Oreillys also has the parts in stock, too, for under 15 bucks. The dealer would prolly want 200+ for parts & labor.

The engine is starting to leak oil between the trans and engine now, so perhaps the car's days are numbered.

 

I just drained the coolant and removed the thermostat housing and changed the thermostat and reassembled...voila... it might help to remove the air filter to give yourself a little more room to piroette...

 

Had the same problem on the Northstar in my Allante. Mine had a factory plastic outlet housing that had cracked. I swapped it for a metal one from a later model N*. Problem solved.

 

Ya, unbolt the air cleaner/computer housing. No need to unplug the wires, just lay it across the intake area. Then the thermostat housing is right there. Get used to taking that 4.6 apart, it's only a matter of time before you are dropping the cradle because of blown head gaskets. In that hell right now with a 98 eldorado with 85K.

 

Thanks - thats what I thought - it just sounded too straightforward.
removing the air cleaner on the Caddy is a 'must'...

I was hoping not to hear that... Is this a common issue?? Is it preventable?
When that happens it will be up for sale as a mechanics special. Hopefully a TX hail storm will get ahold of it before then.
I do not plan to work on it, as it is next to impossible with my tools and skillset. Not worth the $$ for a shop to do it either. I will be looking for another OLD car to replace it.

 

Unfortunately the 4.0 and 4.6 northstars are plagued with undersized head bolts with not enough thread going into the aluminum block. So they pull right out of the block - the the head gasket goes. The failure rate is incredible. Google "northstar head gasket" and you'll see there are entire web sites devoted to guys talking about how to replace gaskets and install threaded inserts into the block. Dealers get about $3500 to do the job.... I'm about 15 hours into mine and about 8 hours left to go. 1st time for me, but I bought the car cheap knowing it needed to be done.

 

So I plan to replace the thermostat and gasket this coming Friday, since I am off and it was leaking about 2 cups a day.
NOW it has stopped leaking for the past 2 days! WTH?? Maybe the GM recommended ground-up walnut shells are doing their job. I guess the gasket needs to be changed regardless...

 

So I got this thing changed tonight.
Getting to it and pulling air cleaner was easy.
Draining coolant is a pain due to the placement of the drain valve.
After draining about half a gallon, I slowly pulled the hose from the t-stat housing. No coolant came out so i guess I had enough drained.

I start loosening the housing bolts, some more coolant pours out and I let it drain until it almost stopped. I removed the top bolt and put it aside. I loosened the bottom more and right before I got it off, a sudden gush of coolant sent tools and parts everywhere...
I did not know the t-stat would have been stuck in there like that, trapping another half gallon of coolant in the block...

I had caught the t-stat housing and put it aside. The telltale "sploosh" meant something had made it into the pan full o' coolant below; it was the socket & extention. The old t-stat was lodged between the frame rail and the rubber bottom cover - it was extracted from below. The old gasket actually made it to the ground; its failure was very evident. The bottom housing bolt - uh - was nowhere to be found...

After an hour of searching, I said the heck with the lost bolt and pulled another suitable one from the engine. It had plenty more to spare... I will get a replacement from the bone yard next time I go. I do not have ANY metric spare bolts.

Reassembly was not a problem and I got it all back together with no leaks. It almost started to overheat at first, but after it was burped, temp went back to normal.

The thermostat has one seal already on it. This seals the water outlet also and no other gaskets are required. An extra cardboard water outlet gasket is listed at the parts store, but it was not needed.

So if not for the one hour bolt hunt, this would have been a one hour job.
Glad it is done.

Of course since Murphy likes me, I bet that bolt I scavenged was the "little bolt that holds the whole @*&! thing together".

 

For what car?
My tale above was from my 97 Caddy - the Aurora uses the same t-stat and would be similar to replace.

 

right,,tnx,,it really works..So I got this thing removed tonight.
Getting to it and pulling air cleaner was as easy as repairing my Ignition Wire Set..

 

Glad it went okay...
I finally found my missing bolt 5' away from where I was working a week later.
I put it back in the engine where I scavenged the one for the t-stat...