Help Getting To My Thermostat

[Oka]

Yeah, about that t-stat. You'll immediately note a down-tilt to the t-state housing once you get there. Given the position and holding everything in place while attaching, I've found it pretty easy for the outer wrapped t-stat gasket to move around in the housing channel and not allow the cover to fully seat. However you do it, just look for a thin concentric gap around the t-stat cover before you tighten everything down.

If you're serious about replacing the temp sensor, consider doing with a valve cover reseal if it's anywhere close to due.

I really appreciate all that info.
Cheers.

[ggleavitt]

1. CTS (Coolant Temperature Sensor) the same as IAT, and some hits identifies them as different items.
Volvo list this in parts catalog as CTS/IAT, maybe just a typo of sorts.
2. IAT being Intake Air Temperature. What's the difference(s)? Where is the IAT?
Sure there's an IAT in the MAF itself.
3. What would be the difference between the IAT and the sensor in the MAF?
None that I can tell, mistaken reference perhaps (see item 1).
4. Does this engine only has one belt? No timing belt?
Aux belt only with hydraulically damped tensioner, replacement interval 150k miles or 10 years. My opinion is 130k miles as there have been numerous reports of spun timing cover stud when the lower idler bearing finally wears out and binds. This engine (B8444S) has internal timing chain(s), you'll see some photos in the links below.
5. The alternator is way back and down there. How on earth can that be replaced if need be?
I've done two on the floor in my garage, it's just time consuming and requires a lot of different tools. See link https://www.swedespeed.com/threads/v8-a ... ht.375921/, it's mostly variations on the old Peng writeup but passenger side axle needs to come out to get the alternator removed and replaced. Genuine Bosch AL0821X if you replace, this is not an area to try and find the cheapest aftermarket part. Prices will vary for this part when core and shipping are factored in but make sure it's a genuine Bosch if you're not replacing with Volvo blue box.

For valve cover gaskets, quite a few folk here on MVS have done the work. Here's one of the original threads where VCG was done as part of a CB shaft replacement- viewtopic.php?p=491723 . I'm re-doing a valve cover seal job on my '06 to get to the front timing cover so that I can fix an unreasonable seep around the crankshaft and the exhaust side, something I should have done from the beginning. I've been posting on Swedespeed, here's one link- https://www.swedespeed.com/threads/v8-v ... nt.286873/ . I'll see about doing a write-up on this site when I perform the re-work. It's a labor intensive job. There's a thread initially started to categorize some of the "regular" V8 work here, was an approximation only and always open for suggestions- https://www.swedespeed.com/threads/stan ... 90.638488/

For every new V8 XC90 owner, I always suggest two things right off the bat:
*Sunroof drains (all models-not just V8), make sure they are not clogged and the little rubber elbow fitting that passes into the base of the A-pillar is attached solidly to the hose and the little drain on the end is clear and somewhat pliable. PN 30753148 (aka 9178983).
*Check the 3-way washer tee that's under the passenger side washer sprayer nozzle. See if the little cap a wiggle or moves at all. If it does, replace as soon as you can as you'll spray down right on top of the motor around the alternator when you wash your windshield. PN 31391513 (aka 9178895). 2-way on drivers side does not get affected by the heat as much as the 3-way but the PN is 9178897 if someone wanted to replace them both.

Very happy with this powerplant but does require some heat related cleanup at around 100-140k mile intervals.

edit 071624- alternator PN is AL0821X.

[Oka]

1. CTS (Coolant Temperature Sensor) the same as IAT, and some hits identifies them as different items.
Volvo list this in parts catalog as CTS/IAT, maybe just a typo of sorts.
2. IAT being Intake Air Temperature. What's the difference(s)? Where is the IAT?
Sure there's an IAT in the MAF itself.
3. What would be the difference between the IAT and the sensor in the MAF?
None that I can tell, mistaken reference perhaps (see item 1).
4. Does this engine only has one belt? No timing belt?
Aux belt only with hydraulically damped tensioner, replacement interval 150k miles or 10 years. My opinion is 130k miles as there have been numerous reports of spun timing cover stud when the lower idler bearing finally wears out and binds. This engine (B8444S) has internal timing chain(s), you'll see some photos in the links below.
5. The alternator is way back and down there. How on earth can that be replaced if need be?
I've done two on the floor in my garage, it's just time consuming and requires a lot of different tools. See link https://www.swedespeed.com/threads/v8-a ... ht.375921/, it's mostly variations on the old Peng writeup but passenger side axle needs to come out to get the alternator removed and replaced. Genuine Bosch AL821X if you replace, this is not an area to try and find the cheapest aftermarket part. Prices will vary for this part when core and shipping are factored in but make sure it's a genuine Bosch if you're not replacing with Volvo blue box.

For valve cover gaskets, quite a few folk here on MVS have done the work. Here's one of the original threads where VCG was done as part of a CB shaft replacement- https://www.matthewsvolvosite.com/forum ... p?p=491723 . I'm re-doing a valve cover seal job on my '06 to get to the front timing cover so that I can fix an unreasonable seep around the crankshaft and the exhaust side, something I should have done from the beginning. I've been posting on Swedespeed, here's one link- https://www.swedespeed.com/threads/v8-v ... nt.286873/ . I'll see about doing a write-up on this site when I perform the re-work. It's a labor intensive job. There's a thread initially started to categorize some of the "regular" V8 work here, was an approximation only and always open for suggestions- https://www.swedespeed.com/threads/stan ... 90.638488/

For every new V8 XC90 owner, I always suggest two things right off the bat:
*Sunroof drains (all models-not just V8), make sure they are not clogged and the little rubber elbow fitting that passes into the base of the A-pillar is attached solidly to the hose and the little drain on the end is clear and somewhat pliable. PN 30753148 (aka 9178983).
*Check the 3-way washer tee that's under the passenger side washer sprayer nozzle. See if the little cap a wiggle or moves at all. If it does, replace as soon as you can as you'll spray down right on top of the motor around the alternator when you wash your windshield. PN 31391513 (aka 9178895). 2-way on drivers side does not get affected by the heat as much as the 3-way but the PN is 9178897 if someone wanted to replace them both.

Very happy with this powerplant but does require some heat related cleanup at around 100-140k mile intervals.

Wow, quite a lot to digest’ in one sitting. I would have to go through your replies many times; but have to tag/bookmark it first.

Thank you for the time it took you to comprehensively explain all that. I whole heartedly appreciate it all.

Hopefully tomorrow, I’ll tackle flushing the coolant and changing the thermostat.

Stay safe enough!
Cheers

[ggleavitt]

Apologies for folks trying to read my last, I wanted to differentiate some items with italics and the entire last half showed all italics. Went back and forth with a text editor, can't figure out what I did wrong in the end.

More importantly though, a correction- the alternator is AL0821X. If you leave off the zero when you internet search, no alternators get returned.

Last but not least, here are a few photo links to help navigate around the motor when you're doing the work:
https://photos.app.goo.gl/biUK5fYifiYobj7g6
https://goo.gl/photos/tcLSKkYEp6KqkbaR9
https://photos.app.goo.gl/Ng9SwZYudUCFPryH8

[ggleavitt]

I did note a photo of the t-stat from the top and when everything is fully seated, there is no gap between cover and housing. This is after replacement:

B8444S T-Stat from top.JPG (65.17 KiB) Viewed 555 times

[Oka]

The issue of putting the key to position 2.
I had brought up this issue in the XC70 forum and was told it is not a big deal.
What do you think?

[ggleavitt]

The "book" way on reconnecting the battery is to have the key in POS II to allow all the vehicle modules to absorb the current in-rush when the primary power source (battery) is reconnected.

I personally think it's the safest way to reconnect but I'm sure I've forgotten a few times over the years to follow my own advice.

Have not read outright any threads on airbags going off but there must be a legitimate reason for the warning.

Good luck with your repair

[Oka]

The "book" way on reconnecting the battery is to have the key in POS II to allow all the vehicle modules to absorb the current in-rush when the primary power source (battery) is reconnected.

I personally think it's the safest way to reconnect but I'm sure I've forgotten a few times over the years to follow my own advice.

Have not read outright any threads on airbags going off but there must be a legitimate reason for the warning.

Good luck with your repair

I started putting the key in that position since it sounds more logical. As you mentioned, no one has complained about not doing as the book says.
Thanks.

[Oka]

Been so pissed. I drained the coolant, disconnected the hoses and the removed the upper bolt to the thermostat housing. The lower bolt was a pain to snap the tool to, even with all the articulated tools I have. I tried all I could, no show. How on earth can I remove this bottom bolt? I was surprised the two bolts are that small, compared to the ones in my 01 XC70, which is high strength, longer and thicker.

I had to strain the coolant and refill the system with it; did not want to use a newly mixed coolant.

Also, for the thermostat, it has a valve on the plate. Does it matter if this valve is at the top or bottom?

Cheers

[ggleavitt]

No idea on the bolt, someone can help with this one as you're right, it's not a high strength part like the hex screws on a good old 5 cylinder.

I believe the t-stat will only fit properly in one direction, you'll see once you have everything apart.