DIY: 2005 Volvo XC90 Thermostat + ECT without removing PS Pump

[oragex]

For the thermostat replacement, the 5 cylinder engines have a drain behind the block, barely visible from above, I believe it's a 13mm nut to undo it. Open the reservoir cap and it drains without splashing anything around right through an empty space behind the engine so no loss, it can be recovered entirely if no coolant flush is on menu. Once drained, the thermostat housing can be split open without any leak of coolant. Better go this way, otherwise the coolant will leak by the hose at the thermostat housing over the alternator, etc. Funny thing to note, the original Volvo thermostat has no burping pin on it, as the system will burp by itself when the engine will run - keep an eye on the reservoir because the level will drop when the thermostat will open. The level will drop again once the engine will cool down.

[cn90]

- In my experience fixing many cars, the engine drain plug is always a pain to undo (to drain coolant).
- The easiest approach is to loosen the LOWER radiator hose and drain from there. Don't even try the plastic petcock at the bottom of most radiators, chances you will break the brittle plastic.
- Once all done, just refill with the correct amount of distilled water + coolant.

[cn90]

- Re BRAND...

- WAHLER is now $110 for the whole assembly.

- I have seen FACET (Made in Italy) for $75. Anyone knows anything about FACET brand?

https://www.fcpeuro.com/products/volvo- ... y-31293699

[oragex]

Don't know facet but Beck & Arnley is decent quality for the thermostat itself, for the coolant sensor, I'd swap the old genuine original one (don't trust aftermarket ones)

[CrossBreed]

Any tips on removing the Coolant Temp Sensor? I can’t get a 19mm socket all the way in, and my McGyver attempts aren’t cutting it...

[oragex]

I think to remember a deep socket did the trick although barely grabbing it. Or maybe just destroy the plastic part with a pliers (one way ticket)

[cn90]

The key thing is using a chrome thin socket. Do NOT use Impact socket (too thick).

[mrbrian200]

Old thread I know. On a side note, I'm running a little experiment with the Gates TH35991 sourced from Europe. Gates updated the design on this thermostat, it now has a rubber seal that actually looks like a better way to do it (to me) than the OE thermostat's rubber seal that gets old and brittle, hence this seal cannot realistically be transferred (the older design Gates TH35991 well documented that it did not have this seal). I pulled a therm-housing off an '08 S60 2.5T at the pick and pull. Testing in a pot of water on the stove. The OE therm started opening the outlet side at 195F (which is correct), with the one passage on the 'back side' fully closing at around 208F. Initially with this new Gates therm these temperatures were off/higher by about 5 degrees F. But I think it has to do with the fingers on the rear that sit down in the bottom of the housing. It doesn't sit at the same position down there, I'm working with it/experimenting to see if I can get it to open/close at the correct temps. The kitchen is busy for the rest of the evening (somebody's makin deep dish PIZZA!). I'll see if the extremely minor/easy mod I just tried corrects the temperature difference or not. If it does I'll be back, possibly with a separate/dedicated thread. If it doesn't work I'll merely edit this to indicate that it didn't work.

EDIT. I determined what needs to be done in order to get the Gates thermostat to work properly in this particular thermostat housing. But it's more involved than I would consider ideal. And probably not something for a novice DIYer to attempt. I would recommend the average/novice DIYer bite the bullet and buy a new ready to bolt on thermostat/housing. I'll outline this 'procedure' I came up with into a doc within a week or so (with pictures I took) and and send it to Matt/Abscate to mull over before deciding whether or not we want this in the wild or not. I did note reviews attached to the listing for this thermostat where people with Turbo-petrol 5s pop it in without modification and say it works fine. But I doubt any of them tried connecting VIDA/OBD to monitor temps or bench tested on the stove like I did. They're probably all running a little hot. (hint, the 'pin' is about 1.17mm too short, but that's not the only thing that's needs to be dealt with)

[jxramos]

What are the dimensions of your T30 tools. It’s a tight spot for sure so that torx socket bit must be on the shorter end and it looks it. It looks low profile and has a 1/4 drive I take it. How tall is the bit when its socket end is resting on a table?

[jxramos]

Follow up question. What is the part number for the middle gasket, the one which sandwiches between the upper and lower housing. I’ve only seen the gaskets for sale which sit between the lower housing and the head of the engine. These are the following part “Volvo Thermostat Housing Gasket - Genuine Volvo 8636573”. So what is that middle gasket you include in the photos?