2004 XC90 T6 Broken Thermostat Nipple Upgrade

[RickHaleParker]

The threads are metric standard. I think the pitch is 1.5 ... might be 1.25.

[songzunhuang]

Were you trying to use a "replacement" OEM-like solution or were you going to completely upgrade using brass like I did? If going for the complete upgrade, then the threads are standard pipe threads. If you use the solution I posted (lots of pictures included), all parts are available at your local hardware store. I have never had a problem with this connection since the update...

[SuperHerman]

See here viewtopic.php?f=10&t=82172&p=445780&hilit=uro#p445780 on how I made the URO nipple function. Over 20k miles on this fix and no issues. I actually think it is an excellent solution - more robust than the original.

[thomascushman]

I upgraded using brass. I tapped the housing out to 1/8 inch standard pipe thread and built it out similar to yours. All is well. My next issue is the darn engine mount. Forgive me if I need to start another thread. But all the videos and explanations I've seen do not show the size flywheel that I have. MY flywheel covers the bolt in the highest position on the engine mount and I cannot get a wrench on it. It appears I need to pull the flywheel just to access the remaining bolt on the mount? I can loosen the lower one, but cannot remove it due to the distance between it and the flywheel but I figured once the mount is a little loose, I can swing it back just far enough and the bolt will come out and the the second as well. But it looks like the flywheel needs to come off... sounds crazy to me? Is there a small secret I am missing?

[songzunhuang]

I am happy to report that this fix is in fact, permanent. It's been over 5 years since this original post and I have never had another problem with a coolant leak at this juncture.

I did recently replace the coolant expansion tank, which had developed a crack. The XC90 continues to serve us well with only regular maintenance and a recent rear wheel bearing replacement. We still love this car.

[RickHaleParker]

It's been over 5 years since this original post and I have never had another problem with a coolant leak at this juncture.

I have not worked out details
1. Find a low pressure point in the coolant system .
2. Tap that point, and connect to the coolant reservoir.
3. Uninstall nipple from Thermostat housing and plug off hole.
4. Plug hole in timing cover.
If we can pull this off, no more hassle getting the timing cover over the nipple and the timing cover will be water tight.

[abscate]

Are there good part numbers to which to index this thread??

[RickHaleParker]

Are there good part numbers to which to index this thread??

The nipple has no Volvo part number. You buy the whole Thermostat housing from Volvo.

I could list the ÜRO part number but that would not be a good part number.

[leoxdeng]

I'm so glad the OP took the trouble to post this super helpful guide. My 2004 XC90 T6 is not due for a timing belt job till 2024 (10 yrs from the last change in 2014), but it's now got a tiny coolant leak inside the timing cover area - either thermostat or the water pump I'd speculate. So I'm going to bring forward the timing belt job and change water pump at the same time. Thanks to the OP I bought all the brass fittings and 1/8 BSP tap and 8.4mm drill bit to go with it - just in case! I previously bought the URO alum nipple but after reading all the negative experiences I sold it off and went for brass fittings.

One question I have is - where is the easiest place to drain coolant? I've previously drained from the radiator drain plug and it was a pain to remove/install the skid plate to access the drain plug. I remember seeing a black plastic 'drain plug looking thing' next to the oil cooler - wonder if anyone has used it to drain coolant before? I've read you can just disconnect the lower hose from the oil cooler to drain coolant, but I'd prefer a less messy method if the aforementioned drain plug near the oil cooler can indeed be used instead.

Many thanks
Namo Amituofo

[songzunhuang]

Namo, I'd take off the skid plate. It'll be less messy in the long run. It's not hard to get under the XC90 since it's got lots of ground clearance. Incidentally, I got an aftermarket skid plate when one of the mounting arms in the rear on my original broke off. It was about 1/3 the cost of an OEM Volvo part. It's not as sturdy, but it should be fine. In the picture below, the aftermarket part is the clean one.

OEM on left

xc90 skid plate.png (960.28 KiB) Viewed 1053 times

Good luck with the fix. Mine has held up extremely well. Car just flipped 159,261 miles on a recent ski trip. I made the upgrade at 101,638 miles back in March of 2015.