DIY: 1998 V70 Thermostat tips/tricks Topic is solved

[cn90]

Try this:

https://www.matthewsvolvosite.com/forums ... hp?t=50844

[cn90]

As mentioned in the beginning of this thread, many year ago, Volvo offered 88C, and 92C types.
Then they switched to 90C only, although you can go to rmeuropean dot com and buy the degrees you want.

I just did a search re 88C, 90C, 92C, and saw that Mahler recently offers 92C tstat: PN TX13-92D.
Has anyone here used this Mahle tstat?

PS: Just bought the Mahle tstat, will report back next week.

[shaker_chi]

I stripped mine and used my handy Irwin stripped bolt remover. I replaced mine with hex heads and haven't had any issues.

[MadeInJapan]

I did the same thing as shaker_chi but had to go buy the extractor set. It is A socket with pieces inside of it that Bite into the outer edge of the bolts. It worked well and now I have several different size ones that I will have for future issues of this nature.

Btw not mention here but how many of you replace the ECT sensor when they replace the thermostat? I had a time with aftermarket ECT sensors as they almost always gave false readings and made me think I was overheating on several different Volvos. It wasn't until I used actual Volvo branded ECTs that things cleared up.

[rspi]

Btw not mention here but how many of you replace the ECT sensor when they replace the thermostat? I had a time with aftermarket ECT sensors as they almost always gave false readings and made me think I was overheating on several different Volvos. It wasn't until I used actual Volvo branded ECTs that things cleared up.

I do not. If it ain't broke don't fix it. I put a new one in our S70 that went bad in 10 days. Installed an old one and it's been fine for 4-1/2 years.

[erikv11]

Btw not mention here but how many of you replace the ECT sensor when they replace the thermostat? I had a time with aftermarket ECT sensors as they almost always gave false readings and made me think I was overheating on several different Volvos. It wasn't until I used actual Volvo branded ECTs that things cleared up.

I do not. If it ain't broke don't fix it. I put a new one in our S70 that went bad in 10 days. Installed an old one and it's been fine for 4-1/2 years.

This sounds similar to what I'm doing. Although I don't see nearly the number of cars rspi does so don't have experience with bad ECTs. Anyway, I harvested some factory ECTs from the junkyard, I have about 4 of them now in the garage. I'm still waiting for one to go bad (happy to wait!) but if I do then I will replace it with one of those. It's useful for troubleshooting too, I've done a swap for that reason a couple times.

[cn90]

The funny thing is: back in 2012 when I replaced the Tstat, it went well for about 1 month, then the ECT went south (with all the symptoms well described in forum), new Volvo OEM ECT (about $50 or so) solved the problem.

The "newer" Volvos with 2.5T (such as 2004-2008 etc., with 2.5T engine), the tstat is sold as assembly for $100!
This includes: housing + tstat + ECT. Kind of a waste b/c Volvo does not want to sell them individually.
So, if only the tstat in 2.5T engine is bad, you are "forced" to buy the whole enchilada.

[cn90]

UPDATE:
- The Volvo OEM tstat (made by Wahler) was installed in July 2011, 5 years and 50K miles later, it is bad, cabin barely has any heat.
- Replaced with Mahle ($14 on line) 92C type. Heat is good again, even with today frigid temp of -10F!
The Mahle tstat is made in Germany.
- A few years ago, I used antiseize on the bolts, so removing is easy this time. So, always use antiseize on the bolts. You will thank yourself later.

[erikv11]

What went wrong with the old stat, did it break, can you see the problem? Just curious.

Of course the heat is good, your engine will always generate more than enough heat to overheat, even when it gets much cooler than -10.

[cn90]

What went wrong with the old stat, did it break, can you see the problem? Just curious.

Of course the heat is good, your engine will always generate more than enough heat to overheat, even when it gets much cooler than -10.

Cosmetically, the tstat looks good, no broken prongs, but I have replaced enough tstats in my life to know that old tstat can fail in 3 ways:
1. Tstat shut off completely ---> engine overheats.
2. Broken prongs: it is always open ---> engine cannot warm up properly.
3. Cosmetic good look (no broken prong) but the wax mechanism fails, allowing the tstat to open too soon: engine cannot warm up properly.
- Temp gauge is usually on the cool side after a run, around 3:30 o'clock or so, this is a tip-off that the wax mechanism has failed.
- In other words, the new Wahler-Volvo tsat came from the factory as 90C, but with time, it may function as a 75C tstat.

Anyway, the new Mahle 92C tstat solved the issue.