DIY: 1998 V70 Thermostat tips/tricks Topic is solved

Post by **cn90** » 12 Aug 2012, 09:21

This is not to re-invent the wheel. Below is a very nice DIY that has most of the detail you need. Please read it.
The problem is that I cannot add pictures to that existing DIY.

Replace Thermostat Volvo 850, S70, V70, C70 or XC70
Replace thermostat volvo 850 s70 v70 c70 or xc70

-----------
There are some "minor updates" as well as tips/tricks hat I want to share:

1. Volvo used to offer 88C vs 92C thermostats, it is now 90C tstat only.
Or you can buy aftermarket Wahler from online vendors that offer different temp.
Wahler is OEM.
If you decide to use any other brands (Vernet, Calorstat etc.), do your research.
But Wahler is the king!

2. The T40 bolts: if not careful, you can easily strip it.
Best is:
- Get 2 new T40 bolts from dealer ($1/each)
- Apply antiseize during install, it makes later removal much easier (I used antiseize in 7 years ago, it came out easy!)
- Long T40 key is a must: I use an 8-mm socket/ratchet for added leverage!
- When inserting the T40 key: make sure you clean all debris (using a nail or small screw driver) from the bolt first! Dirt will not allow the T40 key to fully insert ---> stripping the bolt!
- And yes, when inserting the T40 key, make sure it is seated all the way in for good purchase!

3. My 7yr-old gasket crumbled!
- Place a rag inside the hole to prevent debris from falling inside, this is important!
- Gently scrape the old gasket with a blunt flat screwdriver.
- Then use fine sand paper to finish it ff.
- Remove rag and pick out all debris using a pair of tweezers!

4. Tstat O-ring must fit in the Flange of the tstat like a sandwich.
Otherwise it will leak!

5. Tstat's bleed hole must face the highest point, which is the FRONT of the engine.

See pictures...

: Volvotstat01.JPG (98.47 KiB) Viewed 5291 times

: Volvotstat02.JPG (119.32 KiB) Viewed 5291 times

SpeedyPete · Post by **SpeedyPete** » 12 Aug 2012, 10:09

Hi CN: Can you explain why you feel it is necessary to align the t-stat bleed hole at the highest point? I didn't pay that much attention to the location of the bleed hole when I replaced mine. Also, another option for the T-45 torx bolts is to use grade 5 hex head bolts, M7 I think they were. I was able to pick these up at OSH because it was sunday when I did my replacement. Best Regards, SpeedyPete

byeboy · Post by **byeboy** » 12 Aug 2012, 21:38

On ALL motors, the bleed hole has to be as high as possible to allow trapped air to escape. i wish all engines had a simple Schrader valve mounted high, to allow simple "burping" of trapped air. My 97 Honda Accord had a bolt that you loosened to let the air burble out. Some cars have to be parked (or jacked up)pointing uphill to permit the air in the system to get to an escape route. Its an area paid too little attention in the manufacture of the engines...some, like the Ford V6's, had terrible problems with trapped air causing overheating, which led to blown head gaskets, then warped heads..

Post by **thecheat** » 12 Aug 2012, 22:06

The BMW M30B35 straight six has the purge bolt inches away from the fan blades. Good times there.

This system seems to purge itself. The t/stat I bought didn't have a jiggle valve or hole in it so I drilled a 1/16" hole in the edge and put it in.

mrwillie · Post by **mrwillie** » 16 Aug 2012, 12:26

cn90 wrote:This is not to re-invent the wheel. Below is a very nice DIY that has most of the detail you need. Please read it.
The problem is that I cannot add pictures to that existing DIY.

Replace Thermostat Volvo 850, S70, V70, C70 or XC70
Replace thermostat volvo 850 s70 v70 c70 or xc70

-----------
There are some "minor updates" as well as tips/tricks hat I want to share:

1. Volvo used to offer 88C vs 92C thermostats, it is now 90C tstat only.
Or you can buy aftermarket Wahler from online vendors that offer different temp.
Wahler is OEM.
If you decide to use any other brands (Vernet, Calorstat etc.), do your research.
But Wahler is the king!

2. The T40 bolts: if not careful, you can easily strip it.
Best is:
- Get 2 new T40 bolts from dealer ($1/each)
- Apply antiseize during install, it makes later removal much easier (I used antiseize in 7 years ago, it came out easy!)
- Long T40 key is a must: I use an 8-mm socket/ratchet for added leverage!
- When inserting the T40 key: make sure you clean all debris (using a nail or small screw driver) from the bolt first! Dirt will not allow the T40 key to fully insert ---> stripping the bolt!
- And yes, when inserting the T40 key, make sure it is seated all the way in for good purchase!

3. My 7yr-old gasket crumbled!
- Place a rag inside the hole to prevent debris from falling inside, this is important!
- Gently scrape the old gasket with a blunt flat screwdriver.
- Then use fine sand paper to finish it ff.
- Remove rag and pick out all debris using a pair of tweezers!

4. Tstat O-ring must fit in the Flange of the tstat like a sandwich.
Otherwise it will leak!

5. Tstat's bleed hole must face the highest point, which is the FRONT of the engine.

See pictures...

Volvotstat01.JPG

Volvotstat02.JPG

I stripped my bolt as well a few days ago and need to replace my CTS. Where did you buy the long handled torx bit?? I kinda like that. I've bought very short ones but still can't get a straight shot at the bolt.

Post by **cn90** » 16 Aug 2012, 12:50

mrwillie wrote:...I stripped my bolt as well a few days ago and need to replace my CTS. Where did you buy the long handled torx bit?? I kinda like that. I've bought very short ones but still can't get a straight shot at the bolt.

I don't remember where I bought the long Torx key, might have been Autozone?
It has a name "OEM" brand on the Torx key plastic holder.

Anyway if you google: "OEM Torx set", you will see it.

Example:
http://www.ebay.com/itm/OEM-HEAVY-DUTY- ... 0691470385

Post by **xHeart** » 16 Aug 2012, 13:22

Is it necessary to apply water sealant to the torx screws along with antiseize?

Post by **cn90** » 16 Aug 2012, 13:35

Antiseize is good enough.

instarx · Post by **instarx** » 17 Aug 2012, 04:55

SpeedyPete wrote:Can you explain why you feel it is necessary to align the t-stat bleed hole at the highest point? I didn't pay that much attention to the location of the bleed hole when I replaced mine.

"The highest point" is really a relative term. The thermostat itself is at the highest point of the cooling system and therefore its bleed hole is also at the highest point of the cooling system. Since these thermostats sit level I do not see how rotating the thermostat to any particular orientation could possibly make the slightest difference.

Post by **cn90** » 17 Aug 2012, 06:59

Actually there is a very slight slope at the tstat housing, not much but there is a slope.