Amazon Black Friday deals
IPD sale XeMODeX - Experts in Volvo Electronics

Get email notification of topic replies. Log in or register (free). Amazon Link Buy anything with this and it helps MVS!

How-to: Replacing the Thermostat Housing on a Newer P2 Without Touching the Power Steering

Help, Advice, Owners' Discussion and DIY Tutorials on Volvo's stylish, distinctive "P2" platform cars.

2001 - 2007 V70
2004 - 2007 V70 R
2001 - 2007 XC-70
2001 - 2009 S60
2003 - 2007 S60 R

User avatar
matthew1
Site Admin
Posts: 10799
Joined: Sat Sep 14, 2002 11:03 am
Year and Model: 850 T5, 1997
Location: Denver, Colorado, US
Has thanked: 691 times
Been thanked: 294 times

Re: How-to: Replacing the Thermostat Housing on a Newer P2 Without Touching the Power Steering

Post by matthew1 »

Great writeup, Zeeko. I made your account MVS Contributor level. I'll put this in the Volvo Repair Database.
Help keep MVS on the web -> click sponsors' links here on MVS when you buy from them.
Also -> Amazon link
. Click that when you go to buy something on Amazon and MVS gets a kickback.

1997 850 T5, MSD ignition coil, Hallman manual boost controller, injectors, R bumper, OMP strut brace [gone]
2004 V70 R [gone]

Image
User avatar
oragex
Posts: 5111
Joined: Fri May 24, 2013 6:20 am
Year and Model: S60 2003
Location: Canada
Has thanked: 100 times
Been thanked: 308 times
Contact:

Re: How-to: Replacing the Thermostat Housing on a Newer P2 Without Touching the Power Steering

Post by oragex »

I think it was an industry trend, if I remember BMW along others perhaps also went the same way at about the same year.. hard to follow their logic indeed especially since the coolant temp sensor seems to last much longer
cn90
Posts: 6916
Joined: Wed Mar 31, 2010 9:54 am
Year and Model: 2004 V70 2.5T
Location: Omaha NE
Been thanked: 163 times

Re: How-to: Replacing the Thermostat Housing on a Newer P2 Without Touching the Power Steering

Post by cn90 »

I can understand the industry, simply b/c they do not want the customer to return (less satisfaction, thus their rating), affecting their brand name...but...

- My 1998 S70: tstat failed at 80K (open all the time, thus no heat in cabin), at 100K, the ECT went south.

- I think there is logic both ways:
1. Fix only what is broken to save money <--- DIYers do it this way.
2. "Shotgun" approach: fix them all to save time and prevent "call back" <--- Dealers do it this way.
2004 V70 2.5T 100K+
2005 XC90 2.5T 110K+
User avatar
Zeeko
Posts: 20
Joined: Mon Aug 24, 2015 2:20 pm
Year and Model: 2004 V70 2.5T
Location: United States
Has thanked: 3 times

Re: How-to: Replacing the Thermostat Housing on a Newer P2 Without Touching the Power Steering

Post by Zeeko »

matthew1 wrote: Thu Nov 23, 2017 11:09 am Great writeup, Zeeko. I made your account MVS Contributor level. I'll put this in the Volvo Repair Database.
Thanks Matthew! Hope to contribute more in the future. And thanks for taking the time to edit those photos in where they needed to go- it looks great!
atikovi
Posts: 129
Joined: Wed Sep 20, 2006 7:20 am
Year and Model:
Location: Suburban Washington DC

Re: How-to: Replacing the Thermostat Housing on a Newer P2 Without Touching the Power Steering

Post by atikovi »

Zeeko wrote: Mon Nov 20, 2017 10:44 pm I saw that the temp was dropping into the mid 70's (C) on the freeway- not cool, and this is probably what fried the first CAT.
What is the connection? I never heard a cool running engine would fry a cat.
User avatar
abscate
MVS Moderator
Posts: 23202
Joined: Sun Feb 17, 2013 5:54 pm
Year and Model: 99T5 ,99S70,2005V70
Location: NYC, ALBANY NY
Has thanked: 412 times
Been thanked: 1267 times

Re: How-to: Replacing the Thermostat Housing on a Newer P2 Without Touching the Power Steering

Post by abscate »

If the engine thinks it is cold it will inject more fuel for cold running. This excess fuel can make it back to the cat and burn there instead of the engine, which cooks the cat.
Empty Nester
A Captain in a Sea of Estrogen
1999-V70-T5M56 2005-V70-M56 1999-S70 VW T4 BMW
Link to Maintenance record thread
Link To Volvo Glossary
atikovi
Posts: 129
Joined: Wed Sep 20, 2006 7:20 am
Year and Model:
Location: Suburban Washington DC

Re: How-to: Replacing the Thermostat Housing on a Newer P2 Without Touching the Power Steering

Post by atikovi »

abscate wrote: Sun Aug 18, 2019 5:48 am If the engine thinks it is cold it will inject more fuel for cold running. This excess fuel can make it back to the cat and burn there instead of the engine, which cooks the cat.
First off, it injects more fuel for cold STARTING, not so much for cold running, at least not for a significant period of time, however, even if during that time excess fuel can make it back to the cat, there is problem with the ignition system. Otherwise, every car that operates in the 5-10 minute warm up phase would have fried cats. And second, I wouldn't consider 70C cold running by any means.
User avatar
abscate
MVS Moderator
Posts: 23202
Joined: Sun Feb 17, 2013 5:54 pm
Year and Model: 99T5 ,99S70,2005V70
Location: NYC, ALBANY NY
Has thanked: 412 times
Been thanked: 1267 times

Re: How-to: Replacing the Thermostat Housing on a Newer P2 Without Touching the Power Steering

Post by abscate »

atikovi wrote: Sun Aug 18, 2019 6:22 am
abscate wrote: Sun Aug 18, 2019 5:48 am If the engine thinks it is cold it will inject more fuel for cold running. This excess fuel can make it back to the cat and burn there instead of the engine, which cooks the cat.
First off, it injects more fuel for cold STARTING, not so much for cold running, at least not for a significant period of time, however, even if during that time excess fuel can make it back to the cat, there is problem with the ignition system. Otherwise, every car that operates in the 5-10 minute warm up phase would have fried cats. And second, I wouldn't consider 70C cold running by any means.
I've measure the cold start time and monitored injection length for 10 minutes. It was about 3x normal warm idle and took ten minutes to reach steady state.

I do not know if the ECT reports cold temperatures, the ECM lengthens the injection time again, agreed.

On Denso cars , at least, the cold time is shortened by a high idle of 1500 rpm, and CVVT intake blows excess air into the manifold to heat up the cat fast and consume cold start fuel, so they engineered this thing well.
Empty Nester
A Captain in a Sea of Estrogen
1999-V70-T5M56 2005-V70-M56 1999-S70 VW T4 BMW
Link to Maintenance record thread
Link To Volvo Glossary
darter99
Posts: 2
Joined: Fri Jul 17, 2020 7:15 pm
Year and Model: V70 2.5T 2006
Location: Virginia

Re: How-to: Replacing the Thermostat Housing on a Newer P2 Without Touching the Power Steering

Post by darter99 »

Thanks Zeeko, I used your guide and all went well. I have a 2006 V70 T5. The full assembly cost about $100 including the temperature sensor and the gasket (everything needed). To remove the lower T40 I could reach it with a long wobble extension and T40 bit that is about 1 1/2 inches long. It was a close call because the contour of the housing itself makes it difficult to squeeze that bit in due to the form of that bit. However, I later ordered a long T40 bit (maybe 7 inches) and that easily fits since the 'socket' part of this tool is not close to the T40 bolt. So I advise getting a long bit if possible. Also, I used a round magnet set in a rubber tube to 'grab' that lower bolt. The magnetic pull allowed me to sorta feel what was going on since I couldn't see what was happening. This made it easy to replace that bolt and feel when the threads caught. From reading the other replies I think there may be apples and oranges in this thread. With your car and mine it looks like the replacement of the full assembly is required. There is no 'replacing only the upper half' option unless one wishes to tempt fate by splitting a new part in half. Also when I replaced the full unit I did so with the sensor removed and then the tool needed (I think) was a deep socket 19mm to replace the sensor. This was easy. At no time did I use any gasket sealant and I hope that is the correct procedure. I wasn't really sure about that. It seems to be sealed up just fine. Thanks for your write-up. One last thing: it might appear that the full part (minus sensor) cannot possibly fit in but with the rotation you mention (and no force by the way) there is a perfect spot where it does drop in. Yea, on a dare I could now do this in 30 minutes if all the parts were in place. Maybe 15 minutes actually. But I took my time studying the puzzle so it was a couple of hours for me. Also, none of my bolts were 'stuck' so maybe I got lucky. Also, I drained 3/4 gallon of fluid before working and there was no spillage to deal with. Oh, last point: to locate this leak I could see green crystalline matter at the base of the assembly. Then I fashioned a pressure tester from a reservoir cap and a presta-type bicycle valve from an old bike tube. (Free from bike shop). This worked perfectly and after a few pumps I could see a fine mist spraying from between the two halves of the thermostat housing.
Post Reply
  • Similar Topics
    Replies
    Views
    Last post