Thermostat Housing

[yangotang]

Cold weather has arrived. This post is for those of us who will be replacing their T-stat over Thanksgiving weekend.

http://www.volvospeed.com/Repair/thermect2.php

http://www.matthewsvolvosite.com/tstat.php

I will definitely buy 6 or 7 inch long 40mm Torx bit.

I will soak T-stat housing bolts the day before with PB Blaster.

I will lightly coat the threads of T-stat housing bolts with Permatex Grey RTV.

First Question

Why don't folks put very thin layer of RTV between T-stat housing and block?

Second Question

Which T-stat do I use 87C or 90C?

http://www.online-calculators.co.uk/conver...efahrenheit.php

87C equals 188.6F

90C equals 194F

I have experienced problems with 195F T-stats before, so I am going with 87C (190F). Is a 180 degree T-stat available?

The reason that people don't put a layer of RTV around the housing is because there is already a silicone ring gasket that is used to seal the T-stat. Isn't that silicone sealant stuff pretty detrimental to rubber products? If I recall Correctly those things are designed for use on fiber-based gaskets and don't work optimally on rubber/plastic/silicone? I could be wrong here.

What kind of car do you have? Please put it into your signature. The thermostat temperature depends on whether or not your car is N/A or Turbo.

[robert213]

The reason that people don't put a layer of RTV around the housing is because there is already a silicone ring gasket that is used to seal the T-stat. Isn't that silicone sealant stuff pretty detrimental to rubber products? If I recall Correctly those things are designed for use on fiber-based gaskets and don't work optimally on rubber/plastic/silicone? I could be wrong here.

What kind of car do you have? Please put it into your signature. The thermostat temperature depends on whether or not your car is N/A or Turbo.

Good point!!! I have never owned a car that used rubber o-ring style gaskets before.

I have a 1997 850 with turbo. I would never use a 195F thermostat in a turbo-ed car, so I will go with 190F thermostat. In my other turbo'ed cars, I have always used a 180F thermostat.

[yangotang]

You are correct. 87C is for Turbo and 90C is for Non-Turbo.

[robert213]

You are correct. 87C is for Turbo and 90C is for Non-Turbo.

Have I encountered a problem with Volvo in general -- or a problem with the parts department at my local friendly neighborhood dealership?

I asked for a 87C thermostat for a 1997 850 Turbo. He handed me a box with thermostat. I wish that I wrote down the part number. Fortunately, I opened the box. I noticed that it had "90" stamped on it.

I said that I thought that I asked for a 87C -- this one has "90" stamped on it. I also noticed that the air bleed hole was missing. He said, oh yeah, the 87C has been superseeded by the 90C. The 90C will work just fine.

I said that I have had overheating problems with my other turbo vehicle using 90C. I would like to order the 87C. He said that it was no longer available.

I browsed Volvo Parts. They only show 1 part number. I have no idea whether it is an 87C or 90C. Does anyone know what the part number is for 87C thermostat?

https://www.volvoparts.com/displayProduct.cfm?unitID=114

Thermostat

Model Year: 1997

Model: 850

Part Number: 271664

Your Cost: $ 13.49

[yangotang]

271417 is the 87 Thermostat.

[robert213]

All three of the vehicles that I've owned with a 195F thermostat, have ended up consuming anti-freeze. The other three that I've switched over to a 180F thermostat did not -- and all three of them have over 170K miles. I am very reluctant to use another 195F thermostat, especially in a turbo-ed engine.

http://fcpgroton.com/volvo850cooling.htm

271417 - Thermostat and O Ring - 87 Degrees - $9.00 - Vernet (OEM)

271664 - Thermostat and O Ring - 90 Degrees - $9.00 - Vernet (OEM)

--Edit--

Consuming anti-freeze, as in the fact that small cracks gradually developed over time in the cylinder heads. These cracks allowed anti-freeze to seep into cylinder to be burned -- especially in the morning while the engine is still cold.

Indications...

Large white cloud of smoke from exhaust tail pipe.

Bubbles of air seen under radiator cap.

[robert213]

This morning, I ordered...

http://fcpgroton.com/volvo850cooling.htm

271417 - Thermostat and O Ring - 87 Degrees - $9.00 - Vernet (OEM)

FCP Groton. D.B.A. Foreign Car Parts of Groton, Inc

Foreign Car Parts of Groton, CT

734 Poquonnock Road

Groton, CT 06340

PHONE: 877 634-0063

FAX: 860 445-0511

E-MAIL: info@fcpgroton.com

Price with Shipping was $14.50.

Verify that it arrives in a Calorstat/Vernet box and that it does have "87" stamped on it. Verify that box contains the rubber circle seal.

I was not able to locate a long T-40 Torx bit at Sears (Craftsman) or NAPA Auto Parts. I found one here...

http://www.mcmaster.com/

(630) 600-3600

Enter page number 2609 in search field.

http://www.mcmaster.com/ctlg/DisplCtlgPage...&CtlgPgNbr=2609

3/8" Square Drive, Long

T30 5" Length 6939A84 13.84

T40 5" Length 6939A87 13.84 <--

T45 5" Length 6939A88 13.84

T50 5" Length 6939A89 13.84

[Gioseppe]

very good grasshopper.

snap on. get a snap on tool.

if it breaks, its replaced no questions asked.

mcmaster-carr is great and all, just get quality tools. it really makes the difference.

[robert213]

This afternoon, I found my 190F thermostat from FCPGroton lying on my door step...

http://fcpgroton.com/volvo850cooling.htm

VOL-271417 where the sales rep wrote Wahler on the packing slip

It came in a box with red sides and blue top and bottom with Wahler Thermostat Made in Germany in white letters. Part Number is 4272 87D.

It has "Wahler, Made in Germany" inscribed along the top, and "87" inscribed on the bottom.

It looks identical to the one in this picture,

http://www.volvospeed.com/Repair/thermect2.php

http://www.volvospeed.com/Pics/repairpics/...rmostatECTR.jpg

I had to rotate the air bleed hole closer to the middle.

Last week, I also purchased a 180F thermostat from Stant SuperStat

http://www.stant.com/brochure.cfm?brochure...location_id=168

It comes in a yellow and blue box with "Stant" in red letters. Part Number is 45378. Stant offers a rubber seal which must be ordered separately.

Comparing to the Wahler, the frame appears to be heavier and thicker and made of stainless steel. The spring is much thicker, as well. If I decide to use it, I will need to drill an air bleed hole.

[robert213]

A couple more thoughts...

Rather than draining coolant from radiator, I found it much easier to drain from the block...

http://www.volvospeed.com/Repair/thermect.php

I put jack stands on rear part of engine sub-frame. There is a coolant drain petcock on the rear of engine block on the passegner's side. Loosen with 13mm box-end wrench. Insert and slide a 3/8 inch rubber hose, 2 feet long, over petcock. Place other end in a wide-mouth plastic container, like 1 gallon Tropicana Orange Juice Jug. By hand, open petcock to drain about 3 quarts of coolant.

Also, I replaced my Engine Coolant Temperature (ECT) sensor.

http://www.volvospeed.com/Repair/thermect2.php

Part Number 9186486 listed as 9186486-8 IAT sensor, $63.40 at my local dealership.

It is incorrectly listed as an Intake Air Temp (IAT) sensor. This is the correct part, as the old one on my car had the same part number stamped on its side.

I had a very difficult time disconnecting the old electrical connector. The plastic cover would slide, the wires would not come apart. I pried up on the flip-up door on the sensor side of the connector. Then, I was able to gently use pinch-nosed pliers to pull apart the wires.

[holler1]

I've been getting PO116 code and slow engine heatup. Bought thermostat and temp sensor from FCP Groton as recommended here. I soaked the T40 screws with WD40 a few days ago and tried to remove them today. However, I could not find a long Torx bit locally, and tried a short Torx bit with a long 3/8 ratchet extension and also tried a Torx driver set with about 3" length. I got the front screw out OK but could not free the rear one and somewhat messed up the head of the screw. (I know- should have gotten a long bit first, mea culpa). I ordered a long T40 bit from McMaster-Carr today and will try that next. I have a 3/8 drive manual impact driver and I am tempted to try it if the long bit doesn't work with a ratchet. I noticed the warning about cracking the thermostat housing, but I'm not sure what else to try at this point. Has anyone tried EZouts on these screws? I could probably grip the sides of the screw with locking pliers if it weren't for all the other stuff blocking the way. Thanks for any help.

[Guest Hank Scorpio]

tighten them to 2000 ft/lbs

hahah

[robert213]

I have a 3/8 drive manual impact driver and I am tempted to try it if the long bit doesn't work with a ratchet. I noticed the warning about cracking the thermostat housing,

The problem is that the thermostat housing goes over a rubber seal on thermostat. There is a slight gap which will allow air to get to torx bolt -- forming light rust. After I took out my torx bolts, I soaked them in PB Blaster. After they dried, I applied a very thin layer of Permatex Ultra-blue (sensor-safe) RTV on the threads of both torx bolts. Also, I barely tightened down torx bolts -- just enough for rubber seal to do its job and just enough to keep from vibrating loose -- nice and snug like screwing on an oil filter.

Yes, you will be able to remove the rear torx bolt with 3/8 drive rachet and long torx-40 bit. Another secret that people will not tell you. You can lift up and remove aluminum injector wiring cover from fuel rail. Then, you can remove the two bolts securing the fuel rail to the intake manifold. This will allow you to slide the fuel rail over 1/8 inch (or just enough) to allow your long torx-40 bit to fit on rear torx bolt squarely.

Just don't use short torx-40 bit with an extension. Unless the person who replaced the thermostat in front of you was a monkey, you will be able to remove with 3/8 drive rachet -- just enough rust on torx bolt to be annoying.