2.5L ('98-'01) Thermostat Housing Bolt Torque

[Yardbird]

I replaced the thermostat in my 2000 2.5L yesterday. I couldn't find a torque spec so I went with the general torque rating for a coarse M6 which is 9 NM or about 7 ft lbs. I thought it was too tight and it might crack the cap but I did a search today and found a spec of 15-20 lb ft on here which is about 20 - 27 NM. Do I need to retorque those bolts higher? Thanks.

 

[Eddo Rogue]

If its not leaking, I would leave it be.

 

[sheep herder]

15-20 sounds high for a 6mm bolt.

 

[Yardbird]

It does sound high. The bolts are marked 8.8 and I checked a chart online for that grade and it said 9 NM.

 

[Yardbird]

My Haynes manual says 10 lb ft which is about 14 NM so I'm under that spec at 9 NM. I'm going to stick with the 9 because that's the bolt's rating. Those Haynes manuals cover a lot of years so maybe not the most accurate.

 

[Fredness]

Yeah - gotta watch those, there are 6mm and 8mm - for whatever reason.

 

[tomw]

If it ain't broke, don't fix it. Leave it alone for a while, and then check that it is sealed properly. If it is not leaking, it's doing its job and should be left alone without further supervision. I have yet to use a torque wrench on a stat housing. I do on internal parts, and intake mannifolds and exhaust manifolds. The rest are set to feel lernt over a lot of years. All crankshaft related are torqued, oil pans too, especially, and in sequence. Head bolts by the book.
If you use any RTV or other sealant, be aware that the sealant may ooze out slowly over a day or so, and let the bolt torque get relaxed. That will lead to leakage in some cases. I use no or minimal sealant for that reason alone. Using RTV that is designed to form a gasket, you need to follow the setting instructions, or you will squeeze the RTV out, and there'll be very minimal left to be a gasket. It has to set up before being torqued finally.
tom