thermostat replacement - o-ring position

[cblanche]

Have a 1998 6.5 tD engine in which I must replace the thermostats. I picked a pair of 195 degrees. There is a gasket (o-ring) surrounding the thermostat. One side of gasket is flat and other side is beveled (angling inward). What side (flat or beveled)installs toward the engine housing?

Also, I was informed by a diesel mechanic that a little permatex placed on the face of where the housings meet is necessary. I do not think so. The hosing didn't appear to be affixed with any sort of gasket or seal. Good idea?

Lastly, would a damaged thermostat maintaining a temp no higher than 160 degrees cause poor fuel economy. Or is it the 7 days of below zero weather causing excessive fuel consumption? I understand that the higher the temp, the better the diesel will run.

Any information is much appreciated.

[More Power]

If I remember correctly, the rubber ring fits best when oriented correctly. Try it both ways, then report back.

The 1996 and newer electronic 6.5 must run at 170 degrees or higher for the powertrain programming to operate the engine in its "at operating temperature" configuration. This could affect fuel economy.

The 1994-95 models must be at 140 or higher.

MP

[Bobbie Martin]

Also, I was informed by a diesel mechanic that a little permatex placed on the face of where the housings meet is necessary. You shouldn't need any sealer. The O rings will provide all the seal you need. Just make sure all is clean & smooth. If you have a deep gouge in the mounting surfaces, I might put some silicone sealer on them. I think my thermostats had the O rings on them when I bought them. Are you asking how the entire thermostat goes or just the O ring?