Checking proper thermostat function
 

I have read that it may be common for the external oil cooler thermostat to not open fully. I presume then that the oil lines will still get hot but that circulated volume will be reduced.

How do I confirm proper operation?

My engine with large external radiator style cooler (and fan) still easily gets to 235 on the track and would go right past 250 if I didn't run cool down laps. Even though it's a high hp built engine, it's still only a 2.7, I would think that the single cooler should be able to keep temps lower.

BTW fan is good, fins are not blocked, engine is clean, lines are good (not perfect...but not squashed) and otherwise the engine runs and performs great.

Thanks,
Don

bump

Just start the car, put you hand on the oil lines, and check again when the motor temp approaches 180 degrees. You should feel very warm/hot lines, though this won't tell you if the lines have opened totally. I don't know whether it is common for the thermostat to fail or not, I doubt it since it is really a very simple device depending on wax melting to do its job. But anything's possible. It's hard to know about cooling. I have a built-up 2.7 but use larger than stock oil lines and a big under fender radiator at the front. Without the cooler, a hot day at the track (95+) could easily get the motor above 250 degrees. Now I hardly ever see 220. A fan is pretty much useless after the car gets up to 50-60mph...it really only helps in traffic when there is no air flow. So I'm betting you need a bit more cooling capacity than you have. Jim

Moneymanager is right, after the car warms up to normal operating temps, wait a few more minutes and check your oil lines. Mine gets blistering hot on the flow side and very hot on the return side. The only time I think I experienced partial thermostat opening is in the winter when outside temps are in the 50's. This would cause the external t-stat to slowly open due to the cool air lowering the temperature on the t-stat body. I live in southern california and I see 210 temps when I am cruising the freeway during the hot summer. I also have the carrera cooler, fan, block off plate, and elephant finned lines. With your track use combined with the humidity of the midwest, I wouldn't be surprised to see close to 250 on a hot day. I think your t-stat is working as it should and you might just need more cooling.

Auxiliary Thermostat......
 

Don,

After a run in the track or extended high speed driving, the car should be completely warm-up and the temp. of the oil line going to the external cooler should be very hot to the touch. If if is just warm, there's something wrong with thermostat and time to inspect it.

My SC had only 70K when the auxiliary thermostat failed to open during a track run and oil temp. went sky high (11 o'clock on the gauge). When the thermostat was removed and tested in an oil bath, the valve was stuck and have limited movement.

For peace of mind, I want to know that the thermostat is working alright specially when you experience some sign of overheating.

TD