Which thermostat to us/reuse?
 

I'm finishing up timing chain work on my '97 XK8 with 158000 miles and am changing out the thermostat housing and thermostat while I'm in the neighborhood. The German MotoRad thermostat that came out looks fine and I never had a problem with it. I went to AutoZone for the new thermostat and they pulled up on the options on the screen. Their Duralast piece came up with a price of $9.99, and right below it was a MotoRad option at $115.00. What ?!? Can it be that much better? I bought the Duralast, but was still wondering what made the MotoRad piece worth $115.00, and should I be putting that back in instead of the new Duralast piece?

Any experienced comments would be greatly appreciated.

Thanks,
Mark

Failsafe thermostats
 

Geez, that’s big price difference.

Bear in mind that that some equipment is for racing/track/hot rods etc and then I can understand the difference.

My limited understanding is that fail safe thermostats stick wide open at a set temp., so then cannot go down again. OK for a track car but generally bad for normal cars. You may struggle to get car up to usual operating temperature, from cold, ie starting fans etc. With resulting problems such as Cabin Heater may struggle.

Thermostats are usually cheap, and easily available, so why pay the extra.

I always put thermostats in boiling water to check how far they open. Some thermostats have specs, like 1/2" opening distance. 1/4" is definitely not enough.
I spent very long time diagnosing overheating Corvette, which turned out to be bad brand new thermostat!!! I put old and new thermostats in boiling water and checked which one opened more. Old thermostat opened about 1 /2", new one about 1/4", which led to overheating.

A quick google search will show the average cost of the MOTRORAD thermostat is $11.00 to $13.00. Most of the parts places like to sell them with the housing from $71.00 to $120.00.

If your new Duralast is a 180 degree, you should be fine.....but the "Hot-Water" idea is good, just to check, as your Hot Water is probably set to 220 degrees.....never put an old one back in the car.....(advice from Grand- Dad)

Billy Clyde