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Originally Posted by Doktor Bert
I don't run thermostats in any of my cars and I never have. I simply use a 'hollowed-out' thermostat body, which serves as a sort of restrictor, but will never fail and overheat the engine.
I find my heater performance hot enough to be uncomfortable and engine coolant temperatures hovering around 160° to 175° on a 100° day.
Our coldest winter day here is about 30°F and the average is in the mid 40° range overall.
My 440 Cubic Inch Pontiac with 9.00:1 compression runs at a consistent 155° on 100° days and doesn't get over 175° in traffic with the A/C on.
Never had any adverse wear issues and oil/crankcases are just as clean as those engines I have disassembled that ran a thermostat.
I feel your pain over the broken bolts.... 
Another one of my modifications on all my engines is to replace ALL the bolts/studs/washers in the Coolant and Exhaust Systems with Stainless Steel and a liberal application of Wurth High-Temp Antiseize Lubricant.
On my 300SD, I actually changed every bolt/nut/stud on the outside of the engine over to Stainless Steel, including the Motor Mounts, Vacuum Pump, Oil Pan, and Accessory Mountings. All the washers were replaced with Stainless Steel too.
I even found Stainless Steel Acorn Nuts for the Camshaft Cover...Bert |
I have to take issue with 2 things here. I would NOT remove the thermostat unless you have a specialized purpose in mind, like drag racing. The thermostat in your SD, which typically fails by opening early, has an intended purpose. It reaches ideal operating temperature quickly and maintains it, for the benefit of the engine's reliability and passenger comfort (heat). Second, I would warn you NOT to replace your fasteners with stainless steel ones. Stainless fasteners are typically 18-8 stainless, a soft, austenitic metal. While you might avoid some corrosion problems, you introduce a few others. Stainless steel is notorious for galling, especially in aluminum. This feature alone leaves you in a undesirable condition when you load the fastener up with anti-sieze and tighten it. The threads deflect much more than they are intended to against the hole (and deflect the threads in the hole as well) Torquing fasteners under ideal conditions has enough variability in it, but the same torque value can easily provide too much preload. Reducing the torque to compensate can cause the fastener to loosen and fall out. Moreover, many of the fasteners on the 617 are allen heads (like the M6 screws holding the upper oil pan and the vacuum pump) The 60 degree pressure angle on the head is frequently not strong enough to withstand the forces needed to tighten and later loosen it. In other words, they can cam out. Hell, even the alloy steel screws can cam out under certain conditions. If you remove any corroded screws by all means replace them, but with original type, cad plated, alloy steel screws. PLEASE!
