Hey all! I just got done with a three-day tirade replacing all sorts of things. Valley pan gasket, valve cover gaskets, plug wires, etc. AND the entire cooling system except for the water pump. This includes every hose, the radiator, soft spring thermostat, radiator cap, throttle body heater. I even back flushed the heater core. SO... this is where things went differently than I expected...

With the old, leaky, Dexcool-plugged-up cooling system, per Ultraguage I was running 188 on the freeway and 196 in town. Maybe pegged at 202 sitting in traffic. Now with a fresh cooling system, BMW coolant, and the soft spring thermo, I'm running a consistent 203 on the highway, 207-212 in town, and sitting idle for 10 minutes, 208 with a quick peak at 215 but immediately back down to 210.

I'm assuming I have a couple more days of bleeding ahead of me, but overall, especially with the soft spring thermostat, I would expect at least what I had before. No? I know those temps are within spec, but still, just expected lower.

BTW, heater didn't work before back flushing, and now it'll singe my mustache. Good stuff.

 

Welp, fixed it... The new thermostat was bad and stuck closed. I happened to have another new one on hand, swapped it in, and lo and behold, back to the 190s. BTW, the bad thermostat was a brand new "soft style" from AB that wasn't the gray one.

 

Same thing happened to me. AB has a bunch of bad ones on their shelves and they know it but keep shipping them out.

 

I got mine from Lucky8 not too long ago and it’s a dark gray color 180° hopefully I don’t have issues. Replacing some coolant hoses and thermostat today.

Using prestone green coolant and BG super cool additive

 

I find that people generally do things like flushes and water pump changes....fill with coolant, then do a poor job bleeding or, little particles clog the stat. You then change it with the exact same stat made on the same assembly line with a different outside color and that one works because the first one captured the sediment, dirt that you stirred up/caused.

I have yet to have a stat that doesn't open at its stated temperature.

You have to understand how this system works.

The hot coolant from the top T comes down and mixes with the cool coolant from the radiator. The flow is controlled by this mixing...the temp sensor is also on the other side of the block.

Why did they design it this way? Because huge influxes of cold coolant onto heated parts can result in slipped sleeves, warped heads, failed gaskets etc.

 

Well I just finished mine up and replaced all the coolant hoses, 180 thermostat drain the system hot flushed heater core flush radiator and even ran water through the engine through the top water pump hose. Bleeding this system is very simple! Running like a champ can’t tell of an exact coolant temperature because I’m only going by the gauge on the dash seems to be right in the middle like it used to be so who knows if it’s a 180 or not but it’s never overheated on me.

 

Your relying on your dash gauge that’s a big nono imo

 

Lol! What’s wrong with the dash gauge?

 

It's more of an idiot light than a functional gauge... It has three positions: Cold, Normal, and Oh Sh*t... Normal = 150 - 240...

 

For starters, the factory gauge is pegged at dead middle while the actual temp is oscillating between 170 and 240. That's the difference between me figuring out that the thermostat I installed was bad while blocks from home or waiting to find out it was bad after driving it hours from home into the wilderness.