Thermostat Change

[Ernest]

Looking to replace the 160F thermostat(MrGasket/highflow) that came with the car/engine(ZZ4).

Stays a cool 160F, up to 170F the most during quick summer drives with original type 3row brass/copper radiator, engine wouldnt go past 150F on a 45F day, too cold IMO, not good at all for any engine, so i've decided to step up to a 180F thermostat.

Would it be a good idea to go with another MrG highflow unit or perhaps some other brand that works just as good... stant, robert shaw, etc?


Thanks

 

[melloelky]

i agree your o.g stat is to cold.I've run the shaw'($$$$)and the stant's w/o issue.from what i can tell the diffrence is-the high flow job's have 3 holes drilled in the surround

 

[69hurstolds]

You're engine is going to find its own operating temperature. Thermostats are designed with the main function to shorten the time the engine warms up to operating temperature. Even at 160, most engines will run 190-205 -ish degrees. If your radiator pulls out that much heat, feel blessed. If you had an Olds 455 in that sucker you'd praise all that is holy that you found something to keep you cool.

Most engines are built to spec clearances based on full expansion of the materials at expected operating temperatures of around 200 degrees. Meaning that hotter engines are a bit more efficient, and on the flip side, colder temps run the risk of clearances being too large causing excessive wear. May not be much more, and gas mileage will be a bit worse, but not really enough to notice. You might go from 16.1 to 16.05 mpg for example.

Going with a 180 or even 195 is perfectly fine. If you're having no cooling issues at 160, you surely won't have any at 180 or 195.

 

[Ernest]

No complaint there on how well my cooling system is working, OEM configuration basically... engine driven fan w/fan clutch, complete radiator shroud and the 3row brass/copper radiator.

I've read all over the net from different car forums that most like to run with 195F thermostats because of engine and oil efficiencies that the much warmer heat is needed over the cooler 160F thermostat that would be better suited with racing only situations.

Normally i'd go for the 195F thermostat, but since i run with aluminum heads, i worry about possible over heating issues if it came to that and warping the heads, unless thats a thing of the past, but my fear is probably unfounded since most newer OEM type engines run with aluminum heads only, or like some engines, like the LS3 that run a totally all aluminum engine, and they run around 210F normal operating temps, due to emmissions restrictions im sure.

I figure on going one step up with a 180F thermostat for starters and see how that goes, that should keep me at 180F or so during these mild winters we get here in TX, and see how it goes during the summer time. The thing is also, im not hard on the engine to really get the temps up, its a cruiser, not a racer, but i've occassionaly open it up on the highway, hitting just over 3krpm, but im already rolling along, not much load being put on it versus if i was lauching it all the time from a stand still.

Just wondering if i should use a standard thermostat(pic 1) or high flow(pic 2).... and what is this drilling a 3/16" hole about in the regular type thermostats, some say its to let air out that might be trapped in the system before the thermostat opens. Is that really needed, say like if you just flushed the cooling system then adding fresh mix of 50/50, those of us with an old school radiator can just leave the radiator cap off till be see the water flowing till the engine comes up to temp and the thermostat opens, and any air inside will be let out that way, unless im lQQking at this wrong, feel free to correct me if so.

Thanks

 

[69hurstolds]

There's no good reason to drill holes in your thermostat. I do know LS engines use a sort of pintle valve setup to bleed air when pressure is equalized across the t-stat, but it's not really a bypass per se as when the fluid hits it the valve closes off flow. IIRC, SBC has an internal bypass via the water pump, but that's pulling a memory from 30+ years ago. Oldsmobile V8s have the bypass right in front of the T-stat. You do want the coolant to cycle through the block to prevent hot spotting and more equal heat distribution, but you don't need any going to the radiator until it opens.

Restrictions suck. So if you can get the high flow, use it. Nothing lost by using it, especially since the cost difference is usually negligible. Requred? Not really. Not for what you're doing with it.

 

[Ernest]

Thanks for the input.

When you mentioned the wear and tear on an engine with excesive clearences due to cooler water temps, like mine with the 160F thermostat, and since i have no history on this ZZ4 engine, you may be right.

Story is, when i did the very first oil/filter change with synthetic on the engine after getting the car, nothing seemed amiss looking at the old oil at first, but then i noticed small gold/silver like flakes at the bottom of the drain pan. Now that tells me, unfortunately, thats bearing material, from the mains or rods, who knows where else. But i have changed the oil/filter twice keeping it synthetic since then, the same material persists at the bottom of the drain pain, this engine may be hurt, but it starts immediately, and still runs good and quiet, other than the pinging i hear off and on, i havent quite worked that one out on how to solve it with different timings yet.

Btw, the 160F thermosat i have lQQks due for a change anyway, when i pulled the thermostat from the intake for the very first time, i saw a loose rubber o-ring inside that apparently goes somewhere inside, but who knows when this happened. From this, im thinking this had created its own small bypass and allowing some water to flow through the radiator before it has a chance to heat up in the block, possible keeping the temps cooler than it should have been. Which may be true because when i put the thermostat back in the intake, for now, and after cutting out o-ring, i added more coolant to the radiator from what i had lost, but left the radiator cap off, i then started the engine which was still cold, and i saw water flowing through the tubes of which it shouldnt be doing before the thermostat opens?

 

[abbey castro]

IMO: get a 190 that is what is used OEM. High flow or slow flow get an AC Delco, they spent years coming up with the best flow solution. Why mess with it? I live in Central TX using an OEM 190 with the original radiator. E-fans kick in at 190 and the temp never goes above 195 in the summer heat.

 

[Ernest]

Sounds good, but that will have to be for another time.... i went and hit the local autozone and picked up the MrGasket 180F #4364 thermostat and see how it fairs.

I just have to figure out what my engine needs, not what i think it wants.

 

[Ernest]

So i had a chance to install the MrG 180F thermosat earlier, and sure enough, right on cue, about 180F, according to my temp guage, water started to flow through the radiator, no water flowed before it opened as it should be. I like that the engine warms up faster now, drivability feels better, took it out for a 10mile jaunt, temps hold @ 180F, and its 70F for the highs today, i womped it on the highway, pushing 80mph, felt good.

 

[69hurstolds]