180 Deg Thermostat

[wb292]

I live in a hot climate. It can reach 120 in the summer. If I install a 180 thermostat from 195 will the truck increase the fuel ratio trying to raise the water temp?

 

[df2x4]

I don't believe it will, but I'm no expert. That said, I have been told by several reputable sources that there's no benefit to installing a lower temp thermostat in these engines. In your situation I'd probably leave the thermostat alone and do some cheap cooling system upgrades like a severe duty fan clutch and the 11 blade fan swap (if your truck doesn't have the 11 blade already).

 

[RichLo]

Switching to a lower temp t-stat is usually done to band-aid an underlying problem. If your truck is overheating, even at 120* outside temp you should fix the underlying problem... switch to a better fan blade, flush the cooling system thoroughly and possibly upgrade to a larger radiator.

Engines run more efficient at higher temps, new cars that have electronically controlled thermostats can run in excess of 220 when cruising to increase fuel economy.

 

[PlayingWithTBI]

If I install a 180 thermostat from 195 will the truck increase the fuel ratio trying to raise the water temp

No it won't.

I live in AZ too and run a 194* T-stat. I had issues with my 88 5.7L overheating. After flushing, new water pump, T-stat, fan clutch, and then a 3 row aluminum radiator, I pulled the heads and found it had blown gaskets between cyls 3 & 5 and 4 & 6. Now it runs without overheating even with all kinds of upgrades including aluminum heads.

 

[bobby v]

No it won't.

I live in AZ too and run a 194* T-stat. I had issues with my 88 5.7L overheating. After flushing, new water pump, T-stat, fan clutch, and then a 3 row aluminum radiator, I pulled the heads and found it had blown gaskets between cyls 3 & 5 and 4 & 6. Now it runs without overheating even with all kinds of upgrades including aluminum heads.

You didnt have any indications pete, like water in your oil ?? Mine is running so cool now that I worry there is no thermos ? I barely get to 160' if Im moving at all, of course if Im sitting at a light then it goes up to 200'. Summer time it goes to 220 easily.
What heads did you swap to, how did you know what ones/specs to use or did you do the bottom end at the same time?
Id like to do the Edelbrock Performer Heads with a new manifold and carb, would prefer the Holley Sniper but wow are they pricey
Bobby

 

[PlayingWithTBI]

You didnt have any indications pete, like water in your oil

The only indication I got was it was losing a little coolant (maybe a quart a week) out of the overflow but no white smoke or coolant smell out the exhaust.

What heads did you swap to, how did you know what ones/specs to use or did you do the bottom end at the same time

I did a lot of research online, including the recommended 350 TBI mods from Harris Performance (TBI Chips). He had a lot of good info there but I didn't care much for his tune. One of his suggestions was the Summit Racing (made by Trick Flow) TBI heads. I retrospect I wouldn't have gone with the cheaper electronic components (the Spectral Premium Dizzy sucks).

I didn't touch the bottom end since I've been using Mobil1 from the beginning and the oil is always clean and at the same level at the 5000 mile interval. If/when it does fail I'll probably go to a 383 short block and swap my top end components.

https://www.summitracing.com/parts/sum-162108/overview/make/chevrolet

Here's a link to his 454 recommendations, I'm not saying to follow his to the letter but it's a start. I think he's no longer doing this stuff, he's been sick for some time.

https://harristuning.com/Tbi/recommended-454/

 

[L31MaxExpress]

I live in a hot climate. It can reach 120 in the summer. If I install a 180 thermostat from 195 will the truck increase the fuel ratio trying to raise the water temp?

ALL of these trucks go into closed loop well before 150°F. The ignition timing starts getting retarded around 190°F. I have always run a 170°F thermostat myself which lets the engine run 178-182°F on a 20°F or 105°F day.

 

[bobby v]

Pete, sending email

 

[Mark Gilbert]

I'm here in Phoenix and have found that a lower temperature thermostat will not help. In fact having the higher temp thermostat keeps the coolant in the radiator longer allowing it to cool more before exchanging with the water in the block. This cycling is important.

Even without an engine problem I still had overheating issues if I sat still too long with the A/C on. I ended up running electric fans and now have no issues. Keep in mind running electric fans wrong will make your problem worse.

I would start by checking pressure bleed down on the cooling system to make sure you don't have a blown head gasket. If you are anywhere near Mesa I can help you out. If not you can buy a cheap pressure testing kit at Harbor Freight.

Also check your fan clutch to make sure it is operating properly. as well as making sure your radiator is clear of debris, both inside and out...

 

[L31MaxExpress]

I'm here in Phoenix and have found that a lower temperature thermostat will not help. In fact having the higher temp thermostat keeps the coolant in the radiator longer allowing it to cool more before exchanging with the water in the block. This cycling is important.

Even without an engine problem I still had overheating issues if I sat still too long with the A/C on. I ended up running electric fans and now have no issues. Keep in mind running electric fans wrong will make your problem worse.

I would start by checking pressure bleed down on the cooling system to make sure you don't have a blown head gasket. If you are anywhere near Mesa I can help you out. If not you can buy a cheap pressure testing kit at Harbor Freight.

Also check your fan clutch to make sure it is operating properly. as well as making sure your radiator is clear of debris, both inside and out...

I can tell you first hand that the length of time the coolant is in contact has little to no impact on cooling. You want more volume/flow to fully pressurize the water jacket and keep steam bubbles from forming. The big block truck engines and later 6.5 diesels went to dual thermostats to increase coolant flow for more capacity.

I noticed improved power and throttle response running cooler in hot weather.

My brothers 99 Suburban and my 99 Tahoe both had the HD cooling systems with the 34" wide dual core radiator and 11 blade plastic fans. Neither ran hotter than 190°F with a 170°F thermostat and had great a/c. My express van had the tiny 31" wide single core radiator and 5 bladed metal fan. Even with a 170°F thermostat the Express would run 220-240°F in hot weather and the a/c sucked in town. I upgraded the radiator to a 454/8.1 1-ton Express 34" wide dual core unit and swapped over to a duramax fan blade on a Trailblazer SS fan clutch. It never hit 200°F on the hottest day, running WOT uphill for miles at a time towing my travel trailer.