flushed coolant, new thermostat and still runs hot

[down4thakrown]

i gota 84 k20 burban witha 350 all stock except intake and headers,with a 3 row radiator and it runs hot, while revin at about 2500 rpms in neutral the temp will slowly rise to 210* then drop back to 190 and it keeps doin this over and over. when i drive it even at -0* outside and goin down the free way, it will hits 210 and stays. i flushed the coolant but it still looks very brown and murky. thats how it looked before iflushed it.i put a new thermostat 195* with the spring side down in the intake. should i just buy a new aluminum 4 row radiator?

 

[4X4HIGH]

What you've described is normal for a 195* t-stat. What temp t-stat did you install?

 

[down4thakrown]

What you've described is normal for a 195* t-stat. What temp t-stat did you install?

another 195* i havnt tried the truck on the freeway just i just ran it neutral in drive way and it was bounceing in between 190 and 210. before i changed the thermostat it would stay at 210 on the freeway with a -0* out.

 

[4X4HIGH]

When the engine warms up and the t-stat opens the temp gauge will drop slightly and once the t-stat closes the temp will start to rise slightly and the cycle happens all over again, and again, and again.

 

[down4thakrown]

hmm maybe i should buy a new radiator then, cuz i drove it to washington and hauled 2 older hunting quads a snowmobile and a smaller quad and it kept overheating, makeing me stop to let it cool and add coolant. i plan on useing thsi truck to tow my blazer so i gota make sure this will stay cool. my blazer with a 4 row factory radiator wont go past 150* ever, not idleing or runing down the free way.

 

[down4thakrown]

or should i try a 160* thermostat?

 

[JPOutfitters]

or should i try a 160* thermostat?

as long as you're not running fuel injection a 160 or 180 thermostat will be OK......

My 74 C20 ran a 160 like a raped ape!

My 87 Sub HAS to have a 195 for the fuel injection to perform correctly!

 

[down4thakrown]

ya my blazer runs perfectly fine at 160*. you guys think since i had a 195 thermostat is the reason why it over heats goin up long hills towing a heavy load? while just driving on flat ground it willgo up to 210 and stay there until i let off the gas then it drops pretty fast back to 190 and will stay until i give it gas again

 

[JPOutfitters]

it surely doesn't help those older motors! It's just not going to heat up as quickly during the winter! I recommend purchasing one of those lifetime reusable thermostat gaskets from Autozone's Performance section and running a 160 in the summer and a 180 for the winter. It will literally take less than 5 minutes to change out the thermostat each time with that gasket!!

You still might look into a new radiator.........cheap insurance for a longtime investment.

 

[4xcrazy]

make sure your fan clutch is working good as well, or even upgrade to a heavy duty cooling unit. It helps. I'm running a heavy duty clutch and a 4 row radiator, with a 195 t-stat, and actually have a hard time in the cold weather getting it up to operating temp. it will, it just takes alittle while to get there.

 

[down4thakrown]

well i think im goin to try a 160, i dont mind it takin a little longer to warm up. i just wana be able to tow blazer up hills with out it over heating. then ill just start saving for a new radiator, anybody try one of these?
http://cgi.ebay.com/ebaymotors/ws/e...sid=p4712.m2000054&item=130492771674&viewitem=

 

[down4thakrown]

make sure your fan clutch is working good as well, or even upgrade to a heavy duty cooling unit. It helps. I'm running a heavy duty clutch and a 4 row radiator, with a 195 t-stat, and actually have a hard time in the cold weather getting it up to operating temp. it will, it just takes alittle while to get there.

yep, burban got a brand new heavy duty clutch too. my blazer is the same way with a 4 core cant remember what t-stat it has but i dont think it even gets up to 160. it runs so cool the heater just blows luke warm air.

 

[Jessie James]

I just did a ton of research on this (search my posts) and here is that I found:

The normal and most efficient operating temp for your engine is about 200 - 220 degrees. Therefore it's operating perfectly. Why do you think the thermostat is 195? It's because it opens at 195 degrees. GM and every other manufacturer did tons of research to figure this out and provide the best performance and longevity of your engine. They didn't just guess ...

Your truck is only overheating at about 265 degrees. 210? Completely normal. That's where mine runs.

A 160 thermostat will cause your engine to always run rich, because it will think it's not warmed up, so the choke basically will always be on, which will result in lower MPG, less power, and more emissions. In addition, the lack of heat will cause poor combustion, increased condensation in the exhaust which will rust it from the inside out, and finally the heat won't allow the oil to heat up which will cause it to turn to sludge. Finally, the lack of heat allows carbon build up in the cylinders.

Worst of all, your heater will suck in the winter time, especially with 0 degree weather!!!

All in all, the 160 thermostat won't be immediately apparent, but in a year or two you will wonder why all these other problems are cropping up.

Even with a 160 thermostat it won't fix your overheating problem. It will only cause other issues. If your truck is overheating, having the thermostat open sooner won't make your truck run cooler under load. It'll just run worse every other time.

What you need to do is flush your cooling system with a chemical CLEANER, check your water pump, check your cap, and pressure test the cooling system. If the cap or a leak is not keeping the water under pressure, then the block heats up and boils the water off the sides of the coolant passages. That puts air in the system, which makes it so that the coolant is not touching the block, and voila - over heating.

You have issues, but the thermostat is not one of them.

 

[JPOutfitters]

I just did a ton of research on this (search my posts) and here is that I found:

The normal and most efficient operating temp for your engine is about 200 - 220 degrees. Therefore it's operating perfectly. Why do you think the thermostat is 195? It's because it opens at 195 degrees. GM and every other manufacturer did tons of research to figure this out and provide the best performance and longevity of your engine. They didn't just guess ...

Your truck is only overheating at about 265 degrees. 210? Completely normal. That's where mine runs.

A 160 thermostat will cause your engine to always run rich, because it will think it's not warmed up, so the choke basically will always be on, which will result in lower MPG, less power, and more emissions. In addition, the lack of heat will cause poor combustion, increased condensation in the exhaust which will rust it from the inside out, and finally the heat won't allow the oil to heat up which will cause it to turn to sludge. Finally, the lack of heat allows carbon build up in the cylinders.

Worst of all, your heater will suck in the winter time, especially with 0 degree weather!!!

All in all, the 160 thermostat won't be immediately apparent, but in a year or two you will wonder why all these other problems are cropping up.

Even with a 160 thermostat it won't fix your overheating problem. It will only cause other issues. If your truck is overheating, having the thermostat open sooner won't make your truck run cooler under load. It'll just run worse every other time.

What you need to do is flush your cooling system with a chemical CLEANER, check your water pump, check your cap, and pressure test the cooling system. If the cap or a leak is not keeping the water under pressure, then the block heats up and boils the water off the sides of the coolant passages. That puts air in the system, which makes it so that the coolant is not touching the block, and voila - over heating.

You have issues, but the thermostat is not one of them.

Though this information is good.........if you're running a carb even with electric choke, you can run the 160 during the summer time! You're engine will still warm up and it won't effect your mileage that much....

My '87 with TBI is standard with a 180! ONLY with fuel injection will the thermostat cause that much fuel mileage difference and cause your engine to run rich!! Your electric choke should be adjustable on your carb so that it doesn't have to choke your engine as much until it is warm.......

I will agree to do a proper flush and as I've already stated replace your radiator......my experience is over 20 years of experience as a mechanic and I dont respond with "cookie cutter" responses to be the biggest and baddest know-it-all around.....I respond with experience!

 

[down4thakrown]

I just did a ton of research on this (search my posts) and here is that I found:

The normal and most efficient operating temp for your engine is about 200 - 220 degrees. Therefore it's operating perfectly. Why do you think the thermostat is 195? It's because it opens at 195 degrees. GM and every other manufacturer did tons of research to figure this out and provide the best performance and longevity of your engine. They didn't just guess ...

Your truck is only overheating at about 265 degrees. 210? Completely normal. That's where mine runs.

A 160 thermostat will cause your engine to always run rich, because it will think it's not warmed up, so the choke basically will always be on, which will result in lower MPG, less power, and more emissions. In addition, the lack of heat will cause poor combustion, increased condensation in the exhaust which will rust it from the inside out, and finally the heat won't allow the oil to heat up which will cause it to turn to sludge. Finally, the lack of heat allows carbon build up in the cylinders.

Worst of all, your heater will suck in the winter time, especially with 0 degree weather!!!

All in all, the 160 thermostat won't be immediately apparent, but in a year or two you will wonder why all these other problems are cropping up.

Even with a 160 thermostat it won't fix your overheating problem. It will only cause other issues. If your truck is overheating, having the thermostat open sooner won't make your truck run cooler under load. It'll just run worse every other time.

What you need to do is flush your cooling system with a chemical CLEANER, check your water pump, check your cap, and pressure test the cooling system. If the cap or a leak is not keeping the water under pressure, then the block heats up and boils the water off the sides of the coolant passages. That puts air in the system, which makes it so that the coolant is not touching the block, and voila - over heating.

You have issues, but the thermostat is not one of them.

you do gota point ther, ill start payin more attention to the dark muddy looking coolant. after flushing it with 2 bottles of prestone coolant flush the coolant didnt change at all...still is murkey and brown. when i had the thermostat out the intake water jacket had layer of mud/clay stuff. im pretty sure the rest of the motor is the same way. the intake doesnt look that old ethier. idk if po put lake water in it and left it sit or what, but my water resevoir looks like i scooped water outa nasty water/mud hole. i also just put that in.and im sure all the sludge in the oil valleys dont help ethier, i did the valve cover gaskets and it looks like the previous owner never changed the oil. i only had the burb for less then a year now. next oil change i goin to try to use some sea foam engine cleaner next oil change.

 

[down4thakrown]

my chokes wired open, but the thermo stat i had in there before didnt seem old or bad. i think my radiator tubes are filled with mud/clay/rust....when i bought it, it had a bad water pump. it also has a oil cooler, and after seeing under the valve covers makes me wonder if its getin good oil pressure to rest of motor because of all the sludge build up. my gauge says over reads 20psi idleing and 35-40 cruisin tho. could the oil cooler makeing the gauge give false readings?

 

[ryoken]

not sure why a carbed motor had a 195 therm in it, but anyway...

if your not pulling the 2 block drains, your not flushing the motor... on either side, right above the oil pan rail.. it's the only way to get the sediment out..

 

[parts4now]

Not likey anything to do with your problem, but radiators do clog up externally. I spent a bunch of time under the hood of my old Toyota truck once only to find the radiator clogged with fescue seeds from driving fast through tall grass. My tractor sucks enough stuff into the radiator to need cleaning yearly.

 

[British Slave]

ya my blazer runs perfectly fine at 160*. you guys think since i had a 195 thermostat is the reason why it over heats goin up long hills towing a heavy load? while just driving on flat ground it willgo up to 210 and stay there until i let off the gas then it drops pretty fast back to 190 and will stay until i give it gas again

What kind of transmission?

 

[Jessie James]

you do gota point ther, ill start payin more attention to the dark muddy looking coolant. after flushing it with 2 bottles of prestone coolant flush the coolant didnt change at all...still is murkey and brown. when i had the thermostat out the intake water jacket had layer of mud/clay stuff. im pretty sure the rest of the motor is the same way. the intake doesnt look that old ethier. idk if po put lake water in it and left it sit or what, but my water resevoir looks like i scooped water outa nasty water/mud hole. i also just put that in.and im sure all the sludge in the oil valleys dont help ethier, i did the valve cover gaskets and it looks like the previous owner never changed the oil. i only had the burb for less then a year now. next oil change i goin to try to use some sea foam engine cleaner next oil change.

Yeah, it your coolant keeps coming out brown, I would say you have a clogged radiator/coolant system. You could probably use a few more of those Prestone coolant flush bottles (following the directions carefully) until things get to the point where it's not brown. Remove the block plugs and drain it that way.

And that sludge ... yeah, that's not doing anyone any good. Seafoam!

You could also have a cracked head gasket which is allowing oil into the coolant? I would think you would have noticed the oily residue in the coolant if that were the case.

As far as "next oil change" ... why wait? It sounds like you need to do that this weekend.