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What thermostat should I use?

S

scoutillac

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I got my engine rebuilt and installed this last week. It is a 350 with a mild cam, K&N air fliter,TB spacer, Jet chip, new H2O pump, new fan clutch, and the radiator cleaned out and flow checked. All the sensors are all brand new. The problem is the damn thing is still running around 215 and jumps to 230. I even drilled the little hole in the thermostat flange because someone here, I don't rember who, told me tht would cure the problem. It doesn't go to 260 anymore but it still goes up higher than I feel comfortable with. HELP!!!!! Do I need an elect fan in conjunction with my stock set up, or different thermostat, or a bigger radiator? /forums/images/graemlins/ears.gif
 
what size radiator are you running and what temp thermostat? Can't recomend anything if you don't give info /forums/images/graemlins/wink.gif
 
I'd put a radiator built for a 454 in. You can also get a 160 Degree thermostat.
 
Are you using a fan with at fan clutch, or a fan bolted directly to the water pump.
If you are using a fan clutch, replace it.
Or use a flex a lite fan.
After my rebuild, it no longer ran as cool, but I replaced my fan clutch, the original one, 230,000 miles on it. Try it.Runs 200 210 max with a 160 stat in AZ heat and traffic.
 
Go find ya one of those 3 row Maxi-cool radiators, they are nearly the same as a 4 row rad, but not quite as wide,they have wider, flatter cooling tubes for more cooling surface area to water. hell i replaced the radiator in my other truck with a 2 core maxi-cool and it rides right at the t-stat, maybe little higher during summer, but thats when it's around 115-119 outside.
Also check the fan clutch, you don't need a flex a lite fan if your clutch is working like it should, plus the clutch is quieter.
Make sure you have the correct water to coolant mixture also.
Being a TBI setup, i would definately NOT use a 160 t-stat, it will definately run weird all the time, a 180 is pushing it IMO, i always use a 195 for the TBI to run correctly.
 
The stat is a 190 and there is a fan with a clutch on the rig. Could the fact that I have the rear heater blocked off have any effect on the temp. The rear lines broke on me one day on the way to work and the only way to fix it was to plug the holes and carry on. I still haven't fixed it properly. The plugs are way in the rear of the truck though. I don't know what other info you might need. If it has to do with the cooling system it has been replaced with atleast factory grade parts except for the rear heater lines like I said above. The truck is my 88 burban. It runs at 215-220 until I get on the gas then it jumps to 230. The fan clutch just cost me 68 bucks so I really don't want to replace it with a flex a lite. Could my guage be off by that far? The sender is three days old it better not be off.
 
It sounds like your "typical" running temp is around 215* then? With that showing on the gauge as "normal" it very well could be a gauge/sender/wiring issue.

I would suggest first making sure the temp you are seeing can be verified with a second temperature measuring device. From there you can go on to the more expensive parts that might be a culprit.

I've never had problems with stock gauges just reading higher than they should. (sure, they fail, but typically in an "obvious" fashion in my experience)

IMO with a proper/good radiator, you don't even need a fan while cruising and low load on the engine. (tested it, my 350 never got hot running a two core radiator on flat ground, as long as I was moving over 25MPH)

If you are seeing abnormally high temperatures while cruising at a steady speed (again, after verifying indicated temp is correct) then you've got a problem other than the fan.
 
With a 190 thermostat, 210-220 is just over the thermostat setting. Remember, the temp sending unit is mounted righ upstream of the thermostat and will show the temp of the coolant before it exits the engine. If you are experiencing these temps an a warm day in traffic (espically with the AC on) those temps ain't that warm. HOWEVER it it's a cool day and you are crusing down the road, THAT is a little warm. I would check the fan clutch then the radiator before you get disgusted. Also, how old is the waterpump? And with a fresh engine, things will run a little warm (friction) for a while. Keep us informed on whatever you find.
 
Again the fan clutch is three days old as well as the water pump. I'll have someone verify the temp for me. I have no idea what else to do. I am just so scared of overheating a fresh motor. They aren't cheap. By the way the temp does this whether the outside temp is 45 or 60. I leave work around 11 at night and it is usually around 46 or so. The A/C is not on in my truck at that temp. I'm not that warm blooded. Thatnks for all your help. Any other ideas are greatly appreciated.
 
My friend Rob who did the radiator at the shop said that the radiator looked in good condition inside when they were cleaning it.

Are you running the shroud still?

What is the motor bored out to? .030 over? .060 over? If it's out to .060 over it may be producing a bit more heat too.
 
Oh yeah I am running the shroud. Everything that came on it, went back on it plus more. I don't know what the bore is actually. I'll have to ask. That is a good point. The old motor was .040 over with .017 wear. So that is what .057 total. It ran hot exactly like this. In fact I posted pretty much the same thing a while back about the old motor. I am really getting tired of the heat. I have a built in tranny coler and an oil cooler. So that being said are those things plus the A/C condensor blocking too much air flow? I can remove the condensor or maybe I can get a small push type elect fan to fit between the grill and condensor.
 
GET A MECHANICAL TEMP GUAGE!!!!!!!! Man, I can NOT stress this enough! Here is why...I built my 406 a year ago with all the hi performance goodies and had wrm running temp problems ever since. I put a brand new 3 row in and that wasn't enough....well the last thing I did was I tore the freakin' motor down to a short block and regasketed it thinking I had a headgasket problem. Put it all back together and it was almost worse! Went down to my local Napa and paid $19 for a mechanical water temp guage, installed it, and relized the electric guage was nearly 30 degrees off! Before the electrical guage would read 210-220 in 75 degree weather with the A/C on or off. The mech. reads 195 in the same conditions with the A/C on. Drove around in 98 degree heat the other day and the mechanical guage touched 210-215 in traffic with the A/C full blast. I have a new 4 core rad and 180 stat with extra holes drilled in it just like yours.

To sum it up, pay the $19 bucks for a mechanical guage so you actually know what temp the water is....don't do what I did and say "it has to be more serious." After spending $700 in cooling/motor parts I had to learn the hard way to always double check the simple stuff. /forums/images/graemlins/tongue.gif
 
So what did you do with the wiring? Did you just leave it hangin? If so did it affect the computer at all. The mechanical gauge you used, did it have the long wire wrapped in a coiled wire for the sending line. I have a guage in the garage from a cluster set I bought awhile back.
 
Computer references the temp sender in the intake. The temp sender for the gauge is entirely seperate.

Again, if you can have your temp tested before replacing the stock gauge, you will either save yourself the money of a needless swap, or you will find that the relatively low cost of a new gauge will "solve" your problem. Absolutely ridiculous to pay money for another gauge if the stock one works fine, just like replacing any part without proper diagnosis.
 
[ QUOTE ]
So what did you do with the wiring? Did you just leave it hangin? If so did it affect the computer at all. The mechanical gauge you used, did it have the long wire wrapped in a coiled wire for the sending line. I have a guage in the garage from a cluster set I bought awhile back.

[/ QUOTE ] I didn't do anything, just left the electrical guage intact and it cracks me up now when I see it hit 250 and my mech. is at 200-210.

Dorian can say all he wants about the electric guage being accurate but a mechanical guage would be even more precise and will never "go bad" like mine did.
 
You talk like I'm not here. /forums/images/graemlins/smile.gif

Talk mechanical gauges all you want, it has been proven time and again mechanical and electric are just as accurate. They damn sure do go bad. Anything will fail with time, and gauges do not hold their accuracy no matter what they are.

How do you know your mech gauge is accurate? Ever looked at the aisle with all the outdoor thermometers on it and noticed the slight to large variation among most of them?

Comparing a 20+ year old gauge to a new one is ridiculous and you know it. So is throwing parts at problems instead of diagnosis.
 
[ QUOTE ]
So is throwing parts at problems instead of diagnosis

[/ QUOTE ] I agree with this that is why I posted the question. I figure it doesn't hurt to research all the ideas though. There is a shop down the road with a temp tester. I will ask them to hook it up for me. I am still open to any other ideas for helping my truck run cool.
 
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