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Thermostat Experts Only!
Ok, not sure what to do here, or whether to do anything at all. I have a 180 degree thermostat, don't know if it is drilled or not.
My engine water temp has to hit a little over the 100C mark before the thermostat opens and then it drops like a stone to about 70C. Then it rises quickly to about the 90C mark then falls quickly back to about 80C, where it will fluctuate between 80 and 95C depending on whether I am in stop and go traffic or out on the hiway.. After the initial spikes and drops, it is very steady. On the hiway, it will stay at about 80C and the oil temp will be the same. My question is this: I am always watching that initial spike as I have had the motor overheat once before, and don't want it to happen again. So, I watch this spike with trepidation as I hope and wait for it to fall. Is this normal or should I try another type of thermostat? Are there some that don't spike and fall as much or am I just going to have to live with it. The initial spike is driving me nuts! |
Jim,
I've seen a lot of this with modified cars. Do you have a bypass hose? or internal bypass? Without a bypass engine temps will fluctuate until thermostat opens, the sudden drop you see is your highly efficient radiator. |
I don't see a bypass hose, but an internal bypass is entirely possible. I should probably call Roush and ask them about this.
Will it make a big difference if it does or not? |
No bypass would give an engine higher temps in the heads versus the temps in the lower part of the block from no circulation.
Talk to your engine builder Jim. |
Sounds to me like the T-Stat is binding, hard to open, it aint right I'm is what I'm thinking. I'd put a new one in myself...
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Change the t-stat and burp the system.....dont take any chances....
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I agree with Excaliber, binding thermo. 100c is about 210 f. your thermostat should start opening sooner than 180, and be fully open by 180. or you have a air pocket somewhere
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A 180 thermostat is fahrenheit, and you are talking in Centigrades. No wonder it is all screwed up. Convert everything to Kelvin and you will be OK. :rolleyes:
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You have a bypass on your thermstat housing going to the waterpump. The thermostat will open at the stated temperature but not fully close until 10 degrees below the stated temperature. I would stick with the 180f, the el cheapo, not the high performance thermostat. The high performance one never completely close and it is nearly impossible to get the temp above 160F on a cold day. This results in wearing out your engine, hot pistons and cold cylinder walls.
Thermostat control minimuim temps not maximuim when operating correctly. |
I tried them all, Mr Gasket, Moroso, Stant, holes, no holes. The Stant super stat from NAPA was all over the place. It would open at 210 then drop to 170 clime back up to 190 then back to 170. Then one day it went to 220. I shut the engine off and threw the thermostat in the trash. I have a Gates 180 thermostat now. The temp rises to 200 then drops to 180 and stays there. No holes. The high performance stats would not let the engine get above 160. Waste of money. That's my story and I'm sticking ti it!
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JHV48, you have air in the system! that is what makes the spike (a steam pocket ) cobras are hard to rid of excess air . I jacked mine up in front as high as I could and filled it while squezing the lower hose...if this dosent work ill eat a bug... WD
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I was going to pile-o....uh, I mean answer, but I'm not a thermostat expert.
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...uh yeah, do you need a thermal related degree to respond here? I didn't actually major in t-stats myself. :)
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Replaced the thermostat. Will test tomorrow.
Tested the old one and it wouldn't open fully until the temp hit 200 degrees. And it was a 180 thermostat. |
Quote:
did you test the new one before installing????????? I've had the best luck with the el-cheapo Auto Zone models (180degree), with three small holes drilled in the flange........ David |
I guess i'm not a t-stat expert either BUT 10 years working in radiator shop i would like to think i learned something other than how to make my own fishing weights out of the old solder from radiators.........
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Rusty- what brand of thermostat have you had best luck with being correct for the temp you want ?
What about these "Balanced" thermostats from "cobra valley". Anybody use one ? http://performanceunlimited.com/cobr...hermostat.html |
The balanced one never close 100%. It will take a long long long time for you engine to reach operating temp
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Started it up and let it idle in the driveway. Temp slowly rose and then held at about 95C where the fan kicked in.
No temp SPIKE (at least in the driveway). Will road test it on Friday. |
Over the years I've tried a couple of different "special" t-stats. Nothing has worked better than a plain old ordinary run of the mill t-stat. I don't get it, don't have a clue why that is. I just go NAPA or whatever and get one off the shelf, done.
If it doesn't open until 200 and it's rated 180 then clearly it is defective. I'd say your problem is solved. |
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