Thread: Puzzled over temp sender location

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Coolant flow and heat dissipation works on a perculation theory. Gaskets are perforated to control flow from the rear to the front of the engine. Therefore you see a varied range of temps from rear to front. Heat has all of it's generation at the cylinder and then the coolant has to control head temps by flowing through them and theoretically keep an even base before it hits the radiator. Not perfect by any means but as the years of research between racing and everyday driven cars, the manufactures have compromised the best perculation and flow technology they can for the average applications. You will always see a cooler temp at the back and hotter in the front unless you have a weird problem.

What surprised me the most was the wide variance between the front and back. My gauge starts at 120 and most times it wouldn't get off of that. Now it comes right up to the proper temperature since being relocated. The gauge is brand new and so is the sender, so they should be accurate. I also know the engine wasn't getting too hot because the puke tank never changes as far as water level and the hoses are fairly cool to the touch, at least you can hold your hand on them and not get burned like in my daily driver.

Don

That's another concern Denny. I have a 160 in there, but the engine runs at 150 going down the road. I know the thermostat is opening and closing because I can feel the top hose warm up when it opens. I am getting some blackening inside my headers, so it is possible it is running too cold.

Don

Originally Posted by nitrowarrior

You will always see a cooler temp at the back and hotter in the front unless you have a weird problem.

Huh?? I think that's backwards... On a conventional small-block Chevy (which Don has and I also have in my coupe) the water pump pushes coolant directly into the front of the water jackets. By the time that coolant makes it to the rear of the block it is VERY HOT! If you notice where GM put the temp sending units in Chevy engines, it is either in the front intake manifold water passage or in the left head between #1 & #3 cylinders where it sort of reads an "average" temperature. I made the mistake of putting the temp sender in the right head between #6 & #8 when I first got my coupe running and the temperature went up and down like an elevator. It was always reading between 210 and 260 with a 160 thermostat! I changed hoses, water pump, radiator, thermostat (twice), and the fan; nothing helped. Finally a friend of mine spotted the problem right away - he said "move the sender and your problems will be solved". He was right.

No, I certainly appreciate all of the answers and am not discounting any of the reasons, I hope anything I said wasn't misconstrued as being ungrateful for the responses I got. What I am trying to determine now is if I should go to a higher thermostat to get the temp up a little. This is a strange one for me, because in Florida we NEVER have a car that runs too cool, just the opposite. Plus, I could see a minor variation between the front and back of the engine, but 60 degrees is a huge swing.

What I may do is see how the car does on the trip to Billetproof and then change to a 180 after that if the temps stay too cold on the road. I just thought of something else. I am taking a job at a marina probably within the next week. My friend Craig is the Service Manager there and has one of those infared guns, I could have him shoot the entire block, looking for what the various temps are all over the block surface.

Don