new engine running hot at start up - Chevelle Tech
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post #1 of 62 (permalink) Old Feb 11th, 17, 7:56 PM Thread Starter
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new engine running hot at start up

Not sure if this goes here or cooling so mods move as needed.

New crate ATK383 ( purchased a couple of yrs ago and thanks to life just fired today). Running Dewitt radiator with dual fans, Holley sniper ( not controlling fans at this point), serpentine system.

Ran through all the setups today and turned the key. Fired right up and sounded great. noticed water temp gauge with sender in head right to 250 degrees. Fans never turned on. not sure if water pump moved all the air out but did have coolant in the block. Thought about pulling thermostat but didn't that's how I know water was in intake.

Any suggestions? is this normal for a new build? Engine was dyno run, but has sat for a couple yrs since that point. Changed oil and primed oil before I fired. New to this aspect so any help is greatly appreciated.

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post #2 of 62 (permalink) Old Feb 11th, 17, 8:03 PM
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Re: new engine running hot at start up

Do you have the water pump turning the right way? Some pumps are meant to run the opposite way when using a serpentine setup.
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post #3 of 62 (permalink) Old Feb 11th, 17, 8:08 PM
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Re: new engine running hot at start up

Probably not the same cause but the same thing happened when we fired my friend's 454 first time.


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post #4 of 62 (permalink) Old Feb 11th, 17, 8:15 PM
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Re: new engine running hot at start up

The first thing I would do is either remove the thermostat or one of the pipe plugs in the manifold coolant crossover and fill the radiator until coolant is level with the top of the manifold. You may have a pocket of air in it. Once you get it button backup start the engine and watch through the cap opening for coolant flow when the thermostat opens. If you still don't have any coolant flow after it gets hot I would remove the thermostat and reinstall the housing and fire it up again and verify you have flow across the radiator. If there's still no coolant flow you have a water pump problem most likely
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post #5 of 62 (permalink) Old Feb 11th, 17, 8:21 PM
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Re: new engine running hot at start up

Quote:
Originally Posted by gnicholson View Post
The first thing I would do is either remove the thermostat or one of the pipe plugs in the manifold coolant crossover and fill the radiator until coolant is level with the top of the manifold. You may have a pocket of air in it. Once you get it button backup start the engine and watch through the cap opening for coolant flow when the thermostat opens. If you still don't have any coolant flow after it gets hot I would remove the thermostat and reinstall the housing and fire it up again and verify you have flow across the radiator. If there's still no coolant flow you have a water pump problem most likely
good call here. I have had air locking issues before.
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post #6 of 62 (permalink) Old Feb 11th, 17, 9:18 PM
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Re: new engine running hot at start up

Since you had the dist out, did you use a timing light to retire the motor? Are you sure the temp gauge is correct? Is the thermostat opening? Just a few ideas. Jim

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post #7 of 62 (permalink) Old Feb 11th, 17, 9:24 PM Thread Starter
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Re: new engine running hot at start up

water pump is reverse flow edlebrock that came with concept 1 serpentine kit. that is not my first guess at it being bad. it could be but I think there is air trapped somewhere.

After first quick run, I started to loosen thermostat housing and coolant was pouring out under pressure. I only had engine running a couple of minutes before I got nervous about temp.

I think tomorrow I will look at thermostat housing and maybe just pull thermostat to verify flow? when I did initial fill, it too 4 gal premix to top off radiator. I let it sit for a few days with cap on but not locked so air could vent out.

ATK paperwork says not uncommon to see radical readings as air purges out, but seems fans should have kicked on to help with temp? of course that sender is in radiator by dewitts. so I have 3 temp sensors, 1 in drivers side head connected to gage on dash, 1 in intake manifold connected to sniper unit, and the 1 in radiator to control fans. hard to know which one to trust.
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post #8 of 62 (permalink) Old Feb 11th, 17, 9:56 PM Thread Starter
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Re: new engine running hot at start up

dist went back in at same marks I made before removing. I picked up a timing light today and I will verify tomorrow, it could be off a little, but I don't believe it is drastic.

temp gage is new auto meter with supplied sending unit. it could be faulty, but no reason to link that immediately, but certainly is possible.

I don't know if thermostat is opening. I suspect it is not. I think air is trapped in system. I think head sensor is getting too hot before thermostat opens. I may just be being too cautious because I don't want to damage motor.

I am thinking about trying without thermostat to confirm flow and see if electric fans temp sensor triggers their relays to turn on. that should bring temp down and purge air, correct?
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post #9 of 62 (permalink) Old Feb 11th, 17, 9:58 PM
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Re: new engine running hot at start up

Start the engine with the cap off. Wait for the thermostat to open and water to flow. Stick a water hose inside the radiator on a low flow and force the air bubble out. The reason your seeing that high of temp is because the temp probe for that location is not in water, just hot air. The others are seeing normal temps.

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post #10 of 62 (permalink) Old Feb 11th, 17, 9:59 PM Thread Starter
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Re: new engine running hot at start up

Quote:
Originally Posted by gnicholson View Post
The first thing I would do is either remove the thermostat or one of the pipe plugs in the manifold coolant crossover and fill the radiator until coolant is level with the top of the manifold. You may have a pocket of air in it. Once you get it button backup start the engine and watch through the cap opening for coolant flow when the thermostat opens. If you still don't have any coolant flow after it gets hot I would remove the thermostat and reinstall the housing and fire it up again and verify you have flow across the radiator. If there's still no coolant flow you have a water pump problem most likely
the water pump has a pipe thread on top for a bypass, which I don't have so I have it plugged. would this be a good place to vent air?
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post #11 of 62 (permalink) Old Feb 11th, 17, 10:03 PM Thread Starter
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Re: new engine running hot at start up

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Originally Posted by oldcutlass View Post
Start the engine with the cap off. Wait for the thermostat to open and water to flow. Stick a water hose inside the radiator on a low flow and force the air bubble out. The reason your seeing that high of temp is because the temp probe for that location is not in water, just hot air. The others are seeing normal temps.
if that is the case, would it be normal for the intake to get almost too hot to touch? what damage am I doing or could be doing? how long should it take roughly for thermostat to open (185) if I remember correctly?
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post #12 of 62 (permalink) Old Feb 11th, 17, 10:45 PM
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Re: new engine running hot at start up

How fast did the temp gauge take to go to 250* ? Less than a minute? Few minutes? Is it a electric temp Guage? If it jumped to 250 in less than a minute I would lean towards a bad Guage. Jim

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post #13 of 62 (permalink) Old Feb 11th, 17, 11:10 PM
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Re: new engine running hot at start up

Do you have access to an infrared thermometer? Is it a mechanical or electric gauge?
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post #14 of 62 (permalink) Old Feb 11th, 17, 11:18 PM Thread Starter
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Re: new engine running hot at start up

it probably took a few minutes. I was checking over the entire engine, so wasn't really watching time. I kept waiting for fans to kick on, but never did.

I believe it is an electric short sweep style gauge, but the 12v I hooked to it could be only for lights? Is it possible having the sender in the head is going to give me false readings? I did have it originally in the intake, next to the thermostat housing ( never fired engine) until I installed the sniper unit and used that port for that sending unit.

I feel I am having to engineer this whole system. While I have worked on cars for over 30 yrs as needed, I have never tried to design all the systems myself.
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post #15 of 62 (permalink) Old Feb 11th, 17, 11:31 PM Thread Starter
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Re: new engine running hot at start up

Quote:
Originally Posted by Gulf Coast Chevy View Post
Do you have access to an infrared thermometer? Is it a mechanical or electric gauge?

Yes. I have a cheapo Ryobi that I use to check AC vent output doing remodels sometimes. Not sure how accurate it is . I did shoot it at motor and got some stupid high readings ( like 900) so I don't know how much I trust it.

I'll have to look tomorrow to verify electric or mechanical gauge. It has 12v hooked to it, but it has dash lighting.

https://www.summitracing.com/parts/atm-4737

this is gauge I have installed.
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