New engine running HOT

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dartman59

dartman59

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Hello all. New crate motor--360 LA stroked to 408. Brand new four-row brass radiator. Yesterday was first run for me (had been on the Dyno successfully at the builder's shop). I put two gallons of distilled water and 1.5 gal antifreeze in the radiator immediately prior to starting. I have a new 180 deg thermostat in it. I did the first start, and it ran for a half hour or so, and stayed at a steady 180 degrees. Revved it a little but not anything serious. Then I shut 'er 'h.

This evening, I cleared my tools away, started it up, and took it out on the road for the first time. Within a couple of miles, the temp gauge started to climb and rapidly went up to 250 deg!! Maybe even higher! I shut it down, and sat and waited for it cool down, which it did albeit slowly. When it got got down to 165, I fired it up and drove slowly home, about three mikes. It was at 240-250 when I home.

Any ideas what could be going on? I never burped the radiator--it felt like maybe:tool: there was an air lock in the block. Stuck thermostat? When I did shut it down, it was making weird clanging noises like someone beating on a radiator with a pipe wrench. I hope I didn't fry my new engine!! Thanks in advance or your thoughts no opinions.
 
Definitely burp it, have you checked if you have enough fluid after the initial fill. The banging sounds like the fluid boiling as if not enough in there.
 
I would also check the timing to make sure it is dead on, & make sure the vacuum advance is working if you are using a vacuum advance dizzy.
 
Figured it out. The next day after work I made sure the radiator was full of antifreeze (I was able to add almost a whole gallon!) and I left the radiator cap off and started it up. Checked to make sure my timing hadn't slipped (it was spot on). Waited a little while and I could feel the hoses warming up, but I couldn't see any real movement of the fluid in the radiator ...

At that point I walked over to the cab to check temperature and--yikes--it was already 205-210 and climbing. So I shut it down, removed the thermostat, grabbed a second thermostat I had, and went into the kitchen and filled a pot with water. They were both 195 deg items, and as the water heated up and approached boiling, the "off" thermostat opened right up, but the one I just removed from the motor stayed shut, even after the water boiled and had boiled for 5-10 minutes!! BAD THERMOSTAT ! ! !

I won't tell you the brand, because I don't think that's too rare a thing to happen. Oh, what the hell, it was a Mr Gasket, high performance high flow unit. i guess it can happen to any mfr. I wound up feeling that, with a brand new engine, why didn't I check it to begin with ??!?

Thanks for everyone's thoughts and help.
 
I just went back and read my first post--I guess the thermostat I had in it was a 180 deg. Why it worked on the first run but not the second or third is beyond me.

What do people run mostly? 180 degrees? 195 degrees? Other??
 
180 seems to be the standard. For something with high compression 160.Truth is I run 195 in the slant six,, it likes the heat. It's almost like oil and filters,,It's what works best for you and your comfort level.
 
damn, i just intalled a Mr. Gasket highflow thermo. 180* hope its working properly! after about 15 miles it creeps up from 190 to 220
<---- Daily driver.
 
If you drill that thermostat before it goes in you won't have trapped air and burping problems any more.
That sound in the cooling system definitely sounds like air bubble hot spots.

Something a lot of people don't realize is that a hot spot can develop well before the engine is warmed up by what the gauge says, and cause a loop where it never gets it out of the engine because it vaporizes the coolant causing even more bubbles in the block before the thermostat ever opens to try to circulate it out.

Putting a 1/8 hole in the thermostat housing solves that for good and forever.
 
TrailBeast said:
If you drill that thermostat before it goes in you won't have trapped air and burping problems any more.
That sound in the cooling system definitely sounds like air bubble hot spots.

Something a lot of people don't realize is that a hot spot can develop well before the engine is warmed up by what the gauge says, and cause a loop where it never gets it out of the engine because it vaporizes the coolant causing even more bubbles in the block before the thermostat ever opens to try to circulate it out.

Putting a 1/8 hole in the thermostat housing solves that for good and forever.
Click to expand...

would it be the same to just eliminate the thermostat completely? :cheers:
 
so where exactly wold one drill this 1/8 hole on the thermostat

can we get a photo up here with a spot showing?

thanks
 
BIG-B-Barracuda said:
so where exactly wold one drill this 1/8 hole on the thermostat

can we get a photo up here with a spot showing?

thanks
Click to expand...

On the metal ring between the spring and plunger and the outside edge. I do it to all of mine. It's also important when filling the coolant to "burp" the system. I usually raise the front of the vehicle when going from empty.
 
I always test thermostats in a pan on the stove with a thermometer in the water. Just to make sure they are opening close to what they are supposed to. Even brand new ones.
 
My 408 was broken in and tuned on the dyno without a thermostat. I have a new drilled 180 degree thermostat ready to go in, that I just checked on the stove.

The one on the top left is NEW, the one on top right is NOS, the one on the bottom is a known good thermostat. The temp of the water is 190 and they are all 180 degree thermostats. You can see the new one is open wider than the other two. When the temp hit 200 it was still open more than the others. That's the one I'm going to run.

552A6AEB-2222-44CF-AFE0-2085C29ACA2C_zpsei5dx9b3.jpg
 
BrianT said:
My 408 was broken in and tuned on the dyno without a thermostat. I have a new drilled 180 degree thermostat ready to go in, that I just checked on the stove.

The one on the top left is NEW, the one on top right is NOS, the one on the bottom is a known good thermostat. The temp of the water is 190 and they are all 180 degree thermostats. You can see the new one is open wider than the other two. When the temp hit 200 it was still open more than the others. That's the one I'm going to run.

552A6AEB-2222-44CF-AFE0-2085C29ACA2C_zpsei5dx9b3.jpg
Click to expand...

What brand is it? Do you happen to have the part number?
 
Hey--do you guys think I did any permanent damage by running it with a stuck thermostat? I only went about two miles, but it was making noises like and old boiler, and I know at least part of the block must have been dry and mighty hot and subject to some wild pressure surges when some coolant would flow in and instantly vaporize.

How would I know if I had a permanent damage?? I did check for water in the oil (none--phew) and water vapor in the exhaust ( none). My paranoia tells me it's running a little rougher than at first start, but that could just be me thinking about it too much.
 
dartman59 said:
Hey--do you guys think I did any permanent damage by running it with a stuck thermostat? I only went about two miles, but it was making noises like and old boiler, and I know at least part of the block must have been dry and mighty hot and subject to some wild pressure surges when some coolant would flow in and instantly vaporize.

How would I know if I had a permanent damage?? I did check for water in the oil (none--phew) and water vapor in the exhaust ( none). My paranoia tells me it's running a little rougher than at first start, but that could just be me thinking about it too much.
Click to expand...


A cooling system pressure tester would tell you a lot here, but not everyone has one sitting around.
Just watch that system pressure kinda close for a little while.
It would probably present as an almost constant pushing out of the coolant, because usually the first thing an overheat causes damage wise is a head gasket leak of the compression into the water jacket.

You are probably fine though, but just keep an eye on that for a bit.
 
Just an FYI to all.....

When filling an engine for the first time, to eliminate hot spots, leave the thermostat and housing OFF. Fill the engine thru the thermostat opening in the intake manifold. Once it is near the top, then put the thermostat and housing on. Then fill up the rest in the radiator. THEN STILL BURP IT!!!!!!!!!!!!!!!

Operating temp for our engines is usually 165*-195*. I have always used 180* t stats(NEVER STANT) without any issues. Milodon and Mr gasket are your best choices for t stats as they open WITH the flow of water not AGAINST like Stant, Motorad, etc do. This is necessary for anyone with hi flow waterpumps because the higher flow, in turn means higher pressure, can actually close the thermostat.
 
im struggling with you on this one. i just replaced my mildon 160 high flow thermostat with a new mr gasket 160 high flow. car will run 180 cruising soon as i stop it will start to climb. yours was overheating while running. what fans are you running?
 
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