Did we just kill the brand new engine?

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MoparGirl

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Finally got to the point where we were ready to fire up the new 340. Primed engine according to instructions (spinning/cranking, etc.), hooked up the tach & oil pressure gauge. All fluids filled, gas good, poured about 1/4 gas into new carb and turned the key. BA-BA-BA-BA-SPIT-BA-BA-BA-SPUTTER, more gas...BA-BA-BA-VROOM! Everything going A-OK and then thermostat (determined later) didn't open. Ten minutes into the 20 minute break in and had to shut down IMMEDIATELY. Steam & Spew blowing out the side of the radiator cap. Hosed off, cooled down and removed the top hose, thermostat housing. Bad thermostat. Over $8k into new engine, new radiator, new hoses, fuel lines, carb, basically everything and a stinking $4 thermostat (also new) was bad.

Good news is there were NO leaks whatsoever of anything other than the spew from the radiator. I shut down immediately as soon as the steam started, but did I still screw something up?

What next?
 
No, it should be ok. I like breaking them in with distilled water and no thermostat.
It could not have gotten that hot in 10 minutes if the timing was right.
 
No temp gauge...in hindsight it would have been pretty helpful. The engine just got past the point where to keep it a 2000 rpm was not difficult. The first few minutes it was a test to see if my foot could keep the 2000 rpm static.
 
I know it's a little late for this but I always test the thermostat (old or new) before installing. Pan of hot water on the stove and an accurate thermometer. EG. stamped 180 degF should start opening about 175 and be fully open at 185.
I also drill the disc (or cup if high flow) with a 1/16" hole so the air can get out when filling. Reminds me just recently I had a High flow thermostat fail to open right out of the package when I tested it.
 
I'd guess that the engine is fine. I worked on an S-10 with a stuck t-stat, it built up so much pressure in the engine that it blew the intake manifold gasket out ( v6 with water jackets inside the intake and a stupid plastic manifold ). Replaced the intake gasket, but not the t-stat..didn't know the thing was stuck... 10 minutes later it was overheating again :( but the engine was fine after I replaced the thermostat.
If you are still worried, do a compression test and check the oil, but if it was blowing out of the rad cap and not into the engine, it's fine.
 
You probably didn't hurt anything but after you put in the "new" thermostat, give it a try again....what have you got to lose?
 
Shouldn't be a problem. Replace the T-stat with one tested like Demonseed said. Run the breakin for another 10 to 15 minutes and hopefully all is well.

Jack
 
I break them in with a running hose in the top of the radiator and the lower drain valve open.

I don't have a reason for this and have never seen it mentioned. It's just something I made up when I was 17………. Things never get hot.
 
mopar340dave said:
No, it should be ok. I like breaking them in with distilled water and no thermostat.
It could not have gotten that hot in 10 minutes if the timing was right.
Click to expand...

Exactly, and this is why i love those CSR/summit/jegs type billet water necks with an o-ring instead of a gasket. You can take them on and off in seconds and they seal easily with no problem. Perfect for that purpose. Pricey, but worth the headache.
 
Please start using Milodon or Mr. gasket T-stats.....they ALWAYS open. THey run around 14 bucks I think...they also open WITH the flow of water rather than against like stant, motorad, etc. THis is necessary with hi flow water pumps.

Another tip is to fill the block up thru the t stat opening before you put it in, this way the block has water from the get go.
 
I only use fail safe, that way if they stick they stick open, and as stated it's best to test them before install, good luck and keep us updated.
 
I'm with redfastback, buy the mr. gasket balanced flow t stat, I've run the same 1 in 3 motors now, thats how good they really are.

and adjust the throttle/idle screw to raise the rpm to 2200 instaed of holding your foot there, and you can vary the rpm 2000-2600rpm, this helps send more oil sling to more places on the cam as in cover it with more oil, just don't go above 3000 rpm

so change the t stat, fire it up for another 10-15 min at the 2000-2600rpm idle and finish it off, BUT GET A TEMP /OIL PSI GAUGE 1ST.
 
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UPDATE:

Got the temp gauge installed and working AND received a new Mr. Gasket 160 deg. thermostat in the mail yesterday from Mancini.

Will try everything again with all suggestions noted and applied this weekend.

I'll let everyone know how it goes.

Many Thanks for all the replies!!!
 
Good to hear. You may find that you seem to be running rich with the 160....I switched to a 180 and it ran much better (because it actually achieved operating temp)....but I have a griffin aluminum radiator withe a 2950 cfm fan in a custom shroud. If you have less cooling you may need the cooler thermostat.
 
Me too, 180 is optimal for performance and wear, 160 is too cold, increases wear in the cylinder bores. A hose in the radiator is old school for break-ins, and not very good. Reason is the cylinders and pistons need to get to operating temp to expand and seat rings to an operating temp cylinder bore size. The hose never allows the motor to get to the operating temp and the rings may seat to a cold bore. Keep it safe, test the stat and run a good temperature gauge. You should be ok as lots of that pressure was from the pump deadheading into the radiator. Most stats have the jiggler hole to purge air, if it doesnt, drill said small hole.
 
I've never heard of someone breaking in a engine with a thermostat in place - I've always installed it after I break in the cam and change the oil, re-lash the valves etc. If it starts to get hot I put a shop fan in front of the car, if it's not warming up I block the radiator with some cardboard to keep it around 200*.
 
pishta said:
Me too, 180 is optimal for performance and wear, 160 is too cold, increases wear in the cylinder bores. A hose in the radiator is old school for break-ins, and not very good. Reason is the cylinders and pistons need to get to operating temp to expand and seat rings to an operating temp cylinder bore size. The hose never allows the motor to get to the operating temp and the rings may seat to a cold bore. Keep it safe, test the stat and run a good temperature gauge. You should be ok as lots of that pressure was from the pump deadheading into the radiator. Most stats have the jiggler hole to purge air, if it doesnt, drill said small hole.
Click to expand...
I agree totally with pishta, make sure all the cooling components are good, fill with distilled, pressurize the system if you can to check for leaks, (I use a Stant system checker), remove the tester and leave the cap off, start the engine and keep the throttle on the fast idle cam so the RPM's are around 2000, keep checking the water level and top it off if necessary while you do the initial break-in. Ditch that 160 stat! You can't even get the heater to work decent with it! If everything is good after a half hour or so, I like to readjust the valves (if it has a solid cam) and if there are no leaks, drain and refill the cooling system with 50/50 distilled and antifreeze.
 
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