New Engine Still Overheating During Break-in

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MoparGirl

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Suggestions anyone??

Got thru only 10 minutes of engine break in last week and thought the thermostat was bad. Coolant spewed everywhere out the blowout. This weekend cleaned everything up, hooked up temp gauge, refilled coolant, checked everything for leaks and fired it up without a thermostat and plenty of water ready. Had a house fan set up blowing on high right at the radiator. Five minutes into break-in had to shut it down again as everything overheated and coolant was spewing.

Everything...and I do mean everything ($6500 +) is new. New radiator, new water pump, new engine, new hoses, new ignition/distributor. New, new, new. What the heck is happening here?

It is a 340 bored 30 over. Radiator is new and is stock 22'' Mopar. Water pump is Mopar Perf.

What to try next? Timing? Head gasket issue? Bad water pump? Not good enough radiator? Help please. I'm at a loss.

I am running it with open exhaust for just the break-in because to put the TTI's on it will void their warranty. Stock exhaust manifolds are on it but the exhaust system has been cut off in preparation for the new stuff. Could this be part of the problem?
 
Could it be running lean? What do the plugs look like? color? What is the timing set at? Do you have good flow in the radiator?
 
The Head gaskets only go on one way and have some of the water holes plugged. So I doubt that could be the issue. What timing are you running? What grade of gas are you using. With the thermostat out, could you see the coolant moving in the radiator? Have you tried running it with the cap loose. Its sounds like your cooling system is building up too much pressure. I am in California and had a similar problem but not as severe and when I put racing gas (Unocal 100 Octane) it ran fine. Go figure.
 
Currently using 93 Octane gas (but it has been sitting a while and has additive in it for refreshing fuel.) Coolant was flowing in the system and the cap was off this time.

Will check the timing in the morning.
 
I'm betting it's timing and lean. Pull one of the plugs and see what it looks like too. Good luck and I hope she stays cool for you next time.
 
We found that the additive actually made it run hotter. Do you have any way to have a radiator shop measure the pressure in your system when it is running? The other thing we did that helped was to take the thermostat out and drill 4 small holes in it. You need to run a thermostat otherwise the coolant does not stay in the radiator long enough to cool down. As someone else suggested here, timing and running lean could be a factor.
 
Definetly can be timing and mixture. Timing should be the first thing set as soon as the engine is fired up. Like within the first minute. Also when I break in an engine I set the carb up a little rich for what I think it should be. Helps it run a little cooler.

Like the others said you need either a thermostat or a restrictor washer to slow the coolant down.
 
Even with the termostat out air pockets will cause overheating...if you see water rising at the radiator opening and then spilling out you have air pockets in the block or heads...fill it up run it...spill out some more water...add some more run it again until this stops...that's why I always start with water only...much easier to clean up..8)
 
I like using a garden hose with water to cool off the rad during break in. Just hose it down while the motor is running. Cools it off good and drys up pretty clean.

Timing is likely off but still an egine cooling system isn't made for 2,500 rpms and standing still. Most fans are not large enough to cool the rad off if its hot outside.

The water hose works so good for me I was able to break the cam in for 40 mins a few years back. Just watch for the fan

I just stick the hose in the rad with the cap off to start and after a min place the rad cap on. Sure water gets everywhere but I don't melt, lol
 
I was going to mention the same as fishy68. It's almost like added insurance breaking it in a little rich. I like the running water idea too. I would guess you don't want to do that in the garage though. At least not in mine:)
 
Changed t-stat (made sure it worked first.) Added new coolant. Plugged a vacuum leak on the carb. Pulled a plug and it was a bit lean, but nothing major. Started it up and let it idle for a couple of minutes, tweaked the carb a bit and it stalled out. Now it won't start at all, just reeks of gas.

Pulled a couple of plugs again and they're now black and also reek of gas.

I'm so bummed. My previous visions of dropping a new engine in and turning the key and having utter bliss are now gone.

Didn't even run long enough to set timing which was the first thing on the list to do yesterday. It has been so freakin hot here that working on the car is a chore anyway and to have to BEG this car to run is making me slightly crabby.

Will drain gas (there's probably not much left anyway,) change oil & plugs, and try again. Another thing that sucks is I only get to putter with the car on the weekends cause I work a job that doesn't necessarily end when quitting time comes round. I'd sure like to borrow a few of you Mopar experts for about 5 hours on a Saturday! LOL!!
 
Sounds like your carb is flooded from messing with the adjustments..

set the adjustments properly, let it sit a bit and try starting again.

As for the over heating .....it sounds like you are air locked.

I always suggest installing a "flush T" in one of your heater core lines.

What doing this does is bring a closable vent to the top side of the cooling system so you can open the vent and " burp " the air out of the system as the temperature raises and you can add more water/coolant to the radiator.

what I normally do ( If the vehicle does not have flush T ) is open the radiator cap....pour my fluids in...start the car......hold the throttle at about 2,000 rpm which sucks all the air and gets it circulating .....and with the radiator cap open any of the air circulating in the stem will pass through the radiator and exit.....keep checking to make sure to add more coolant/water when needed.

sounds like a simple fix, don't beat your self up over it
 
MoparGirl said:
Changed t-stat (made sure it worked first.) Added new coolant. Plugged a vacuum leak on the carb. Pulled a plug and it was a bit lean, but nothing major. Started it up and let it idle for a couple of minutes, tweaked the carb a bit and it stalled out. Now it won't start at all, just reeks of gas.

Pulled a couple of plugs again and they're now black and also reek of gas.

I'm so bummed. My previous visions of dropping a new engine in and turning the key and having utter bliss are now gone.

Didn't even run long enough to set timing which was the first thing on the list to do yesterday. It has been so freakin hot here that working on the car is a chore anyway and to have to BEG this car to run is making me slightly crabby.

Will drain gas (there's probably not much left anyway,) change oil & plugs, and try again. Another thing that sucks is I only get to putter with the car on the weekends cause I work a job that doesn't necessarily end when quitting time comes round. I'd sure like to borrow a few of you Mopar experts for about 5 hours on a Saturday! LOL!!
Click to expand...

Your carb flooded. Make sure and fix that or you'll ruin another set of new plugs and possibly wash down the cylinder walls which is really really bad on a new engine. What adjustments did you make on the carb? If you adjusted the float levels it sounds like they are too high so screw the adjustments back in some. If you didn't adjust the float(s) it's possible you have some dirt in one of the needle and seats causing it not to seal. In that case the needle and seats need to be taken out and cleaned and make sure you have a good fuel filter before it so it won't happen again. BTW: I'm assuming you have a Holley carb. If it's a Carter AFB/Eddelbrock performer style carb the needle and seats are internal so the carb has to be taken apart to access and clean them. Wish I were close to you to help but I checked your location and I'm nowhere close. Maybe post your general location and see if anybody on the board is close so they can help. If you can't get help and to get the carb right your welcome to send it to me and I'll go through it and rebuild it and set it up for you application. You just pay the shipping. Most any carb will fit into a medium size USPS priority flat rate box so it only costs $11 to ship them. Pm me if you need that. Tracy
 
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