New build overheating
 

I have only taken my new build out once, but it overheated to the point of puking out of the radiator. When measuring the coolant dripping out, it was only at 180°. I have confirmed working 160° thermostats. Today I am going to try running without thermostats. My question is, if it is a timing issue do I need to advanced or retard the timing?

Basically everything is new
40 Flathead
4” crank
Dual strombergs
New dennis carpenter radiator
Stock exhuast

Thanks!

Re: New build overheating
 

Do you have a mechanical temp gauge if not you need one to confirm that it is overheating. Filling the radiator too much can also result in excess fluid being expelled as it heats up. When cold, coolant should just cover the tubes.

Re: New build overheating
 

If the coolant level in the radiator is anywhere near the fill neck it's too full and will push out when it warms up. You should see coolant but no higher than that. Run the stats...better for the engine for sure...and I'd use 180. I'll bet you're just fine and it's just too full.

Re: New build overheating
 

I don’t think it’s too full. Temp guage was fully pegged and it spit fluid out for a good 10 minutes.

Re: New build overheating
 

I second the 180 stats. Your engine will run a bit hot for a couple hundred miles since it is new and tight. And your radiator will find the right coolant level. I agree with everyone, it may not be overheating. You can buy cheap infrared heat guns. Use one at different spots on the engine and heads to check temps. I wouldn’t worry about temps around 200 at warm idle.

Re: New build overheating
 

Might be leaky head gasket...Check for bubbles in coolant/radiator...

Re: New build overheating
 

How long did you run it before it did this?

Re: New build overheating
 

Fritz, I drove around my block several times. Probably 3 miles or so. I’m not ready to take it on real streets.

Will check for bubbles today. Does it need to be hot for this test or can I tell when cold? After other head gasket issues when I put it together, I hope this isn’t the case.

I’ll buy a heat gun today. Been meaning to do that anyway. I think I’ll also hook up two aftermarket temp gauges I have that show what temp it’s at.

Re: New build overheating
 

I have removed stats and put them in a pan on the stove with a thermometer to make sure that they open when they should, just to make sure.

Re: New build overheating
 

Take the radiator cap off when cold and look for bubbles in the coolant as it runs. You can buy test kits that check for exhaust gasses in the coolant also. The mechanical temp gauges are a good idea. And the temp gun can help locate hot cylinders or hot spots, if there are any, and the temps of the upper and lower radiator hoses and tanks.

Re: New build overheating
 

Did that last night and all was fine. I was really hoping one wouldn’t open but both functioned perfect.

Re: New build overheating
 

My wife can't find her turkey thermometer ???

but I have one just like hers in my 1923 Ford !

Re: New build overheating
 

Did you drill small holes in the thermostats? And did you place them on the head water necks, or down the hoses near the radiator?

Re: New build overheating
 

Did you mark your crank pulley with TDC so you have an ability to determine total advance? As long as you know where TDC is, then you can always use a "dial back" timing light to figure out what your total is.

Re: New build overheating
 

Also, while I know you're on the initial stages of wanting to get this one the road - try not to boil/overheat it like you did before . . . that can be a bit hard on the block. ;)

Re: New build overheating
 

I drilled two small holes so I could wire them to the necks of the heads. That ok?

Yep, definitely not trying to overheat it! I was cringing the whole time!

Re: New build overheating
 

It could be just that it was built with minimum tolerances and is just tight. When I had the engine in my Corvette (327/350) rebuilt, I couldn't let it idle for more that 2-3 minutes or the temperature would start to climb. As long as I kept it moving it was OK. I talked to the engine rebuilder and he said it just needed to "break in". It went on like this for the first 2000 miles at which time I was ready to bring it back to him, when everything miraculously straightened out. This was the same guy who put a Hi-Flow, Hi-Volume oil pump in it that kept the pressure gauge pegged, even at hot idle. I have to think this guy was an "oil pressure freak" and built everything super tight. After it loosened up and I replaced the oil pump with a stock unit, it has been an excellent runner; plenty of power, idles and drives nice, with water temperature and oil pressure right on factory specs.

Unless you find something specifically wrong, I'd give it a few more miles. But like the man said, don't let it overheat to any extent.

Re: New build overheating
 

Yep I’m hoping it’s just new. I certainly wasn’t able to really get it past 20-25 mph in my neighborhood and I also stopped a few times while it idled a few minutes and I adjusted other things. I’ll be testing again in an hour or so. Will report back. Have a heat gun now and will be running my analog gauges to see how hot it actually gets.

Re: New build overheating
 

Re torque the heads now that you have warmed it up.

Re: New build overheating
 

Yep. I’ve re torque the heads after every time I’ve gotten it even just a little heated up.

Just drove it. I was only able to put another temp guage on one side because the cheap connector snapped in the head on the second one. So, after I got that fixed I filled with straight water and did the drive around the hood several times. The dash gauge was pegged to the hot side when the aftermarket analog was at 130 or so so there’s something up with that. I drove about 20 minutes and then it puked. Temp guage was at 190-195. Aiming my new temp gun at each cylinder (by plugs) was about the same, right around 190. I’ll drive again when it cools to see if maybe I just over filled it but how do y’all feel about 190-195 temp?