Overheating

[Daba]

I took my 30 tutor out for a maiden voyage idling in the driveway it does not overheat at all. I took it for a short drive about a mile and a half and on the way home it overheated. I opened the pet cock after the motor cooled and flushed the radiator for about 20 minutes with the car running then I replaced the cap let the car run another 20 minutes or so and had no issues however, I went for a ride on the same trip about a mile and a half it overheated again. The car is new to me and I just did a complete tuneup and set the timing. It runs really great except for the overheating. Any help or suggestions would be fantastic thanks Daba

[WHN]

Check your timing again. You could have it too retarded.

How far down are you placing the advance lever when you are driving?

I just sold a Model A, and the new owner had the same problem. He was not advancing the timing enough. Car was firing while the cylinders were going down. Explosion charge was still burning on exhaust stroke and going out the exhaust valves. Exhaust manifold will get really hot, and your car might also back fire.

Good luck.

[Daba]

I put the lever all the way down there was no backfiring but once it overheated there was a definite lack of power. I will recheck the timing this morning. After I recheck the timing I will take it for another ride and possibly not put the lever down so far to see if that helps.

[LeonardS]

Are you sure it was overheating or did you overfill the radiator and it was burping out the excess?

[Patrick L.]

These monsters tend to block up the radiator after decades of use/misuse.

It's easy to remove the hoses and back flush the radiator and block. The rear portion of the block fills with rust/crud and the rear cylinders can tend to run hot. This isn't hard or too time consuming. I'd rather try the flush first than to just replace the radiator. If you're like me though you'll get wet.

[rotorwrench]

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Setting the timing in only a task of adjusting the timing to open points with full down spark lever at top dead center on the #1 cylinder's compression stroke. The actual adjustment of running timing is the task of the operator. After start, the usual setting is about 1/4 of the way down the quadrant at idle. Full advance is around 3/4 of the way down the quadrant. A person is going too far if they adjust the spark lever to full down advance during normal road speeds. Some engines need more or less advance depending on condition of the engine or compression ratio on those engines that have been modified with high compression heads.

Overheating can also mean problems with cracks inside the combustion chamber, a leaky head gasket, or blockage of the tubes inside the radiator.

[GeneBob]

I had a similar problem with a modified engine setup. Turned out to be lean at higher RPM. AFTER rechecking your timing (making sure the lever is all the way up when you set the timing to TDC). You might want to make sure your carb is not dirty and going lean at higher RPM.

[Daba]

The motor was rebuilt several years ago and never driven until now so I don’t think it’s a motor problem. I just re-timed it again and took it for a short ride, with my point and go thermometer it said the top of the radiator was 156° and the bottom was 158° It did not overheat that I could tell. I will take it for a longer ride when my wife is able to follow me in the event that something goes wrong. If it does overheat again I will definitely pull the hoses and try to flush the motor and radiator a little better. When I opened the petcock and flushed it earlier I did not see any chunks of rust come out but the water was rusty I do not want to put in antifreeze and have it all boil out I’ll let you know how I make out later this afternoon I will take it for a little bit longer of a ride thanks for all your help.

[Big hammer]

The radiator ISN’T cooling! You should have a drop of 20-30* between the top and bottom

[WHN]

Originally Posted by Daba

The motor was rebuilt several years ago and never driven until now so I don’t think it’s a motor problem. I just re-timed it again and took it for a short ride, with my point and go thermometer it said the top of the radiator was 156° and the bottom was 158° It did not overheat that I could tell. I will take it for a longer ride when my wife is able to follow me in the event that something goes wrong. If it does overheat again I will definitely pull the hoses and try to flush the motor and radiator a little better. When I opened the petcock and flushed it earlier I did not see any chunks of rust come out but the water was rusty I do not want to put in antifreeze and have it all boil out I’ll let you know how I make out later this afternoon I will take it for a little bit longer of a ride thanks for all your help.

Water is a better coolant than antifreeze. I am not saying to not use antifreeze, just mentioning that there is a difference.

I like your bottom radiator temperature. I would question why the top would be cooler? I don’t know how the radiator could add heat.

The Model A has a syphon cooling system that is aided by a water pump. Unlike modern cars, the water pump was placed at the out flow not the inflow of the engine. The syphon moves about 30 to 35 GPM when the engine is fully warmed up. Normal running temperature at front of engine is about 165 degrees. Your 156 degrees at top of radiator would make me happy.

Keep us informed. Enjoy you new car.

[jeepguy1948]

I'm not saying that I am certain that it is your problem but the plain truth is that the radiator can get clogged up beyond the point that flushing will fix it. It has happened to me and there is nothing you can do but replace it or take it to a good, old school radiator shop (which of course are getting harder and harder to find). There is a test that you can do that goes like this... Fill the radiator, disconnect the bottom hose, time how long it takes to drain. If it is clogged it will drain slower. The only problem is that I cannot remember what time is ok and what time is not but I'm sure 10 people will respond to this with the figures. Let us know how it goes.

[Certimafied]

I agree with Big Hammer your radiator isn't efficient enough, Its blocked somehow.

I had a very similar thing as you with my 28. Could idle it all day with no issues temp was on the money. After about a mile of running it would want to get hot. My water pump began seeping too (unrelated to the overheating but a problem none the least) while I had the radiator out to do the pump I back flushed it and found the tubes were clogged internally by some sort of sealant or something. Anyhow she runs just right even in the 90+ temps we've been having here.

[burner31]

I thinking along the lines with rotorwrench (post #6), in that it is more of a operator issue with setting the spark lever while driving, that is something that comes with finding the right lever position for your driving condition, trail and error and persistence are your tools.
But of course continue on the radiator, run vinegar for about a week, and do not forget to flush well and then again with a full box of dissolved baking soda before your final fill'

[1931 flamingo]

Pick up a point and shoot temp gun at Harbor Freight and ck themp at top and bottom of rad before you do anything. JMO
Paul in CT

[ETAModel]

One more thing to consider. If your motor is running too lean it will overheat. It took me a while to find the happy place on my GAV to keep the water from boiling out. About 1/4 turn off bottom works for my Fordor. Also had to get used to not filling the radiator over the top tubes, or expansion will make it throw water on my windshield.
Good luck.

[nkaminar]

Radiator: It should dump all the water within 2 to 3 seconds. Take bottom and top radiator hoses off and block the bottom with a rubber ball or something. Fill radiator and remove ball. It should empty within 3 seconds.

Thermostat: If you have a thermostat, remove it for summer driving.

Timing: The trick is finding the knee in the advance curve. That is where one click further advance will not improve engine performance and one click retarding will hurt performance. The optimum timing will change depending on conditions, such as pulling a grade.

Fuel Mixture: The engine will run hotter when lean. The fuel/air takes longer to burn. A little bit on the rich side will allow the evaporation of the fuel to help cool the engine, like your body cools with sweat. Too much rich and the engine will again run hotter because again the fuel/air takes longer to burn. Open up the GAV until the engine starts to run rough then close it down just to the point where the engine cleans up.

[Daba]

I did take it out for another run and it seems fine now I did take the advice and not overfill it which I tend to do. I did reset the timing but didn’t notice much of a difference and it’s running performance I think I was pretty much spot on before. I did adjust the gav and retarded the timeing a bit that seemed to work I am on flat Road no Hills. I will venture further on a daily basis hopefully the problem is solved. Thanks for your advice and look forward to asking more questions soon. Thanks Daba

[1crosscut]

Daba since this is a rebuild that hasn't been driven until now check the torque on the head nuts and make sure they are at 55 lbs. A "fresh" head gasket install will need to be re-torqued several times until it settles in and stays at 55 lbs. If the torque is low it quite possible you are pushing combustion gases into the cooling system when warmed up and under a load. It will look a lot like an overheating issue.

[jack backer]

Engines need to break in friction rates on a fresh rebuild can be high. run it awhile before doing anything drastic.

[Smokedtires]

I just experienced the same thing I my maiden voyage. Engine rebuilt, 33 miles on it. Overheated at idea and while driving. New radiator is ordered. Pulled old radiator and noticed I didn't have a thermostat either, so ordered one of those as well. Good luck, hopefully we'll be back up and running soon.