VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1937-1945 38 Generator, plus

I burned up the generator today.

I had installed the new choke knob and cable and thought I would fire the thing up and see if the knob worked and confirm that the hot air bypass closed when the car got warm. It had not been closing at all and I thought that might be the cause of my running hot problem. I wound it up and got it so that it would open but I wanted to check on when it was opening.

It started up fine so I got out of the car to look at the bypass valve. I noticed a light shooting out from near the front of the engine but I caught it out of the side of my eye so I thought it might have been the reflection of the sun off a car in the street. It seemed odd to me but there were sparks on the commutator at the brushes that I hadn’t remembered seeing before.

I got back into the car and pulled the throttle out a little to speed the heating of the engine and the valve. When I got out to look at the valve again, I saw a couple of sparks shooting out of the front of the generator, right near the pulley. I thought that the bearing had gone, so, angry, I shut the car down and went to clean the family room.

After the car had cooled down, I went back to the garage and took the generator off and apart. Several of the windings on the armature had been bent and cut, the covering on the field coil was gone on the back end of the generator and there was a fine powder (assumed to be the field coil cover) several places in the generator housing.

Fortunately Skip advised me years ago to buy as many engines as possible so I have a spare generator. The question is, when you mount the new generator do you short the generator to the battery on the regulator before or after you connect all the wires to the generator?

Sorry it took so long to get to the point, but I’ve had a bad day….

Thanks,

Brian

Before you start the engine jump between the Bat. and Gen. terminal on the regulator.Just enough to cause a spark.They are the terminals towards the engine.

"Hot air by-pass"..I assume that you are refering to the heat riser.If the thermostatic heat riser spring is functioning correctly it will never allow the heat to open the heat riser by just running the engine.It may relax a bit but not open unless you would place the engine under power.It will open when driving as it gets hotter then and the exhaust pressure will force it open.

Smile - it could be worse :)

Did you correct your overheating problem?

I had a simular problem with the generator on my '34 years ago.We were coming back from StLouis and the generator quit generating around Rockford.When I took it apart I found the rear bushing ground up and the armature hitting the fields.The bushing had not been recieving any lubrication because the felt wick that the oiler "oils" had turned to stone and prevented oil from reaching the bushing.I had rebuilt the gen. years before but never opened the plate on the rear of the end frame to inspect.

If I slip the thermostatic spring off of the pin it will be about a quarter turn out of position on a 75 degree day. I've noticed that when the engine is warm, moving the valve will effect engine performance.

If my engine is running hot then it should also open. If I can almost melt the engine and that valve stays closed, something is wrong. I think that the valve should open under normal operating conditions but the question is what temperature should be measured that tells you the valve should be open and what is that temperature?

I haven't exactly solved the heat problems. When the engine runs it seems okay but when I stop the heat rises and there are gurgling sounds inside the engine. Sometimes there will be a momentary overflow between half to one and a half minutes after the engine has stopped. It never has overflowed when operating.

Right now it seems to be running cooler but I'm still not happy with it. When it runs hot it isn't repeatable so I can't tell if what I am doing, which isn't much, is having any effect or its some sort of random thing where the engine overheats on it's own volition.

Thanks,
Brian

Have you had the radiator looked at?

I haven't taken it out, I used a thermometer to check the temperature of the radiator and it is relatively consistent across the surface horizontally and changes vertically. That indicates that it is flowing through the radiator okay and I'm getting good transfer. I think the problem is in the engine, something is either not set right or I installed it wrong. If the radiator were bad the engine temperature would just rise until it got too hot. It's only when I turn it off that I have a problem.

The question is, what temperature is that thermostate supposed to open the heat riser valve? All my manual says is it will open "as the engine is warms up".

Thanks,

Brian

Answer to question - when the manifold gets DARN hot...for lack of using the other D word.As I mentioned just allowing the engine run with no load will not generate enough heat to open the valve.In the winter it may not open at all with the cold air blasting on it.After driving the car at 40 MPH or so for 20 minutes in warm weather it should be open except may close slightly at idle....open at higher engine speeds.The valve is hinged off set so the exhaust pressure helps over come the spring tension so as to open it when engine is under load.

There is no given "off and on" temperature.Depends on outside temp, manifold temp. and exhaust pressure.If you think its causing other engine problems wire it open and try it.It will not cause the engine to over heat unless its stuck in the closed position.Then engine could over heat under extreem load and speed conditions as it. the heat riser. over heats the incoming mixture and the engine would run lean

Chev Nut is absolutely correct! I installed a new old stock thermostatic spring on my manifold heat riser on my '51 Chevrolet several years ago and it performs exactly as Chev Nut described. The heat riser on my car will never open at idle, but after I drive it at highway speeds for awhile then it will open.

:)

They done said it again folks!! All I have found that needs to be done is be sure the flapper and weight work freely and the thermowhatamacallit spring is on , I have freed up several on cars that had been running fine, probably for years, most were frozen closed.

I think a lot of us worry too much, If the car isn't loseing a bunch of coolant (use a 50/50 mix of coolant and h20) and isn't steaming out the overflow and the heat gauge is around mid scale or just a little over, and don't peg out you probably just need to drive the car more.

To insure the car don't get hot just carry 2 gallons of premixed 50/50 coolant in the trunk,it will cause the engine to run cooler.

My stock "38" would dribble out the overflow after shutting the car off. I lowered the level of the coolant in the rad. an inch or so, and no problems. Mac

NOW I understand!! It's Darn hot. That's probably a celsius number, I think I was sick during that class....

I lowered the coolant level but the pump moves that stuff through the engine pretty fast and it looked rather violent splashing around the lower I left the coolant level. I think everything might be okay for now. It does stay about 190 while driving and even at hot idle it will only climb to 200 until I get going again. It just seems like there must be a part of the engine that is about to go subcritical and is completely untouched by coolant while driving, then I stop, the coolant rushes in and the boiling begins. IT just doesn't seem right, that's all.

Also, I don't trust any replacement parts made now, such as the thermostate. The only part that fit correctly was the Hampton coach interior, every gasket, seal, or other was to short, to thin, or the wrong material and didn't fit up at all like the original.

Thanks again,
Brian

Brian
Unless you have a coolant overflow bottle and appropriate radiator cap the radiator will always be about an inch below the filler neck. This is mainly due to coolant expansion under heat.
On systems without the overflow tank I dont fill above this point as it a waste of time and coolant/water (which is a very scarce commodity here).
As for the flow rate, if the engine was hot when you looked it is not surprising as the thermostat would be near full open allowing close to full flow but if engine was cold (you can still hold the lower thermostat housing) get a new thermostat as there should not be much flow at this stage.
Tony

Yeah, a new thermostat is in order, go to a parts store, NAPA is fine and tell them you want a 160*F thermostat, (this is a one sixe fits all item the same theomostat will fit a Crosley up through a Cat diesel, the Cat diesel may use two side by side.The parts store probably will only have a 180*F, but that is ok your heater will work better.Just remember that water boils at 212* and freezes at 32*F a 50/50 mix of water & coolant freezes at below -30* and boils around 240*F+ (in bad water country I use distilled water, it is still cheaper than beer) and Mr Goodwrench coolant, Zerex, Prestone, Peak or any Ethyleneglycol based anti-freeze & coolant. I don't use the already mixed stuff, I use my own water, nor do I use the newer GM red antifreeze in the old cars with copper radiators.If your car engine was cooled for years with well water, pond water, windmill water, tap water and no coolant with corrosion inhibitors the water jacket may more than likely be full of rust and crud, which will flow over into the radiator and plug it up.

Mr Mack is right about the coolant mix but most of the brands he mentioned I have not heard of. Definitely use the ethyleneglycol based concentrate and make sure it has rust inhibitors in the mix are suitable for copper cored radiators (a lot of radiators are alluminium these days).
Dont use more than 50 /50 mix and not less than 30% coolant. A excess of coolant can be just as bad as not enough, the coolant will cause corrosion in a overdose situation.
Tony

I measured down to the coolant and it is at least a inch below the bottom of the fill nozzle. I ran it again last night and everything is fine, temp between 180 and 190 until I shut the engine off, then it climbs to 212, the engine seems to gurgle and in a about 30 to 90 seconds there are bubbling sounds, one every 10 seconds or so, coming from the radiator. It didn't overflow though.


I tightened the tension on the heat riser spring, but only a little. It still opens at between 1/2 and 3/4s of Darn hot. The manual states that over tight causes poor performance, it doesn't say anything about under tight.

There is a local cruise Friday night, I think I'll take it there and see how the engine does.

Thanks,
Brian

I think I'm running about 30% now. I back flushed the engine and radiator and lost a little due to an error in volume of my recovery vessel.

Thanks,
Brian

You still have a cooling problem.The gurgling should not be heard unless you were driving 70 MPH on a 100 deg. day and then shut it off.

And, 180 to 190 degrees while driving is too hot as well.

:( :( :(

If you were forced to guess, what would you say the gurgling is and what is the cause.

Brian

I would guess the cooling passages in the block or head are restricted or blocked somewhere. When you turn off the engine it stops the flow and the block raises the reduced coolant temp to 212 and it boils. The only place it can go is the rad.

The water jackets are probably loaded with rust.Would be neceaasry to remove the side freeze plugs to check.The rust was over 3" deep in my '39 engine.Never caused it to overheat but the block finnaly cracked in that area.