Packard Forum Index » Pre-War (1899-1942)

My 1941 120 is continuing to overheat somewhat quickly, in spite of having completed the following:
1) flushed the system, including removing the plug from the rear of the block.
2) the radiator was removed and completely rebuilt at a competent radiator shop. The shop did tell me the radiator was flowing poorly and had numerous leaks following their “shop cleaning”. Thus, I am confident the radiator needed this repair.
3) replaced thermostat with a 160 degree NAPA thermostat. I did confirm the new thermostat was opening at the correct temperature, before I installed it.
4) I did not replace the water pump, but the shaft seemed tight and there is no leaking or noise from the pump.
5) the engine starts easily and runs very smoothly. Thus, I am assuming the water pump is not the culprit.
6) coolant is clearly circulating as the radiator becomes very hot, after the thermostat opens on a cold start.
7) I did not remove any of the “freeze plugs”, during the engine flush.
The engine was overheating rapidly, prior to the above repairs, and I am not sure that any of the above has made a major difference.
I currently have the hood removed and have only let the engine idle in my garage, since completing the above repairs. I am assuming this is not the root of my issue.

I am at a loss as to what to try next?

I would appreciate any thoughts or experiences of others.

Thanks
Jim

Other culprits in no particular order:

Partially plugged exhaust
Incorrect timing
Partially plugged water distribution tube
Water pump impeller clearance too large causing cavitation
Lower hose partially collapsing internally
Blown head gasket leaking combustion heat/exhaust into the coolant

I've had a car with a blown head gasket do the above. It ran like nothing was wrong, but would overheat eventually. It basically pressures and heats the coolant, which then causes the coolant to boil over, loosing coolant. Which then makes it over overheat even futher.

Is it actually boiling over? Never trust the gauge inside the car. Use one of those IR (laser) Thermometer to check the temp at both the front and rear of the engine, and top of radiator.

If the back is significantly warmer, that usually indicates a plugged water distribution tube.

Thank you for your thoughts.

The radiator becomes very hot, within just a few minutes of idling, and coolant is being pushed out of the overflow in a somewhat steady stream. I have not permitted the engine to reach a full boiling over, but I believe I am quite close.

I will use the IR heat gum today to check temperatures at the locations you suggest.

A follow up question:
Is there a written procedure, or can someone describe, how to access and remove the coolant heat distribution tube? The manual provides little insight, and I am wondering how much of the engine and other components need to be removed, eg does the radiator need to come out and/or do any of the body components require removal?

If the tube is beyond repair, does someone sell a replacement?

Also, I am assuming a compression test may tell me if I have a blown head gasket? There is no obvious steam or smoke coming from the exhaust …..I have blown a head gasket in a modern car and I am familiar with the sea of steam/white smoke that results from this.

Thanks for additional insights.

Jim

Do you fill the radiator to the top? If you do, some coolant will be ejected as the engine warms up.
Be sure it is actually overheating. It is normal for the engine to get hot, and 170 to 190 F is normal.
A modern thermostat may not work well with the pre-war system.
If the radiator shop told you the radiator was flowing poorly AFTER cleaning, it may be the culprit.
A product called Thermocure may improve the situation. Use exactly as directed.
If any loose debris remained in the engine after flushing, some of of it may have got into the radiator, It takes very little debris, like rust flakes, to restrict radiator flow, especially if it is already partially clogged
As suggested above, be sure timing is correct, and be sure the fan belt is doing its job.
Many Packards used a honeycomb type radiator core, and they can be very hard to clean out.

As to detailed service and removal instructions, about the only halfway decent writeup in a service manual on servicing the tube that I can remember seeing is in the 51-4 radiator and cooling section. The info is basic and shows the engine out of the car. One bit of caution: The article shows using a wire hook inserted iin one of the cooling holes to pull the tube out. In long time unserviced tubes there is a good chance the tube will be stuck in the block. Start trying to pull very gently because if you go in and pull hard on a stuck tube with just the wire it will most likely only result in a torn hole. If it doesn't seem to want to move you may need to use a long very thin stiff piece of metal such as a broken bandsaw blade to work down and around the outside of the tube to break up packed debris or calcification. Hopefully yours is still the original brass tube because a scarier situation is if you find someone installed one of the cheap aftermarket steel tubes that has now rusted into pieces.

As far as detailed info on what body items need to be removed, I don't think Packard ever wrote anything. Like so many of their early service articles and procedures, they only covered with any detail a completely new procedure.. If a new model year service operation was still similar to earlier models it was down to the mechanic to figure out what he needed to do or change for that car. Obviously the water pump and radiator is removed on all models. From there, since the tube length is just short of the block length it is dependent on year and model and how long of distance between block and opening for a straight shot out of the block is available. The tube is somewhat fragile and does not bend so needs to be almost all the way out before it can even be angled slightly..

As to front of body clearance, I believe all prewar models and some postwar cars with the narrow vertical grille openings will need the grille or front clip removed. You could lay a straightedge on top of the head above the tube opening and extend it out to verify if there would be any side clearance at the grille opening. When it comes down to exactly what to remove at that point, several on the forum have said on prewars it is easier to remove the front clip than trying to just do the grill but I don't have experience on those years to say.

I have not tried to buy a tube in several years but I believe there have been some recent posts on the forum saying the posters were able to get one from Max Merritt. No idea what the Kanter situation is since the change in ownership but also worth checking.

Head gasket leaks can be difficult to detect.
Older Packards do not cool well when idling, at best.
If you have an accurate heat gun, checking the temperature at the point where the water enters the upper tank should give you an idea of what is going on. Check a metal surface, not the hose. The temperature ought not be over 200 to 205 F at that point after driving the car a few miles.
When filling the radiator cold, leave about 1 to 1 1/2" of space above the water level, then run the engine until the thermostat opens, then stop it an let it cool. Then re-check the water level. If it is about where it was, put the cap on and go drive the car. I'd carry a few gallon bottles of water, just in case.
Be sure the radiator cap is the correct one for your car.

Quote:

Lots of good suggestions have already been shared, but I'll add my two cents. It would be good to have more details about how hot it's actually getting. For example, from cold, start your car and record times and temps at several points such as, top and bottom of rad and front and back of engine.

When did this start? What lead up to this becoming an issue? Did it slowly get worse, or appear suddenly? Do you think it's better since getting the radiator repaired? It may be hard to know without having measured temps before and after in a similar manner.

After reading your feedback, it sounds like a circulation issue to me. Considering what you have already done, it would seem that either the pump or distribution tube would be the culprit. And given that your rad had low flow issues, maybe the distribution tube is suffering the same. What did the rad shop find was plugging the rad? If the distribution tube is plugged maybe the flush you did wasn't able to clean it out? Did you find that the flush cleaned anything out? Rust? Calcium build up? Other?

If you have a flow issue caused by a plugged distribution tube I would expect the rear of your engine to get hotter quicker than the front. Once the thermostat is open and you can see coolant is flowing through the rad you should be able to increase rpm a bit and note some increased flow if the pump is pumping and things are reasonably clear.

If you're concerned it might be a bad head gasket you should be able to tell by pulling your spark plugs and inspecting them. One of them will be different, steam cleaned so to speak. There could also be signs of coolant in your oil and oil in your coolant.

Post some more info when you can.