Packard Forum Index » Post-War (1946-54)

Since it looks like a rebuild is in the works the next concern is the cooling system.

Does the Packard have a fan shroud?

All this car has is the "core support" and a shroud in front of the radiator.

In the past the temp gauge would show very hot in traffic, especially after cruising and then slowing down to a stop.

We would run a infrared thermometer at the water neck when the gauge showed too hot and it only showed 195 F but who knows how accurate that was.

The radiator was cleaned out and when I disassembled the engine the cooling system looked clean.

Perhaps it was the gauge itself that was showing too hot???

My plan is to boil water and then run a ground wire to the sender and stick the sender in the pot of hot water and then watch the gauge indication and record the gauge indication and compare it to the actual measured temperature in the pot as the water cools.

I guess I should check the thermostat for proper opening as well.

Of all Packards the 22nd/23rd series 8s and Su8s (not the Customs) seem to be the most critical with regard to the adequacy of the cooling system as they get older.

1. No fan shroud.
2. If it really is running hot (more than 10-20 degrees over the thermostat value), then I'd suggest:

a. Simply cleaning the radiator isn't adequate, you should have a gravity flow-rate test performed.
b. Pull the water pump, check the impeller clearance.
c. Remove and clean the water distribution tube.
d. With the tube out, and possibly one or more core plugs removed, physically clean as much of the water jackets as you can, followed after reassembly by the traditional oxalic acid cleaning regimen.
e. Check all of the other things that can be associated with overheating such as blown headgasket, retarded ignition timing, restricted or undersized exhaust components, weak (soft) lower radiator hose collapsing, dragging brakes, incorrect fan belt width and adjustment, lean mixture, vacuum leaks, fan-to-core clearance, etc.

No factory shroud although there have been some fabricated by owners and one aftermarket "one size fits all" type frequently found on ebay, Little late now but I'd be curious how far your fan normally sits from the core. Most are less than an inch but some models were quite a bit farther away. Another common problem is the water distribution tube. Make sure it is clean and in good condition -- also water pump impeller is tight and nothing worn to create large distances between it and the pump casting and cover plate.

IMO, it would be a good idea to change the thermostat if it is the old bellows type. They are inexpensive enough to just change it even if not that old. You can then make sure it is the correct one or even select a cooler temp range. Standard was 160 but Packard offered a lower temp of around 150 and higher around 180.

The thermometer could be an issue. The electric type can drift and also read incorrectly if rust or grease interferes with ground to the sender. Bad or dirty connections elsewhere can also affect the reading. Believe that particular sender is the long bimetal type rather than a short pure resistance type. If so you will not be able to get a good resistance reading since it is basically an on/off operation. The water temp and a heater affects a bimetal strip in the sender which changes the frequency of the on/off. The on/off time allows the gauge bimetal to heat or cool and determines how far the needle will deflect.

Sometimes having a mechanical thermometer permanently installed and hidden is an advantage to double check the electric. Unfortunately there is no easy way to install a second sender unless it is in a radiator hose or an adapter is made to go under the thermostat housing.

EDIT: along with O_Ds recommendation on the radiator gravity test is a question of is the radiator itself correct. Is it the original? One poster had frequent and longstanding issues with his 56 overheating. Had done everything recommended and possible to find the problem and was finally contemplating getting an oversize radiator made. Upon opening the radiator the shop found that at some time in the cars past someone had replaced the original radiator core with one considerably smaller. Haven't seen any recent posts from him but last I heard a correct radiator solved the problem.

Very good suggestions. I will use it as a checklist when I put the engine back in.

THANKS!!!

Bill

What is the Water Distribution Tube???

I looked in the water jacket after the water pump was removed and I saw a copper or brass "thing" in the water jacket.

Is this what you are talking about?

What does it do? How do I know if it is installed correctly???

As always...THANKS!!!

Bill

Many flathead inline engines had a water distribution tube.

It is nothing but a plain metal tube with strategically placed holes. Cooling water goes into it from the water pump and gets distributed to each cylinder evenly.

Without the tube, all the coolant would stream straight up into the upper rad hose without cooling the engine.

Do you have an infrared temp sensor? You can get them at hardware stores for $30 or so. Check the temp of the engine in various spots. The front of the engine should be the same temp as the back. If the front is cold and the back is hot, the tube is rusted out.

Most times they were made from galvanized steel but some were made of brass. The brass ones don't rust out. I believe the brass ones were made for marine engines.

Packard water distribution tubes are brass, though some aftermarket replacement ones (Dorman, for one) were galvanized steel. Chrysler also used steel in their flathead 6s and 8s. So unless it was replaced at some time with a steel tube the end won't be rusted away, but it can be packed with debris such that the last hole or two that directs cool water to the exhaust valve seat area will no long function; typical end-result if the situation is allowed to persist is overheating, especially at the rear of the block, and a cracked block at the exhaust valve seat spreading often to the cylinder wall. Thus the reason why it's suggested to remove and inspect it, and clean if needed.

It can only install one way.

Normally I learn at least one thing new every day. Since I was introduced to PackardLand...I am learning MULTIPLE new things every day.

This forum is great. THANKS ALL!!!