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paulg3@sbcglobal.net

I am having a trouble similar to what Owen wrote about in July 07 Forum. The car generally runs normal, but spikes to high after about 10 minutes idling. It will then cool back down at normal driving. I just had the radiator re-cored with a new 4 core. ($575 for core , $75 labor to re-install, antifreeze, test, ect. 684.50 total "ouch").
The new radiator seems to have remedied a boiling over problem and hard restart when the engine is hot.

The radiator man said the thermostat was either removed (before I got the car) or is stuck open. Will a new themostat help?

A friend thinks that the brass tube is clogged, and that the temp gauge is spiking because the coolant is not reaching the rear of the block where the coolant gauge pick up is. How do you test that the tube is blocked?

( I may invest in a digital themometer on sale at Sears this week for $59)

Did Owen find any other answers last year?

Despite all that you've been thru, and much, much more, we've never found the problem with overheating in that 23rd series Eight, and the owner has reluctantly ordered an electric radiator fan. I hate to see this because it's just masking the fundemental problem, but we finally just ran out of ideas and patience. The owner thinks it may be from a shifted core when the block was cast, and I don't have any experience to either accept or reject that hypothesis.

But it's an excellent idea of check your water distribution tube because if clogged, it does indeed restrict cool water flow the the rear exhaust valves seats (which can lead to cracked engine blocks) and the temperature sending unit. Unfortunately for you, the time to check it was before the radiator was reinstalled because to get it out you have to remove the radiator and water pump. But I'd still do it, removing the radiator isn't fun, but isn't all that bad either. If the front engine mount has deteriorated much, you may have to put a jack under the oil pan and raise the engine a bit to get the lower waterpump bolt out. Then with the pump removed, use a hook or piece of coat hanger wire to pull the water distribution tube out. Inspect, clean or replace as necessary, and I'd further suggest that while the pump is off, you remove one of the rear core plugs and blast the water jacket with a hose and nozzle in hopes of removing any built-up sludge.

Other things we considered and some of which we checked include cracked cylinder head or block, blown head gasket, faulty gauge or sending unit, undersize exhaust or tail pipe or overly restrictive muffler, fan belt too small and bottoming out in the pulley rather than gripping the flange sides, and more.

The Custom 8 used a much more efficient fan with 5 blades; don't know if it will fit and have clearance, but the hub on the water pump shaft is larger so you'd have to change that to try it out. How far is your fan blade from the radiator? His was quite far compared to other cars we looked at and measured, more than 1-5/8 inches, and we considered making a spacer to move the fan closer, but did not do so. I still like the idea.

On some of our recent 92 degree days, in single-lane construction traffic, my gauge reads up to "just below" the Hot mark, which I am pretty pleased with.

My 22nd Series 288's fan is less than 1/2 inch from the radiator. I've thought about mounting some sort of shroud on it, but have lately decided that I'm probably OK.

I have just changed from a 180 to a 160 degree thermostat which brings the normal operating temp down to just above middle on the temp gauge. The 180 degree thermostat had been maintaining it at close to the Hot mark at all times.

Jay

Thanks Owen and Jay. Do you think a new thermostat would keep the engine cooler when iding?. I don't quite understand the purpose of the themostat other then helping with heat in the Winter. The man who installed the radiator said it was either removed or stuck open. Do I have to get one from a Packard supplier (Kanter or Mirratt) or can I go to Autozone or the like?

I just bought a infared thermometer on sale at Sears.

You can pick up a thermostat locally but if the retainer ring was removed with thermostat and left out then that will probably be a vendor item or also available from SoCal region of PI.

I'm sure you know all of the following and have already checked them. But, just in case.
1. Check the heat riser on the exhaust manifold. Is it stuck closed or partially closed?
2. Check the ignition timing. Packard 8s have a tendency to run hot if it isn't correct.
3. Check the water distribution tube. Is it plugged, crushed, or rotted?
4. Rebuilt water pumps sometimes have the backing plate that is not smooth. If it isn't, water cavitation can occur and the efficiency of the pump is reduced.
5. Use an original Packard water pump. Some of the after market pumps are not quite the same as the original and are not as efficient.
Good luck with solving the problem. I hope the above helps.

I installed a 160 degree thermostat today and it seemed to help. The temp gauge didn't spike to hot at idle like it did before. The thermostat had in fact been removed when last serviced before I bought it. I'm glad someone pointed out about the retaining ring because I then knew to look for it. Thankfully, they left it in the outlet so I only had to get the thermostat itself. I went with the 160 degree at Jay's suggestion, and also the AEA tune-up sheet I downloaded said that it could open at 148 to 156 degrees.

It was only about 80 degrees here today, but it ran just a little higher then center on the gauge, came to normal at about 40 mph, and I let it idle for 10 to 15 minutes after it was hot and the gauge only went to about halfway between center and hot. It cooled back down to center after driving a bit.

We'll see what happens on a hotter day, but at least
I had no problems with hard restart when it was running a while.
Thanks again for all your interest.

Great news! Sounds like you're now having the same experience as I am with temperature.

I've heard, but don't know, that it makes a difference having the thermostat in place beyond what you'd expect the thermostat to do. As, I'd expect having NO thermostat to make the engine run as cool as possible at all times. It seems to not be the case, and I'm not sure why that is.

Maybe that's just urban legend. But I know my car ran cooler after installing my thermostat.

On another site some time back several theories about the reason thermostats helped cool were thrown out for discussion. IIRC a couple that got the most agreement were:

1. The thermostat adds a restriction that slows the coolant and keeps it from swirling and leaving "empty" areas in block so it can better pick up heat.

2. The coolant flow is slowed through the radiator allowing heat to transfer more effectively.

To back up that claim, instances of washers instead of thermostats placed in outlets were cited.

I wouldn't know if either is the answer or even plausible but am sure some of the guys versed in thermodynamics can shed some light.

I've heard the same thing. Cooling systems are designed with the restriction of the thermostat as part of the system. If the thermostat removed, it can result in LESS cooling efficiency.

I suspect the cause is cavitation in the water pump. Cavitation occurs when there is a low pressure area, allowing air bubbles or steam bubbles to form.

This is an important factor in the design of boat propellers. Cavitation can reduce their efficiency markedly. The bubbles can even eat away the metal of the propeller.

I have seen the same eating away of the surface inside water pumps, as is seen on propellers.

The thermostat or washer, provides a certain amount of back pressure on the system which prevents cavitation and maintains water flow under all conditions.

So usually removing the thermostat will not reduce temperature. It will only take longer to overheat. And, it could even make the overheating condition worse.