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

I have a '52 327 completely rebuilt. Radiator is like new, fan is fine, 160 thermostat, timing set correctly, reman. waterpump with correct belt tension.
But I'm still overheating. I can idle the engine indefinetly but after a few miles of regular driving the guage goes to 200+ and it boils over. I drove it in a parade over the weekend, it idled along fine (guage reading 160 +or-) but when I drove home just 3 or so miles it boiled over.
When I installed the waterpump I saw the end of the distribution tube but was unsure at the time of its purpose and did not remove and clean it.
The tube appeared to be just that, a tube. It did not look as though it had two sections to allow water to flow to a certain part of the engine first (ie. the back).

Question 1:
If it were marginally blocked would the result be what I'm experiencing?

Question 2:
If I were to remove it completely what would be the result?

Thanks in advance,
Joe

That is a really severe condition, can't say I've ever encountered that one before, at least not to that extreme. I suspect something is restricting the higher volumes the pump puts out at higher engine speeds. I suppose if the water distribution tube was more than marginally blocked, let's say severely blocked, enough water might pass thru to cope with the pump volume at idle, but at higher pump speeds (road speeds) and consequent volumes it was unable to handle the larger flow volume. Thus you might have the same coolant volume flow at idle as you had at road speed. So the answer to question #1 might be "perhaps".

Answer to question #2 is that you'd likely run the risk of a cracked engine block at the exhaust valve seats on one or more of the rearmost cylinders as the cool water flow would tend to take the easiest exit first, that being from the most forward cylinders.

It's a good practice and should be a standard practice to remove and examine the water distribution tube whenever the pump is removed. You should of course do that, but I have the feeling there may be some other culprit at play here. When you say the "radiator is like new", just what do you mean? It "looks like new"? It's been boiled and flow-rate tested? It has a new core? I'd be inclined to consider a partially restricted radiator as a prime suspect.

Somewhat of a lesser possibility is a restricted or soft radiator hose that collapses and restricts flow at higher engine speeds. This is why many cars used coiled springs inside the lower radiator hose to prevent it from collapsing at higher suctions.

If your pump is somehow modified and hi flow, get a hi flow 160 thermostat. They resist the high pressure trying to close the stat, had that problem on a pontiac V8, don't know that the coolant flows the same way here.


Also, you could be looking at a fuel/exhaust issue here? Exhaust too small or maybe your cruising circuit ion the carb is too lean? If the idle was adjusted correctly you'd stay cool but once you started driving on the cruising circuit, if it's not jetted properly or you have some sort of vacuum leak, you'd run lean which equals hot in a hurry.

Good thought on the overly-restrictive exhaust system, every so often that's the culprit.

Just a thought, The drop on the radiator cap could be wrong. Don't remember what it should be but you can measure the radiator neck. With cap removed,of corse, measure the distance from the top surface of the filler neck to the surface inside where the cap is supposed to seal and compare that to the cap. You may find out that the cap you have may only measure 3/4" where the filler neck measures 1 inch. It would be like running the car with the cap removed. When I got my car the cap was wrong which caused pretty much the same thing you are experiencing.



Good Luck

Note: the engine may be boiling over and then overheating not overheating and then boiling over. That statement should generate some discussion.

Quote:G'day Joe,
to PackardInfo. My thoughts, in addition to the others from the more experienced here, relate to your block as well as the water distribution tube. Were the block;s water jackets thoroughly cleaned before the engine was rebuilt to remove any crud buildup? The water distribution tube can be easily cleaned, the main problems are removing the radiator and water pump to access it, but I believe it can be done in car. Ensuring these are free of any buildup or loose particles will certainly help in the cooling system doing its job effectively.

And, I invite you to include your '52 in the Packard Owner's Registry here, together with a pic, any known history and how you acquired it?

I agree with the suggestions already made here. My first check would be the radiator cap. If that is OK, I would them check the water distribution tube. If it is clogged it will cause the back couple of cylinders to overheat at cruising speeds where there is more heat generated and the water then can't circulate fast enough to these cylinders. I would then check to see if a mouse has created a house in your muffler tail pipe which causes back pressure. One other item to check is to see if the manifold heat riser is stuck in the closed position.
Good luck and try to enjoy the problem solving aspect of this situation.