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new rebuild engine new radiator good water pump water jacket good said engine builder help.

Did rebuilder know that water jacket should have an inner plate with numerous holes.

Possible cause, timing??

What exactly is it doing? Boiling over, or just high on the gauge? Or heating up and quitting? Oil pressure OK?
Could be anything from not having the clearances right to just an air pocket.

Not at all unexpected or even uncommon that a fresh rebuild will run hotter than before the rebuild. The contribution to total heat generation from frictional sources like new rings wearing in to cylinder walls is much higher but should begin to subside in a few hundred miles. Assuming you've checked all the obvious things, unless you're actually boiling over I'd wait until the engine has accumulated a few hours of running and evaluate again at that time.

I agree with Owen that a fresh, tight motor may well put more heat into the cooling system than one that is broken in.

Here's the problem I have with the idea that this is common today.

Think about it - when these cars were new, weren't they "tight" ?

Think about it - when these cars were new - especially when we are discussing cars whose prices, in today's money, approached or exceeded fifty grand......would Packard had gotten its reputation if its cars overheated ?

Packard's pre-war reputation was well-deserved and well-earned - provided its customers with a well-engineered, high quality product.

Whether it was one of the "Junior" series Packards, or one of the big ones, the buyer got an outstanding buy, and a superior product in whatever price-class Packard competed in.

If these assumptions are correct, than clearly people are doing something very wrong these days in repairing Packards.

Given how over-engineered, including how over-cooled Packard products in ANY price class were, it shouldn't take much imagination to realize that many restorers today are doing what today's customers want - costume jewelery that can move under its own power from the trailer to the show field.

My recommendation to anyone who actually wants to drive and enjoy their Packard, is to find out more about the Packard product, and what it would do as a motor-car if given half the chance !

Quote:

True, but when these cars were new their cooling systems were at their best and able to handle an engine's additional heat generated during the break-in period.

(o[]o)

Exactly so JW. And it would lead one to question if the "new" radiator is at least the equivalent of the OEM radiator.

Actually, they weren't "tight" in that the earlier engines were run by electric motor for quite some time, and then powered up with city gas for a while before installation. Regardless, the engine should not be so tight that extraordinary heat is developed. Retarded timing will make a huge amount of heat, and the effect seems more pronounced on low compression engines than otherwise. My thermodynamic training has receeded too far into the past to ground that observation in science.

If you know who did the machine work then check on the piston clearances being used. For modern pistons the clearances should be .002-.0025 inches. If the motor stops abruptly when shut off then it is tight enough to cause hot running.

However the water jacket issue is well considered. If the back of the motor is much hotter than the front then there is a distribution problem.

temp running 190 boils over in about 5 min run time all I know engine builder say water jacket was good will try to change timing could water be moving to fast to have time to cool.