1929 LaSalle Radiator frothing

[Rohan Millar]

Two of our 1929 LaSalles have been having radiator issues, with the radiators frothing and overflowing. It seems to occur when the vehicles are under load, such as driving uphill, but where we live, uphill is driving west and downhill is driving east on the highway. One vehicle has a reconditioned engine and the other has an original engine and both vehicles have newer radiators. The vehicle with the original engine recently dropped half the contents of the radiator on the road while waiting to turn.

Before we really go to town and pull lots of things apart, are there any suggestions from the group for possible causes and easy troubleshooting?

[Steve Passmore]

This is just my experience with slightly later cars, I don't own anything as early as yours but every time I see a car pressurizing the rad and overflowing its a radiator issue.   The core tubes just can't pass water through  fast enough to keep up with the pump.   The fact that you say both cars have new rads and both cars are suffering may be the clue.    Have the radiator cores been replaced exactly as per original size and number of tubes?

[Rohan Millar]

Steve,

Thanks for your reply and it's a good question - I don't know the history of the rad replacements, but it's a good starting point. The vehicle with the reconditioned motor was purchased as a rolling chassis, so we don't know what was actually done in the rebuild. The vehicle with the original engine had been in storage for quite a while and while it was run regularly, it had not been driven for any distance for at least two years to the best of my knowledge. We'll have a good look at the rads and go on from there.

Rohan

[rcr]

If you have ruled out combustion in the coolant (bad head gasket or a crack)  1929 Cadillac and LaSalle engines are prone to have a loose water pump impeller once warmed up which slips badly and really shows up under a load. The reason is that the impeller is only pinned to the shaft on one side (pin does not go all the way through) and rusts and breaks away with time. Remove the hose and see if you can move the impeller with gentle pressure. If so it is a simple fix to put a new pin in place. I usually use a tapered pin backed up by a set screw to secure.

[Rich in Colorado]

Rohan,

I'm really new to the Cadillac, I just bought a '58 Fleetwood.  Saw your post and if you rule out the items the other guys are suggesting you might try what worked for me, if you are using anti-freeze.

I have a 1928 Model A Ford.  It has a non-pressurized cooling system.  I don't know if Cadillac had pressurized or not back then.  My car would froth a lot after I got it running.  Newly redone radiator, newly rebuilt engine.  Drove me crazy.  Tried all kinds of things, new head gasket, waterpump.  Anyway I talked to a old Model A guy (is there any other kind?) and without hesitation he said use Sierra antifreeze/coolant.  It is a diferent formula, (Propylene Glycol).  It fixed my problem.  I have had the car now for well over 20 years, and it never did it again.

Apparently, some cars with non-pressured systems will churn up standard anti-freeze.   The standard parts stores didn't have it, I bought mine at NAPA.
Cheap fix if it works, Good Luck,
Rich in Colorado