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Dear Packard friends,
I have completely overhauled my 1951 327cui engine (complete overhaul kit from Kanter with new hydro tappets).
I have also cleaned all the oil ducts.

Now I have the problem that the engine runs very quietly when cold and the valves are not audible, but as soon as the engine warms up then 1 valve rattles extremely loudly (the warmer the engine the louder).

I use a multigrade classic engine oil with SAE 20W50.
Is it possible that this oil becomes too thick when the engine is warm and this causes the noise with a hydro tappet?
According to the manual, the engine should be run with HD20 engine oil.

What else could be the cause (I don't think a new hydro tappet has a fault, do you?).

Is it possible to replace a hydro tappet with the engine installed without removing the cylinder head?
What exactly do I have to do?

Thanks for your help.
Georg from Austria

I can answer only the last question. You must remove the head in order to change lifters but, of course, the first step would be diagnosis to see where the problem is. For my own Packard work I attached a pressure gauge to a long flexible hose which I connect to the oil galley on order to get an accurate reading.

There are two likely possibilities:

1) The first is that you didn't check the clearance correctly for that particular tappet after you (presumably) ground the valve seats. Now the clearance is too tight for the lifter to pump up. It should be 0.030 to 0.070 cold using a gage. There were instructions on how to do this in the Kanter kit with the new tappets using one of the tappets as a gauge. A gage is also available from Pacific Northwest Packards, or you could use one of your old tappets (slightly risky).

2) The second is that particular tappet is bad for one reason or another. It could be dirty, but if it works at cold but not at hot it is more likely bad than dirty. There is a video on "Speedwell Garage" Youtube Channel where he discusses testing tappets. Ross has also on occcasion tested tappets for one. Since you are far in Australia that might be difficult. Ross made a few tappet testing tools or you can make one yourself.

Also there has been much discussion on this website using the term "noisy lifters".

Just an FYI that Pacific Northwest Packards no longer sells the gauge.

Quote:
Hi Georg (gbuchner), the relationship between oil fluidity and engine temperature is exactly the opposite; the warmer the engine, the thinner the oil.
However, the manufacturer's information is not about fluidity, but rather about viscosity. As the engine temperature increases, the viscosity of the oil decreases.




Your SAE 20W50 is very suitable for Central European conditions.


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Georg (gbuchner), is that your red beauty?




Great weather, great car.




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