oil pressure problem

ed thomad · #1 (**permalink**) 04-21-2004, 10:18 AM

I have a 1978 spider. I rebuilt the engine last year. In the last few weeks I have noticed that when the engine is cold it has about 50psi of oil pressure at idle and about 55psi at highway speeds. After it warms up it does not show any pressure at idle and about 40 at highway speeds. The oil light never comes on. When it is warm at idle I can hear a slight tapping sound. It does not sound lite valve noise. Could this be an oil pump problem, or a rod bearing? Any advise or suggestions would be appreciated. Thanks Ed

Johan · #2 (**permalink**) 04-21-2004, 11:55 PM

What kind of oil do you use, as some sorts get really thin when they warm up.

Johan

Keven · #3 (**permalink**) 04-22-2004, 08:09 AM

I would first verify your oil pressure reading with a mechanical guage. If you have the same readings, you probably have thrown a crank plug.

**Roadtrip** · #4 (**permalink**) 04-22-2004, 08:13 AM

Ed - Check you exhaust manifold. A slight exhaust leak sounds a lot like valve tick. As far as the oil pressure goes, I assume you're using 20W50 oil? According to Alfa, zero indicated oil pressure is ok at idle, as long as the oil pressure light is not on. The oil pressure light works off a different sender unit and comes on when below 5 psi. 40 psi is a little low at off-idle engine speeds, but your gauge may be off also. Before you start blaming the engine, I'd double check the accuracy of the gauge and sending unit. Being a freshly rebuild engine, it seems unlikely that you've got rod or bearing problems.

As an aside, if you see a sudden and dramatic drop in oil pressure . . . . get some when the engine is cold, but dropping to zero as it warms up, that would be an indication of a blown out oil passage plug in the crankshaft.

ed thomad · #5 (**permalink**) 04-22-2004, 10:06 AM

Thanks to for the advice. Is it possible to remove the oil pan with the engine in place? If I have lost a plug in the crank I will need to do this Thanks Ed

**Roadtrip** · #6 (**permalink**) 04-22-2004, 10:14 AM

Based on your symptoms, I doubt it's a dislodged plug. I'm not even convinced there's anything wrong.

To answer your question, however . . . yes, but you have raise the engine a little. The other part of the crankshaft plug issue, is "which one?" Not all the plugs can be repenned in-situ. If it eventually comes down to something like that, you should be able to take the lower pan cover off and look for an errant plug rolling around the bottom. Of course you'd have to check the upper shelf of the oil sump also . . . not hard to do with just the lower cover off.