Paul,
Let me begin by asking if you were responding to an earlier post of mine?
If so, note that wrote, "almost dry" not "dry. " What I meant by
thet was that the bearings were not floating in oil, as they would have
been after a day or so of inactivity.
I think the OP was speaking of a MGB 4 cyl engine. That's post I
responded to.
Yes, in the case of my engine and the original OP's, AIR, if the engine
isn't cranked for 10 - 15 seconds before allowing it to start,, the rods
will rattle after starting, until the oil flow & resulting pressure
comes up. That's why I make a practice of cranking the engine for
10-15 seconds unchoked, before choking and starting it. This is only
if the engine has not been started for more than two days.
I hope this clears any confusion for you,
CR
On 5/21/2013 2:58 AM, PaulHunt73 wrote:
> Oil does leak down from the system, be it galleries or filter, the
> longer it is left parked. The quality of the oil filter has a major
> impact on this, but even switched off fully hot and left for a few
> days my V8 bearings were still swimming on oil when I removed the big
> ends and main bearings, so to say they are 'dry' at start-up is
> definitely not correct. That engine is notorious for low oil pressure
> and a slow rise, the factory moved the gauge tapping from the output
> of the oil filter to the output of the pump in order to allay customer
> fears - but making absolutely no difference to the bearings of course,
> even so even when just left overnight it takes several seconds for the
> gauge to even start rising, and takes maybe 10-15 seconds to reach
> full pressure. Left overnight the roadster is pretty
> well-instantaneous to register pressure, after a couple of weeks or
> more it is about five seconds from the start of cranking, having fired
> up after 3 or 4 seconds.
>
> 15 seconds to see oil pressure is way too long. Can you hear the
> knocking straight away? Or only after a few seconds of running and
> before pressure builds? If straight away it's likely that worn
> bearings are the cause of the slow rise. If only after a while then
> it's likely that the residue of oil on the bearings is being lost
> before oil is available again, and that is causing bearing wear.
>
> PaulH.
>
> ----- Original Message -----
>> ... Result: no oil in the main gallerie untl the engine runs a bit,
>> the passages fill up and the pressure comes up to normal. You hear
>> the almost dry rod bearings rattle until they get oil.
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