David Councill wrote:
> Well, I have similar problems with a fresh rebuild on a 72 engine. I
> went ahead and replaced the pressure relief valve including the cap,
> spring, and a metal space that fits in the cap (I noticed that was
> missing when I did this). I used the up-rated spring and had a hell of a
> time getting it pressed in. Once done, all that did was increase my max
> psi - the car still can see 10-15 psi on a low (650 rpm) idle. That is
> hot. When cold, the car now idles with a starting idle psi of 60-70, and
> 90 psi at speed. After maybe 10-15 minutes of driving, I'm down to 10-15
> psi at idle but still running a solid 75 psi at 3000 rpm (but can drop
> to as low as 50 at 2000 rpm). So that low rpm psi is still troubling.
>
> But the 72B uses a mechanical gauge so perhaps I have a restricted oil
> line or maybe the gauge isn't that accurate. Or my only other theory is
> the oil pump. One thought is close tolerance between oil pump inlet and
> bottom of oil pan? I had a problem fitting it on, not sure why, so I had
> to pound out the bottom of the oil pan to get it to fit (something I
> read on this list). And to make matters worse, I think I tightened the
> oil pan bolts too tight but I left that alone since I have no leaks.
>
> I know the book states 10-25 psi for a warm idle and technically I'm
> within spec but in all my previous MGBs, it was very rare that the psi
> would drop below 40 at idle. So my low pressure at idle bothers me and
> I'm still looking for a resolution, if there is one. So I'm with Thomas
> on this one, at least on the low idle. But I'd be even more concerned if
> the psi was below 50 when driving with rpms 2500 or higher. Perhaps the
> relief spring is the place to start but it is a real bitch to get the
> nut pressed down in order to get it in the threads. I made a little tool
> that was essentially a bolt and a union that I could use to push against
> the body of the car and the nut that finally made the job a bit easier.
Sounds to me like knackered bearings, or a worn crank, probably both.
-Rock http://www.rocky-frisco.com
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