Paul - as Roger Parker has said in his experience of UK Police V8s, 'What
hot idle oil pressure?". That hot idle does seem low but things may well be
a little different on the stand. Mine (unknown history but 50k+ in my
hands) will idle at 20 on a hot (OK, UK hot) summers day after a blast down
the motorway. However if I continue to let it idle it will drop towards the
figures you mention, but I didn't used to let it idle at that, choosing to
run it with a bit of fast idle to keep the pressure up. One thing I have
noticed since installing the Burlen fan sensor is that the hot idle oil
pressure is noticeably higher than with the original item, because the
Burlen has lower thresholds. But I know you have the Burlen (unless you
have found an original since July), just as well you don't have the
original.
Cheers,
PaulH.
----- Original Message -----
From: KILE, PAUL D <Paul.Kile@Aerojet.com>
To: 'V8 Rover List' <buick-rover-v8@autox.team.net>; 'MG V8 List'
<mgb-v8@autox.team.net>
Sent: Tuesday, September 05, 2000 4:18 PM
Subject: RE: Muddying the waters?????, plus head gasket question
> I've got a nicely rebuilt 3.5 Factory MGB-GT V-8 engine on a test stand,
> sorting out any problems before reinstalling it in the car. The engine
has
> had all new parts installed, the crank has miked out at standard/standard
> after nitriding, and the oil pump gears are new with a new MG BHH 1348 oil
> pressure relief spring. Here are my pressures, taken using a Smiths 0-60
> PSI dual gauge (original gauge from car with 90,000 miles on it):
>
> Cold at startup: Idle (800RPM) - 40PSI 2,000 RPM - 50 PSI
> Hot (~200 deg F): Idle (800RPM) - 10-12PSI 2,000 RPM - 40 PSI
>
> After years of running 4-cylinder engines, the hot idle pressure on this
V-8
> is a little disconcerting, but after reviewing all the previous posts and
> David Hardcastle's information I believe these are OK numbers. I think we
> are just not used to seeing these low idle pressures, since most big
> American V-8s have idiot lights and not pressure gauges.
>
> The one thing I don't understand is why 20/50 oil would be detrimental to
> road engines, as mentioned below. I have used 20/50 as the standard oil
in
> most of my MG and older Toyota engines, with no ill effects. This is the
> grade that is recommended by the manual. It is only recently (last 15
years
> or so) that the lighter viscosity multigrades have been specified,
> culminating in 5W-30 for my wife's 96 Camry V-6. I still believe in 20/50
> for my older engines, particularly here in California where the
temperatures
> can get over 100 deg F.
>
> Here's my other question. When we rebuilt the MG V-8, we torqued the
lower
> row of head bolts to ~30 foot pounds, to prevent the recently identified
> issue of blow-by into the valley. Now I have two very minor oil seeps out
> of the gasket below the rear RH and front LH head bolts! It would appear
> that in attempting to correct one anomaly, we have caused another. Any
> ideas? I am tempted to just re-torque the lower rows of bolts back to the
> originally specified torque and be done with it.
>
> Cheers,
> Paul Kile
> 1974 Factory MGB-GT V-8
> (wishing he could make the Convention this year, but maybe next year)
>
>
> -----Original Message-----
> From: trevor_easton@dofasco.ca [mailto:trevor_easton@dofasco.ca]
> Sent: Tuesday, September 05, 2000 4:52 AM
> To: buick-rover-v8@autox.team.net
> Subject: RE: Muddying the waters?????
>
>
> So David Hardcastle says
>
> > . ... The Rover V8 does not like modern
> > lightweight oils, in fact 5W-50 oil could, under certain circumstancs
> > be detrimental to the engine. Thin oil cannot be pumped in volume in
> > the same way as heavier oils, although the pressure will be
> > maintained.
> >
> How can it maintain the pressure against what would appear to be the same
> (Or lower due to thinner oil) system restrictions if it isn't pumping the
> same or greater volume?
>
> Heavy (20/50) oils are fine for worn engines and "fast and loose" racing
> engines but unnecessary for and detrimental to most road engines. Even
tuned
> ones. If you are making adequate (per the manual) oil pressures at working
> rpm's then your engine is receiving adequate lubrication. If your oil
> pressure is low at idle but normal at higher revs even this is OK, just
> means that your lube system is low restriction (worn maybe) but adequate
> volume is coming from the pump because when the revs rise so does the
> pressure. Another question is of course what is idle. My 3.9 will idle at
> 350 rpm with 5 psi or less oil pressure when hot (190F, 10/30 GTX) at a
more
> reasonable 700 rpm the oil pressure is 15 psi rising to 35 psi at 2500 and
> not going any higher because the relief valve has opened. It reaches maybe
> 45 psi when cold.
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