On Wednesday, February 15, 1995 1:16AM Frank wrote
>What are your experiences/knowledge pertaining to the 1500/1600/1725 Alpine
>engine mortality? The word in general seems to be that these motors don't
>last long. I hear about and am experiencing an oil pressure problem. Are
>the 1725 motors any more reliable than the others? How long might any of
>these motors last, in miles, under hard use? What sort of reliability
with mods like >the Holbay (Tony, Steve)?
Sorry to be so long in replying - One of those 4 day Canadian
weekends!!
Frank, it sounds like the project is now ALP1725 - sounds
encouraging!!
I did some reading about oil pressure and the following is
an article from the 1994 SAOC 1994 Members Handbook
OIL PRESSURE - THE LOW-DOWN
At over 2,500 rpm., the normal hot oil pressure on Series
I to IVa Alpines is 50 p.s.i. and on Series V Alpines is 40
p.s.i.. Naturally an early car with a 1725cc engine should
also be 40 p.s.i.
At tick-over ( idle to you guys!!) at approximately
850 rpm, the pressure will be in the region of 15 - 20
p.s.i. and from there up to full pressure, the pressure in
p.s.i. will be approx. twice the rpm in hundreds. When
the engine is cold, even the pressure at tick-over will be
around 40-50 p.s.i. and will rise to about 10-20 p.s.i.
above normal when running at normal revs.
After sustained high speed cruising (80+mph) the
pressure will drop by about 5-10 p.s.i at all revs. due to
the higher oil temperature. This effect will be more
pronounced with old oil.
The figures should be obtained on any alpine
engine in reasonable condition, even after quite high
mileages ( in my case around 160,000 without a crank
grind or any oil pump work.) If your oil pressure isn+t up
to these figures even with new oil and filter then it+s time
to do something about it, for it+s generally true to say that
on these engines low pressure isn+t caused by wear but,
unattended to, will surely cause wear.
The most common cause of low oil pressure, not
necessarily accompanied by rattle on start-up, is the oil
pressure relief valve jamming open after high mileage
causes a ledge to be worn on the piston which catches on
the hole in the side of the cylinder. Rotating the piston is
a good temporary cure but plan on changing the valve.
An occasional \, easy to fix, cause of low pressure
with rattle on start-up is a leak in the fuel pump
diaphragm and a blocked drain hole in the pump body.
The dip-stick should smell of petrol and the oil will be
very thin
If your low pressure isn+t caused by either of
these, then I+m afraid it+s "off with the sump time" time.
Paul Norton
Seems to me, his comments indicate these engines can
stand up to the test.??
I have been concerned about my oil pressure also
but have installed a Series V oil cooler which helps. I also
changed from Castrol to Penzoil 20-50 - that was an
improvement. I only drive my Alpine from May to Nov. It's been
5 years since i rebuilt it and it seems to be o.k. and takes a fair amount
of punishment.
>will a 1725 bolt up in place of a 1500/1600? Can you use the 1500/1600
transmission?
In response to Frank+s question I have done the opposite
with no problem.The one thing you have to watch is that the clutch fulcrum
bracket on the earlier engines is larger and the Series V
bell- housing interferes with it and you can+t tighten it
flush with the block. Use the later bracket, it+s slightly
shorter.
I wanted to use the later clutch ( 71/2") but the
hole pattern on the flywheel didn+t match - so I changed
to the 1725cc flywheel which is lighter. I was concerned
about this, as my 1592cc is a three bearing crank and the
1725cc engine is a five bearing crank. I thought the
lighter flywheel would create more whip on a three
bearing crank. I checked with Rick M at S.S.and he said
it should be no problem and so far it hasn+t been.
Eventually, I would like to do the opposite to what
Frank asks - When my 1592cc craps out I have a spare
1725cc to put in - hopefully disguised as a Series II engine
with Zeniths etc. Has anybody done that ??
Tony Leeming Nanaimo, Vancouver Island,
British Columbia, Canada. (tleeming(at)city.nanaimo.bc.ca.)
1963 Sunbeam Alpine Series 2 ( My Pine )
1976 Mercedes 450SLC
1983 Toyota Landcruiser SW
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