A-65 mechanic question

Bertie the Bunyip wrote:

Philippe
:

Bertie the Bunyip wrote:


spring oil pressure relief valve P/N 21352


Philippe - doesnt that relief valve control the upper limit i.e.
opens at pressures greater than 35psi? - Mike

I agree but with a very weak spring, it work for me... Why not try
this first? ....


If you have a weak spring, your higher power settign OP will also be
low.

Yes, it was...



oops, sorry, he didn't say it was normal, but he didn't say it wasn't...

Bertie


Bertie - my upper OP is within the limits of 10-35PSI.
It's my OP at idle that concerns me.
Specifications for the A-65 show an acceptable range of between 10-35
and I'm concerned I may be below that range at idle ( at operating
temp).- Mike

Do we all agree that a pressure relief spring probably will not figure
into the fix for the problem of raising my OP at idle? - Mike

Michael Horowitz
:

Bertie the Bunyip wrote:

Philippe
:

Bertie the Bunyip wrote:


spring oil pressure relief valve P/N 21352


Philippe - doesnt that relief valve control the upper limit i.e.
opens at pressures greater than 35psi? - Mike

I agree but with a very weak spring, it work for me... Why not try
this first? ....


If you have a weak spring, your higher power settign OP will also be
low.

Yes, it was...



oops, sorry, he didn't say it was normal, but he didn't say it wasn't...

Bertie


Bertie - my upper OP is within the limits of 10-35PSI.

your pressure above idle should be 30-40. If it's below 30 you don't have
enough pressure. 10 is the lower limit for idle only.

It's my OP at idle that concerns me.
Specifications for the A-65 show an acceptable range of between 10-35
and I'm concerned I may be below that range at idle ( at operating
temp).- Mike

Do we all agree that a pressure relief spring probably will not figure
into the fix for the problem of raising my OP at idle? - Mike

might do if your pressure above about 1,000 rpm is less than 30 once your
oil is warm!


Bertie

In article ,
says...

snip

Bertie - my upper OP is within the limits of 10-35PSI.
It's my OP at idle that concerns me.
Specifications for the A-65 show an acceptable range of between 10-35
and I'm concerned I may be below that range at idle ( at operating
temp).- Mike

Do we all agree that a pressure relief spring probably will not figure
into the fix for the problem of raising my OP at idle? - Mike

As the engine ages the pump wears and pump clearances open up so that
it pumps less volume. The bearing clearances also increase so oil
flows through them easier. The result is a drop in oil pressure. This
shows up more at idle since the pump puts out the least volume then.

As the RPMs increase, the pump puts out more volume and the pressure
builds until the pressure relief opens up to bypass the oil flow to
limit the max pressure to 35 PSI.

Even on a new engine, the pressure relief doesn't have much effect at
idle since the pump is not putting out enough oil to build the pressure
up enough to open it. If you have 35 PSI at idle when warm something
is wrong ... probably not enough bearing clearance.

The solution to the problem is to go to a slightly thicker oil that
doesn't flow through the increased clearances as fast. That lets the
pump build up pressure easier at idle. Don't go too thick or it can be
a bad thing if the relief can't hold the pressure down.

As the engine ages the pump wears and pump clearances open up so that
it pumps less volume. The bearing clearances also increase so oil
flows through them easier. The result is a drop in oil pressure.

I've seen that in my A-65 and others. The original potser had had
his bottom end redone, so unless the mechanic paid no attention to
crank wear and put things together with big clearances, I'd say that
the accessory cover needs to come off and the pump fixed. The most
likely wear is the aluminum pump cavity, since it sucks unfiltered oil
and is easily scored up. If it's a homebuilt the cover plate could be
lapped and the pump housing face machined lightly to reduce the
endplay. If there's serious scoring the whole accessory cover needs
replacing. And where do we find a new A-65 cover these days?

Dan

Michael Horowitz
:

Bertie the Bunyip wrote:

Philippe
:

Bertie the Bunyip wrote:


spring oil pressure relief valve P/N 21352


Philippe - doesnt that relief valve control the upper limit i.e.
opens at pressures greater than 35psi? - Mike

I agree but with a very weak spring, it work for me... Why not try
this first? ....


If you have a weak spring, your higher power settign OP will also be
low.

Yes, it was...



oops, sorry, he didn't say it was normal, but he didn't say it wasn't...

Bertie


Bertie - my upper OP is within the limits of 10-35PSI.
It's my OP at idle that concerns me.
Specifications for the A-65 show an acceptable range of between 10-35
and I'm concerned I may be below that range at idle ( at operating
temp).- Mike

Do we all agree that a pressure relief spring probably will not figure
into the fix for the problem of raising my OP at idle? - Mike


Um, no, the range for the A-65 is 10 minimum for idle, but it's 30-40 for
higher settings. If you've got less than 30 when your oil is hot,
youhaven't got enough, unless you've got an a-65 I've never seen! My old A-
50 was the same, BTW What's the source of info for your figure of 10-35?


Bertie

groups.com:

As the engine ages the pump wears and pump clearances open up so that
it pumps less volume. The bearing clearances also increase so oil
flows through them easier. The result is a drop in oil pressure.

I've seen that in my A-65 and others. The original potser had had
his bottom end redone, so unless the mechanic paid no attention to
crank wear and put things together with big clearances, I'd say that
the accessory cover needs to come off and the pump fixed. The most
likely wear is the aluminum pump cavity, since it sucks unfiltered oil
and is easily scored up. If it's a homebuilt the cover plate could be
lapped and the pump housing face machined lightly to reduce the
endplay. If there's serious scoring the whole accessory cover needs
replacing. And where do we find a new A-65 cover these days?


Here's one place. I'm not sure if they have covers, but they have come up
with a lot of stuff for me...


http://www.preferredairparts.com/engine.htm


Bertie

Bertie the Bunyip wrote:




Um, no, the range for the A-65 is 10 minimum for idle, but it's 30-40 for
higher settings. If you've got less than 30 when your oil is hot,
youhaven't got enough, unless you've got an a-65 I've never seen! My old A-
50 was the same, BTW What's the source of info for your figure of 10-35?


Bertie


http://www.mooneymite.com/articles/continental.htm
and elsewhere - Mike

Michael Horowitz
:

Bertie the Bunyip wrote:




Um, no, the range for the A-65 is 10 minimum for idle, but it's 30-40
for higher settings. If you've got less than 30 when your oil is hot,
youhaven't got enough, unless you've got an a-65 I've never seen! My
old A- 50 was the same, BTW What's the source of info for your figure
of 10-35?


Bertie


http://www.mooneymite.com/articles/continental.htm
and elsewhere - Mike


Note that it says 30-35 for cruising. I have a Continental manual in my lap
and it specifies 30-40 for cruise. 30 is fine though towards 40 is better,
but if you have less than that at anything above about 1500 revs and you're
not running sewing machine oil, you don't have enough to keep from scraping
bits of metal together on your cam or your bottom end.


Bertie

Bertie the Bunyip wrote:

Michael Horowitz
m:

Bertie the Bunyip wrote:



Note that it says 30-35 for cruising. I have a Continental manual in my lap
and it specifies 30-40 for cruise. 30 is fine though towards 40 is better,
but if you have less than that at anything above about 1500 revs and you're
not running sewing machine oil, you don't have enough to keep from scraping
bits of metal together on your cam or your bottom end.


Bertie

Bertie - I think I'm fine at the high end. My only concern is the
minimal OP at idle. - Mike

Michael Horowitz
:

Bertie the Bunyip wrote:

Michael Horowitz
om:

Bertie the Bunyip wrote:



Note that it says 30-35 for cruising. I have a Continental manual in
my lap and it specifies 30-40 for cruise. 30 is fine though towards 40
is better, but if you have less than that at anything above about 1500
revs and you're not running sewing machine oil, you don't have enough
to keep from scraping bits of metal together on your cam or your
bottom end.


Bertie

Bertie - I think I'm fine at the high end. My only concern is the
minimal OP at idle. - Mike

OK, well if your pressure is good at the high end, it's probably not the
relief valve. Any adjustment or replacement I've ever seen on that usually
changed it right across the board. In fact, if it's OK at the high side and
you replace it or put some washers in or whatever, you'll probably find it
going over the top on the high side and staying there. OTOH, it costs
nothing but a bit of time to try it.


Bertie