A-65 mechanic question

[Michael Horowitz]

My A-65 had the lower half redone.
At operating temp. and at idle, the oil pressure is certainly below
15PSI and may be below 10.
I asked the company that did the work and they replied "we don't worry
about low pressure at idle".
Continental says a minimum of 10PSI.
I'll get my A&P to put a real pressure gauge on to see what the
pressure is.
In your experience, does idle typically produce less than 15PSI or am
I looking at a problem?

[Bertie the Bunyip]

Michael Horowitz >
:

> My A-65 had the lower half redone.
> At operating temp. and at idle, the oil pressure is certainly below
> 15PSI and may be below 10.
> I asked the company that did the work and they replied "we don't worry
> about low pressure at idle".
> Continental says a minimum of 10PSI.
> I'll get my A&P to put a real pressure gauge on to see what the
> pressure is.
> In your experience, does idle typically produce less than 15PSI or am
> I looking at a problem?
>

If it's just had a bottom overhaul and broken in, you should see a bit
under thirty at an idle of around 500 rpm if you have healthy oil pressure
at higher power settings. Down to twenty might be reasonable, but I'd say
something is wrong if you have less than ten at idle. Might very well be
your gauge though, as you say.. ..

[Philippe]

Michael Horowitz wrote:

> My A-65 had the lower half redone.
> At operating temp. and at idle, the oil pressure is certainly below
> 15PSI and may be below 10.
> I asked the company that did the work and they replied "we don't worry
> about low pressure at idle".
> Continental says a minimum of 10PSI.
> I'll get my A&P to put a real pressure gauge on to see what the
> pressure is.
> In your experience, does idle typically produce less than 15PSI or am
> I looking at a problem?


spring oil pressure relief valve P/N 21352

Just install a new spring and you get higher oil press.
I do that and my pressure jump to the high side of the normal range.
It cost me 2 euros (2.6$) for this paperless new spring.
The new spring was 1" longer than the 40 year old one.

If it don't work, you may suspect your engine bearings are in poor
condition.

By
--
Pub: http://www.slowfood.fr/france
Philippe Vessaire ҿӬ

[Michael Horowitz]

Philippe > wrote:

>Michael Horowitz wrote:
>
>> My A-65 had the lower half redone.
>> At operating temp. and at idle, the oil pressure is certainly below
>> 15PSI and may be below 10.
>> I asked the company that did the work and they replied "we don't worry
>> about low pressure at idle".
>> Continental says a minimum of 10PSI.
>> I'll get my A&P to put a real pressure gauge on to see what the
>> pressure is.
>> In your experience, does idle typically produce less than 15PSI or am
>> I looking at a problem?
>
>
>spring oil pressure relief valve P/N 21352
>
>Just install a new spring and you get higher oil press.
> I do that and my pressure jump to the high side of the normal range.
>It cost me 2 euros (2.6$) for this paperless new spring.
>The new spring was 1" longer than the 40 year old one.
>
>If it don't work, you may suspect your engine bearings are in poor
>condition.
>
>By

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

[Ron Wanttaja]

On Wed, 25 May 2005 21:41:27 +0200, Philippe > wrote:

>Just install a new spring and you get higher oil press.
> I do that and my pressure jump to the high side of the normal range.
>It cost me 2 euros (2.6$) for this paperless new spring.
>The new spring was 1" longer than the 40 year old one.

There are other potential reasons for low A-65 oil pressure. See the third
paragraph:

http://www.bowersflybaby.com/tech/fenton.htm#studs

Ron Wanttaja

[Philippe]

Michael Horowitz 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? ....

By
--
Pub: http://www.slowfood.fr/france
Philippe Vessaire ҿӬ

[Bertie the Bunyip]

Philippe > sednews:k13gm2-
:

> Michael Horowitz 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.



Bertie

[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...

--
Pub: http://www.slowfood.fr/france
Philippe Vessaire ҿӬ

[Bertie the Bunyip]

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...

He said his wasn't..


Bertie

[Bertie the Bunyip]

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

[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

[Bertie the Bunyip]

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
>

[sleepy6]

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.

[[email protected]]

>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

[Bertie the Bunyip]

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
>

[Bertie the Bunyip]

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

[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

[Bertie the Bunyip]

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

[Michael Horowitz]

Bertie the Bunyip > wrote:

>Michael Horowitz >
:
>
>> 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

[Bertie the Bunyip]

Michael Horowitz >
:

> Bertie the Bunyip > wrote:
>
>>Michael Horowitz >
:
>>
>>> 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

[[email protected]]

>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.

It isn't the oil pressure that keeps metal bits apart, it's
the oil itself. Oil pressure is needed only to get the oil to the
places it has to go. If it's a light oil, less pressure will work, and
a heavier oil might need more pressure to keep it moving. My A-65
seldom sees more than 25 or 30 psi in cruise, and works just fine. If
the weather is really cold I'll use an automotive 15W40 oil in it to
keep it happy. Beware, though, of using an auto oil if the engine has
hundreds of hours of aero engine oil operation; the auto oil will
loosen a lot of accumulated crud in the case and that stuff will get
pumped all through the system or maybe plug up the screen.

Dan

[Bertie the Bunyip]

egroups.com:

>>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.
>
> It isn't the oil pressure that keeps metal bits apart, it's
> the oil itself.


OK, fair enough for the Valve train, but the bottom end?

Oil pressure is needed only to get the oil to the
> places it has to go. If it's a light oil, less pressure will work, and
> a heavier oil might need more pressure to keep it moving. My A-65
> seldom sees more than 25 or 30 psi in cruise, and works just fine. If
> the weather is really cold I'll use an automotive 15W40 oil in it to
> keep it happy. Beware, though, of using an auto oil if the engine has
> hundreds of hours of aero engine oil operation; the auto oil will
> loosen a lot of accumulated crud in the case and that stuff will get
> pumped all through the system or maybe plug up the screen.
>

You've not been using AD aviation oil? That'll do the same thing if you've
been using straight mineral.


Bertie

[[email protected]]

>You've not been using AD aviation oil? That'll do the same thing if you've
>been using straight mineral.

I use AD for the rest of the time, but auto oils have more cleaners in
them.

Dan

[Bertie the Bunyip]

egroups.com:

>>You've not been using AD aviation oil? That'll do the same thing if
>>you've been using straight mineral.
>
> I use AD for the rest of the time, but auto oils have more cleaners
> in
> them.
>
>
OK, I still think you're wrong about oil pressure. Though I've had some
engines with gravity feed oilers, (which needed frequent overhaul, BTW) I
can't see a flim being sustained in a big end, for instance, without a
goodly pressure flowing constantly to it. IOW the oil would quickly squirt
out of the side of the bearing leaving it dry...




bertie

[[email protected]]

If there was a lot of bearing clearance in the mains, the rods
might run a little dry, for sure. The rods are fed oil through the
crank from the main bearings, and too little pressure might result in
most of it getting away at the main bearings. In some simpler engines
the oil is fed only into one end of the crank, and if the pressure is
low it will reach the first rod OK but can't fight centrifugal forces
back through crank axis to the next rod. I don't know of any aero
engines that are single-point fed, but there are plenty of industrial
engines like that.
The key to good rod and main bearing lubrication is
clearances as small as the manufacturer will allow, and this also
reduces oil consumption by keeping the cylinders as dry as possible.
(Cylinders are typically lubricated by oil flung off the main and rod
bearings.) The pistons and rings have relatively little pressure on
them and need very little oil. In any engine or compressor I've seen
that failed due to lack of lube, the bearings were always the first to
go.

Dan