Low Oil Pressure at Idle, Volvo AD31B in the Tropics
 

On Thu, 25 Oct 2007 08:55:27 -0700, Capt John
wrote:


Stay away from switching to synthetic on an older engine, they tend to
develop oil leaks.

John

Yep!

Brian W

Low Oil Pressure at Idle, Volvo AD31B in the Tropics
 

On Thu, 25 Oct 2007 12:04:53 GMT, Brian Whatcott
wrote:

On Thu, 25 Oct 2007 11:05:13 +0100, "Alec"
wrote:

...
Try a heavier grade of oil, not one of the modern wide range synthetic or
semi synthetics multigrades.

Alec

I'm not arguing with this general advice. But the sentence I
quoted shows a mindset that may not tie to reality.

A synthetic almost as thin as water when cold, can STILL be thicker
than a thick mineral oil when really hot. Its viscosity vs
temperature slope is that much flatter. That's why they are rated
multi-grade. The synthetic doesn't burn off and has better high
pressure film strength.

Brian W


One thing to try before anything else is pull the oil cooler and see
whether it is stopped up. If you have ever broken a water pump
impeller the bits are still probably in the inlet of the oil cooler.

I nearly went crazy trying to solve a similar problem after a fellow
ran aground on a mud bank. Finally discovered the heat exchanger tubes
full of mud after someone told me the boat had been aground and I
noticed there was no inlet strainer.


Bruce-in-Bangkok
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address is a spam trap)

Low Oil Pressure at Idle, Volvo AD31B in the Tropics
 

Bruce in Bangkok wrote:
I nearly went crazy trying to solve a similar problem after a fellow
ran aground on a mud bank. Finally discovered the heat exchanger tubes
full of mud after someone told me the boat had been aground and I
noticed there was no inlet strainer.

Also the heat exchanger tubes can get slowly clogged with marine buildup
so the engine eventually starts to run hot. The problem seems to just
appear suddenly so its easy to misdiagnose, and can appear in older
engines as a drop in oil pressure due to the higher engine temp. I am
working on an engine now that this has happened to. There are some
commercial products to clean this growth out. I have this heat exchanger
pickling in Rydlyme Marine solution which seems to be working, but I
suspect most of the products are the same.
Red

Low Oil Pressure at Idle, Volvo AD31B in the Tropics
 

On Oct 25, 8:45 pm, Brian Whatcott wrote:
On Thu, 25 Oct 2007 08:55:27 -0700, Capt John
wrote:

Stay away from switching to synthetic on an older engine, they tend to
develop oil leaks.

John

Yep!

Brian W

I heard that if you switch and do not switch back you will not have
leaks.

Anyone switch to synthetics and stay switched?

Joe

Low Oil Pressure at Idle, Volvo AD31B in the Tropics
 

On Fri, 26 Oct 2007 05:05:53 -0700, Joe
wrote:

I heard that if you switch and do not switch back you will not have
leaks.

Anyone switch to synthetics and stay switched?

I did it with an older sailboat diesel once. It was a disaster. The
engine developed a major oil leak around the main bearing seal in no
time at all. I've never used synthetics since then.

Low Oil Pressure at Idle, Volvo AD31B in the Tropics
 

"Joe" wrote in message
ups.com...
On Oct 25, 8:45 pm, Brian Whatcott wrote:
On Thu, 25 Oct 2007 08:55:27 -0700, Capt John
wrote:

Stay away from switching to synthetic on an older engine, they tend to
develop oil leaks.

John

Yep!

Brian W

I heard that if you switch and do not switch back you will not have
leaks.

Anyone switch to synthetics and stay switched?

Joe

I've only switched in the cars... no problems at all. According to the local
mechanic, you can mix oil and synth without problems.

--
"j" ganz @@
www.sailnow.com

Low Oil Pressure at Idle, Volvo AD31B in the Tropics
 

On Fri, 26 Oct 2007 09:47:29 -0700, "Capt. JG"
wrote:


Anyone switch to synthetics and stay switched?

Joe

I've only switched in the cars... no problems at all.
According to the local
mechanic, you can mix oil and synth without problems.

I've used one quart of Castrol synthetic to 3 quarts of Castrol
mutigrade changed each 4000 mile interval since new,
for over 300 k miles on two festivas, where the engines
work for a living.

Brian Whatcott Altus OK

Low Oil Pressure at Idle, Volvo AD31B in the Tropics
 

On Sat, 27 Oct 2007 00:16:42 GMT, Brian Whatcott
wrote:

On Fri, 26 Oct 2007 09:47:29 -0700, "Capt. JG"
wrote:


Anyone switch to synthetics and stay switched?

Joe

I've only switched in the cars... no problems at all.
According to the local
mechanic, you can mix oil and synth without problems.

I've used one quart of Castrol synthetic to 3 quarts of Castrol
mutigrade changed each 4000 mile interval since new,
for over 300 k miles on two festivas, where the engines
work for a living.

Brian Whatcott Altus OK


Not to be picky, but why a mix of synthetic and multigrade?


Bruce-in-Bangkok
(Note:displayed e-mail
address is a spam trap)

Low Oil Pressure at Idle, Volvo AD31B in the Tropics
 

On Sat, 27 Oct 2007 13:08:19 +0700, Bruce in Bangkok
wrote:

I've only switched in the cars... no problems at all.
According to the local
mechanic, you can mix oil and synth without problems.
-
I've used one quart of Castrol synthetic to 3 quarts of Castrol
mutigrade changed each 4000 mile interval since new,
for over 300 k miles on two festivas, where the engines
work for a living.

Brian Whatcott Altus OK
-
-
Not to be picky, but why a mix of synthetic and multigrade?

Bruce-in-Bangkok

I once witnessed an extreme pressure oil bench-test.
Basically, a ball bearing is pressed hard onto a rotating shaft
and left to run. With mineral oil, there was soon a good flat.
With synthetic, the ball held in there, much longer.

But then, they cut the synth lubricant with mineral, and
the wear life held up at fair dilutions.

So, in view of the cost difference, and knowing they are
designed to be completely miscible, I used the 1:4 cut.

Finally, the makers started marketing a synth mix, but I do
it myself still - its no trouble to do. (The only precaution I take
is to use both types from the same maker - I chose Castrol)

I have read often enough, that synthetic can be searching in old
engines and unclog them or loosen seals and also that they
may not carry crap as well, and staying runny, the oil can
drain from cylinder walls
so it could be hard on startup, but the improved flow at
startup makes that point moot, I'm guessing.

Brian Whatcott Altus OK

Low Oil Pressure at Idle, Volvo AD31B in the Tropics
 

On Sat, 27 Oct 2007 13:11:25 GMT, Brian Whatcott
wrote:

On Sat, 27 Oct 2007 13:08:19 +0700, Bruce in Bangkok
wrote:

I've only switched in the cars... no problems at all.
According to the local
mechanic, you can mix oil and synth without problems.
-
I've used one quart of Castrol synthetic to 3 quarts of Castrol
mutigrade changed each 4000 mile interval since new,
for over 300 k miles on two festivas, where the engines
work for a living.

Brian Whatcott Altus OK
-
-
Not to be picky, but why a mix of synthetic and multigrade?

Bruce-in-Bangkok

I once witnessed an extreme pressure oil bench-test.
Basically, a ball bearing is pressed hard onto a rotating shaft
and left to run. With mineral oil, there was soon a good flat.
With synthetic, the ball held in there, much longer.

But then, they cut the synth lubricant with mineral, and
the wear life held up at fair dilutions.

So, in view of the cost difference, and knowing they are
designed to be completely miscible, I used the 1:4 cut.

Finally, the makers started marketing a synth mix, but I do
it myself still - its no trouble to do. (The only precaution I take
is to use both types from the same maker - I chose Castrol)

I have read often enough, that synthetic can be searching in old
engines and unclog them or loosen seals and also that they
may not carry crap as well, and staying runny, the oil can
drain from cylinder walls
so it could be hard on startup, but the improved flow at
startup makes that point moot, I'm guessing.

Brian Whatcott Altus OK


Interesting. I had always assumed that synthetic oils were more
durable as they stood up to high temperature better but your test
seems to say that they have a higher lubricity factor.... Or perhaps
it is the resistance to heat. But, for whatever reason it seems that
they provide better lubrication.

So - why not 100% synthetic? Cost?


Bruce-in-Bangkok
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address is a spam trap)