Aerated oil

Mofosheee · Wednesday at 3:38 PM

I have '73' 850 with a fresh engine that I ran for approximately 5 minutes then shut down when I noticed well flowing aerated oil being returned to the oil tank, similar in appearance the attachment. Prior to run, the oil system was fully primed and filled. Proper routing of oil lines was verified. Kicking the engine over showed return oil being delivered to the tank and valve train. My bad....... oil pressure gauge was not installed.

So, I'm hunting for answers on Access when I stumbled upon a comment made by LAB sometime ago (thank you) attachment. It's obvious that the return system will suck in some air. This happens by design. But, is it too much and an indication of an abnormal condition? I understand the system but, I don't have the experience to make the qualified call. Me thinks, better safe than sorry.
Thank you again!

Tornado · Wednesday at 3:45 PM

If sump fully drained/dry and new filter fitted, I'd expect aeration to occur for a while as the scavenge pump will be slurping away whatever dribbles down from above for a while...recall it pumps 2x the feed pump rate...so there will be little to no excess in sump.
The filter also takes a while to fill and clear oil trapped air, so bubbles to be expected from there as well.

Any cloudiness, milkyness of fresh oil will disappear after a couple of runs. Typically that is just moisture in the fresh oil and needs to be heated off.

mean gene · Wednesday at 3:45 PM

Some oils tend to foam quicker than others. What oil are you running? There "used" to be additives to help stop foaming

Grandad · Wednesday at 4:05 PM

All sounds normal to me

robs ss · Wednesday at 4:07 PM

I think it is more an indication of which oil you're using.
As Les rightly pointed out, the scavenge (return) side of the pump is sucking air with the oil 99% of the time. Judging by gear thickness compared to the pressure side the return to the tank will be 50/50 oil/air.
The oil filter (I presume you have one?) should settle things down a bit.
Cheers

Triton Thrasher · Wednesday at 4:07 PM

If you are the mechanic who built the bike, you shouldn’t be surprised to see air in the scavenge flow.

Mart UK · Wednesday at 4:46 PM

After fitting an XS650 reed valve in the breather hose, I no longer see froth in the oil. I wasn't looking for nor expecting that affect. Not really questioned why, just noticed it, not complaining.

baz · Wednesday at 6:09 PM

Mofosheee said:
I have '73' 850 with a fresh engine that I ran for approximately 5 minutes then shut down when I noticed well flowing aerated oil being returned to the oil tank, similar in appearance the attachment. Prior to run, the oil system was fully primed and filled. Proper routing of oil lines was verified. Kicking the engine over showed return oil being delivered to the tank and valve train. My bad....... oil pressure gauge was not installed.

So, I'm hunting for answers on Access when I stumbled upon a comment made by LAB sometime ago (thank you) attachment. It's obvious that the return system will suck in some air. This happens by design. But, is it too much and an indication of an abnormal condition? I understand the system but, I don't have the experience to make the qualified call. Me thinks, better safe than sorry.
Thank you again!

It's normal

Schwany · Wednesday at 6:32 PM

It'll look like pale green Guinness on occasion. 6 minutes is a short run time. My guess is if you put an oil pressure gauge on it you would have normal oil pressure. I personally would not bother. I've had the line come off and an oil pressure gauge has graduated to just another failure point. They do look cool though and if you have a Jones to install a good one go for it. They can save an engine if you are paying attention to one while enjoying a ride.

kommando · Thursday at 12:57 AM

Air in the oil is normal as the return side of the pump has double the feed side capacity, aerated oil is not. If the oil does not settle to being normal then change to a different oil

Mofosheee · Thursday at 5:49 AM

Schwany said:
It'll look like pale green Guinness on occasion. 6 minutes is a short run time. My guess is if you put an oil pressure gauge on it you would have normal oil pressure. I personally would not bother. I've had the line come off and an oil pressure gauge has graduated to just another failure point. They do look cool though and if you have a Jones to install a good one go for it. They can save an engine if you are paying attention

So then, it's the nature of the beast. I'd rather ask a dumb question than ruin an engine. Oil press gauge is intended to be temporary. Yes, an oil filter is installed. Another oil/filter change with 30W Valvoline non-detergent in it's near future. Next run will be longer and pending good oil pressure, I'll quit being a bish and run it. I very much appreciate everybody's 2 cents worth.

Triton Thrasher · Thursday at 5:52 AM

I view an oil pressure Bowden gauge as a temporary test instrument.

You could argue that an electric one is pretty safe from acute leaks.

YING · Thursday at 7:26 AM

Mofosheee said:
So then, it's the nature of the beast. I'd rather ask a dumb question than ruin an engine. Oil press gauge is intended to be temporary. Yes, an oil filter is installed. Another oil/filter change with 30W Valvoline non-detergent in it's near future. Next run will be longer and pending good oil pressure, I'll quit being a bish and run it. I very much appreciate everybody's 2 cents worth. Rex

YING · Thursday at 7:28 AM

Rex,
Is that 30W non-detergent oil just for breaking in your engine?
Mike

Schwany · Thursday at 9:33 AM

It was not a dumb question at all. Rebuilding an old Norton twin engines is not inexpensive, and not really that much fun (at my age anyway) so it is good to be cautious.

Mofosheee · Thursday at 9:34 AM

Triton Thrasher said:
I view an oil pressure Bowden gauge as a temporary test instrument.

You could argue that an electric one is pretty safe from acute leaks.

Did you intend to write bourdon gauge? This is what I purchased and will be using. https://www.ebay.com/itm/234399733208
Thanks again!

Mofosheee · Thursday at 9:35 AM

YING said:
Rex,
Is that 30W non-detergent oil just for breaking in your engine?
Mike

Yes, 30W non-detergent Valvoline

Mofosheee · Thursday at 9:39 AM

Schwany said:
It was not a dumb question at all. Rebuilding an old Norton twin engines is not inexpensive, and not really that much fun (at my age anyway) so it is good to be cautious.

I with you. I building it for somebody I don't know and don't wanna do it again. The clock is ticking.

htown16 · Thursday at 12:16 PM

I would never run 30w even for breakin. This is what I have used before

#10635 LUCAS ENGINE BREAK IN OIL. SAE 20W-50. HIGH ZINC 1 QUART

1 Quart of Lucas Engine Break-in Oil, SAE 20W-50 (High Zinc). The initial start up of a new engine is critical to its performance and life expectancy. How well and how fast the rings will seal could make the difference between winning and losing. Compatible with Ethanol, Methanol and high octane...

benningautoparts.com

YING · 2024-12-14T04:31:01-0700

Mofosheee said:
Yes, 30W non-detergent Valvoline

Rex,
I would be very leery of using that straight 30W oil for your initial break-in.There are a lot of better alternatives.
Mike

Aerated oil

Mofosheee

Attachments

Tornado

mean gene

Grandad

robs ss

Triton Thrasher

Mart UK

baz

Schwany

kommando

Mofosheee

Triton Thrasher

YING

Pittsboro,NC

YING

Pittsboro,NC

Schwany

Mofosheee

Attachments

Mofosheee

Mofosheee

htown16

#10635 LUCAS ENGINE BREAK IN OIL. SAE 20W-50. HIGH ZINC 1 QUART

YING

Pittsboro,NC

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