Oil leak question, what makes one a "bad" one?

[dweymer]

I have been curious for a while what makes an oil leak a bad one, meaning potentially damaging. I know all leaks could lead to failure if oil levels are not kept up, but say I want to go for a 3 hour drive??

I had a bad leak, replaced the oil light sender, and now have a much smaller leak. After warm and driven some I park it and turn off the engine, it drips to create a puddle about 3"x8" overnight; no more drips.

I am thinking about letting it run with a pan under it so I can measure the amount, but without varying the throttle(and oil pressure) it won't be realistic. Any ideas, comments?

BTW I am pretty sure it is my flywheel seal.

Can a thicker oil help? recommendations?

[nesslar]

Not to presume that you don't know about the system in our cars, but how high is your oil level when the engine is warmed up? All the way to the top mark on the dipstick?
When I first got my 911, the fluid changes prior to my taking delivery included filling to the top mark, and the first night in my garage I had a puddle similar to what you have described.
Now I only fill to about 40% of the way up from the bottom mark and I take care to prevent the level from going any lower. This might help you.

[dweymer]

Oil level is maintained just below the halfway point.

[petrolblue83911]

In my opinion bad leaks are the following,


-leaks that are large enough so that you need to add oil on that 3 hr drive you talk about (this would mean you are loosing more than a quart pr hr of driving. a leak this bad would likely show a big puddle every time you stop

-leaks that piss oil onto the top of the engine


-leaks that get lots of oil into the heat exchagers and as a result fill the car with oil smoke when you use the heat.



other leaks I can live with.

For example, I have 3 small leaks that have been present since i got the car a few yrs ago. over 18k miles they havent changed, I generally add a quart every 1000 miles, my car has 150k miles on it, and doesnt smoke. if I let my car sit for several weeks i get a puddle the size of a pie plate or so, but in total this is less than 1/8 of a quart of actual oil.

-just my opinion on it.

-small leaks like what I have aren't hurting anything. I don't neglect to check my oil regularally with the car properly warmed up, and none of us with air cooled 911's should neglect rutine oil inspections so if there was a big change in level I would know about it.

[defcon65]

If your 911 leaves a smallish oil spot on the garage floor that never really grows in size or changes location, You can live with that. Everything else, fix - especially if you must continually add oil for short trips. That's living on borrowed time IMO.

[dweymer]

I am really just trying to gauge how much oil i am loosing. Any thoughts on this:

Warm up by driving, fill the gas tank up etc.
Bring oil level when warm to a notch in the dipstick(halfway btw full and empty)
Go for half hour ride down the highway.
Stop, and see how much oil i need to add to bring it up?

Maybe I am just being a goofball about this, but I just rebuilt the engine and don't really want to melt it by being stoopid!

[DW SD]

Originally posted by dweymer
I am really just trying to gauge how much oil i am loosing. Any thoughts on this:

Warm up by driving, fill the gas tank up etc.
Bring oil level when warm to a notch in the dipstick(halfway btw full and empty)
Go for half hour ride down the highway.
Stop, and see how much oil i need to add to bring it up?

Maybe I am just being a goofball about this, but I just rebuilt the engine and don't really want to melt it by being stoopid!

Just use standard procedure for measuring oil level and carefully note the difference. Maybe start with 1/2 a quart over your normal. If it is pissing out, I wouldn't do it. If it is dripping quickly, it should be OK to test the delta.

Also, make absolutely sure that the temp is the same at both checks. A small difference in temp can throw off results. Also, idle prior to measuring for the same amount of time. I think factory calls for 1 minute before checking oil level.

Doug

[RarlyL8]

Man, you guys are in denial. If you have to ask the question you've got a problem.
A drop is manditory 911, but a puddle?

[Jetjockey]

I would not accept a small puddle of oil. I used to fly a lot in single engine airplanes. We used the assumption that a small oil leak was the beginning of what could be a large oil leak. Large oil leaks have the potential to be life ending events in a single engine plane. Thus any oil leak was addressed in a quick manner.
In a car, the loss of even all oil would be costly but almost certainly not deadly. I would be thinking more about if the flywheel seal leak will damage the clutch disk and cause more expensive repairs down the road. I would also think about friends wanting you to park on the street or drive another car to keep their driveway oil free.
Because the engine was just overhauled, this means it will leak for a long time and many miles before the next overhaul if you choose to do nothing. I may be able to tolerate it if I knew it was due to be rebuilt in a year or two. In this case if the car were mine, I would drop the engine myself, replace the flywheel seal and be done with it.
On a side note, my flywheel seal was found leaking on PPI inspection. The car was driven very infrequently and mechanic said flywheel seal is notorious for leaking if not driven regularly. He said it will stop leaking or dramatically slow down when you start driving the car regularly. He was right and the leak stopped completely when it became my daily driver. Had the leak not stopped I intended to drop the engine and fix it myself. I am sure I would have done a lot of "while you are in there" work like replacing crankcase breather hose seal etc.