brown oil???

[jasonw]

Long story short. Overheated b&s quantum a couple times, now i fill it with fresh oil and after 5 minutes it looks like nasty old brown oil. The oil in the tractor for example still looks new every 25 hours when I change it. Is this dirty fresh oil a sign of something wring?

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[Fisher]

Lawn care business tips

Overheating probably has caused a slight sludge problem which in turn is dirtying up your fresh oil. May try flushing it.

[SuperiorPower]

Have you flushed it out more than once? Personally, I doubt that it is sludge. At least in my experience I have yet to see that caused by overheating. I would try filling it to the "full" mark, running it a few minutes, draining it, and repeating 2-3 times or until it clears up.

Also, does it have good compression? How did the oil look before it was drained?

[Fisher]

Originally Posted by SuperiorPower

I doubt that it is sludge. At least in my experience I have yet to see that caused by overheating.

I'd agree that a one or two time overheating may not result in sludge immediately as It would take longer to build up. Though sludge is caused from oil heating rapidly and hotter than it was designed to do (depending on oil and detergents present) is it not?

I've not actually had any sludge build up in my equipment (previous statement was based on general automotive knowledge) but I have seen what appeared to be the early signs of the oil getting burnt, would this be related to the compression issue? Oil staying on and burning on the cylinder walls and the blending back with the oil?

[jasonw]

Compression was and is great, lowers a bit after warm up but should be fine. Before over heating it the oil looked great, now new oil looks dirty and old after running very little. This motor for the most part is brand new, not under warnety anymore but only has about 5-6 hours on it.

[Steve]

Compression was and is great, lowers a bit after warm up but should be fine.

How are you checking it?

[jasonw]

Steve I'm using the dipstick.

[Steve]

Ohhhh I thought you were checking the compression with it running Didn't know how you would do that.

[jasonw]

I thought you wanted to know how I was checking the oil lol. I'm just checking compression by feel with the pul chord

[SuperiorPower]

Originally Posted by Fisher

I'd agree that a one or two time overheating may not result in sludge immediately as It would take longer to build up. Though sludge is caused from oil heating rapidly and hotter than it was designed to do (depending on oil and detergents present) is it not?

I've not actually had any sludge build up in my equipment (previous statement was based on general automotive knowledge) but I have seen what appeared to be the early signs of the oil getting burnt, would this be related to the compression issue? Oil staying on and burning on the cylinder walls and the blending back with the oil?

From my understanding, oil breaks down when it gets too hot. This does cause sludge. I am not sure about the affect of it heating to quickly as I have never heard how that would affect it or if it did. It is possible though. Here is an interesting article about sludge and what causes it.

Also, I am not sure about the cause of the oil being brown or if that is possible for it to burn on the lower end of the cylinder. But with this being a newer engine, I doubt it is compression related. What I might suggest is posting that question over on Bob is the Oil Guy Forum. There is a wealth of oil knowledge there. I would make sure to mention that it is an air cooled engine since this makes a big difference.

Now, here is a freebie..... NEVER use Pennzoil in your air cooled engines. Unless you hate them, of course. I have seen way too many engines where the owners tried to save money and used Pennzoil for their oil changes. Pennzoil seems to break down a lot easier than some other brands. They would bring an engine in that had thrown a rod or had locked up. I would expose the crankcase and turn to them asking if they had used Pennzoil. Their jaw would drop to the floor and they would ask how I knew. The 1/2" thick layer of sludge in the bottom of the crankcase might be a clue. Not changing the oil often enough would likely also be contributor to it.