First oil change question.

[Shinyknight]

Have about 4 hours runtime on my compressor. Oil is looking dark brown..using royal purple. I see people do oil change by just removing the small screw below the window to drain the old oil and just top it back. Wouldn't there still be some oil left that didn't get drain? So my question is, would it be better to take off the crank case and wipe the inside clean, or just do what the manufacturer recommend and just drain by the screw hole. My only concern is getting it to seal after taking it off. I hear some people having trouble getting the crank case seal and leaking oil. 

 

[STO]

So the short version is you don't need to worry about it, just drain the oil through the drainplug and then replace it. This is how it is done pretty much everywhere and on everything from industrial equipment to compressors to your car. 

The longer answer, the why, gets back to what exactly oil is supposed to do. Your oil is supposed to clean and lubricate. Sure you could go through all the trouble of getting every last drop of old oil out, but what would that accomplish? Synthetic oils don't really break down and lose lubricity like conventional oils, and so mostly what you're trying to do is just get the crap suspended in the oil out of your crank case. You can get almost all of it out by just draining the oil, particularly when hot if you've just run the compressor a bit. That last little bit at the bottom will be mixed in with your new oil and some of it will be removed at your next oil change. Basically, it isn't hurting anything and is no big deal. If your compressor had an oil pump and filter, it could probably run a lot LOT longer than 4 hours between oil changes on royal purple full synthetic as well. 

I hope that helps answer your question. 

 

[jarmstrong]

what he said, also, you can tip the compressor a little, so all the oil runs out the drain plug. Just like changing oil on your car,you do not remove the oil pan, only remove the drain plug

 

[DirtyDovi]

STO nailed it.

Having worked most of my life in the automotive field, I've done thousands of oil changes over the years.. 
Obviously, we can't all tip our vehicles, but, we 'can' tip our compressors.. I have to do the 1st oil change on my Yong Heng and use RP lube too.. 
Mine's dark enough that I figure I'll do it a bit early. When the bolt is removed and the oil stream runs thin, I'll angle / tip the comp towards the front.. 
That'll help some of the oil more towards the back make its way to the front and drain out too.. But nothing crazy.
I've always done that with my airbrush and other smaller hobby compressors, and it works really well.

2 things.. 
1 Remove the oil filter thingamajig 1st, so the oil will flow out faster.. 
2 Be careful installing / tightening the drain plug - so not to x-thread or over-tighten / strip threads.

Other than that - Good to go!

 

Sam -

 

[DirtyDovi]

Derp, I forgot to mention..

When your oil is draining / drained, just do a quick inspection of what comes out.. 
You'll want to check for anything somewhat shiny - metal particles, metal filings, etc.

 

[Shinyknight]

Ok thanks guys. I was about to tear it apart to clean every bit of oil inside. I guess I'll just tilt and drain from the small hole.

 

[airgunfans]

... My only concern is getting it to seal after taking it off. I hear some people having trouble getting the crank case seal and leaking oil. ..

If you are talking about the Yong Heng, this is a very valid concern, I have taken the crank case cover off and had a hard time putting it back on. For some reason, the rubber seal is made a bit smaller than the cover so you have to stretch it in all directions and put it quickly in place before it shrinks back to the original size. That time window is just several seconds.

 

[Hubertus]

it takes just a couple of minutes to remove the crank case cover

just make sure that you got some engine gasket sealant if the original rubber gasket gets damaged.

 

[DirtyDovi]

I've never been one to reuse gaskets..
For the most part, I've always replaced with new, or made new.. 
Cork and rubber are both options, but a really nice and painless method is to use RTV Sealant. 

"Permatex High Temp RTV Sealant" 

https://www.amazon.com/Permatex-High-Temp-Red-Silicone-Gasket/dp/B0002UEN1A/ref=sr_1_6?hvadid=241901399749&hvdev=c&hvlocphy=9058784&hvnetw=g&hvpos=1t1&hvqmt=e&hvrand=1304487829411458790&hvtargid=kwd-32167275218&keywords=high+temp+rtv+sealant&qid=1556297487&s=gateway&sr=8-6 

And here are a few vids to show how it is applied:

https://www.youtube.com/watch?v=UXN4FqQH-xM 

and 

https://www.youtube.com/watch?v=21CvanhKILA 

Personally, I'll grab a can or 2 of brake-cleaner, and spray down all of the components/parts that I'm working with 
to get any trace of oils / debris off from the surfaces before applying.. Then continue..

If there are any areas of previously stuck gasket, etc. It is best to use something like a sharp flat razor blade 
to remove it - keeping the surface straight / true - Vs. using something like emery / sand paper, a die grinder, etc. 
While that's okay if you know what you're doing, if not careful, too much material can be taken away and that'll cause issues..

Hope that helps a bit.

 

Sam -

 

[Shinyknight]

... My only concern is getting it to seal after taking it off. I hear some people having trouble getting the crank case seal and leaking oil. ..

If you are talking about the Yong Heng, this is a very valid concern, I have taken the crank case cover off and had a hard time putting it back on. For some reason, the rubber seal is made a bit smaller than the cover so you have to stretch it in all directions and put it quickly in place before it shrinks back to the original size. That time window is just several seconds.

Im actually talking about the hatsan lighting compressor.

 

[airgunfans]

I've never been one to reuse gaskets..

The rubber seal behind the crank case cover of Yong Heng is not just a gasket but a diapham isolating the bigger cavity in which the connecting rod moves and the smaller cavity just behind the crankcase cover. There is a small hole in the diapham allowing oil to freely flow between the cavities but not air . I think the purpose of such design is to prevent the air around the stirrer ( the small metal rod at the end of the connecting rod ) , which contains a lot of stirred-up oil droplets, from going to the breather tube. If that piece of rubber is replaced with RTV sealant, I believe a LOT more oil mist will be sprayed out from the breather tube when the compressor is running . Definitely not a good thing for your health.