Ground run up to prevent corrosion

[N601RX]

I've always heard that a ground run up would not get the oil hot enough to dry the moisture out. In normal flight my oil is around 190. I'm doing some work right now and unable to fly. Today I pulled it outside and cranked it up. In a few minutes at around 1700 rpm the oil was up to 180. I reduced the rpm to 1400 and the oil continued to climb to 210 and the cylinder temps leveled off at just under 350. The engine seemed happy at 1400 and I was in a clean area so I set the brake let it run for about 35 minutes. The oil stayed around 210 and cylinders around 350. I was very surprised at this as I've always read it wouldn't work. This is on a F with stock cowl and lasar oil cooler relocation kit. Has anyone else ever tried this?

[orionflt]

The biggest problem with doing the ground run is that the engine isn't run long enough to vaporize any water that has accumulated in the crank case. The truth is if you run it long enough on the ground to get the temps up, you might as well enjoy a couple of laps around the pattern.

[N201MKTurbo]

Why didn't you just taxi out and fly? Was the weather crappy?

[Marauder]

Why didn't you just taxi out and fly? Was the weather crappy?

Around here it is: FICON ICE BRAKING NIL

Sent using Tapatalk

[kmyfm20s]

If you have a preheaters just plug it in before and after your run up for a while and it will get rid of any moisture.

[kerry]

If you're unable to fly and your plane and its sitting for some time you could consider using silica dehydrating plugs.  I bought my plane from someone who stored it this way for years.  He would replace the silica beads every so often.

[N601RX]

The belly and a few other things are off right now while we are doing some work on it, so flying it isn't an option. I've been busy with some other things around the house and at work so it is taking longer than expected. Since putting the new motor in last year, I have not let it set more than 10 days without flying.

[Danb]

I started a thread last month due to my inability to fly for awhile, it was a consensus to consider a engine dehumidifier and camguard. I used to use avblend.. A tempest aa1000 engine saver can be purchased for $190.. Seemed like a good recommendation from our friends on mooneyspace. Happy flying. I'll be back in the saddle in a couple weeks...good luck Dan

[N601RX]

I remember your thread as well as a couple of others where this subject has came up.  If it was going to be setting for an extended period of time I would not hesitate to buy or build a dehumidifier. I think most all of us get in a situation at least one or twice a year where we don't get to fly every 10 days for whatever reason.  Every time this subject has come up it has been the consensus that it is not possible to get the temperature on a ground run that is necessary to evaporate the water. From what I saw yesterday it appears that all that is needed is a fast idle. I wish I had experimented more and saw if less throttle could be used. I did use some faster speeds to began with, but now don't think that was necessary  I did try leaning to peak RPM and that seemed to add another 10 deg of temperature to the oil.  I suppose a piece of tape over the oil cooler might help some also, but it wasn't necessary.  The OAT was 55deg yesterday when I done this.  Here is the JPI data.

[N201MKTurbo]

Around here it is: FICON ICE BRAKING NIL

Sent using Tapatalk

 

Yes the weather was especially bad here yesterday. There were clouds obscuring the sun at about 10000 feet and it only got up to 75.

 

I'm sorry, I couldn't help it....

[Marauder]

Yes the weather was especially bad here yesterday. There were clouds obscuring the sun at about 10000 feet and it only got up to 75.

 

I'm sorry, I couldn't help it....

 

 

[jetdriven]

I remember your thread as well as a couple of others where this subject has came up.  If it was going to be setting for an extended period of time I would not hesitate to buy or build a dehumidifier. I think most all of us get in a situation at least one or twice a year where we don't get to fly every 10 days for whatever reason.  Every time this subject has come up it has been the consensus that it is not possible to get the temperature on a ground run that is necessary to evaporate the water. From what I saw yesterday it appears that all that is needed is a fast idle. I wish I had experimented more and saw if less throttle could be used. I did use some faster speeds to began with, but now don't think that was necessary  I did try leaning to peak RPM and that seemed to add another 10 deg of temperature to the oil.  I suppose a piece of tape over the oil cooler might help some also, but it wasn't necessary.  The OAT was 55deg yesterday when I done this.  Here is the JPI data.

I've though about this long and hard as well.  Running the engine on the ground it looks like you got the oil hot enough to boil off water, but you had to put water into the oil by running it long enough to get it warm. So it may take 20 minutes of hot oil temps to boil off the water, which means 30-40 minutes of ground running.  It seems to me it is causing a problem which needs a solution. 

 

You want to recoat all the internal parts with oil so it can go another 14 days with corrosion protection. For me the solution is crank the engine and run it at 1000 RPM for 30 seconds, then shut down. Burns 2oz of fuel. No water added. Internals coated with oil.  FWIW even then, I think its only safe to do this one time between flights.

[N601RX]

I had already done a quick 45 second run about 10 days ago, so this one needed more.  I should be back flying before another 10 days are up.  With the ground run I was able to get the oil above 212 which I have never saw in flight. I know this discussion has come up several times before and just wanted to let others know that low RPM ground run will heat the oil enough to get the moisture out and the cylinders still stay at a reasonable temp.   I'm guessing with some experimentation it might be possible to block most of the cooler with tape and lower the RPM more. 

[jetdriven]

As soon as we move to the real hangar next month I am building a "Don Muncy Special" silica gel dehydrator.

[kujo806]

I had to do something similar back in December.  I am in a partnership on a plane that had not been run in about a month.  The weather in Iowa has been absolute you know what seemingly all winter.  The rare day the weather was nice, I was busy and apparently the other partners were too.  I started it up and let it run for a while to get the oil temp up.  I didn't run it hard on the ground or anything like that.  It would be hard to convince me that this was worse than letting it sit for a few months without touching it.

[jlunseth]

Around here folks will leave their engine heater plugged in with the oil cap loosened.  Nobody is thinking this will boil off oil, just keep any moisture moving up and out of the crankcase.

[Danb]

Byron let me know how that works out   it seems like a great idea!!

[DonMuncy]

Byron,

Feel free to get in touch if I can help with and advice or parts I may have.

[Mooney65E]

I had already done a quick 45 second run about 10 days ago, so this one needed more.  I should be back flying before another 10 days are up.  With the ground run I was able to get the oil above 212 which I have never saw in flight. I know this discussion has come up several times before and just wanted to let others know that low RPM ground run will heat the oil enough to get the moisture out and the cylinders still stay at a reasonable temp.   I'm guessing with some experimentation it might be possible to block most of the cooler with tape and lower the RPM more. 

 

I rarely see oil temps over 200 degrees even during multi hour flights in the Summer. Should I assume there is condensation created moisture in my engine at all times until I change the oil? Should I restrict airflow through my cooler and  aim for hotter oil temps to burn off moisture during every flight?

[N601RX]

Like you I never see those temps either in flight. I was just pointing out that the ground run produced as high or higher temps than normally found in flight. I just mentioned restricting air flow thought the cooler as a possible way of reducing the time of the ground run and reducing the rpm of the ground run.

[jetdriven]

I rarely see oil temps over 200 degrees even during multi hour flights in the Summer. Should I assume there is condensation created moisture in my engine at all times until I change the oil? Should I restrict airflow through my cooler and  aim for hotter oil temps to burn off moisture during every flight?

The temp of the oil in the hottest part of the engine such as the cam and cylinders is 20-40F higher depending on what you read. So a 190F oil temp ought to boil off the water.

Kujo806, I asked Ed Kollin about running it 30 seconds and he was still adamant it was bad. He said after a ten minute run and let it cool down the valve cover area has ounces of water in it.

[kujo806]

The temp of the oil in the hottest part of the engine such as the cam and cylinders is 20-40F higher depending on what you read. So a 190F oil temp ought to boil off the water.

Kujo806, I asked Ed Kollin about running it 30 seconds and he was still adamant it was bad. He said after a ten minute run and let it cool down the valve cover area has ounces of water in it.

It ran for 15-20minutes in this instance.  I wouldn't shut down after 30seconds any time if I could help it.  That is bad on the battery and engine.  Oil temp came up to nominal before I shut down.  If after a ten minute run there is that much water in the valve cover area, wouldn't the water be there after flying an hour too assuming the oil temp came up to nominal in both cases?  In this weather I don't really ever see higher than nominal oil temp.

[aaronk25]

It ran for 15-20minutes in this instance. I wouldn't shut down after 30seconds any time if I could help it. That is bad on the battery and engine. Oil temp came up to nominal before I shut down. If after a ten minute run there is that much water in the valve cover area, wouldn't the water be there after flying an hour too assuming the oil temp came up to nominal in both cases? In this weather I don't really ever see higher than nominal oil temp.

Ya but if you limit your operation to 30 sec nothing gets warm enough to put any considerable amount of moisture into the crank case. Can you explain how this is bad for the battery and the engine?

[DS1980]

As soon as we move to the real hangar next month I am building a "Don Muncy Special" silica gel dehydrator.

Can you provide the blueprints?

[kujo806]

Ya but if you limit your operation to 30 sec nothing gets warm enough to put any considerable amount of moisture into the crank case. Can you explain how this is bad for the battery and the engine?

Well this weather is hard on batteries and starters in general, and if you don't run the engine for a while the battery will not get a good charge especially considering generators and alternators don't reach their max capacity until you run higher RPM (generators are worse). I guess if you use a trickle charger this isn't as big a deal.  As for the engine, the moisture is created by combustion right?  Any engine run at all will create water vapor.  In fact, I would think more of this water (and other emissions) would reach the oil and crank case when cold because there is more blow by when everything is cold and hasn't expanded yet.  Also, when you first start the engine, you will be running fairly rich.  Whether it is my car or plane, I prefer to run it a while so you reach normal operating temp and don't shut it off while running rich.  Just my $0.02.  Again, I fully agree that it is better to go flying, I would rather do that than idle on the tarmac anyway, the problem is that sometimes it is not an option, and I think running at idle for a while (up to nominal oil temp) is better than letting the plane sit for months.  I only did this once and it was after a month of no flying.