Another high oil consumption thread

ArrowFlyer86

ArrowFlyer86

Pattern Altitude
PoA Supporter
Joined
Jul 17, 2019
Messages
1,933
Location
Chicago suburbs
Display Name
Display name:
The Little Arrow That Could
The oil burn rate on my Lycoming IO-360-C1C6 has been pretty consistent at 1-1.25qts/10h (assuming I keep it right around 6qts). This morning after I got back I noticed that there was substantially more oil usage (or oil leaked...). I don't normally check oil until my next preflight, but this time I saw my nose gear door and the nose gear itself was unusually oily). So I checked the oil during post-flight it used nearly 1/2qt in a 1h flight, which is really alarming and not something I've encountered before.

The only thing that stood out was that this was the first time flying this season where it was really cold (28F on the ground, ~20F at cruise). The oil temp, while in the green, never got to its normal level (180) even running at 65% power and with the winterization plate on. IDK if that would contribute to higher oil use, I don't really recall that happening in previous cold wx flying, though I also don't normally fly a ton when its <30 F.

Before I cart it into my local A&P and cross my fingers, are there any recommendations or troubleshooting steps aside from popping the cowl off and looking for leaks? Or explanations that could potentially not involve bigly AMU spending? :oops:

**Also, sorry if this is redundant with the C210 guy thread here. His issue seemed a little more nuanced and chronic than mine.**
 
Last edited:
Absent an obvious leak source, I would check the plugs for a cylinder with unusually oily plugs. If that is found, then you have somewhat isolated your problem.

Sudden high oil consumption happened with my x-340. One cylinder plugs were unusually oily. This is what we found despite good compression.
 

Attachments

  • IMG_20211027_155820_01.jpg
    IMG_20211027_155820_01.jpg
    320.9 KB · Views: 35
  • IMG_20211027_155817_01.jpg
    IMG_20211027_155817_01.jpg
    347.5 KB · Views: 35
  • IMG_20211027_155828_01.jpg
    IMG_20211027_155828_01.jpg
    218.2 KB · Views: 35
Noted on the spark plugs, thanks!

As for obvious leak sources... When I popped the upper cowl off and looked it appeared to be oily right in the red highlighted region. There was a little more oil there before I dabbed it with a paper towel and took the photo, and is consistent with where I saw oil dripping down mainly on the right side of the lower cowl/gear-door.

1698700553694.png

1698700333328.png
 
First thing I'd do is clean the engine thoroughly, replenish the missing oil and ground run the engine for a bit. There are a number of things that could be causing a leak in that area and it could be your problem but you may have multiple things going on at the same time too.
 
mondtster said:
First thing I'd do is clean the engine thoroughly, replenish the missing oil and ground run the engine for a bit. There are a number of things that could be causing a leak in that area and it could be your problem but you may have multiple things going on at the same time too.
Click to expand...
Sounds like a plan. I'll go clean the engine thoroughly now :)

In that area, what would be some of the top culprits that come to mind?
 
Did you preheat before you started? If not you might have blown something out. Personally, I wouldn't fly that plane until a mechanic looked at it.
 
PaulS said:
Did you preheat before you started? If not you might have blown something out. Personally, I wouldn't fly that plane until a mechanic looked at it.
Click to expand...
The plane is in a heated hangar. After a 35 min flight it sat in on the ramp for 30 minutes before I started it back up to fly home. I did not pre-heat it after it sat on the ramp for 30m.

I'm going to bring it to an A&P before it flies again. For my own knowledge (and sanity) I'm just trying to see if there is any troubleshooting I can do to isolate the cause before I taxi it over to the shop. Understandably a bit nervous.
 
If you checked preflight after a decent sit and post-flight relatively soon all the oil may not have drained back into the sump. If it truly lost 1/2 qt in 1 hr, something’s amiss.

At this point would have it looked at regardless.
 
ArrowFlyer86 said:
In that area, what would be some of the top culprits that come to mind?
Click to expand...

The external oil line from the prop governor runs right above that area. There is also a 3 way joint between the accessory case cover, the main crankcase, and the oil pan that oftentimes will start to weep as the engine ages. The oil fill tube is adjacent to that area as well and oftentimes people overtighten the dipstick which eventually loosens the entire tube and causes a leak at the base of the tube. There are other possibilities as well but those are common.

High oil consumption can come from a lot of different things. A methodic approach to determining the source is necessary or else a lot of time and money could be spent guessing and you may be no closer to finding the source.
 
ArrowFlyer86 said:
The plane is in a heated hangar. After a 35 min flight it sat in on the ramp for 30 minutes before I started it back up to fly home. I did not pre-heat it after it sat on the ramp for 30m.

I'm going to bring it to an A&P before it flies again. For my own knowledge (and sanity) I'm just trying to see if there is any troubleshooting I can do to isolate the cause before I taxi it over to the shop. Understandably a bit nervous.
Click to expand...
30 minutes on a ramp is nothing, it couldn't have cooled down enough to be an issue. Good job catching it, I hope it's a cheap fix.
 
Easy check: filler cap gasket and filler tube tightness. Filler tubes can leak at top or bottom.
Lots of air swirling around in there during flight. Where the oil ends up may not be indicative of where it started, so as mondtster said, clean the engine.
 
Decowl, wash the engine with mineral spirits, run til warm, then shut down and look closely for leaks. Should be able to narrow it down that way. As others have said, common culprits are rubber hoses on oil return lines and oil filler tube base.

This is a helpful gadget.

www.harborfreight.com

Engine Cleaning Gun

Amazing deals on this Engine Cleaning Gun at Harbor Freight. Quality tools & low prices.
www.harborfreight.com www.harborfreight.com
 
First - I really appreciate everyone's comments and input here.

I spent a couple hours last night cleaning the engine. I didn't have mineral spirits handy so I just wiped down every thing I could so there was no more oil or residue. The only area that is not satisfactory is the lower cowl where all the oil built up and dripped off the gear doors, no amount of shop towels seems to get that off completely and there is still oily residue. We're going to wash the engine tomorrow at the shop per the A&Ps plans.

One thing that did stand out was the oil filler tube was very, very loose, I could rotate it easily with 3 fingers. I tightened it up (only by hand for now).

Also, as for clues... the oil buildup on the engine was disproportionately on the RH side. Only trace amounts were on the LH side. But I spent probably 4/5 of my time cleaning the right hand side of the engine compartment and lower cowl.

When I came back this morning no additional oil had built up anywhere. Doesn't tell me a ton, I guess, but good.

Tomorrow the plan from the shop is to take a quick look at the engine and make sure nothing is obviously messed up. Then wash it properly with a solvent. Then ground run it and check. And then if all good, go fly the pattern and then bring it back for another look.
 
Separately, if anyone can recommend a wash to use for mineral spirits that would be greatly appreciated. And a general process for how to clean it (e.g., I assume you don't indiscriminately spray the whole engine compartment?). Any recommendations are appreciated.
 
You can buy a gallon jug of mineral spirits at Walmart or just about anywhere that sells paint. I spray down everything in the engine compartment, then blow it off with compressed air.

If your oil filler tube was loose, that is probably the source. Don't over tighten it or you'll squeeze the silicone gasket out. Finger tight is sufficient. Does it have a lug to safety wire it?
 
Ed Haywood said:
You can buy a gallon jug of mineral spirits at Walmart or just about anywhere that sells paint. I spray down everything in the engine compartment, then blow it off with compressed air.

If your oil filler tube was loose, that is probably the source. Don't over tighten it or you'll squeeze the silicone gasket out. Finger tight is sufficient. Does it have a lug to safety wire it?
Click to expand...
Yeah, it has safety wire but poorly applied by the last shop that fixed it on there.
I used a wrench to tighten it but it's barely more than hand-tight at this point. I didn't want to overtighten it for fear of messing it up. Figured when I bring it into the shop on Thursday they can help me do it properly (and re-safety wire it so it doesn't have so much room to loosen).

Good to know on the mineral spirits at Walmart... I thought there might be a more aviation/FAA approved version of the chemical that would cost a billion dollars but be approved for use on engine cleaning :)
 
Many shops use Stoddard solvent, which is basically the same stuff. Mineral spirits is an excellent degreaser, won't harm paints or plastics, and is petroleum based so won't cause rust.
 
As much as I wanted it to be the oil filler as the issue, I don't think that's the whole story.

After cleaning the engine I did a ground run* for 15mins with a full run up and found a bit of oil pooling up immediately after.

It seems to start right here in the photo and then drip down. I can follow the path of the drips down to subsequent pooling areas. Now where it originates from is the real question...

Tomorrow we do the full cleaning with the A&P and we look at it together.

*While doing the ground run I left my hangar door open thinking it wouldn't be an issue. Turns out I angered the hangar neighbors next to me because I was gassing them with my exhaust goin right back into the hangar complex. Whoops! Lesson learned to close the hangar door before I do such a long ground run.

PXL_20231101_185345063.jpg
 
You've got it narrowed down pretty good. Give that area a quick washdown, run it again for a shorter period like 5 min, then look closer. How does the area where the oil filter seals to the adapter look?
 
Took it to the shop. Cleaning the engine for them paid off, appreciate the recommendations on that.

It was very easy for them to isolate the leak after a short ground run as coming from this junction between the housing connected to the prop governor and the accessory case. We're going to replace that gasket and clean everything in there.

PXL_20231102_180958491~2.jpg
 
Got the plane back. The shop cleaned the engine with mineral spirits, replaced the aforementioned gasket, and put it back together.
I did a ground run (haven't flown yet) and to my pleasure there was no oil build-up anywhere in the engine. Last time it was notable how much there was (see previous pics).

However, I nearly shat my pants when I popped the cowl off and saw this green goo on the bolts. I thought it was a dye for detecting oil and I'd sprung a leak but they said it's torque seal, something I'd previously not heard of... Looks more like a blob here than when I googled photos of it online lol.
Anywho, flight test later today... wish me luck.

1699386621534.png
 
Did a few laps in the pattern, decowled and couldn't find so much as a drop of oil in the engine compartment!

I'll do an actual flight in the next couple days before declaring complete victory, but so far so good.
 
You must log in or register to reply here.
Back
Top