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High Oil Consumption

C

cjbouldin

Active Member
I would like some opinions ( Oh Boy!) about high oil consumption on a fairly new overhauled Titan Eagle IV EX O-361-A1A. When I say new it has about 120 hours but was overhauled in 2004. It has piston oilers and a cam oiler with 9.5:1 cylinders. I bought the airplane, an RV8A, in June with about 80 hours. The prebuy didn't show up anything but you know how that goes.

What I'm seeing is oil use of about 1 quart every 2-2.5 hours. There isn't any significant oil on the belly, the plugs are clean w/o oil fouling, the compressions are good (>70) but what a boroscope found was some oil pooling in 2 cylinders and a slight scratch in one of those cylinders. Now, my mechanic suspects that the engine wasn't broken in well and/or the oil ring in those cylinders aren't seated or possibly installed incorrectly or even broken. His suggestion is to run some mineral oil for 25 hours and see if the consumption changes for the better. If not, then pull the cylinders and send them back to ECI for rehoning or repair. We don't suspect the intake valve guides in this case. Do engines with piston oilers typically use more oil?

Any thoughts from the engine experts out there?
 
How much oil do you try to keep in her? If you put 8 qts in, you can expect it to blow it out quickly...
 
tinman said:
How much oil do you try to keep in her? If you put 8 qts in, you can expect it to blow it out quickly...
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I usually try to keep between 6 and 7 but I did bump it to about 7.5 quarts. I wouldn't think that 7 or even 8 quarts would show up in the cylinders. It would show on the belly?
 
Oil pooling

Chris,
I wouldn't worry too much about oil pooling in the cylinders.
When I clean my spark plugs I look down through the spark plug hole with a flashlight. Just to see if I see anything unusual. I often see some oil pooling.
Like about a teaspoon of oil maybe. And my engine uses a quart every 10-15 hours.

Your cylinders may not have "broken in" properly, but some oil pooling is normal. IMHO.

I run the oil level around 6 quarts. At 5-1/2 I add a quart.

Mark
 
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Engine storage?

With very low time on the engine in around 5 years, do you know if the engine was stored (pickled) or was it hung on the airplane? Cylinder wall rust can cause the consumption problems you describe. The cure is the same as your mechanic has outlined for a poor break-in, take the cylinders off and re-hone. Just a thought.

John Clark
RV8 N18U "Sunshine"
KSBA
 
The only fix is going to be to remove the cylinders, have someone hone the cylinders, and put new rings in. Rings are cheap, about $16 for a set. Then break in the rings following ECI's breakin instructions, which works well. I OH'ed a 540 last year and it uses a quart every 30 hours, oil stays really clean.

7 quarts is way too much oil...My O-360 is definitely the happiest around 5 quarts. It will throw out anything over that, and the further above 5 quarts, the quicker it throws it out.
 
rocketbob said:
The only fix is going to be to remove the cylinders, have someone hone the cylinders, and put new rings in. Rings are cheap, about $16 for a set. Then break in the rings following ECI's breakin instructions, which works well. I OH'ed a 540 last year and it uses a quart every 30 hours, oil stays really clean.

7 quarts is way too much oil...My O-360 is definitely the happiest around 5 quarts. It will throw out anything over that, and the further above 5 quarts, the quicker it throws it out.
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I have run it at 5 quarts too but I decided that it didn't make too much difference in the consumption. When you say it throws it out I'm assuming thru the breather and it would most likely show on the underside. I really don't have much on the belly though. I'll try running it at 5-6 and see what happens. My oil temps seem to run higher a bit with lower oil levels.
 
Too much oil

If you go over 6 QTs. it just gets whipped up by the crank and puked out. A 360 Lyc. will still make oil pressure with as little as 2 Qt.s in the pan. Suggest you lower your oil level and recheck consumption numbers. There is lots on this in the archives and the conclusions are always the same as above.

Larry
 
Mark Burns said:
Chris,
I wouldn't worry too much about oil pooling in the cylinders.
When I clean my spark plugs I look down through the spark plug hole with a flashlight. Just to see if I see anything unusual. I often see some oil pooling.
Like about a teaspoon of oil maybe. And my engine uses a quart every 10-15 hours.

Your cylinders may not have "broken in" properly, but some oil pooling is normal. IMHO.

I run the oil level around 6 quarts. At 5-1/2 I add a quart.

Mark
Click to expand...

Thanks Mark, its reassuring to hear someone affirm oil pooling. Consumption though is bothersome.
 
While you are testing the new oil levels try setting the MP around 19-20. Try that and see what happens. My guess is the lower level of oil will help a great deal, the lower MP will help a little more. After that if you are not happy, it time for cylinder honing and proper break in.
 
rocketbob said:
The only fix is going to be to remove the cylinders, have someone hone the cylinders, and put new rings in. Rings are cheap, about $16 for a set. Then break in the rings following ECI's breakin instructions, which works well. I OH'ed a 540 last year and it uses a quart every 30 hours, oil stays really clean.

7 quarts is way too much oil...My O-360 is definitely the happiest around 5 quarts. It will throw out anything over that, and the further above 5 quarts, the quicker it throws it out.
Click to expand...

I have the same engine and about the oil consumption as "cjbouldin." I let it get down to 5 and then refill up to 6.

I typically see 70-72 psi running at 6. As the quantity approaches 5, the oil pressure drops as low as 65. That's when I start getting concerned and add a quart to bring it up to 6.

Just curious, Bob, what you see for oil pressure when running at 5 quarts or less?

Mike
 
Chris,
Sounds like you are simply the victim of a bad break in. As stated before if they are steel cylinders the only fix is to remove them, hone them, install new rings and follow a solid breakin procedure to the letter. Just currious what the inside of your exhaust pipes look like?
Ryan
 
Sounds like poor break in. Another thing that I have seeen happen is when the rings were installed on the pistons, the mechanic doing the work lined the ring gaps on all the rings in the same spot. This something that should NOT be done, it will allow oil to leak by over time. The gaps in the rings should be staggered and NOT lined up. I would try readjusting your level, and you are probably going to end up pulling the cylinders and getting them rehoned. Also, when you order the new rings for the cylinders, there is an end gap in the rings that you usually have to filed the rings down a little bit to obtain this dimmension. Someone might have put them in without checking this gap or got the gap to big, I have seen that also cause problems. An engine with that few hours on it should not be blowing oil by the rings. There is an issue, its just a matter of finding what it is.
 
131RB said:
Chris,
Sounds like you are simply the victim of a bad break in. As stated before if they are steel cylinders the only fix is to remove them, hone them, install new rings and follow a solid breakin procedure to the letter. Just currious what the inside of your exhaust pipes look like?


Ryan
Click to expand...


Nice light gray residue.
 
MNAv8or said:
Sounds like poor break in. Another thing that I have seeen happen is when the rings were installed on the pistons, the mechanic doing the work lined the ring gaps on all the rings in the same spot. This something that should NOT be done, it will allow oil to leak by over time. The gaps in the rings should be staggered and NOT lined up. I would try readjusting your level, and you are probably going to end up pulling the cylinders and getting them rehoned. Also, when you order the new rings for the cylinders, there is an end gap in the rings that you usually have to filed the rings down a little bit to obtain this dimmension. Someone might have put them in without checking this gap or got the gap to big, I have seen that also cause problems. An engine with that few hours on it should not be blowing oil by the rings. There is an issue, its just a matter of finding what it is.
Click to expand...

Here's a thought. I'm purely speculating but as I understand the function of piston oilers, their main purpose is to cool the cylinders by shooting a fine jet of oil to the underside of the piston. If the piston crown is at 1000+ degrees would some of that oil vaporize and be expelled as oil vapor out the breather? I can tell you that they do a very good job of cooling the piston and keeping cylinder head temps cool. I see 280-300 max on even very hot days. The negatives are high oil temps (230) and possibly higher oil consumption. Is this theory valid?

I'm really trying to understand why oil usage is consistenly high before I pull cylinders and spend too many "freedom chips".

Thanks to all for your insight! Great forum!
 
cjbouldin said:
The negatives are high oil temps (230) and possibly higher oil consumption.
Click to expand...

Could be why you are "using" more oil. While 230 is not in the "red" it is quite warm. Have you looked into improving the oil cooling? Cheaper than an overhaul.
 
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Test it first

Before you take it apart, I'd sure try running with 5 1/2 to 6 1/2 for a while and see if you are just blowing it overboard. 7 1/2 is just asking for having it
coughed out somehow.
 
Test it first

Do a compression check and see where your numbers are. If your ring end gaps are aligned you will see numbers in the low fiftys and they will not fix themselfs. It cost me $100 for the re-ring kit for a 0360 cylinder.
 
CHTs and OT out of spec

Your CHT readings, if accurate, are lower than what is required for the parts (rings in this case) to do their job. Additionally, the pistons won't fit the bores as they are designed to...so, you COULD have glazed bores. Judging from your reported oil temps, this is a distinct possibility.

You really should adjust your baffling to get the CHTs up where they belong. 380F should be your max allowable cruise settiing, with about 340F as your low alarm setting. Cyl temps below 320F will cause the upper ring to stick, which makes the 2nd ring cover both rings' jobs....which it cannot do, leading to its failure, and then the oil ring goes south. The scratch in that cyl bore is a clue to ring failure, tho it is no guarantee.

Ring failure will show up as a lot of oil coming out the breather, but a good air/oil spearator will mask this symptom. Do you have a separator installed?

If you decide to re-ring the engine, get a ring set, and have someone who knows what they are doing (aircraft cylinders, please -- the pattern left by the honing tool is critical) to hone the cyls. Re-assemble, and re-install. Use Phillips X-CY 20W-50 for break-in, an for the rest of the engine's life. Use of mineral oil is not necessary.

You can send the cyls to ECI and have 'em re-barreled if they are out of spec -- this is cheaper then new cyls if your heads are OK. The cyls come back with the latest bore coating, new valves, seats, & guides along with new pistons and rings, and gaskets to install 'em. This would be a worst case fix -- re-ringing the engine might be all you need.

Also, get a cooler that will bring your oil temps down to 200F or so, or maybe get enough air to the one you have so it can do it's job. 230F in cruise it too high; 170F is too cold.

The low CHTs & high oil temp combo suggests to me that your baffling around the cyls allows too much cooling there, robbing air from the cooler.

The ring job won't work for long if you don't fix the CHT and oil temp problems. You have a bit of work to do to get around your situation entirely.

Good luck, and carry on!
Mark
 
Heart Attack !!!!

>>380F should be your max allowable cruise settiing, with about 340F as your >>low alarm setting

Mark, you're killing me :). I run 300F in cruise and have for the last 1,000 hours or so.

Walter Atkinson chimed in here a few times and said those temps were fine. There was no reason to raise temps. Sounds like we have a difference of opinion among the pros :-(.

John
 
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