Oil Loss, High Oil Temp .....

[funvee]

Heeeeelp,

 

Ok here is the whole skinny.

 

I am in Canada but bought my 67 F last October from Oregon.  The plane had about 3900 tt and 600smoh but it had one low compression (75/76/61/72)  When flying it back from Oregon, I noticed the Oil temp was running high.  It was up around 220 and the oil pressure was dropping off so I stopped and added 2 liters when my pressure had dropped under 30.

 

My next stop was to drop the plane off where it was getting it's import inspection and it's first Canadian Annual.  I told the AME about the oil problem and he said he'd have a look.

 

When I finally got my plane back from the annual and import, I was told that he had sent my oil cooler out for a rebuild and a full flush/flow test.   "Everything should be fine now" but he thought I had a set of rings likely responsible for the oil loss.

 

When I flew it the 1 hour back to my airport, I notice it was still high (220-240) and it was -10 C out that day so I should have had plenty of cooling.  When I got there and let the plane sit and cool off, I noticed it had 'Lost' 1 litter of oil (on only 1 hr flight).  No noticeable oil on the belly and no carbon buildup in the exhaust tip.

 

Discussed with my mx and he thought we'd start with the rings on the low cyl.  Turns out the scavenger ring was broken in 3 pieces.  Replaced that set of rings and redid compression (76/77/71/76).  Still high oil temp and same oil loss.

 

I noticed that after flying, if I shut down and quickly went to feel the oil cooler, it was ice cold every time.  No matter how hot the temp gauge had read or how cold the OAT was.  Flying at -35c I still had temps 220-240 and I was still loosing about 1L/Hr.

 

So, next we thought it might be the pressure relief valve failing and letting the oil flow straight out the bottom dump hose or that the Vernatherm was failing and not sending any oil to the cooler.  So, we changed them both with new ones and still same problem.

 

Then, took the oil cooler out and my mx ran varsol though it to see how it was flowing and everything was fine.

Tested the cooler hoses to make sure they both flow ok and they where fine too.

 

(We have done 3 Oil changes and cut filters since trying to figure this out... all where nice and clean)

 

Next, we thought we better verify the gauge.... We took an accurate thermometer, a tin pan of fresh oil, the sender probe and heated it all with a heat gun.  We verified the gauge in the plane was accurate with the thermometer all the way to 260deg.  It was amazing how accurate it was.

 

Next up, my mx wanted to cover the cooler because he thought the oil might be getting over cooled (and getting too think to flow) due to the -20c temps we had been flying in.  

 

So, today, I did aluminum tape over the cooler and went out flying.... Heat went through the roof and was over 260deg (in cruise with OAT -15c) so I brought it right back and got down on the ground as quick as possible.  After stopping, I went up front and the cooler was hot for the first time EVER... That was the first time I even felt a bit of heat on the cooler but obviously covering it completely didn't work because it didn't get any cooling (even though it proved it can flow ok under some circumstances).  Also... on that flight, I wanted to "verify" whether or not the oil was dumping through the pressure relief valve so, I taped a condom over the tube bottom and was hoping to see if fluid was coming out instead of just moisture vapour but the condom had ripped right off so no indication what happened there.  The inside of the dump tube had very thin oil in it if I stuck my pinkie in there... and the oil was strangely new looking (no blackening at all like it is on the dipstick).

 

My mx is running out of ideas what is causing the high oil temp and what is causing the loose of oil.  We are going to check the valve guides as soon as his new valve wobble test tool arrives off of backorder but in the mean time.....      Heeeeeeelp!   Any ideas would be greatly appreciated.

 

 

So in summary, I'm "loosing" 1L/Hr of oil and my Oil temp gets really hot ~240deg, following that my oil pressure drops right down under 50 and keeps goind down until I land and add more oil.

 

I am looking at the oil relocator kit from Lasar but won't do that unless it is going to fix my temp problem.  I'm ok with the cooler where it is if it would just work.  

 

If you made it to the bottom of this long winded description, thanks!  

 

Shawn

[Alan Fox]

I have an E model with the SWTA cowl mod , so it is lIke the F model with the cooler in the back..... My oil temps were always in the 240 range like yours , almost touching the red line on the gage....Although it was in the green , it didnt sit well with me.... I pulled the cowl to to change the oil temp sender , and saw an air take off for a 1"scat near the oil cooler that was open, I put a AN bolt with two 1.5 inch washers to seal it off , also I made two pieces of baffling that sealed the two sides of the cooler that dont bolt to the baffling , The end result was my oil temp dropped about 40 degrees....  The baffling is huge with oil temps....

[Piloto]

Check the oil cooler bypass thermostatic valve. If the valve is set to a high temp oil will not flow thru the oil cooler thus it feels cool. The valve is located on the back on on the accesory cover next to the oil cooler hose fitting.

José

[funvee]

Check the oil cooler bypass thermostatic valve. If the valve is set to a high temp oil will not flow thru the oil cooler thus it feels cool. The valve is located on the back on on the accesory cover next to the oil cooler hose fitting.

José

Vernatherm was replaced.

[funvee]

I have an E model with the SWTA cowl mod , so it is lIke the F model with the cooler in the back..... My oil temps were always in the 240 range like yours , almost touching the red line on the gage....Although it was in the green , it didnt sit well with me.... I pulled the cowl to to change the oil temp sender , and saw an air take off for a 1"scat near the oil cooler that was open, I put a AN bolt with two 1.5 inch washers to seal it off , also I made two pieces of baffling that sealed the two sides of the cooler that dont bolt to the baffling , The end result was my oil temp dropped about 40 degrees....  The baffling is huge with oil temps....

My cooler is right up front beside the ram air intake but I was thinking about doing the relocate STC to move it to the back of Cyl 4 but I'm not sure if that would be significantly better cooling than having it open to the front flow of air from the prop.   

[N601RX]

My F has not been going above 190 with the current OAT's. I do have the Lasar oil cooler relocation. I had some broken rings before overhauling and was burning 1.5-2 qts hr. It was evident that something wasn't right with those 2 cylinders by just looking at the plugs. The compressions were still reading low 70's. You can also verify that the cowl flaps are opening and staying open the correct ammount. If there are any large air leaks around the baffeling it will increase the air pressure in the lower part of the cowl and prevent air from being drawn through the oil cooler. The lasar relocation kit also comes with 2 new hoses and gets the hoses away from the exhaust pipe, so it isn't a bad deal especially if you need new hoses anyway.

[funvee]

My cooler is right up front beside the ram air intake but I was thinking about doing the relocate STC to move it to the back of Cyl 4 but I'm not sure if that would be significantly better cooling than having it open to the front flow of air from the prop.   

I forgot to mention... I think that scat tube you are referring to is the fuel pump cooler air flow (thats what my mx told me)  

[N601RX]

The oil cooler relocation adds a scat tube for the fuel pump.

[funvee]

My F has not been going above 190 with the current OAT's. I do have the Lasar oil cooler relocation. I had some broken rings before overhauling and was burning 1.5-2 qts hr. It was evident that something wasn't right with those 2 cylinders by just looking at the plugs. The compressions were still reading low 70's. You can also verify that the cowl flaps are opening and staying open the correct ammount. If there are any large air leaks around the baffeling it will increase the air pressure in the lower part of the cowl and prevent air from being drawn through the oil cooler. The lasar relocation kit also comes with 2 new hoses and gets the hoses away from the exhaust pipe, so it isn't a bad deal especially if you need new hoses anyway.

I would KILL for 190  

We just did a new compression test on the weekend and my mx said the plugs all looked perfect when he pulled them.  I don't know if the valve guides could lead to this problem but he say's he's running out of ideas unless there is a specific issue with m20f's and proper cooling.  Thats why I thought I better post here for more specialized help.  

[funvee]

The oil cooler relocation adds a scat tube for the fuel pump.

my F has that scat tube come straight through the back baffle on Cyl 4. basically right where the relocated cooler would go if I go that route.

[N601RX]

The stc includes a long piece of scat hose that runs from the front on the engine back to the fuel pump.

[N601RX]

One other thought.  Are you sure you have the correct oil cooler?  For the IO 360 it should be a double pass cooler.  The inlet and exit are both of the same end. A single pass will have the exit on one end and the inlet on the other.

[M204ever]

Do not focus too much on the oil temp. Check the pressure relieve valve and find out where the oil disappears.

If there is no leak you either burn or drain it. Remember according to Lycoming the engine is still healthy with only 2 quarts of oil.

[funvee]

One other thought.  Are you sure you have the correct oil cooler?  For the IO 360 it should be a double pass cooler.  The inlet and exit are both of the same end. A single pass will have the exit on one end and the inlet on the other.

My inlet/exit are both on the bottom of the unit. One on port side bottom and other on starboard bottom.

[funvee]

Do not focus too much on the oil temp. Check the pressure relieve valve and find out where the oil disappears.

If there is no leak you either burn or drain it. Remember according to Lycoming the engine is still healthy with only 2 quarts of oil.

That is the problem, we can't figure where the oil is going. No sign of it on the belly of the plane, no sign of it on the plugs, no sign of it as smoke coming out the exhaust and no leaks inside the engine bay.

I know that a lot of posts on this sight have said running hot is ok but I disaggree.... As soon as my temp gets hot, my pressure starts dropping until I am forced to land and put more in. Once it starts, it doesn't seem to stop unless I can get the temp down to the green.

When I look at the oil on the dipstick after hot flight, it is more like water than oil in that it is super thin.

[duke]

Double check mag timing. Also dial prop with guasge to double check timing mark.My F ran hot when I bought it and I found the timing was off. It had the cowl closure and oil cooler relocation mod on it. It now runs nice and cool.

cyl head between 300 and 350 , never gets close to red.

[funvee]

Double check mag timing. Also dial prop with guasge to double check timing mark.My F ran hot when I bought it and I found the timing was off. It had the cowl closure and oil cooler relocation mod on it. It now runs nice and cool.cyl head between 300 and 350 , never gets close to red.

I forgot to mention that mag timing was done in our process of elimination. However, I don't think there was anything done with the prop using a gauge. I'll ask him today.

Just for clarity sake... My only temp that is high is my oil. My head temps are not out of the green (we haven't tested that temp probe though so I guess it could be reading good when its actually not.

[jlunseth]

I don't have a solution for you, but do wonder a little if you have a problem.  My question is whether the "oil loss" you are seeing progresses.  In other words, if the plane sits for a couple of days and you then take off with 7 qts of oil, and you land and have 6 qts.  Then the plane sits again for a few days.  Do you then still have 6 qts or is it back up to 7?  Also, many engines do not like high oil levels and will just blow out a quart or so until they are happy at around 6 qts. (my engine capacity is 8).

 

You will appear to lose about a quart of oil just by flying, it distributes around inside the engine and the level in the pan will go down.  If the engine sits for a couple of days, and it usually takes at least that, the oil drains to the pan again and the level comes back up on the dipstick. 

 

I don't have an F, my oil temps in my 231 are quite a bit cooler, but I have heard that F's tend to run hotter.

 

There is a problem that happens in low temp operations with the air oil separator.  It can freeze up and partially or fully plug the oil flow resulting in either higher or lower than normal temps.  The cure is to take a good long time on the ground letting the engine warm the engine compartment.  The oil cooler needs to be warm before takeoff, once you get in the air and get full air flow through the engine compartment it will start to plug up quickly.  It is flaky, if it fully plugs I will normally see very low temps.  If it plugs and opens and plugs and opens the temps will be all over the place.

[funvee]

I don't have a solution for you, but do wonder a little if you have a problem.  My question is whether the "oil loss" you are seeing progresses.  In other words, if the plane sits for a couple of days and you then take off with 7 qts of oil, and you land and have 6 qts.  Then the plane sits again for a few days.  Do you then still have 6 qts or is it back up to 7?  Also, many engines do not like high oil levels and will just blow out a quart or so until they are happy at around 6 qts. (my engine capacity is 8).

 

You will appear to lose about a quart of oil just by flying, it distributes around inside the engine and the level in the pan will go down.  If the engine sits for a couple of days, and it usually takes at least that, the oil drains to the pan again and the level comes back up on the dipstick. 

 

I don't have an F, my oil temps in my 231 are quite a bit cooler, but I have heard that F's tend to run hotter.

 

There is a problem that happens in low temp operations with the air oil separator.  It can freeze up and partially or fully plug the oil flow resulting in either higher or lower than normal temps.  The cure is to take a good long time on the ground letting the engine warm the engine compartment.  The oil cooler needs to be warm before takeoff, once you get in the air and get full air flow through the engine compartment it will start to plug up quickly.  It is flaky, if it fully plugs I will normally see very low temps.  If it plugs and opens and plugs and opens the temps will be all over the place.

My oil loss is definitely proved to be gone and not just a drip down problem in that we have tried doing multiple 2 and 3 hr flights with a solid 24 hr period of sitting after flight before taking a reading. When I fly the 2 hour ones and check it the following day I will be down 2Qt and the 3 hr ones will be down 3qt.

We have also tried a variety of different starting quantities to see if my F 'likes' a certain level. So far we have tried 4, 5, 6 and 6.5 qt. the 6.5 qt lost even more than normal so we chalked that up to the plane not liking more that 6qt.

I'm not sure what the air / oil seperator is but I'll look into that for sure!

Thanks

[CajunMooneyguy]

Hi. What viscosity oil are you running? 15W50? Try running a straight 50 wt. it makes sense that the oil pressure drops a little with hotter oil.... But it shouldn't KEEP dropping to Zero! Does it ever stabilize "in the green"? What is the time on the bottom end? It's a common sign of excessive main bearing wear to have low oil pressure while the engine is hot and idling. Oil temps of 240 and mildly above, wont necessarily hurt the engine, as the oil still will retain its lubricative qualities..... But temps above 240 will drastically shorten the oils lifespan. 25hr between oil changes instead of 50 are recommended. Now.... As far as oil loss.....my bet is its going out the breather. Try an Air/oil separator. The condom blew off because of the crankcase pressures, but an air/oil separator will catch the oil mist and vent air overboard. It has a drain at the bottom and can be used to recover the blown out oil. They cost anywhere from 2-400 bucks. Google it and/or look up "Aircraft spruce and specialty" and search for it.

[DonMuncy]

My 231 doesn't have a Lycoming, but at one time I had a serious oil loss problem. It turned out to be a bad front crank seal, allowing the crankcase to be pressurized, blowing the oil out the breather.

[carusoam]

Back to the condom catcher technique, this time, tie it on allowing it to breath. Tie it on tight using something to obstruct a seal...

I would expect a quart leaked this way would be all over the exterior???

The lower ring on the pistons is special for it's oil retention skills. They can break and oil escapes. Quarts leaked this way should leave a mess in the cylinder.

Have you had the chance to use a camera down the spark plug holes?

These are ideas of a non-mechanic with the intention of supporting you with your decision making.

Best regards,

-a-

[funvee]

Hi. What viscosity oil are you running? 15W50? Try running a straight 50 wt. it makes sense that the oil pressure drops a little with hotter oil.... But it shouldn't KEEP dropping to Zero! Does it ever stabilize "in the green"? What is the time on the bottom end? It's a common sign of excessive main bearing wear to have low oil pressure while the engine is hot and idling. Oil temps of 240 and mildly above, wont necessarily hurt the engine, as the oil still will retain its lubricative qualities..... But temps above 240 will drastically shorten the oils lifespan. 25hr between oil changes instead of 50 are recommended. Now.... As far as oil loss.....my bet is its going out the breather. Try an Air/oil separator. The condom blew off because of the crankcase pressures, but an air/oil separator will catch the oil mist and vent air overboard. It has a drain at the bottom and can be used to recover the blown out oil. They cost anywhere from 2-400 bucks. Google it and/or look up "Aircraft spruce and specialty" and search for it.

I normally run 15w50 but we have tried 50w on one oil change to see if it made a difference but it wasn't noticeably better.  I've never had it keep dropping past 30psi but that's because I always find and airport to put down at if it gets that low.  Usually it's down around 2.5 qt when the pressure gets that low.

 

If the temp gets over 240 and the pressure starts dropping but I get down on the the ground in an hour or less, the pressure will come back up once the temperatures drop when it is on the ground idling at 1200rpm or less.  (assuming I haven't lost more than a Qt or 2 from the start of 6qt.)

 

It is 4000tt and 700 smoh right now.

 

I will go look at AS for a seperator now.... I tend to think I might have 2 issues, one blowing out the breather and possibly a valve guide problem that might be letting oil enter the combustion chamber directly through the valve.

 

Thanks

[funvee]

My 231 doesn't have a Lycoming, but at one time I had a serious oil loss problem. It turned out to be a bad front crank seal, allowing the crankcase to be pressurized, blowing the oil out the breather.

 

I'll bring it up with my mx to see if he thinks that could be the problem.

 

Thanks

[funvee]

Back to the condom catcher technique, this time, tie it on allowing it to breath. Tie it on tight using something to obstruct a seal...

I would expect a quart leaked this way would be all over the exterior???

The lower ring on the pistons is special for it's oil retention skills. They can break and oil escapes. Quarts leaked this way should leave a mess in the cylinder.

Have you had the chance to use a camera down the spark plug holes?

These are ideas of a non-mechanic with the intention of supporting you with your decision making.

Best regards,

-a-

I was out there flying tonight and had planed to do that exact thing, thinking that the pressure might have been why the condom failed and then I forgot to bring one  .  I am planning on putting a piece of hose sticking out the top of the condom and then securing it so the pressure can get out easy but oil should pool for inspection after flying.

 

That lower ring (the scavenger ring) with the coil in it is the one that had failed on the one cyl that had the low compressions... We were sure that was the original problem but the oil loss didn't go away even after the compressions where restored with the new set of rings.

 

My mx used a bore scope to look into the cylinders and said they looked good.  I was hoping he'd bring it out again when I'm there so I can look too.  If nothing else, I'd be cool!  

 

On the oil all over the bottom part... I think the problem here is that the oil has been changed so often lately and is so clean that the bottom of the plane doesn't "show" like it is covered but when you look close, there is a fair bit of oil on the bottom... It's just really clean oil and maybe some dirt from taxiing.    No black oil here.  

 

If the OAT gets warm here, I was hoping to take out a pressure washer and clean it spotless so I can see exactly what is new on the bottom after a test flight.

 

Thanks