Too lean, too rich... nothing works

[N201MKTurbo]

2 hours ago, Skates97 said:

I feel you... We left Pagosa Springs, CO KPSO yesterday morning, it was a nice 55°F outside and landed in KIWA where it was approaching 100°F. We spent the day with my folks and took off at 18:00 for the trip back to SoCal when it was a balmy 111°F, we were the only GA plane moving at KIWA...

I know, there was no traffic on the box, I thought it was broke! CHD cleared me to land 10 miles out. 

[MikeOH]

Yep.  Similar story here.  A week ago my wife and I went to Columbia, CA (O22) for a long weekend and it was 108 when we landed.  Left Sunday morning at 10 am and it was 100 already.  I, too, struggled mightily with oil temp, CHTs were okay, though. Oil temp has always run high on my plane, and on the return flight it was pushing redline!  I've been through overhauling the oil cooler, new oil lines, baffles, and having the vernatherm checked.  Frankly, I'm not sure where to look next...but I sure don't want to repeat the stress of that flight!

[A64Pilot]

12 hours ago, MikeOH said:

Yep.  Similar story here.  A week ago my wife and I went to Columbia, CA (O22) for a long weekend and it was 108 when we landed.  Left Sunday morning at 10 am and it was 100 already.  I, too, struggled mightily with oil temp, CHTs were okay, though. Oil temp has always run high on my plane, and on the return flight it was pushing redline!  I've been through overhauling the oil cooler, new oil lines, baffles, and having the vernatherm checked.  Frankly, I'm not sure where to look next...but I sure don't want to repeat the stress of that flight!

Define “high”

‘When I put the 29” tires on my Maule I fought “high” oil temps, replaced vernatherm etc, even added a lip on the cowling exit to form a low pressure area to pull more air through the cowling etc.

Called Exxon wondering if I should shorten oil change interval, Exxon service rep was very nice and explained that the engines oil temp limits were engine limits and no where near the oils limit, oil limits were WAY beyond published engine limits, so no worry with the oil.

Called Lycoming and got passed on to an Engineer and was informed that the temp limit wasn’t even close to an actual engine limit but was actually a number that should indicate that there is a problem that needs addressing, the engine can handle higher temps fine, the limits were indicators more than actually physical limits, so if your close to  limits but not beyond them and it’s an unusually hot day, that could well be normal.

‘I was running close to 200 continuous and would push 220 in a climb.

Worked out that there was absolutely nothing wrong with the airplane, just normal that in hot Wx that oil temp goes high, can’t fix what isn’t broken.

So depending on how high your temp was, it may have been normal.

 

Lastly have you had your oil temp gauge checked? I mean checked as in placed in hot water? “shooting” the sending unit with an IR temp gun will give you a good idea too and is easy.

[Ragsf15e]

17 hours ago, MikeOH said:

Yep.  Similar story here.  A week ago my wife and I went to Columbia, CA (O22) for a long weekend and it was 108 when we landed.  Left Sunday morning at 10 am and it was 100 already.  I, too, struggled mightily with oil temp, CHTs were okay, though. Oil temp has always run high on my plane, and on the return flight it was pushing redline!  I've been through overhauling the oil cooler, new oil lines, baffles, and having the vernatherm checked.  Frankly, I'm not sure where to look next...but I sure don't want to repeat the stress of that flight!

That’s exactly how I felt, chts were manageable at about 385ish but oil temp was 210ish in the climb.  In cruise it seemed to cool down better with cowl flaps trailing which made sense due to more air.  Also I climbed at 130mph.  Usually I use 120, but more air = more cooling.  It’s a slow climb, and stressful as you said.

Last year at annual I got a new oil cooler and vernatherm was tested, so I think this is flying in hot weather…

Edited June 29, 2021 by Ragsf15e

[MikeOH]

@Ragsf15e @A64Pilot

"High" was touching redline, 245F on my G3 whose sensor is mounted at the front of the engine; the ship's gauge needle remained just in the green.  This was in the climb at 120 mph.  In cruise I was seeing 225F on the G3, and several needle widths away from redline on the ship's gauge.  CHTs were 390 max in climb, and 330-360 in cruise.

Even in more 'normal' temps, my oil temp NEVER regulates at anything near 180F; it's always at least 200F.  I'm beginning to wonder if I should just replace the vernatherm and see what happens; my A&P said it tested 'good' but I'm not really sure what he did.

[Ragsf15e]

10 minutes ago, MikeOH said:

@Ragsf15e @A64Pilot

"High" was touching redline, 245F on my G3 whose sensor is mounted at the front of the engine; the ship's gauge needle remained just in the green.  This was in the climb at 120 mph.  In cruise I was seeing 225F on the G3, and several needle widths away from redline on the ship's gauge.  CHTs were 390 max in climb, and 330-360 in cruise.

Even in more 'normal' temps, my oil temp NEVER regulates at anything near 180F; it's always at least 200F.  I'm beginning to wonder if I should just replace the vernatherm and see what happens; my A&P said it tested 'good' but I'm not really sure what he did.

I sent my vernatherm and oil cooler to Pacific oil coolers.  They were supposed to overhaul the cooler and test the vernatherm.  Unfortunately they said my cooler was too corroded inside so I got a new one, but they tested the vernatherm as good.  They don’t cost much if you don’t need a new oil cooler.  Kind of funny that an oil cooler can corrode… isn’t it coated in oil?  Anyway, my temps were 15 degrees less than yours, but I believe my vernatherm is good.

 

[MikeOH]

Just now, Ragsf15e said:

I sent my vernatherm and oil cooler to Pacific oil coolers.  They were supposed to overhaul the cooler and test the vernatherm.  Unfortunately they said my cooler was too corroded inside so I got a new one, but they tested the vernatherm as good.  They don’t cost much if you don’t need a new oil cooler.  Kind of funny that an oil cooler can corrode… isn’t it coated in oil?  Anyway, my temps were 15 degrees less than yours, but I believe my vernatherm is good.

 

Thanks! I had my oil cooler overhauled by Pacific, they are 5 minutes from my hangar, but never thought to have them test the vernatherm. Much cheaper than just shotgunning with a new one.

[carusoam]

Typical test for the vernatherm is to put it in water with a thermometer and observe what temp it opens and closes at…

Then compare to the specs…

They have been known to stop working properly…

Get your hands on the specs before running the test…

Probably best to do with a camera keeping an eye on everything…

Standing by and observing may take a while…

PP thoughts only…

-a-

[A64Pilot]

Yeah 245 is high, but from my researching that a cruise of 200 is actually close to ideal, 180 is meant as a min, where I was using it as a target.

‘Anyway a Vernatherm does not work the way many think , we think with cold oil it blocks the flow of oil through a cooler and opens when hot like a car thermostat does, but that’s not how it works, when oil is cold the Vernatherm is open allowing oil to flow though the cooler and to bypass it, when oil gets hot it closes off the bypass portion making all oil flow though the cooler. It works this way because if it worked like a cars thermostat then it would allow a slug of cold oil to go through from the cooler when it opened, but by allowing oil through all portions when cold, it all warms up equally.

‘For this reason it’s important when trouble shooting high oil temp to ensure that the Vernatherm fully closes as in measure it’s length when hot and look for a wear circle on both the Vernatherm and it’s seat to ensure it fully closes.

With both high oil temps and high cyl head, I’d suspect airflow, where were the cowl flaps if equipped?

Edited June 30, 2021 by A64Pilot

[MikeOH]

If 200 is ideal, then why would the vernatherm be designed to activate at around 180?

While my CHTs, at 330-360, were higher than normal, I didn't consider them excessive (the 390 in climb was not great).

Cowl flaps were wide open.  Frankly, on my F, I see very little increase in speed, yet I'll always run hotter by 10 to 20 degrees with them closed.  So, I rarely close them.

[A64Pilot]

13 hours ago, MikeOH said:

If 200 is ideal, then why would the vernatherm be designed to activate at around 180?

While my CHTs, at 330-360, were higher than normal, I didn't consider them excessive (the 390 in climb was not great).

Cowl flaps were wide open.  Frankly, on my F, I see very little increase in speed, yet I'll always run hotter by 10 to 20 degrees with them closed.  So, I rarely close them.

Any thermostat has two temps, one is the cracking temp where it just begins to open and the second is the fully open temp, they are gradual devices, it’s not an on or off thing.

The rated temp is I believe the cracking temp. From the oils perspective 200 is better than 180, 200 is more likely to actually cook off all the moisture.

‘Most all high performance automobiles as a example have an oil cooler, the oil cooler uses 195F coolant as the cooling medium, so it’s actually an oil heater unless oil temp is over 200, so they maintain oil temp somewhere usually between about 220F and 195F.

It was Exxon that told me that they like to see oil temps of around 200 when I called asking if I should shorten oil change intervals as I ran 200+ but under 220 during Summer months. 180 is the min acceptable number. They couldn’t speak for the engine but said their oil is happy and not experiencing any degradation until temps way above the engines max temp rating.
So if they are correct and as they manufacture the oil I assume they are, the oil temp limit is an engine, not an oil limit. 

‘Now I assume Exxon wasn’t a super oil and Shell is similar. I ran Exxon Elite back then, and just used my last quart the other day.

[A64Pilot]

13 hours ago, MikeOH said:

 

Cowl flaps were wide open.  Frankly, on my F, I see very little increase in speed, yet I'll always run hotter by 10 to 20 degrees with them closed.  So, I rarely close them.

I see very little if any difference in speed on my J too, I will do whatever is necessary with cowl flaps to stay in the middle of the green arc myself, I don’t have a monitor.

[A64Pilot]

Lycoming says continuous oil temp should be between 180 and 220, and seemed to indicate that he Vernatherm rated temp is the fully extended temp, not it’s beginning to move temp.

http://www.yeeles.com/Reference/Hi-Temps.pdf

[MikeOH]

I go with data, not anectdotes.  Here is the Savvy data on my oil temps vs. my cohort (over 10,000 flights).  It's pretty clear my temps are much higher than they should be for other Mooney M20F/Js.  I also have some low power flights (sightseeing at 50-55% power) where the temp is stable at, what a surprise, around 185F.  I am beginning to wonder if my vernatherm is not completely closing (not fully expanding) so at higher power levels not enough oil is making it to the oil cooler.

 

[carusoam]

Inspect and clean and check the vernatherm…

Some fins get bent and block airflow

Some tubes fill with sludge… an IR thermometer may help identify tubes that have been blocked…

Might be time for an oil cooler OH…

PP thoughts only, stuff I read around here…

Best regards,

-a-

[MikeOH]

17 hours ago, carusoam said:

Inspect and clean and check the vernatherm…

Some fins get bent and block airflow

Some tubes fill with sludge… an IR thermometer may help identify tubes that have been blocked…

Might be time for an oil cooler OH…

PP thoughts only, stuff I read around here…

Best regards,

-a-

@carusoam

Perhaps you missed my earlier comments; easy to do with a long thread.

1) I had my A&P check the vernatherm and seat....but, not really sure what he actually did as I wasn't present.

2) Fins are fine, new baffles from GeeBee were installed

3) What tubes do you mean?  I replaced the oil lines to/from the oil cooler.

4) I had Pacific Oil Cooler overhaul my oil cooler.

 

Any other boxes I didn't check?

[A64Pilot]

Have you verified whatever your using to get he temps.

I’ve seen people spend thousands chasing a bad gauge.

[MikeOH]

3 hours ago, A64Pilot said:

Have you verified whatever your using to get he temps.

I’ve seen people spend thousands chasing a bad gauge.

@A64Pilot

My Insight G3 oil temp sensor is installed at the front of the engine; the factory gauge is also installed with the sensor in the back of the engine.  The factory gauge has no numerical markings; just green and red-line.  My A&P has told me the nose sensor location will read higher and that is consistent with what I see on the factory gauge: when the G3 was showing close to red-line, the factory gauge was still just below red-line.  Seems doubtful both gauges are off, but you are correct that I have not independently verified with a known calibrated instrument.

[A64Pilot]

No your good with two gauges in my opinion, one verify’s the other.

‘I had a customer that had chased high oil temp and done several illegal modifications to the aircraft from knocking a hole in the cowling and even installing a second oil cooler.

He got caught by the FAA I believe and returned the aircraft to the factory and we returned it to drawing specs, it was winter, later that same year as the temps began to rise he called me and said it’s running hot again.

‘So I flew out to see what was going on and had asked him to not start the aircraft that day, I got in the cockpit and turned the battery on and the oil temp was something like 60C, so I said Jerry I had asked you to not start the aircraft, he said he hadn’t and I told him I think I have found your problem, swapped the gauge with one I had brought with me, temp read 20 or so and I had him load the hopper with water and go fly hard, he came back feeling foolish and said it stayed in the green.

‘He and his mechanic never checked the gauge, and in desperation because he had to have the aircraft to make a living and even to make payments on the aircraft, started modifying any thing he could think of to get that oil temp down.

But he never checked the gauge, and you woud be surprised at how many people don’t. 

[A64Pilot]

I would start with your Vernatherm as it’s easiest, look for a wear ring on the tip of the vernatherm that matches the seat in the engine, look to ensure the engine seat is smooth and even. Measure it and do the hot water thing and measure it again to see how long it grew as they get old they don’t grow as long, the operating principle is I believe a wax pellet  melting, it’s amazing that they are as accurate as they are.

‘I did something stupid chasing my high oil temp, I changed the Vernatherm and if anything the temp got higher. so I removed the new one and noticed it had two washers on it. I can only assume one was stuck to the engine when I removed the first one and I didn’t notice it and when I installed the new one of course now there were two.

‘At least that’s what makes sense, stupid newby mistake.

‘Anyway after the Vernatherm, how old are the hoses? I would normally jump to cooler, but you have had it overhauled already, hoses can collapse, or have been kinked in the past and the fire shield hides the kink.

‘If there is a restriction in the cooler / hoses the vernatherm has a spring on it and will open up and allow oil to bypass the cooler, so you may not see a big pressure drop like you would expect from a restriction.

[MikeOH]

6 hours ago, A64Pilot said:

I would start with your Vernatherm as it’s easiest, look for a wear ring on the tip of the vernatherm that matches the seat in the engine, look to ensure the engine seat is smooth and even. Measure it and do the hot water thing and measure it again to see how long it grew as they get old they don’t grow as long, the operating principle is I believe a wax pellet  melting, it’s amazing that they are as accurate as they are.

‘I did something stupid chasing my high oil temp, I changed the Vernatherm and if anything the temp got higher. so I removed the new one and noticed it had two washers on it. I can only assume one was stuck to the engine when I removed the first one and I didn’t notice it and when I installed the new one of course now there were two.

‘At least that’s what makes sense, stupid newby mistake.

‘Anyway after the Vernatherm, how old are the hoses? I would normally jump to cooler, but you have had it overhauled already, hoses can collapse, or have been kinked in the past and the fire shield hides the kink.

‘If there is a restriction in the cooler / hoses the vernatherm has a spring on it and will open up and allow oil to bypass the cooler, so you may not see a big pressure drop like you would expect from a restriction.

@a64pilot

Yet, again:  I have replaced the hoses to/from the oil cooler.  I have had my A&P check the seat and the vernatherm.

Now, I know the oil cooler was overhauled as I took it to, and picked it up from, Pacific Oil Coolers personally.  I could see that the baffles and oil hoses have been changed.  BUT, I really do not know what my A&P did when checking the vernatherm and seat.

So, at this point, I'm just going to replace the vernatherm with new and check the seat myself.  I have a friend that is an A&P who is willing to supervise and sign off.  They're like 0.3AMU and I just don't feel like screwing around soaking and measuring the one I've got.

I will check washers!  Never thought of that, thanks!

 

[carusoam]

On 7/2/2021 at 8:05 PM, MikeOH said:

@carusoam

Perhaps you missed my earlier comments; easy to do with a long thread.

1) I had my A&P check the vernatherm and seat....but, not really sure what he actually did as I wasn't present.

2) Fins are fine, new baffles from GeeBee were installed

3) What tubes do you mean?  I replaced the oil lines to/from the oil cooler.

4) I had Pacific Oil Cooler overhaul my oil cooler.

 

Any other boxes I didn't check?

Shortness of memory…    Long threads are a killer!

The tubes I am referring to are the ones carrying the oil internally in the cooler, and do the actual heat exchanging…

Failing oil coolers often collect sludge in these tubes…. And they get blocked… one or two at a time…

Oil can easily find a way through a different tube, so a sludge filled tube may not get flushed out….

 

An IR thermometer works pretty well at seeing tubes that are not working properly… they stop carrying hot oil…

PP thoughts only, not a mechanic…

Best regards,

-a-

[GeeBee]

When I was I the SuperCub community, oil cooling was a constant problem. Mostly due to low airspeeds. Tight cowlings are a requirement. A light test (dark hangar, place alight below and look the front for light) as well as theater smoke pushed with a fan to see flow helps in discovering air flow problems. Some airplanes, especially banner tows, require two oil coolers.

After you have made sure the cowling is tight, make sure the air has a place to go. Have you installed or changed the exit air flow? A small thing like a SCAT tube route change can have a big effect and create "air dams". Cowling air flow is part science, part art. Make sure the airplane is conformal to the original certification configuration or STC configuration.

Also make sure there is no leak between the cooler and the baffle it bolts against. You want 100% of the air though the opening going through the cooler. Leaks create span wise flow on the face of the cooler.

In the case of this Mooney, I would be looking seriously first with light and smoke tests. Verify exit flow. Assuming it is a tight, I would replace, the Vernatherm and the oil cooler. I've seen a lot of "Overhauled" units not doing their job that check "good" on the bench. Both are cheap enough to go new.

https://www.kitplanes.com/oil-cooler-101/

 

 

[MikeOH]

18 hours ago, carusoam said:

Shortness of memory…    Long threads are a killer!

The tubes I am referring to are the ones carrying the oil internally in the cooler, and do the actual heat exchanging…

Failing oil coolers often collect sludge in these tubes…. And they get blocked… one or two at a time…

Oil can easily find a way through a different tube, so a sludge filled tube may not get flushed out….

 

An IR thermometer works pretty well at seeing tubes that are not working properly… they stop carrying hot oil…

PP thoughts only, not a mechanic…

Best regards,

-a-

@carusoam

Makes sense.

However, item 4 on my already done list was having the oil cooler overhauled by Pacific Oil Coolers.  Made zero difference.

[MikeOH]

11 hours ago, GeeBee said:

When I was I the SuperCub community, oil cooling was a constant problem. Mostly due to low airspeeds. Tight cowlings are a requirement. A light test (dark hangar, place alight below and look the front for light) as well as theater smoke pushed with a fan to see flow helps in discovering air flow problems. Some airplanes, especially banner tows, require two oil coolers.

After you have made sure the cowling is tight, make sure the air has a place to go. Have you installed or changed the exit air flow? A small thing like a SCAT tube route change can have a big effect and create "air dams". Cowling air flow is part science, part art. Make sure the airplane is conformal to the original certification configuration or STC configuration.

Also make sure there is no leak between the cooler and the baffle it bolts against. You want 100% of the air though the opening going through the cooler. Leaks create span wise flow on the face of the cooler.

In the case of this Mooney, I would be looking seriously first with light and smoke tests. Verify exit flow. Assuming it is a tight, I would replace, the Vernatherm and the oil cooler. I've seen a lot of "Overhauled" units not doing their job that check "good" on the bench. Both are cheap enough to go new.

https://www.kitplanes.com/oil-cooler-101/

 

 

@GeeBee

Great article!

Now, I'm wondering if I have a blow-by problem!  I use about a quart every 6-8 hours, and it turns black pretty fast.  But, compressions are all above 75.  Is there a specific test for blow-by to determine if it is excessive?