High oil temp - ream vernatherm seat

[Bob_Belville]

Sorry Marauder et al, I can't remember the thread where I and others have worked on reducing oil temps. I know I owe a pirep.

 

Yesterday we reinstalled the Oil Filter Adapter after sending it to the engine shop to have the vernatherm valve seat reamed. (This repair is described in Lycoming SI 1316A.)

 

I flew this morning for about 40 minutes, climbing at high power and Vy up to 6500' OilT stayed below 200F! And I was able to level at 6500 and cruise at 72% power with the cowl flaps closed. OAT @ 6500 was 24C. Before the seat ream job that power setting would have had the OT climbing toward 210F. 

 

Happy, happy, happy. 

 

(Last year I had sent the O cooler and VT valve to Pacific. I've been tweaking baffle seals for 3 years... 

[N201MKTurbo]

Did you also replace the vernatherm  Was the cone on the vernatherm scored?

 

I have always thought that, even with an imperfect seal, the majority of the oil would go to the cooler and the amount of hot oil leaking past the seal would be insignificant.

 

I wouldn't tear my engine apart for 10 deg. , but I would have it re-machined if I had it off.

[Marauder]

Sorry Marauder et al, I can't remember the thread where I and others have worked on reducing oil temps. I know I owe a pirep.

Yesterday we reinstalled the Oil Filter Adapter after sending it to the engine shop to have the vernatherm valve seat reamed. (This repair is described in Lycoming SI 1316A.)

I flew this morning for about 40 minutes, climbing at high power and Vy up to 6500' OilT stayed below 200F! And I was able to level at 6500 and cruise at 72% power with the cowl flaps closed. OAT @ 6500 was 24C. Before the seat ream job that power setting would have had the OT climbing toward 210F.

Happy, happy, happy.

(Last year I had sent the O cooler and VT valve to Pacific. I've been tweaking baffle seals for 3 years...

Glad you figured it out. I don't think I ever saw a temp above 200° but will look at my JPI data.

Sent from my iPad using Tapatalk

[Bob_Belville]

Did you also replace the vernatherm  Was the cone on the vernatherm scored?

 

I have always thought that, even with an imperfect seal, the majority of the oil would go to the cooler and the amount of hot oil leaking past the seal would be insignificant.

 

I wouldn't tear my engine apart for 10 deg. , but I would have it re-machined if I had it off.

The vernatherm had gone to Pacific with the cooler and was checked out. (I took the filter and adapter off. Lynn put the adapter back on and I finished it up. He signed the log, probably will bill me for 30 minutes.)

 

I'm thinking it has made at least 10F difference. Well worth it to me. Higher OilT pulls the O Pressure down to or below 60 psi. 

 

Don Maxwell had encouraged me to ream the seat since I had done everything else. He says is does not take much of a leak at all to raise OilT.

[Browncbr1]

I was cruising yesterday and my oil temp was around 200-203, then, I started a gradual descent without touching any power settings. The only difference was nose down. My oil temp went up and triggered my 210 degree alarm. All chts and oil pressure was ok. I had about 6.5 qts oil in there. I landed and put a quart in there and flew back home with same power settings... Still around 200 degrees, but didn't ever get up to 210. Does anyone have any starting point suggestions for helping this? 67 F Using Exxon elite 20w-50 Oat at 7000 was mid 70's

Thanks

[Bob_Belville]

I was cruising yesterday and my oil temp was around 200-203, then, I started a gradual descent without touching any power settings. The only difference was nose down. My oil temp went up and triggered my 210 degree alarm. All chts and oil pressure was ok. I had about 6.5 qts oil in there. I landed and put a quart in there and flew back home with same power settings... Still around 200 degrees, but didn't ever get up to 210. Does anyone have any starting point suggestions for helping this? 67 F Using Exxon elite 20w-50 Oat at 7000 was mid 70's

Thanks

What was your cruise altitude, power setting?

I'm a little surprised that OT went up in descent. I assume airspeed increased. Mine OT will go down in a near-red-line descent. 

Oil level makes a difference. I suppose at least 5F hotter @ 6 vs. 7 qts.

I use Aeroshell 100W year round.

I suppose cowl flaps remained closed? My CF make a big difference with OT.

[M20F]

I had some gaps around my oil cooler (relocated to rear) at the top and bottom. Put some RTV around top/bottom and it is 178-181 in now even in long duration climbs (120 mph). Previously I would get into the yellow at times (forget the exact temps). It doesn't look particularly pretty but I was amazed how tricky airflow in the cowl/baffling can be and that sometimes simple things yield great results. YMMV.

[Browncbr1]

Right, that's why I was confused why oil temp went up with more airspeed. I was at 7500' 22.9" 2500rpm when I pushed the nose over. I went from about 140 indicated airspeed to about 150. I thought maybe it had to do with the position of the JPI OT sensor. It's on the front of the case.

The previous owner used Exxon elite 20w-50, but he lived in MN... I've been debating if I should switch to aeroshell 100 plus, as I'm in a more mild climate and I always use my tanis heater below 50 degrees. Do you think oil weight comes into play with OT? My oil cooler is right up front on the original cowl. I would have thought that it should run cool enough with as little as 6qts, but adding oil seemed to have helped it.

[Bob_Belville]

I had some gaps around my oil cooler (relocated to rear) at the top and bottom. Put some RTV around top/bottom and it is 178-181 in now even in long duration climbs (120 mph). Previously I would get into the yellow at times (forget the exact temps). It doesn't look particularly pretty but I was amazed how tricky airflow in the cowl/baffling can be and that sometimes simple things yield great results. YMMV.

Yeah, I have about 2 tubes of HT silicone around my oil cooler which is in the rear behind #4 cylinder. 

[Bob_Belville]

Right, that's why I was confused why oil temp went up with more airspeed. I was at 7500' 22.9" 2500rpm when I pushed the nose over. I went from about 140 indicated airspeed to about 150. I thought maybe it had to do with the position of the JPI OT sensor. It's on the front of the case.

The previous owner used Exxon elite 20w-50, but he lived in MN... I've been debating if I should switch to aeroshell 100 plus, as I'm in a more mild climate and I always use my tanis heater below 50 degrees. Do you think oil weight comes into play with OT? My oil cooler is right up front on the original cowl. I would have thought that it should run cool enough with as little as 6qts, but adding oil seemed to have helped it.

I can't speak to the oil type and effect on temp. I suppose the major advantage of the multigrade is its lower viscosity when cold.Mike Busch on oil: http://www.avweb.com/news/maint/182909-1.html

 

The position of your oil cooler in the front might be the reason airspeed does not help. I think that area behind the prop is a dead air area. Someone here may be able to point us to documentation of that counter-intuitive phenomenon. 

[philiplane]

Aircraft oil viscosity is rated at 210 dF, and thermal breakdown doesn't occur till above 265-280 dF.

 

Your engine will operate just fine with oil temperature in the 190-210 degree range. 240 and above is cause for concern. Below 190 is also cause for concern.

 

Water doesn't boil out of the oil until it's in that range anyway. Most aircraft engines suffer internal wear and rust due to low oil temperature. That's much more harmful than your temperature range, which is just about ideal. If you have lower pressure at 210 than at 180, your oil pressure spring probably needs replacing, and the pressure needs adjusting while the engine oil is at 200 dF, and the CHT exceeds 300 dF. This allows the regulating parts to be at the correct temperature. Calibration of the gauges is important because you need accurate information to make adjustments. Many gauge problems stem from poor grounds in the airframe, so you can get different readings depending on the electrical load. 

[Andy95W]

Right, that's why I was confused why oil temp went up with more airspeed. I was at 7500' 22.9" 2500rpm when I pushed the nose over. I went from about 140 indicated airspeed to about 150. I thought maybe it had to do with the position of the JPI OT sensor. It's on the front of the case.

There are stories, perhaps anecdotal, that when Paul Loewen (LASAR) was doing the testing for his lower cowling closure he found lower oil temperatures during testing. The answer appeared to be that the really large guppy mouth took in so much air at higher air speeds that it would actually over pressure the lower part of the cowling so air would actually reverse course and flow forward through the oil cooler. Not sure if that's true, but it's a good story and a possible factor if you have an original unmodified cowling.

Aircraft oil viscosity is rated at 210 dF, and thermal breakdown doesn't occur till above 265-280 dF.

 

Your engine will operate just fine with oil temperature in the 190-210 degree range. 240 and above is cause for concern. Below 190 is also cause for concern.

Agree, but the oil temperature probe is not located at the hottest oil location, which would be somewhere in the vicinity of the cylinder heads. I still think that cooler is better, within reason.

[Browncbr1]

Thanks for the input guys. Because I will be relaxing mags soon, I think I will install a new vernatherm while it's accessible. The one that is in there is nearly 20 years old now and I saw in this thread that being a source of problem. My a&p said he would ream it as well to ensure a good seat.

[Bob_Belville]

Thanks for the input guys. Because I will be relaxing mags soon, I think I will install a new vernatherm while it's accessible. The one that is in there is nearly 20 years old now and I saw in this thread that being a source of problem. My a&p said he would ream it as well to ensure a good seat.

There's a Lycoming SI for the reaming, probably requiring renting a tool from Lycoming. Or do what we did, shipped the filter conversion housing off to our friendly engine builder who turned it around in one day. The seat can only be reamed 0.010". A new Vernatherm is $300+. A new conversion part kit might be $700. if the seat is too far gone. 

[Browncbr1]

There are stories, perhaps anecdotal, that when Paul Loewen (LASAR) was doing the testing for his lower cowling closure he found lower oil temperatures during testing. The answer appeared to be that the really large guppy mouth took in so much air at higher air speeds that it would actually over pressure the lower part of the cowling so air would actually reverse course and flow forward through the oil cooler. Not sure if that's true, but it's a good story and a possible factor if you have an original unmodified cowling.

This may be why the temp went up with increased airspeed. The cowl had increased air pressure, which limited airflow into the cowl through the oil cooler. It sounds like I may benefit from a cowl closure more than I originally thought.

[Bob_Belville]

This may be why the temp went up with increased airspeed. The cowl had increased air pressure, which limited airflow into the cowl through the oil cooler. It sounds like I may benefit from a cowl closure more than I originally thought.

You would benefit from the LASAR mod that moves the cooler back behind #4 cyl. "Oil cooler relocated by Lake Aero Style STC SA2513NM"

[Browncbr1]

You would benefit from the LASAR mod that moves the cooler back behind #4 cyl. "Oil cooler relocated by Lake Aero Style STC SA2513NM"

That's probably a better way to address the issue. Thanks for reminding me of that !

[N601RX]

I had to replace the filter adaptor a few years ago. The pma version of the filter housing is $150. The Lycoming version was a couple of times more.

[N201MKTurbo]

With my previous Mooney (M20F) I had the vernatherm reamed per the SB. I just took the filter adapter to the local engine shop they did it for about $20.

[Bob_Belville]

With my previous Mooney (M20F) I had the vernatherm reamed per the SB. I just took the filter adapter to the local engine shop they did it for about $20.

That's exactly what my A&P did with mine. We sent it to Triad in Burlington NC. Haven't seen the bill yet but I expect it to be minimal.  

[Bob_Belville]

I had to replace the filter adaptor a few years ago. The pma version of the filter housing is $150. The Lycoming version was a couple of times more.

I haven't really shopped one, Ms. Google brought up Chief who shows a complete conversion kit at around $500. I think that included the genuine Lycoming part.

[Guest]

Lycoming SB 518C calls for inspection of the vernatherm valve, and SB 240W calls for mandatory replacement during overhaul.

Clarence

[tony]

Lycoming SB 518C calls for inspection of the vernatherm valve, and SB 240W calls for mandatory replacement during overhaul.

Clarence

Service Bulletins are not mandatory.   They only things that are mandatory during an overhaul is what's called out in the FAA approved overhaul manual; frankly if my memory is still working, there isn't much. 

[Guest]

Service Bulletins are not mandatory.   They only things that are mandatory during an overhaul is what's called out in the FAA approved overhaul manual; frankly if my memory is still working, there isn't much.

Thanks for the pointer, however SB's contain a wealth of great information and product improvements, which may be helpful to this thread.

Clarence