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Topic-icon Low Oil temprature

  • John Barco
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6 months 1 week ago #1290

I own a turbo Arrow IV that is experiencing low oil temperature. I am wondering if any other Arrow owners have experienced a similar condition.

Here are is the history and the facts:

The engine is a TSIO 360 FB with GAMI's, a Merlyn waste gate control, Tight baffles, a factory cowling and 900 hrs SMOH.

I usually cruise at 65% power (30" @ 2300) and usually LOP. I have experienced no history of high cyl temp or oil temp. The aircraft is usually operated West of the Rockies at various altitudes. Cyl temps usually run in the low 300's F and the oil temp is currently running about 140 F.

It has been colder here in the West this winter, but I cannot get the oil temp up to 180 F or so.

Continental support suggested a stuck vernatherm. Foolishly and expensivaly I changed it without further diagnosis. No change in operation.
I have been told by TCM support that the oil cooler only is operated when the vernatherm sences a higher oil temp, and only as required. So it would seem that the oil is just not getting hot enough.

A test was preformed by covering about half of the cowling inlet and blocking some of the incoming upper deck air in flight. Cyl temps went up to about 360 F and oil temp went up to about 170 F. Seems like too much cold air was coming in, more than adequately cooling the cyl's and not allowing the oil to heat up to a temp I would like to see. I haven't verified the accuracy of the oil temp gauge or sending unit, but since the both the cyl and oil temps come up when inlet air is restricted, it seems doubtful that it is just the accuracy of the guage.

Don't get me wrong, I am a graduate of GAMI's Advanced Pilot Seminars and I am a believer that cooler cyl temp are better and reduce ware. My concern is getting the oil temp high enough to vaporize any moisture in the oil.

Has anyone experienced similar conditions? Does anyone have any comments or suggestions? Could I possibly just be chasing a ghost?

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6 months 1 week ago #1295

I believe you need to keep your blank off plates in place during winter ops. The CHTs you're getting are no where near the suggested upper limit of 400 deg, so you're in no trouble there.
It's important to get the oil temperature up to at least 180 on the gauge in order to "cook off" moisture that occurs in the engine due to condensation and moisture that is produced during the combustion process.
I looked through the airplane parts manual and couldn't find any mention of what are called cold weather baffles, or cold weather blank off plates for either the oil cooler or inlet air.
Nor did I find any mention of a placard advising blank off plate usage.
Continental issued Service Information Letter (SIL) 10-6 for the installation of a different Vernatherm valve for installation in IO-550 N and TSIO-550 C engines due to problems with low oil temperatures in the Cessna Corvalis 300, 350 and 400 airplanes. The new Vernatherm opened at higher temperatures which prevented oil from circulating in the oil cooler at lower temperatures. I have no idea if this could be a solution for your airplane. The new Vernatherm is part number 657496.
SIL 10-6 was issued because a solution was needed for "engines that exhibit low oil temperatures (below 160 degrees F in normal operation)"
This indicates that Continental feels that 160 deg F is the lower limit of allowable oil temperatures.

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6 months 1 week ago #1296

I own a Turbo Arrow III, same engine, cowling, etc. and have the same problem. It's solved by installing the winterization kit when the ambient temperature is 50 degrees F or less. Take a look at 8.29 Winterization in your POH on page 8-15. I'm assuming it's the same in the Turbo Arrow IV. The winterization plate is located on the right hand side of the firewall and is installed over part of the oil cooler.

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  • John Barco
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6 months 1 week ago #1297

Apparently oil is only routed through the oil cooler when the oil gets hot enough to open the vernatherm (around 180 F). So if the oil is not hot enough (as in this case), and is not being routed through the oil cooler, then the winterization plate that blocks 1/3 of the oil cooler makes no difference. Never the less, it is installed.

Beginning to believe that just cooler that usual air recently is not letting the cylinders get hot enough to heat the oil enough. I'll evaluate it again when the air temp comes back up. Would have thought that an engine in cruise would be able to adequately heat the oil to a higher operating temp. Apparently not.

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6 months 1 week ago #1298

Apparently oil is only routed through the oil cooler when the oil gets hot enough to open the vernatherm (around 180 F). So if the oil is not hot enough (as in this case), and is not being routed through the oil cooler, then the winterization plate that blocks 1/3 of the oil cooler makes no difference. Never the less, it is installed.

Beginning to believe that just cooler that usual air recently is not letting the cylinders get hot enough to heat the oil enough. I'll evaluate it again when the air temp comes back up. Would have thought that an engine in cruise would be able to adequately heat the oil to a higher operating temp. Apparently not.

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  • Brenton Haskell
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5 months 3 weeks ago #1309

The Piper part number for the Turbo Arrow III is 67849-00. I have the same low oil temp problem. I tried to get the winterization kit but no one seems to have it and most don't even know it exists. Certainly, mine was long gone from the right side of the firewall!

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