Difference in Oil Temperatures; EDM-700 vs factory

[robert14]

A year ago I purchased and upgraded a 1965 M20E, including the addition of an EDM-700. The engine has 500 hours SMOH. The readings from my EDM-700 and factory guages have always been different. The EDM-700 tempature sensor is screwed into the right front of the engine block right behind the prop. The factory temperature is on the back of the engine near the oil filter. The guages have been calibrated, the oil cooler is new, and the 85 deg C ver... has been removed, tested and replaced. All the hoses are new. Here is the scenrio:

1. At room temp, in the hanger, they read the same.

2. At runup, they both are the same until about 160 deg.

3. At climb-out, 120 MPH, the EDM-700 temperature begins to climb above the factory guage.

4. At cruise and 25-25, the factory guage is reading 222 deg while the factory guage is at 200 deg.

5. If I close the cowl flaps, the temperatures go up to 228 (EDM-700) and 205 (factory guage). 205 deg is well within the green on the factory guage. 228 would be on the edge of the green on the factory guage.

6. Mixture does not effect the temperature.

7. After landing and engine shut-off, the EDM-700 temperature compares withing one degree of my handheld IR sensor pointed at the temperature probe on the front of the engine at 195 deg F. The factory guage is reading 185 -190 deg F.

Any thoughts on this temperature difference? Does anyone have any temp data from their 65 M20E? Is the location of the probes causing the diffeence?

[sellis]

This is normal because of the location of the probes. The ship gauge probe is after the oil leaves the oil cooler.

[robert14]

Thanks for the help Stacey. One more question. CHTs 1 and 3 run within 5 deg of each other. CHTs 2 and 4 run within 5 degs of each other; however, 2 and 4 run 40 to 50 deg hotter then 1 and 3. Is this normal? 

[drpep]

Interesting data you are presenting. I just got off the phone earlier today with a tech from JPI. A few months ago I replaced my JPI 700 WITH THE EDM 830. The display of the 830 is exceptional!. After a number of orientation flights in my 67E I noticed a difference between my factory panel gauge and the JPI. During the hottest period in August the JPI climbed to 218 while the factory instrument read approximately 190. Recently I have been getting readings at 25 square of 215 on the JPI and 185 on the factory. The techy at JPI pointed out what you already know that the placement on the front of the engine of the JPI will read higher. He suggested up to 10 degrees but not as many as 30 degrees as I am experiencing. My mechanic advised me to have the air cooler serviced which I did. It was determined by the manufacturer to be working properly. My mechanic felt my air cooling over the oil cooler and the engine was very good. 

In summary, I am still uncomfortable with the temperature spread but do not know what else I can do. I asked JPI if the tempt probe could be malfunctioning and he assured me that was extremely unlikely given it was a thermocouple. He did suggest I could try switching one of the identical probes off the cht to the oil temp and see if the readings were the any different. Not sure of this but may try it this weekend. 

[robert14]

PePerry, I also talked with the JPI guy. He assured me that a 20 deg difference was normal. That is probably as good as it is going to get. What about your CHTs between the left and right side? Are the left ones hotter then the right ones? You may have to download and plot the CHTs to verify the difference.

[robert14]

PePerry, we are both seeing a 30 deg difference between the two probes. Interesting. My veritheum is set to 85 deg C (185 deg F). Do you know what yours is set to?

[robert14]

PePerry, I also talked to the folks who do my oil analysis, Lab One Aviation. They told me 20 to 30 deg difference was normal based on their discussions with their other customers. If you are having oil analysis done, you might talk with them to get their thoughts. Just another data point. My Mooney mechanic told me that my temps are normal for M20Es and Fs.

[robert14]

PePerry, another data point: there is a pilot report of a 1967 M20F on the internet. Go to Google and search for "Mooney M20F report". The report will be the first item listed. The report includes oil and CHT temperatures recorded from test flights of three different M20s: an M20C, an M20 E, and an M20F. These are measurements taken from the factory guages. I do not believ the M20E oil temp, 160 deg. Probably a bad sensor or guage. But the M20F temps are interesting. They were getting between 195 and 205 during the climb, the same as I am seeing on my factory guage.

[drpep]

Thanks for the feedback Robert. I will download my info from the JPI and I will check my veratheruem setting and get back to you. 

Philip

[carusoam]

Quote: drpep

JPI pointed out that the placement on the front of the engine of the JPI will read higher. He suggested up to 10 degrees but not as many as 30 degrees

[robert14]

I just purchased the Mooney engine cooling kit mod as specified in Mooney Service Bulliten M20E-182-1. Does anyone have any experience with this mod? Thanks.

[robert14]

Mooney sold me the M20-182-000 kit for about $240 and overnighted via UPS. It took my mechanic 6.5 hours to install. The outcome is extrodinary. My oil temps, even during climp are now 200 or 199, on the EDM 700. My factory guage shows a steady 190 to 195 deg. That is a 25 deg drop in oil temp. My CHTs have gone down almost 40 degs. Before you spend the money on a new cowl, you might want to try the Mooney kit. The price is right. I also have the actual data downloaded from my EDM 700. Robert

[DaV8or]

Quote: robert14

Mooney sold me the M20-182-000 kit for about $240 and overnighted via UPS.