New Engine Overheat Problem

Guest Discussion
#1

I really need help here - I’m headed for a real issue as the weather gets warmer.

I’ve noticed a significant escalation in the oil temperature in my SR20 on takeoff, and in cruise. I thought it might be running the Tannis during warmer weather - that was eliminated. I thought it might be my new 2700 RPM takeoff settings - that was eliminated.

Here’s the scenario. 800FPM climb, just my 215 pounds and full fuel, OAT 40 degrees F on ground/ 35F at 6000’ altitude, 2600 RPM climb, new SB screen installed. Oil temp 220 on climb, 210 sustained in cruise. This can’t be right or good!

What should I be looking to? Bad sensor? Is there something on the plane akin to a thermostadt in a car?

Andy

#2

From pure memory…I think in the POH the engine ‘oil cooler’ is suppose to kick-in at +170 degrees. This thermostat would act like the one a your car governing water circulation. That’s were I’d start…I’d also quickly change the oil, maybe it has ‘broken down’ due to foriegn substances.

#3

Andy,
This is a common problem on all SR-20’s. Early models are the worst offenders. The latest design cowling is supposed to improve the situation. Perhaps as summer sets in some of the folks on this board can chime in with their experiences. It’s a tough challenge for a designer to balance “cooling drag” against “cooling effectiveness”. The -20 cuts this equation very close. If you don’t have the cowl vent mod you might want to give it serious thought.
Assuming you don’t have any mechanical problems inducing more heat into the system,( i.e. failing main or rod bearings for example) and all engine cooling baffeling is in place about all you can do is manage the situation. Reduce climb rates or “step climb” if necessary. You might play with the mixture a bit, reduce engine rpm, etc. You are wise to take this issue seriously as excessive oil temperatures will cause major problems in the long run. I have experienced first hand what can happen when oil is run at the limits of it’s intended temperature range. It gets real ugly. How many hours on your engine?

#4

My engine has 220+ hours on it. I’ve experienced the “normal” SR20 problem last summer, and was able to deal with it okay. Now it appears to be much, much worse. I’ll look into the cooler. Oil was changed 5 hours ago.

Thanks for the inputs.

Andy

Andy

#5

Andy,
If all else fails and if you have engine monitoring…you can lean on the way out in climb (Deakin recommends this too on with monitoring). I have done this at about 1500-2000agl…an average of 30-40 degrees cooler oil temps! EGT way down too while still climbing at 750…just a little slower…105 or so vs. 115-120…but the engine likes it better for sure.
To me something else is amiss if it wasn’t this bad last summer. good luck

#6

Andy,
Any updates concerning the high oil temps you were/are experiencing?

#7

Andy,
Don’s LOP suggestion is good advice – works great, if done properly, but that’s really only possible with Engine Monitoring (my opinion - I know others disagree). But… you have that, right?
Also agree with Don that if things were better last summer, you have something definite wrong. Suggest you have the Vernitherm valve checked – it’s a pretty exact equivalent to the thermostat in the cooling system of a car, except it diverts oil around the oil cooler until proper operating temp is reached. If it sticks, oil is never sent to the cooler…

Note: Pic is a Vernitherm valve, but may not be OUR Vernitherm valve.

FWIW, my SR20 also wanted to run hot during climbs last year, but always settled at 180 during cruise, even fully rich. LOP always got me to 150 or less, and I actually made a point of running ROP occasionally because I believe that too-low oil temps aren’t always a good thing. During cruise in the winter, for instance, I sometimes can’t get oil temps ABOVE 120 without going back to ROP. I haven’t had the cooling mod done yet - that’s scheduled for next week.

#8

Just test flew today, and problem is fixed. Problem with oil cooler.

Andy

#9

Andy,
Can you provide details as to what was actually wrong with the oil cooler?