The International Cessna 170 Association

Below what temperature should we start considering installing a winterizing kit to block off some of the cowl inlet? 170B with C-145.

I was flying the other day below 40F and noticed the cylinder head temp was lower than normal in cruise and dipped below the minimum mark during landing.

Cold Wx is usually more of a problem for starting and requires a pre-heater and/or working fuel Primer.

Before making the following comments I’d caution you to ascertain your instruments are Calibrated and KNOWN to be Accurate.

This is a subjective matter and I would suggest that if you are experiencing Cyl Head temps below 250-F and Oil Temps continuously below 140-F that you might consider a winterization kit. I live down in Texas where most of the state is below the Arctic Circle (excepting Amarillo, of course)... and I have not flown (a 170) in ambient temps below 0 so take that into consideration. However, I have operated all over the lower 48 and never felt the need for the kit. Northerners, Alaskans, and our Scandanavian Members probably have a different opinion. A non-working primer is a larger problem, IMO. YMMV

Of course, I’m thinking if you take off with it and find the engine running too warm (usually cyl heads) you must land to remove it. And I’ll add that a winterization kit is intended to help In-Flight engine temps. Proper Pre-Heat is more important to avoid engine damage, IMO. I use a low-output electric forced-air heater for several hours before attempting a start below freezing.

If you fly regularly below freezing you might consider the benefits of multi-grade engine oil.

The kit I have is marked on the cowl block off plate “Remove above 60 f” or something like that. That’s the hole that blows on the case. The cylinder block offs are marked not to be used above 20f. I have not used them in NY yet and probably won’t.

Unscientific observation leads me to say the cowl block plate adds about 20f when the OAT is in the low 30’s. Without the plate my oil temp is usually 100 over OAT. On a summer 85 degree day my gage indicates 185-190. In the thirties with the plate on my temp indicates 150.

FWIW, the O-200 in my Legend Cub acted the same way.

You didn’t mention if you have a six cylinder temp gauge or not. Without that I would not be comfortable blocking off airflow over the cylinders.

If you are “on the fence” in decision-making on this item, you might wish to think about:

1-They are uncommon and difficult to find.
2-They add realism and originality to your accoutrements.
3-We have a Member who makes very-original appearing copies. (See TradeMart and Flypaper)
4-Possession may add value to your sometime-sale.
5-At some point they may become even rarer.
6-It may be better to have one and not need it....

The Owners Manual has this comment about the winterization kit:

For operation at temperatures con- sistently below freezing, a winteriza- tion kit consisting of plates for clos- ing cowl openings is available at your dealer for a nominal charge.

The Cessna cowl plate limit is 30°F and below. Not 20°F as was stated. The sump plate is 60°F and below.

When I was flying in temperatures in which my oil temp would not rise to a level I wanted to boil out water, I installed the plates. I usually observed Cessna's limits.

I’m in central TX, and it sounds like I don’t need it. I don’t intend to fly much below freezing. Here is a pic showing my oil temp was fine, head temp on the lower side. My guess is this head temp is only on one cylinder.

Bruce Fenstermacher wrote:The Cessna cowl plate limit is 30°F and below. Not 20°F as was stated. The sump plate is 60°F and below.

When I was flying in temperatures in which my oil temp would not rise to a level I wanted to boil out water, I installed the plates. I usually observed Cessna's limits.

The NOS winterization kit I donated to the auction at the last convention came with unattached decals which agreed with Bruce’s numbers, both for the cowl plates and the sump plate. I reproduced them as stickers for my “owner produced” plates. Even beyond the (probable) legal requirement that they be there, they’re a good reminder to think during preflight about whether you actually need them for any given flight.
BTW, that’s my whole-airplane preheat system hanging from the ceiling behind the left wing root.

I don’t know if it was my brain or my finger that failed me when I posted the 20 degree number for the use of the cylinder block off plates.

Picture of the kit available from one of our members, which work and fit great.

I have found that I can easily run the oil pan portion of the winterization kit almost 9 months of the year here in Western Washington. Of course we are cooler and wet much of the year.

cessna170bdriver wrote:[.

The attachment 435A13B8-0A1F-42DA-80C9-A0ABFC4DA562.jpeg is no longer available

BTW, that’s my whole-airplane preheat system hanging from the ceiling behind the left wing root.

That’s mine through the ROPs and above the left land/taxi lights of the 170:

The problem with the baffle plates that I have seen in Alaska is using the plates when having low ground temp but with an inversion and higher temps aloft, usually in the spring. The cylinder temps and oil temp can climb above limits quickly and must be watched closely with the plates on. I quit using them.

0ooh...lately I’ve been suffering tractor envy

c170b53 wrote:0ooh...lately I’ve been suffering tractor envy

That pic was actually taken to illustrate how I mounted an ATV carrier-basket as a tool-carrier to someone. I got somewhat lucky finding that tractor only a few miles away, 50 hp diesel, no emission controls (1996 model) with less than 400 hrs on it.

hilltop170 wrote:The problem with the baffle plates that I have seen in Alaska is using the plates when having low ground temp but with an inversion and higher temps aloft, usually in the spring. The cylinder temps and oil temp can climb above limits quickly and must be watched closely with the plates on. I quit using them.

So, it looks like checking temps aloft should be part of deciding to use the plates. Inversions don’t seem to be common in this part of the world, so I hadn’t considered that. I do have to pay attention to forecasts, as mornings in the 20s can turn into afternoons in the 40s. I’ve flown with the cowl cover plates in temps as high as 35, and I do have to increase climb speed to to keep CHTs below 400F.