View Full Version : Oil Cooler Problems

04-28-2010, 04:27 PM
I have a Niagara Thermal Products 200002A oil cooler installed on an ECI 0340 Stroker on my BackCountry SuperCub. Originally installed on the rear baffle, the system ran hot from the first flight a little over a year ago. By hot I mean it gets up to 215 to 220 within 20 minutes or so. Longs climbs gets it to red line and you have to reduce power to control the heat. CHT and EGT are just a tad higher than I'd like but not out of line, 375 and 1375 would be a typical average.

I have moved the cooler down to the firewall with the air outlet aimed at the largest part of the cowl opening on the left side. First attempt I took at 3 inch scat from the left rear baffle to a good sized plenum on the oil cooler. Very little if any change in temps. Second attempt I brought a 2 inch scat from the right rear baffle down to that same plenum on the cooler. Very little if any change in temps with now a 2 inch and a 3 inch coming into the plenum. Third change I made a baffle/duct to try to take full advantage of the suction at the cowl opening to pull more air through the cooler from the rear baffles. Very little change if any it temps.

Seems to me that doing these things I have had to increase the airflow through the cooler. Do I have a bad cooler? Are there coolers that are better (Stewart Warner)? Read lots of stuff here on cooling and it seems on these installs you have one of two problems, one set of us can't get the temps up and the other set of can't get the temps down. I guest you know what group I'm in - I'd like to try the other problem for a while. :-? I welcome any ideas.

04-28-2010, 04:53 PM
For what it's worth, I have a Aero Classics (Pacific, Niagara 20003A) 8000074 - 9 row cooler. I think yours is a 7 row? I have no problems with oil temps, in fact I need a cooler block for the winter because it never goes above 160F without. My cooler is rear baffle mounted.

Here is a nice cross reference chart:

04-28-2010, 05:02 PM
Yes, mine is a 7. Have been real tempted to get a 9 row but thought maybe I should get some imput from others with experience here before I go that route.

Darrel Starr
04-28-2010, 05:34 PM
Gerald, have you taken the Vernatherm valve out and tested it? Or, there may be a way of just removing it for your operation to get more flow through the cooler.
I have a 9 row Niagara on a 160hp 0-320. It will run 215F oil temp on a 90F day with CHT and EGT similar to yours.
Some of the high HP Huskies have a large movable flap to help move air through the engine compartment. Also, I heard this plane had two coolers but I didn't see it.
Backcountry at Oshkosh showed the following set up, I think it is the Mackey S2. Seems that a lot of people are trying to get more cooler efficiency.

04-28-2010, 05:47 PM
What's the OAT ?
What have you seen happening to your oil pressure?

Maybe it's not the oil cooler.

Maybe you should be doing more to cool the whole engine.

What sort of shape is your engine baffling in? Is everything good and tight in there? I mean REALLY TIGHT. Seal up every seam and hole. Holes in the baffling around the starter and alternator brackets? Eliminate any place where air can get to the bottom side of the cowling through the front of the nose bowl?

Do you have a lip on the trailing edge of the bottom cowling? That can help improve the efficiency of the pressure cowling.

Maybe all those ducts and scat hoses through the baffling are being counterproductive? I.e., reducing the pressure on the top side of the engine, resulting in less air flowing through the cylinder fins,...reducing the cooling and making the engine run hotter?

Question: is the air on a rear mounted oil cooler supposed to be pushed through the oil cooler,...or pulled??

(?? Does that make any sense, or am I off-base regarding engine cooling ??)

Jim W

04-28-2010, 06:32 PM
Should have added that the baffling is very tight all around. I did originally have air coming into the low preasure side from the airfilter/carb hole in the bottom cowl that has been sealed. Yes, I also have a fairly large lip on the back edge of the bottom cowl to pull air out.

Air temps here in AZ of course are higher but even on 50* days oil temps go up higher than they should. In fact that is one of the puzzles, oil temps don't change with OAT as much as it seems like they should.

I've looked at Wayne's install last year at JC and some of the others as well. That is why I placed the cooler where I have it now with the baffle/duct to somewhat simulate that method. Wanted to test before I cut through the firewall.

Darrel Starr
04-28-2010, 07:35 PM
Gerald, how about the Vernatherm valve? If it were blocked you would get just a small flow of oil through the cooler even at high oil temps.

04-28-2010, 08:27 PM

04-28-2010, 09:01 PM
On same subject, I have had the same oil cooler on my 12 for 45 yrs! Oil temps can go up to 235 in the summer in Utah. Will the new Niagra aluminum cooler make as much difference as they claim? Anyone recently changed theirs?

04-28-2010, 09:57 PM
Gerald---I have the same cooler on my 0-375 and in the summer when I have to climb up to 9000 ft to clear the Sierras I have seen 240F oil temp and I have to extend a very shallow climb.

If I don't have to climb much during the hot summer it will see 215F which doesn't bother me.

The Stewart Warner will definately cool better but maybe not enough for the hard hot climb.

I am considering installing a small cooler on the firewall right side (running in tandem with the left side) with scat comming from the right baffle with a shutoff butterfly controled from the copit.

The Pawnee's had two coolers and most aerobatic's have two.

I hate to add the weight but I fly in 110F heat

04-28-2010, 11:02 PM
Is it possible to remove the vernatherm to remove that restriction to the flow of oil to the cooler? Any problems with doing that other than oil temps not coming up enough?

04-28-2010, 11:55 PM
Gerald, when I got my Cub about 2 1/2 yrs. ago, I installed a vernatherm thinking this was a slick way to have consistent oil temps - which it is assuming the thing works. About 6-8 mos. later I started having progressively (and unseasonably) higher oil temps. After checking out the cooler, which was fine, I pulled the vernatherm to discover that it had failed in such a way that the plunger was cocked and not sealing against the seat. I ditched the VT and went back to a blocker plate in cold weather. Problem solved. By the way, if you lose the VT vou have to install a viscosity valve. -- GEOASPEN, I replaced my stock cooler last summer with the Niagara. In my case it reduced temps about 10 degrees across the board and shaves about 3.5 lbs off the nose if memory serves. A good product in my opinion.

04-29-2010, 01:15 AM
Niagra Air Parts Cub Cooler...a drop-in replacement for the Harrison cooler that keeps the oil too cool below 60F ambient temps...airflow through the cooler is an arcane subject, and subject to a lot of discussion. So, I just upgraded to the most efficient one that I knew would work, and didn't fight with it, like I did with my CHT's...


Installation Instructions

# All Aluminum Construction

# Cooling Efficiency is improved by more than 50%

# Almost 4 lbs lighter than the original Harrison oil cooler

# Now available for PA-18, PA-19, PA-20, PA-22

Direct Replacement

04-29-2010, 02:51 AM
I was also running the2002a oil cooler, up until about 2 months ago. I had similar problems with the oil getting to hot in the summer. I switched to the 2003a cooler and have been very happy with it so far. Last weekend I flew, and the outside air temp was about 55 f, I was still partialy taped off and saw oil temps around 205. I am sure if I would have pulled the tape off it would have been around 180-190. I was running it pretty hard too, most of the time between 2500 and 2600.

04-29-2010, 10:02 AM
It seems alot of these "stroked" engine have heating issues. You need to look at where the heat is coming from. WHat is the difference between a stroked engine??

04-29-2010, 10:28 AM
Been my experience with the guys I fly around with is that the 20002A is to small. Had one on a PA18 and it ran hot also. Put on the 20003A and it ran cooler. Got a field aproval several years ago to put a 20006A on a 135 cub and it worked great.

04-29-2010, 10:46 AM
More power=more heat...

04-29-2010, 05:51 PM
I have rec'd some pm's and the replies here. Great help. Got to an interesting page at Van's Airforce site. That explains the oil flow better than some others.


Also http://img390.imageshack.us/img390/2117/lycacccaseoilschematic.jpg

It appears at this point that either my cooler just is not large enough or the vernatherm is not seating well.

Any other input would be helpful.

05-03-2010, 09:30 PM
For you all who are interested in this cooler information. I talked to Pacific Oil Cooler people today. According to their tests the 10599R Stewart Warner Cooler (8 row) is equal to their Aero Classics 13 row in cooling capacity. SW has a different patented vane design that works better than the others.

05-26-2010, 02:45 PM
Gerald, did you get a Stewart Warner 10599R oil cooler? If so how does it work