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Engine baffling/baffle seal

J

Jettison

Member
Hey all, I recently purchased a flying RV-7 that has consistently high oil temperatures (210-225). It has the IO-360-A1B6 (angle valve, 200hp) engine.

First off, it doesn’t appear to have all of the baffling/baffle seal installed relative to other RV’s I have seen (at least in the front). Is there a schematic somewhere that shows what it is supposed to have?
 

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A couple things

I have an RV-4, a bit different, but the principles are the same. Yours are generally correct, but looks to have quite few voids and wrinkles/escapes. Not sure if your upper cowling has "ramps", but on the -4, they are a glassed in transition to smooth the airflow up and over the cylinders. On the lower cowl, you should have rubber seals that go up over the aluminum baffle ramps. I have a friend who built a -7 with very tight baffles and he still fought high temps. He ended up putting one of the servo driven cowl flaps in the side flat area of the cowl. Your exit area is equally important to be correctly matched to the inlet volume..cant get more in if it cant get out. ive attached a couple reference photos of mine.
 

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To answer your original question, there are several threads here concerning that. Van's has a set of 11x17 drawings for the RV-7 baffle kit, but some on the forum have said that the RV-14 baffle instructions are more thorough and the concept is the same. Take a look: https://www.vansaircraft.com/wp-content/uploads/2018/01/47_14.pdf

My plane has a plenum, so I don't have much experience with this. But the airflow through the D-shaped openings can account for a lot of losses. Not only when flow is bypassing the upper half and pressuring the bottom half a problem, but flow from the top of the cowling opening can induce turbulence and create pressure drop where you don't want it.
 
They look to be in the correct locations. Maybe not the best at stopping leaks. I see the front cylinders have high block plates. Might need to start playing with trimming those down to allow more air over the cylinder #1 and #2 fins. Double check all gaps are sealed in between the cylinder too.
 
Jettison said:
Nothing attached to either cowl, if that is what you mean…..
Click to expand...

The lower cowl usually has the seal riveted to it at the front---done in such a way that the seal can be pulled up and onto the floor of the inlet cooling tin. Air pressure pushes the seal down, and keeps it in place. Both sides of the inlet opening will usually also have the seal mounted so as to overlap the cooling tin.

Here are a couple good reads. https://vansairforce.net/community/showthread.php?t=141528 https://vansairforce.net/community/showthread.php?t=37835
 
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pazmanyflyer said:
They look to be in the correct locations. Maybe not the best at stopping leaks. I see the front cylinders have high block plates. Might need to start playing with trimming those down to allow more air over the cylinder #1 and #2 fins. Double check all gaps are sealed in between the cylinder too.
Click to expand...

Yes, they are tall.
 

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Jettison said:
Hey all, I recently purchased a flying RV-7 that has consistently high oil temperatures (210-225). It has the IO-360-A1B6 (angle valve, 200hp) engine.

First off, it doesn’t appear to have all of the baffling/baffle seal installed relative to other RV’s I have seen (at least in the front). Is there a schematic somewhere that shows what it is supposed to have?
Click to expand...

The seals are in poor condition, but set that aside for a moment. The angle valve engines typically require a larger oil cooler than the parallel valve engines. The photos seem to show a small Niagara, so I'd expect high oil temps even with good seals.
 
DanH said:
The seals are in poor condition, but set that aside for a moment. The angle valve engines typically require a larger oil cooler than the parallel valve engines. The photos seem to show a small Niagara, so I'd expect high oil temps even with good seals.
Click to expand...

The seals being in poor condition is dissapointing since the airplane only has 110 hours on it……

Any idea which cooler would be the right one to buy?
 
Not an RV, built I have a O-360 angle valve and went with a 13 row oil cooler and a 4” plenum for the oil cooler
 
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Take a look at the inside of your upper cowl and look for any witness marks from the baffle material. They rub a good bit and will leave marks where the contact is good. Same for the baffle material itself. If any parts of the baffle are still shiny after 110 hours it's not making contact with the upper cowl and leaking there.

My plane only uses half size inlet blockers in the winter, summer time they come out completely.

Next look at the sealing of the inter cylinder baffles for leaks directly into the lower cowl area. Like others have said, lots of good info out there about how to use a light and sealer to close off those leaks.

Personally I would address the baffle issue before heading down the path of changing the cooler etc. There is a lot to be gained from good sealing and efficient use of every bit of cooling air.

Oddly, baffling and cooling are an issue with almost every RV until the details get worked out, but the direction offered to the builder is slim.

This problem has been overcome before, you'll do it too! Good luck
 
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Oil cooler details

DanH said:
The seals are in poor condition, but set that aside for a moment. The angle valve engines typically require a larger oil cooler than the parallel valve engines. The photos seem to show a small Niagara, so I'd expect high oil temps even with good seals.
Click to expand...

Dan is spot on, maybe supply some more details (pics) of your oil cooler. Angle valve engines (Or engines with piston squirters) tend to run hotter oil temps and lower CHT's.
 
You might double check the engine manual and see what constitutes high vs acceptable oil temperatures. For example, I was surprised when I looked up CHT temperatures...
 
Oil temps in cruise or climb ?

Jettison said:
Hey all, I recently purchased a flying RV-7 that has consistently high oil temperatures (210-225). It has the IO-360-A1B6 (angle valve, 200hp) engine.
Click to expand...

Oil cooler does look a little smallish for an angle valve. I have an angle valve 390 and mine is larger. Are you using cruise climb to get to altitude? Need to ensure air gets as much pressure as possible into the oil cooler. Tight baffles will help.
 
Jettison said:
Here you go:
Click to expand...

It looks like an NDM/Niagra cooler, which is insufficient to cool the oil coming out of an IO-360-A1B6.

Consider changing to a SW/Southwind/Meggitt 8406R or Aero-Classics HE 8001602. These are the same size as the NDM, however the fin pitch is much tighter and the construction is a bit different (solid end tanks, instead of ribs)

Pick one up from Ebay or an Aircraft Salvage site and send it to Pacific Oil Cooler for overhaul...Way less expensive than the new-Aircraft Spruce route.
 
I am climbing at 100-120 knots up to cruise, full throttle, and prop at 2500.

Interestingly, my CHT’s have stayed pretty cool 327-346 in cruise (max limit 500). Oil temps 213-225 in cruise. Lycoming manual says oil temp 180 degrees is desired, 245 max.

I have read that the angle valve tends to run cooler CHT’s and hotter oil temperatures. This seems to be the case here, but I will try to get the oil temps down through baffling, and possibly, a larger oil cooler.

I have not found any drawings for the 7 that show the baffling. I have most of the drawings for the airplane, but am missing a few. Is there any metal baffling just inside the cowl openings, or is it all baffle seal/fiberglass?
 
The seal material across the back doesn’t seem to have any curl to it. I wonder if it is blowing out?
 
Some of the seals show wear and some don’t which makes me think there are leaks.

Do you have a picture of the inside of the top cowl? Looking for blow by (dirty streaks) and evidence the seal isn’t touching the cowl (lack of wear).
 
Jettison said:
I am climbing at 100-120 knots up to cruise, full throttle, and prop at 2500.

Interestingly, my CHT’s have stayed pretty cool 327-346 in cruise (max limit 500). Oil temps 213-225 in cruise. Lycoming manual says oil temp 180 degrees is desired, 245 max.

I have read that the angle valve tends to run cooler CHT’s and hotter oil temperatures. This seems to be the case here, but I will try to get the oil temps down through baffling, and possibly, a larger oil cooler.

I have not found any drawings for the 7 that show the baffling. I have most of the drawings for the airplane, but am missing a few. Is there any metal baffling just inside the cowl openings, or is it all baffle seal/fiberglass?
Click to expand...

Those CHTs are very good. Are you sure the oil temp is that high? Perhaps a sensor issue? I would not discount that possibility.

I recommend getting the FWF plans for the RV-14 which has a lot of excellent hints on how to do the baffles that are applicable beyond just the RV-14. They helped me with my RV-8.

https://store.vansaircraft.com/rv-14-14a-firewall-forward-plans-14-plans-fwf.html
 
I would second the suggestion that your oil cooler is the cause of the higher than normal oil temps. Can you calibrate the oil temp probe to be sure of the temp you are seeing?
The other question is how high do they need to be before you have to do something about it? 180F is the ideal temperature, but the limit is 245F.
As long as you are below 245F there is no pressing need, in the short term, to do anything.
Consider your options, collect the parts, figure out how to mount the larger cooler and supply it with air, and then make the change - and possibly improve the baffle seal at the same time.
 
Just a somewhat related note. As a registered builder you can go onto the Van's site and download any of the drawings for my plane. I'm not sure how it works for a non-builder purchaser, but I would contact Van's and see if you can have the ownership transferred to you. You might then be able to get access to all of the plans online. Worth a shot anyway.
 
My RV-7 has an angle valve, I am in CO and experience elevated oil temps in cruise climb, it seems to be a common feature with angle valves. I have the RV-10 oil cooler mounted on the firewall with 4" scat tube directly behind #4. As mentioned by another, my CHTs are also cool (due to the oil squirters). With the larger oil cooler I am able to keep the oil temps within the acceptable range. My numbers are 220 during climb on a 75 deg day and can get the temps in the low 200s in cruise.
 

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Definitely require a larger oil cooler. DanH has some solid posts along with his oil cooler selection.

Don't let the your CHT's trick you, it is the undersized cooler. Up/down larger/ smaller are not much help in design, so follow posts with numbers and data to select your cooler.

Also - plan on a 4" duct, rounded inlet from rear baffle, and firewall (or engine mount) mounted cooler with a good diffuser to guide the air to it.

You can fix the baffles in the mean time to get some flight time fun while sorting the cooler design, getting the digital plans from Vans, and hardware procurement.

You might consider the RV10 cooler mount, custom diffuser, and the RV14 flow valve and exit ring.
 
Just another data point…I have an older angle valve on my RV-7. Oil temps were a bit higher than I liked, 210-215 in climb. Would drop to 200 in cruise. A friend told me about an AD out on the vernitherm. Sure enough, mine was affected so I replaced it with a new vernatherm. I was pleasantly surprised with climb temps and cruise all lowered by 15 degrees. (Oil cooler is 10 row on #4 aft baffle.)
 
ryschneider said:
My RV-7 has an angle valve, I am in CO and experience elevated oil temps in cruise climb, it seems to be a common feature with angle valves. I have the RV-10 oil cooler mounted on the firewall with 4" scat tube directly behind #4. As mentioned by another, my CHTs are also cool (due to the oil squirters). With the larger oil cooler I am able to keep the oil temps within the acceptable range. My numbers are 220 during climb on a 75 deg day and can get the temps in the low 200s in cruise.
Click to expand...

Can you send a picture of the oil cooler side? Thanks, this info is valuable as it is the same engine that I have.
 
Loren said:
Just another data point…I have an older angle valve on my RV-7. Oil temps were a bit higher than I liked, 210-215 in climb. Would drop to 200 in cruise. A friend told me about an AD out on the vernitherm. Sure enough, mine was affected so I replaced it with a new vernatherm. I was pleasantly surprised with climb temps and cruise all lowered by 15 degrees. (Oil cooler is 10 row on #4 aft baffle.)
Click to expand...

Do you have that AD handy?
 
Stewart Warner (now Meggitt I think) specifications here:

https://www.danhorton.net/Misc/SW Oil Cooler Specifications.pdf

Airflow coolers here:

https://www.airflow-systems.com/category/aircraft-oil-coolers/

I'd suggest a 10599 or larger. I use a 10611 mounted remotely. You're seriously size limited if mounted directly behind #4 in particular with the RV-8 cowl.

If mounted remotely, mass flow through the cooler is influenced by ducting choices, the shape of the cooler entry plenum, and the deltaP.
 
I've seen other installations of this 13 row oil cooler attached to the engine mount with adel clamps and fiberglass shroud, or a remote version that is similar. I chose the direct firewall with the RV-10 mount kit, I'm not sure which is better but this has worked so far. The clearance is within about 1/2" of the engine mount tubes and other various parts. I also closed up all the air leaks on the edges of the oil cooler and the #4 baffle.
 

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