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automotive type oil cooler

Assuming you have checked all the normal stuff (baffles, sealing, sensor accuracy, birds nests), I highly recommend that you install a viscosity valve in your engine if nothing more than a low cost and easy troubleshooting step. In most cases its a simple 30 minute activity to drop in and you dont need to remove the Vernatherm.

You will be shocked, trust me.
 
The reason I recommend the viscosity valve as a troubleshooting step is because it eliminates the well known issue of poor Vernatherm plunger sealing. Even with good sealing, there is still a lot of leakage with a Vernatherm, and most are far from "good". The viscosity valve plugs that leak path and lets you evaluate the rest of system performance without polluting the results with some unknown % of internal leaking. The viscosity valve plunger is $30 bucks from Spruce if you cant find one laying around an A&P's junk drawer.

Its a lot cheaper and easier than plumbing a new cooler.
 
Problem isn't the cooler or the vernatherm, its the lack of airflow through the cooler. I have a 13 row cooler mounted on the firewall with a 4" duct feeding it off the back of the #4 cylinder. I am running a sam James cowl with a plenum, there just isn't enough air available in high alpha climbs to run it. I have measured it extensively with a digital manometer. There is only a 1.8 in/h20 drop across the cooler in climb. In cruise I get a 3.2 in/h20 drop with my cowl flap open, oil temp drops into an acceptable range for me (205-210), but a little warm for some of my less risk tolerant friends. It has a little over 100 hours on it and it hasn't come apart yet :) CHT's in climb are great, I can hold Vy to whatever altitude I want and the hottest cylinder is right around 400. I could divert air from the cylinders to feed the cooler, but I don't want too....I am running SDS EFI, I think I can control a fan based on oil temp with it, so I thought about a cooler with a fan on it. This isn't exactly a stock 360 either, everything is against it as far as oil temps go. Cold air intake, 10:1 compression, piston squirters, custom Cam, etc. For what it is it actually cools pretty well, but it could be better.
 
Here are some photos of the current install. The elbow has guide vanes in it to smooth airflow.
 

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That elbow looks like it would be relatively rigid, especially if it has flow smoothing vanes inside. With the cooler mounted to the firewall seems like it would self destruct in short order due to engine shake during startup and shutdown.
 
Problem isn't the cooler or the vernatherm, its the lack of airflow through the cooler. I have a 13 row cooler mounted on the firewall with a 4" duct feeding it off the back of the #4 cylinder. I am running a sam James cowl with a plenum, there just isn't enough air available in high alpha climbs to run it. I have measured it extensively with a digital manometer. There is only a 1.8 in/h20 drop across the cooler in climb. In cruise I get a 3.2 in/h20 drop with my cowl flap open, oil temp drops into an acceptable range for me (205-210), but a little warm for some of my less risk tolerant friends. It has a little over 100 hours on it and it hasn't come apart yet :) CHT's in climb are great, I can hold Vy to whatever altitude I want and the hottest cylinder is right around 400. I could divert air from the cylinders to feed the cooler, but I don't want too....I am running SDS EFI, I think I can control a fan based on oil temp with it, so I thought about a cooler with a fan on it. This isn't exactly a stock 360 either, everything is against it as far as oil temps go. Cold air intake, 10:1 compression, piston squirters, custom Cam, etc. For what it is it actually cools pretty well, but it could be better.

I suggest you have recreate the oil cooling issue on the RV-14 running the IO-390-EXP111 engine - and the reason Van’s went to a 5” hose feeding the oil cooler.

As your CHTs are good, there is air more available to steal for the oil cooler. The other answer is to live with it and manage by how you operate the plane.

As a side note - years ago (back when oil cooler selection was not great) one RV-6 builder solved his hot taxi and climb oil temp problem by adding water spray onto into the cooler air path. This was done by repurposing a automotive widow washer pump and tank. His only complaint was he should have put in a larger tank.

Carl
 
The reason I recommend the viscosity valve as a troubleshooting step is because it eliminates the well known issue of poor Vernatherm plunger sealing. Even with good sealing, there is still a lot of leakage with a Vernatherm, and most are far from "good". The viscosity valve plugs that leak path and lets you evaluate the rest of system performance without polluting the results with some unknown % of internal leaking. The viscosity valve plunger is $30 bucks from Spruce if you cant find one laying around an A&P's junk drawer.

Its a lot cheaper and easier than plumbing a new cooler.

Michael, could you elaborate a little on what the viscosity valve is and where it goes? A search on Aircraft Spruce turned up nothing.

I've never heard of this, and probably many others haven't either. It sounds like I might benefit from one.

Thanks.
 
He is referring to the spring and plunger shown at the top of the accessory housing in this picture.
 

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ehh that picture is pretty small. Here is the service instruction it came from.
 

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The james plenum does not have a very good diffuser function from the inlets to the heads, and is a little restrictive at front face of the heads.

Tweaking category - radius for exit flow from aft baffle to your cooler "hole" a nice radius like a penny or nickel dimension will help. Due to the low aft position of the plenum (for RV4) it is pretty close to the head and can get warmer air ingested. Any picts would help, but you should get the gist here.

Shifting the balance from engine fins to cooler fins. There is a lot of air going by the barrels on the inside and not giving a lot (if any) extra cooling. Being a parallel valve you can add some wrap up the inside about half way up with no risk and will measurably shift the airflow to the cooler. No effect on the CHT.

I see your test was extreme on purpose, but just dropping the RPM to 2500 will greatly reduce the HX to engine and oil. Climbing at 100-105 kts on hot day, and maybe dropping MAP to 25 @ 400 ft then back in at 3000 (cooler air). Are options to keep the OT in line.

I don't think the summit thing is going to do much good or fit in your FWF very well.

You mentioned cowl flap (?) , do you have the standard James IO cowl exit?

I am assuming you have done the extreme sealing of all the baffle leaks that allows air bypass fins and escape unheated?
 
Being a parallel valve you can add some wrap up the inside about half way up with no risk and will measurably shift the airflow to the cooler.

Can you elaborate on this? Pics would help if you can find some.

Of course I could pull the power back, what fun is that? :) Planes very flyable as it is, and the oil temp is manageable. Just trying to make it so you don't have to think about it. Standard long sam James cowl, added an electric cowl flap from antisplat aero. It helps, delta p goes from 2.8 to 3.2 with it open. Yes, I have used many tubes of sealant.
 
two things to try...

Two things...

1. Change the oil cooler to the HE version or the actual Stewart Warner/Southwind/Meggit-Troy version with -[solid]- end tanks (10610R or 10611R whatever fits) ; the fin spacing is different than the clones.

2. Change the diffuser on the front of the oil cooler from the flat-faceted version into a custom molded shape without any edges to trip up, or induce turbulent flow.
 
ehh that picture is pretty small. Here is the service instruction it came from.

Thanks. So I gather that Michael (Toobuilder) is suggesting that the plunger and spring be installed. If I understand its function, it forces oil through the cooler always, unless the oil pressure is too high (as it would likely be when the engine is cold) and only then bypasses the cooler. I am inferring from Michael's suggestion that very often Vernatherms don't seal fully and always allow some oil to bypass the cooler, whereas the pressure valve would more reliably force all the oil through the cooler.

Does that about cover it?

At one time, I convinced myself that my Vernatherm was closing fully, but I don't remember how I did that. I do remember heating it in a pot of water on the stove and measuring the extension of the cone on the end, and I do remember seeing slight witness marks on the cone all the way around, suggesting that it was seating properly in the housing.
 
Michael, could you elaborate a little on what the viscosity valve is and where it goes? A search on Aircraft Spruce turned up nothing.

I've never heard of this, and probably many others haven't either. It sounds like I might benefit from one.

Thanks.

Yep, Jake shows it. This scheme is also used with people who use a ball valve to control oil flow for winter ops. Several good threads on it here.

Though the plunger itself is cheap, the specified spring is insanely priced. I went to the local hardware store and found a suitable replacement for a fraction of the Lycoming price.


EDIT: Yes Steve, you have the concept down cold.
 
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Thanks. So I gather that Michael (Toobuilder) is suggesting that the plunger and spring be installed. If I understand its function, it forces oil through the cooler always, unless the oil pressure is too high (as it would likely be when the engine is cold) and only then bypasses the cooler. I am inferring from Michael's suggestion that very often Vernatherms don't seal fully and always allow some oil to bypass the cooler, whereas the pressure valve would more reliably force all the oil through the cooler.

Does that about cover it?

At one time, I convinced myself that my Vernatherm was closing fully, but I don't remember how I did that. I do remember heating it in a pot of water on the stove and measuring the extension of the cone on the end, and I do remember seeing slight witness marks on the cone all the way around, suggesting that it was seating properly in the housing.

I did this when I suspected a vernatherm issue and it helped to rule out the vernatherm. There are two potential issues with them. First, is problems in the wax area and that can be tested by heating and observing the growth length of the plunger from room temp to 185*. The second is poor sealing. On some oil filter adapters, the holes are too big and it is hard to get it on in proper alignment with the hole that the plunger sets into (Lyc really should have put an index pin in that interface). Witness marks are a good guide and there is an SI for re-cutting the hole if it is mis-shaped or damaged.

FYI, There is a very close tolerance fit in the wax area. I had one that didn't meet the growth length spec. Upon disassembly, found some carbon build up in that area (it sees a lot of oil). After cleaning and re-assembly, it met the spec and is still working 800 hours later. It is my belief that many failed VT's can be repaired, though my experience sample size is still just one.

Larry
 
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More info requested

Just trying to confirm what is being suggested -

Install BOTH a Vernatherm AND a viscosity valve (spring and plunger)? If I read the SB correctly, you remove the viscosity valve when you install the Vernatherm.

Does anyone know if you can do this on the standard adapter as well as the B&C angled adapter?
 
Yes, you are to remove the "viscosity" valve and install the vernatherm is what that SI was issued for. However, if you install one, and keep the vernatherm, the vernatherm will essentially be doing nothing, as all the oil would be controlled by the "viscosity" valve. I think..... never tried it or stared at it long enough to be certain. All this will do is force oil through the cooler, a closed vernatherm does the same thing. In my case both the vernatherm and the oil filter housing are brand new, I know they are closing and seating. So a "viscosity" valve shouldn't make a difference in the amount of oil going through my cooler. If I get some free time I may stick one in and fly just to prove this, but not high on my priority list ATM.
 
In all the engines I have experience with, the vernatherm and the viscosity valve live within different bores and do not interfere with each other. In these cases, the installation of the viscosity valve simply renders the vernatherm inoperative. Some in my circle will remove the viscosity valve when winter comes and just let the vernatherm do its half assed thing. It takes little effort to remove the viscosity valve (about the same time as it takes to add a block off plate to the cooler)

That said, I believe there are some configurations out there where the tip of the vernatherrm will protrude into the space occupied by the viscosity valve - so in that case it has to be one or another.
 
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That said, I believe there are some configurations out there where the tip of the vernatherrm will protrude into the space occupied by the viscosity valve - so in that case it has to be one or another.

That's a good point that has been discussed by DanH. Since he is galavanting around the West somewhere, below is a post of his. Note the last paragraph.


"Important note: take a close look at the cutaway drawing in the upper right of the 1008B illustration. If you're using an old-fashioned oil screen (unlikely) or a filter adapter with the vernatherm oriented like the old oil screen (your right angle adapter), it is possible for the tip of the vernatherm to foul the oil plunger if you have both installed in the same engine. There's another Lycoming SI addressing this issue."
 
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Wraps in raw form.

Most of the wraps are under the baffles, but the barrels are wrapped up the insides too. The wrap is DanH shared, 8 oz fiberglass impregnated with high temp RTV sandwiched between polyethylene sheet. One side is peeled off before cure and applied wet to the fins. The exterior sheet is removed post cure. This is hard to do after all together, but adding some aluminum HVAC tape could be easy test of the concept for your installation. Just up half the side though not past vertical.

The intersection baffle under/between the barrels is quite bad about leaking, use a flashlight when dark to see where it leaks.


Fin_Wrap 01.jpg Fin_Wrap 02.jpg

Fin_Wrap 03.jpgFin_Wrap 04.jpg

Fin_Wrap 05.jpg
 
That is extremely interesting. It may be a while before I get the time to do it, but I’m definitely trying that. Baffles come off just as easily as they go on…:)
 
That is extremely interesting. It may be a while before I get the time to do it, but I’m definitely trying that. Baffles come off just as easily as they go on…:)
Wrapping the cylinder barrel will mostly help with the CHT and not your oil temp. The same thing can be accomplished, though not as great, by making sure your baffle's sides (on the bottom side) are sealed so air can not escape that and will remain in the fins all the way to the end. Just get a tube of high temp RTV and seal the edge/sides of the baffle that wraps around the fins.

As for your oil cooler setup, I am only guessing, but I suspect those turns from the baffle to the oil cooler might be creating enough turbulence that you don't get enough air passing thru your cooler. It is also possible that something on the exist side is affecting the flow.

I am sure you know this but as a reference, my RV7 with the oil cooler mounted behind #4 cylinder baffle never had any cooling issue. In fact I had a oil shutter on it to bring the oil temp to 180-185 even in the summer time.
 
?.. In my case both the vernatherm and the oil filter housing are brand new, I know they are closing and seating. So a "viscosity" valve shouldn't make a difference in the amount of oil going through my cooler...

Yep, thats what I thought too. I bought the airplane with 58 hours TT and the engine was installed as a brand new from the factory certified engine.

Viscosity valve made a huge difference for me. It think I had one of those fabled "Friday evening shift" assembled engines (not the greatest attention to detail)
 
Disagree with premise.

Wrapping the cylinder barrel will mostly help with the CHT and not your oil temp.

As for your oil cooler setup, I am only guessing, but I suspect those turns from the baffle to the oil cooler might be creating enough turbulence that you don't get enough air passing thru your cooler. It is also possible that something on the exist side is affecting the flow.

Good comment on flow losses to the cooler but the flow balancing not helping the oil is a different matter.

The idea is that there is a line contact of baffling the lower side of the barrel fins and is a lower restriction for air than all of it going through the fin channels and doing cooling, thus reducing airflow. Also when the air goes through the channels it becomes turbulent therefore increasing the heat transfer coefficient.

Reducing this airflow marginally increases the plenum pressure and allows more mass flow through the oil cooler. That is . . unless there are leaks in the cooler air supply that thwart the flow.

But - - yes the CHT is likely to get lower as well.
 
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Agree with premise

The idea is that there is a line contact of baffling the lower side of the barrel fins and is a lower restriction for air than all of it going through the fin channels and doing cooling, thus reducing airflow. Also when the air goes through the channels it becomes turbulent therefore increasing the heat transfer coefficient.
We are in agreement in the premise. My point was that one can accomplish pretty close to the wrap by ensuring the air will stay in the fin channels all the way to the end. If the round portion of the baffle is held tightly against the fins and the sides are sealed, air has little place to scape and will remain in the channels. Of course if one is willing to remove all the bafflings and start again, that may yield a better result.

To the OP:
In my conversation with Airflow system owner, he indicated that the cooling fins in the cooler is built so tightly that allows for more cooling and will limit airflow thru it and it is not affected proportionally by how much air you get pass it.
This somewhat confirms my experience. In my 14, I went from a 4" duct to a 5" duct which roughly has 1.5 time the surface area and was expecting a very pronounce change in my oil temp. To my surprise I saw reducing my oil temp only by 5F at best at cruise and a little bit more at slower speed where pressure is less.
 
You must have misunderstood Mr. Genevro, he has a chart on his website showing that heat rejection is indeed proportional to the amount of air flowing through the cooler....increasing the size of the duct feeding the cooler does not equal more flow to the cooler, although too small of a duct could limit your flow. air takes the path of least resistance, if its down through the cylinders rather than out your 5" duct then so be it. That is why we are talking about restricting the airflow through the cylinders by wrapping them. if you increase the path of resistance there, more air will go elsewhere, like to the cooler.
 

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Yep, thats what I thought too. I bought the airplane with 58 hours TT and the engine was installed as a brand new from the factory certified engine.

Viscosity valve made a huge difference for me. It think I had one of those fabled "Friday evening shift" assembled engines (not the greatest attention to detail)

I happen to own an FAA repair station that has an engine shop. I/we assembled this engine in house. I am certain that the vernatherm is seating as designed. In fact, if you stay in cruise long enough and high enough, the vernatherm does its job quite well and the oil temp regulates at around 185-190. My issue is definitely air supply related, particularly in high alpha climbs (my pitch attitude at Vy is about 11 degrees....) That being said I orded a new spring and check valve, I will try it and see what happens. I do think it will send a larger quantity of oil to the cooler than a vernatherm. It won't increase the airflow though..
 
That being said I orded a new spring and check valve, I will try it and see what happens. I do think it will send a larger quantity of oil to the cooler than a vernatherm. It won't increase the airflow though..

Let us know the result. I have a upright B&C adaptor on my IO390 engine. I am going to look to see if I have the same prevision on my engine. Although technically and based on Lycoming I don't have oil temp issue, around 200 in cruise, but since I am more used to the 180 level oil temp, I like to bring it down if I can.
 
....he indicated that the cooling fins in the cooler is built so tightly that allows for more cooling and will limit airflow thru it and it is not affected proportionally by how much air you get pass it....

You can't divorce the design parameters and a change in one will influence another. Air flat sucks as a cooling media compared to other fluids, i.e specific heat. "Built so tightly" was probably referring to increasing the heat transfer surface area for the given cooler cross section. This would also decrease the air flow through it (and thus the LMTD); however, nothing beats surface area for maximizing the heat transfer for a set of given boundary conditions.
 
Let us know the result. I have a upright B&C adaptor on my IO390 engine. I am going to look to see if I have the same prevision on my engine. Although technically and based on Lycoming I don't have oil temp issue, around 200 in cruise, but since I am more used to the 180 level oil temp, I like to bring it down if I can.

Typically, the viscosiy valve is mounted on the accessory case itself, not the filter adapter or screen housing. If you know where to look, you cant miss it.
 
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