Thoughts on the Oil Cooler

[Andy95W]

1 hour ago, EricJ said:

The alternator will last a lot longer if it has cooling air.   How much is a question, I suppose.

Yes, but the engine will last a lot longer if the cooling air goes through the cylinder fins, not the big gaping hole around the alternator.

[Andy95W]

14 hours ago, mccdeuce said:

Bringing this up again:  should there be a baffle or seal that should close up the massive holes in the alternator intake area?

 

[jetdriven]

It's just a piece of silicone baffle material riveted to the baffle to close up the gaps around it. 

[mccdeuce]

8 hours ago, Yetti said:

OH My yes, yes there should be.  Get creative with baffle material or the thick felt and some safety wire.   Mine has a plastic cover that rotates with the shaft that goes between the pulley and the shaft

Do you have a picture of your setup? I should close the gap around the tensioner or around all the alternator?

[carusoam]

1) I see the variation of different generators might cause some difference in seal design.

2) The important air flow is directed at the coils of the electric generation.

3) Andy is showing a fan on the front of his alternator.

4) Mcc has no integral fan on his.

5) the M20C used a hose to bring air from the front of the cowl to cool inside the generator.

6) make sure the air to cool the alternator is allowed to enter and exit the device.

7) It looks like additional cooling of the alternator is possible, but at the cost of messing with the airflow for the engine.

8) There also seems to be some oddity of alternator mounts...  somebody has thrown Mcc a challenge.  The belt adjustment/mount seems to have eliminated the seal...

9) the manufacturer of the alternator probably has a more appropriate mounting kit to go with the STC for the device that will better match the airframe needs...?

10) GB is giving some helpful guidance as it is a business for him...

PP thoughts only, not a mechanic.

Best regards,

-a-

Edited May 25, 2017 by carusoam

[fellis]

On 5/1/2016 at 9:12 AM, INA201 said:

#4 is the hottest and goes into the 410-415 range during warm day climbs while oil temp will eat up about 65-70% of the green scale under similar conditions.  All temps settle down under cruise.  Does the gasket fix the gap in this photo or is it the other black one pictured? Thanks guys for the help.  

Been chasing the problem of #4 running hot for over a year now. Changed silicone on cowling, plugged up every small hole with RTV, checked and inspected baffling with top cowl on for any gaps or leaks, all with no results in reducing high temp. Did some more research and examined and took a close look at the sheet metal shroud on the back of the #4 cylinder that partially covers the back part of this cylinder and appears to act like a funnel for the incoming air being diverted to the oil cooler. Bent this up about an inch went for a short light and temperatures dropped to where variation is less than 20 degrees between ALL cylinders. Running in the 370's now on number 4 where temps would routinely be in the 380s and 390's. Saw no change in oil temps from previous. 

 

[carusoam]

I just realized @INA201‘s oil cooler had some scars on it... something to look into if it is news to him too?

It looks like scars caused by rubbing while vibrating... OK if they don’t cause an oil leak.

Best regards,

-a-

[PT20J]

I replaced my M20J engine with a factory rebuilt IO-360-A3B6 last October. I reused the baffles (they were in good shape) but replaced the baffle seals with GeeBee seals that fit great. At 75% cruise I generally see CHTs about 1- 360F, 2-380F, 3-360F, 4-375F. (These are at peak EGT; CHTs are a little cooler LOP with less spread). Though these are in a good range and the spread isn't bad, I found it interesting that the hottest cylinders are on the left side. Perhaps the air filter and oil cooler which are on that side may be robbing some air from the cylinders. I also noticed the big hole in the baffle in front of the alternator and covered it with aluminum tape as an experiment. That made absolutely no difference in CHTs, so I removed the tape figuring Mooney must have had a reason for putting a big hole in the baffle in front of the alternator.

At MooneyMAX Bob Kromer recommended rigging cowl flaps open about 1 inch. He said it cruises a couple of knots faster. I tried it and it lowers CHTs but I didn't notice any speed increase (or decrease). So, if your CHTs are a bit high, this might be the easiest fix.

Skip

[ArtVandelay]

I replaced my M20J engine with a factory rebuilt IO-360-A3B6 last October. I reused the baffles (they were in good shape) but replaced the baffle seals with GeeBee seals that fit great. At 75% cruise I generally see CHTs about 1- 360F, 2-380F, 3-360F, 4-375F. (These are at peak EGT; CHTs are a little cooler LOP with less spread). Though these are in a good range and the spread isn't bad, I found it interesting that the hottest cylinders are on the left side. Perhaps the air filter and oil cooler which are on that side may be robbing some air from the cylinders. I also noticed the big hole in the baffle in front of the alternator and covered it with aluminum tape as an experiment. That made absolutely no difference in CHTs, so I removed the tape figuring Mooney must have had a reason for putting a big hole in the baffle in front of the alternator.
At MooneyMAX Bob Kromer recommended rigging cowl flaps open about 1 inch. He said it cruises a couple of knots faster. I tried it and it lowers CHTs but I didn't notice any speed increase (or decrease). So, if your CHTs are a bit high, this might be the easiest fix.
Skip

Was the big hole for the ram air that was removed?
My cht2 is about 35° lower than the rest.
My left cowl flap is from a Mooney with dual,exhausts, so even close, the left cowl flap has a opening for air to flow out.


Tom

[PT20J]

2 minutes ago, ArtVandelay said:

Was the big hole for the ram air that was removed?
My cht2 is about 35° lower than the rest.
My left cowl flap is from a Mooney with dual,exhausts, so even close, the left cowl flap has a opening for air to flow out.


Tom

Ram air was in the center below the spinner.

From various postings, there seems to be a lot of CHT variations in Js. 

The left cowl flap on the early Js had the big opening similar to the right (exhaust side) cowl flap. At S/N 24-1616 it was changed to the flush fit design.

Skip

[jetdriven]

It’s the reverse. The older planes have the flat cowl flap. Later models (205?) had the bump cowl flap. 
 

seal that big gap in the center under the spinner. Air escapes there too

we took the air ramp off the #4 cylinder completely. #4 is cooler and oil temp is unchanged. 

[INA201]

1 hour ago, jetdriven said:

It’s the reverse. The older planes have the flat cowl flap. Later models (205?) had the bump cowl flap. 
 

seal that big gap in the center under the spinner. Air escapes there too

we took the air ramp off the #4 cylinder completely. #4 is cooler and oil temp is unchanged. 

I agree with the ramp removal as an option. My theory is that the air hitting the cowl openings really just adds pressure to the upper part of the engine compartment. That higher air pressure forces air through any opening there is. The ramp really only blocks air from the backside of number 4 more than it pushes air up into the oil cooler. Blocking air from leaking out anywhere is the key imop.

[PT20J]

2 hours ago, jetdriven said:

It’s the reverse. The older planes have the flat cowl flap. Later models (205?) had the bump cowl flap. 

You're right -- I got it backwards (funny, since I've owned one of each!)

I've thought about removing the ramp on #4. Still can't figure out why my #2 is the hottest though - everything looks right.

Skip

[Guest]

25 minutes ago, PT20J said:

You're right -- I got it backwards (funny, since I've owned one of each!)

I've thought about removing the ramp on #4. Still can't figure out why my #2 is the hottest though - everything looks right.

Skip

In Kent Paser’s book Speed with Economy” he suggested altering the inter cylinder baffle by trimming to increase the airflow around the cylinder.

Clarence

[INA201]

Here is a link.

http://www.eaa393.org/Presentations/ScotS_rev_SwEconomyKentPaser2006.pdf

[jetdriven]

1 hour ago, INA201 said:

I agree with the ramp removal as an option. My theory is that the air hitting the cowl openings really just adds pressure to the upper part of the engine compartment. That higher air pressure forces air through any opening there is. The ramp really only blocks air from the backside of number 4 more than it pushes air up into the oil cooler. Blocking air from leaking out anywhere is the key imop.

I agree 100%