Thoughts on the Oil Cooler

[INA201]

Good afternoon.  The oil cooler on my 78 201 hasn't been rebuilt in at least 25 years. Has anyone had their old oil cooler rebuilt and noticed improved CHTs, oil Temps, and maybe oil pressure.  I also have a small gap in the pic below.  Should there be a gasket or something to fill that space? My mechanic didn't think I should rebuild it but I wanted to see what you guys thought.  Thank you for your responses in advance.  

[N201MKTurbo]

If it ain't broke, don't fix it

[Bob_Belville]

I've been chasing high oil temp for 4 years. One step was to send the cooler and Vernatherm valve to Pacific. Can't say that it made any difference. I have and I would recommend you seal any gaps around the cooler with high temp RTV.

[Mooneymite]

I had my oil cooler re-done when I replaced my engine.  A lot of vanes were straightened out, all the bugs were gone, both the new and the old engine seemed to run at exactly the same oil temps, despite the refurbished oil cooler.

[Jim F]

I know this sounds anal but I treat the air that cools our air cooled engine like the water in a water cooled engine. Any leak is a loss. A small leak of air is just a small leak but a lot of small leaks is a large leak. Seal the area so all the air goes through the oil cooler.

jim

[INA201]

Thanks for the responses.  I ordered some black high temp 3M RTV and going to seal everything I can.  I may send off the cooler one day but I'm not too concerned at this point.  If folks were seeing a big difference it might have been worth cleaning it up.  Doing some spring cleaning, every bit helps.

[jetdriven]

There is a silicone rubber gasket that fastens to the baffle that the oil cooler rides against.  Also, if you're dealing with a warm #4 cylinder, you can remove the ramp baffle that obscures a large part of the cylinder.  The J oil cooler is very large for that size engine and I have never seen higher than mid scale oil temps. 

[M20F]

20 hours ago, N201MKTurbo said:

If it ain't broke, don't fix it

This +1.  As a group pilots waste a lot of money fixing things that ain't broke and often the fixing leads to breaking.  If temps are where they should be and everything is wonderful, enjoy!

[INA201]

53 minutes ago, jetdriven said:

There is a silicone rubber gasket that fastens to the baffle that the oil cooler rides against.  Also, if you're dealing with a warm #4 cylinder, you can remove the ramp baffle that obscures a large part of the cylinder.  The J oil cooler is very large for that size engine and I have never seen higher than mid scale oil temps. 

#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.  

[PaulB]

There is a silicone rubber gasket that fastens to the baffle that the oil cooler rides against.  Also, if you're dealing with a warm #4 cylinder, you can remove the ramp baffle that obscures a large part of the cylinder.  The J oil cooler is very large for that size engine and I have never seen higher than mid scale oil temps. 

Do you have a picture of this? Keeping #4 cool on warm days has often required cowl flaps in trail despite sealing all the holes and fixing all gaps in the baffling with RTV.

[jetdriven]

18 minutes ago, 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.  

There is a silicone rubber gasket that fastens to the baffle that the oil cooler rides against.  Also, if you're dealing with a warm #4 cylinder, you can remove the ramp baffle that obscures a large part of the cylinder.  The J oil cooler is very large for that size engine and I have never seen higher than mid scale oil temps. 

 

You have the gasket. Sealing that tiny gap next to the oil cooler isn't your problem, I don't think.  But take a look at the main engine baffle on the top of the rear baffle.  It's shot. I bet you have a lot of air leaks with those old baffles.  I'd change them out.  It's like 100$ and a few hours, but it made a big difference for me. 

[Bartman]

Your engine baffles are as bad or worse than mine before I had them changed. I used the Gee Bee precut baffle seal kits and matching valve cover gaskets in Blue.  Hot weather is not here yet, but so far both my CHTs and oil temps are significantly improved in climb and cruise.

We used some RTV on the gaps around the oil cooler, but not as big as those in your photo.

[INA201]

These are old pictures.  Based on input and great advice from you guys on Mooneyspace I did the baffles a couple of months after getting the plane. while we are at it what do you guys think about the hole around the alternator? It looks like a pretty big chunk of airflow getting through down there.  

[ArtVandelay]

1 hour ago, INA201 said:

These are old pictures.  Based on input and great advice from you guys on Mooneyspace I did the baffles a couple of months after getting the plane. while we are at it what do you guys think about the hole around the alternator? It looks like a pretty big chunk of airflow getting through down there.  

I think the air flow thru that hole is outward, towards the front when cowls are closed. I say this because Ive found oil in the front lower part of the engine, dripping off the fuel injector servo after an oil change where the oil was spilled from the filter removal.

[Guest]

1 hour ago, INA201 said:

These are old pictures.  Based on input and great advice from you guys on Mooneyspace I did the baffles a couple of months after getting the plane. while we are at it what do you guys think about the hole around the alternator? It looks like a pretty big chunk of airflow getting through down there.  

Ideally sealing the baffle around the alternator is the right thing to do.  The best cooling and speed comes from the best pressure differential between the top of the engine above the cylinders and the pressure below the cylinders.

Also the alternator does not normally have a cooling fan.

Clarence

[INA201]

Does anyone have a picture of how the alternator should look and fit in?  The black one inch hole to the left of the alternator is tied in to a tube that runs to the back of the alternator to cool it I'm thinking.  It does seem like the fan on the front of the alternator could pull air to the lower part of the cowl and mess up the pressure differential too.  Has anyone else seen this type of set up? 

Thanks,

Scott

[Browncbr1]

That hole with 1" scat tubing was there to cool the generator.   Your alternator probably doesn't need it unless there is an air inlet flange on the alternator.    Consult with your mechanic though.  

Edited May 1, 2016 by Browncbr1

[mooniac15u]

1 minute ago, Browncbr1 said:

That hole with 1" scat tubing was there to cool the generator.   Your alternator probably doesn't need it unless there is an air inlet flange on the alternator.    Consult with your mechanic though.  

Did any M20Js have generators?

[Guest]

57 minutes ago, Browncbr1 said:

That hole with 1" scat tubing was there to cool the generator.   Your alternator probably doesn't need it unless there is an air inlet flange on the alternator.    Consult with your mechanic though.  

I would guess that at some point the alternator was replaced.  The replacement came with a cooling fan and a cooling blast tube on the back.  The installer then added a small flange and a piece of Scat duct to cool the new alternator.

Clarence

[N601RX]

One thing that hasn't been mentioned is that part of the overhaul will be a hydrostatic pressure test to insure the integrity of the tubes. 

[mccdeuce]

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

[carusoam]

In a similar situation, the M20C used chunks of felt to block airflow around the starter and generator...

i don't see any rivet holes where something may have been attached.

Airflow should be going in over the top, then going down through the cooling fins, before exiting out the bottom of the cowling.

We have a silicone seal and baffling expert on board MS here who sells kits for baffling improvements...

Best regards,

-a-

[Yetti]

9 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?

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

[Yetti]

What's weird is your bolt and tension bracket are on the wrong side.  Mine are tightened from inside the cowl

[EricJ]

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