Engine driven fuel pump cooling shroud... necessary? Original?

[Raymond J1]

The plan for the canvas, with the original dimensions

Silicon canvas for fuel pump cover.pdf

And the new silicone canvas rebuilt for my engine.

Edited April 16, 2022 by Raymond J
Amendement

[Raymond J1]

Presentation of the canvas, control and minor changes :

Previously, I put photos and a plan of the parts of this gas pump cooling cover such as according to the origin. The disappearance of this hood on most engines has a reason, which I will expose.
For me, this part is a safety element, especially for airplanes that operate under warm saisons, it has a real reason to be on the mechanical pump but it is necessary to make modifications, minor and major, so that the reason for removing it is not dominant. Mooney never came back to this part that is not listed in the spare parts manual...

Minor change #1, the diameter of the passage for the air inlet duct sleeve. Originally, it is 1" 1/4 in diameter, but the brazing cord does not allow the canvas to be glued properly. To allow a good bonding and also guarantee a better connection length of the scat air duct, it is preferable to make a passage hole whose diameter is 1"1/2. Thus, the weld seam is avoided.

Pict 1 : new silicon canvas with 1"1/2 , Pict 2 : Old canvas and the 1"1/4 passage. Note the lack of glue and the deformation of the canvas near the hole, due to the brazing cord of the sleeve

 

 

Minor change #2, Metal-metal contact reserve due to vibration: In the canvas there is a passage hole for the fuel pump drain. Before gluing, it is necessary to increase the distance between the diameter of the hole in the canvas and the edge of the metal frame of the hood. The minimum dimension of this distance is 1/4", this corresponds to the black felt trace visible in the photo. A cutout along the radius is ideal.

 

Edited April 16, 2022 by Raymond J

[outermarker]

Thank you so much Raymond. I will be making the part very soon and your insight is much appreciated!

[carusoam]

Fantastic details JR!

Thanks for sharing them all!

Best regards,

-a-

[Raymond J1]

Thank you, but it's not over, we have to explain now why this part disappeared from the engines and what is necessary to do to be able to use it. On the contrary, the conditions for the original part to still be usable.

[outermarker]

I'm surprised that the shroud was glued to the aluminum. Mine was not and I thought mine was still original. If it is glued, was high temperature silicone used as bonding agent?

[Raymond J1]

On 4/22/2022 at 9:31 PM, outermarker said:

I'm surprised that the shroud was glued to the aluminum. Mine was not and I thought mine was still original. If it is glued, was high temperature silicone used as bonding agent?

For the original canvas, the gluing is carried out with neoprene glue ("contact" glue among the Anglo-Saxons), which holds the temperature once polymerized (up to 130 ° C (260 °F) without problems). For the silicone canvas, I use a silicone glue for gluing joints (silicone) on the glass doors of ovens, this glue is resistant to 350 ° C (660 ° F).

[outermarker]

Hi Raymond,

Why did you make a cutout instead of a slit like the other fuel lines? When I removed the shroud, I saw evidence that the shroud frame had been wearing into the fuel pump housing.  Did you build up that area with high temperature RTV? Did you secure the shroud so that it won't settle on top of the fuel pump with time and age? Oh yeah, the drawings are GREAT! 

I am going to try High Temperature Silicon rubber (1/8"). I'll do a final fit this weekend. The rivet size is 3/32" or 2mm. After the final fit I'll seal up the cuts that were made to fit over the hoses with high temp rtv.

albert

Edited April 29, 2022 by outermarker
added text and photos

[powder_hounder]

While the weather in Chicago is garbage for flying for what seems has been going on 3 weeks now, I decided to un-cowl my plane to change the oil and inspect things.  It's hard for me to believe, but I've owned my Mooney for 21 years now and I've never pulled the fuel pump cooling shroud off for inspection.  I removed it and brought it home with me to see if I can recondition it.  The textured fiberglass/silicone baffling has seen better days and looks similar to the photos posted by others, maybe worse.  It looks like over the years someone has cut a large section of the baffling out to make it easier for installation and removal which has caused the whole thing to rattle around and make wear marks in fittings.

Since my baffling is so mutilated it's not very useful for using as a template for making a new baffling.  By chance @Raymond J1 and @outermarker did you keep your paper template for when you created your replacement baffling?  If yes, would you be willing to share it with me?

 

[Raymond J1]

On 4/26/2022 at 9:23 PM, outermarker said:

Hi Raymond,

Why did you make a cutout instead of a slit like the other fuel lines? When I removed the shroud, I saw evidence that the shroud frame had been wearing into the fuel pump housing.  Did you build up that area with high temperature RTV? Did you secure the shroud so that it won't settle on top of the fuel pump with time and age? Oh yeah, the drawings are GREAT! 

I am going to try High Temperature Silicon rubber (1/8"). I'll do a final fit this weekend. The rivet size is 3/32" or 2mm. After the final fit I'll seal up the cuts that were made to fit over the hoses with high temp rtv.

albert

The cutout for the side of the aluminum boss of the membrane drain. The gummed canvas should not rub with the aluminum.
The slots are located on the steel fittings sides, for dismantling the hood every 100 hours without having to touch the fittings... On steel, the canvas can rub.

It is the gummed plate resting on the steel fittings that holds the metal frame at a good distance from the top of the pump. When this canvas sags, there is wear by friction as we have noticed...
If the oil filtration screen has remained the original one.

If your engine has been modified and it is equipped with a cartridge filter base with vernatherm incorporated, there is another problem... The hexagonal head of the vernatherm pushes on the pump cover, which causes even more failures.

If you are a real American, the rivet size is necessarily 3/32"...
If you are a bad American anxious to become a good Frenchman, you must use a 2 mm rivet.

Do not forget to slip a washer under the head of each rivet...

 

Edited January 18, 2023 by Raymond J1

[Raymond J1]

On 1/17/2023 at 3:34 PM, powder_hounder said:

While the weather in Chicago is garbage for flying for what seems has been going on 3 weeks now, I decided to un-cowl my plane to change the oil and inspect things.  It's hard for me to believe, but I've owned my Mooney for 21 years now and I've never pulled the fuel pump cooling shroud off for inspection.  I removed it and brought it home with me to see if I can recondition it.  The textured fiberglass/silicone baffling has seen better days and looks similar to the photos posted by others, maybe worse.  It looks like over the years someone has cut a large section of the baffling out to make it easier for installation and removal which has caused the whole thing to rattle around and make wear marks in fittings.

Since my baffling is so mutilated it's not very useful for using as a template for making a new baffling.  By chance @Raymond J1 and @outermarker did you keep your paper template for when you created your replacement baffling?  If yes, would you be willing to share it with me?

 

At the top of the page, you can download the plan for cutting according to the original size.

This is the canvas that is suitable if your IO 360 A1A has the original oil filter.

If the oil filter has been replaced by a cartridge filter base with vernatherm, it is necessary to cut the gummed canvas in a slightly different way and make some small adjustments on the frame.

Those details coming soon... See you soon.

[philiplane]

On 1/17/2023 at 9:34 AM, powder_hounder said:

While the weather in Chicago is garbage for flying for what seems has been going on 3 weeks now, I decided to un-cowl my plane to change the oil and inspect things.  It's hard for me to believe, but I've owned my Mooney for 21 years now and I've never pulled the fuel pump cooling shroud off for inspection. 

 

 

You should replace the pump if it's that old. The diaphragms get brittle with age and fail at the worst moment. There are two diaphragms, the upper keeps the engine oil off the lower one. When the upper fails, you will see oil dripping from the drain hose. Not long after that, the fuel diaphragm will fail, and if it does, fuel can go overboard, or into the engine.

[Mooney-Shiner]

On 1/18/2023 at 5:06 PM, philiplane said:

You should replace the pump if it's that old. The diaphragms get brittle with age and fail at the worst moment. There are two diaphragms, the upper keeps the engine oil off the lower one. When the upper fails, you will see oil dripping from the drain hose. Not long after that, the fuel diaphragm will fail, and if it does, fuel can go overboard, or into the engine.

This is a good point.  Its my first time seeing any notes on the when to replace/repair the mech-pump. I will have a closer look at the drain hole next time to see if I'm getting oil there.

[gmonnig]

My 65' E does not have a shroud around the fuel pump. Just a blast tube. My engine was new in 2019 and wondered if that blast tube was even required. I don't remember having a blast tube or shroud on my 540 plane either but that was carbureted and less PSI.

[powder_hounder]

On 1/18/2023 at 4:06 PM, philiplane said:

You should replace the pump if it's that old. The diaphragms get brittle with age and fail at the worst moment. There are two diaphragms, the upper keeps the engine oil off the lower one. When the upper fails, you will see oil dripping from the drain hose. Not long after that, the fuel diaphragm will fail, and if it does, fuel can go overboard, or into the engine.

@philiplane good point.  Without pouring through the logbooks I don't know when the fuel pump was replaced last.  I'm guessing at last overhaul.  My engine is approaching TBO (offhand think it has 1800hrs), but it may take me another 4-5 of flying before I reach TBO.  You think it's worth replacing it at this point, or wait for overhaul?

 

[powder_hounder]

On 1/22/2023 at 10:05 AM, gmonnig said:

My 65' E does not have a shroud around the fuel pump. Just a blast tube. My engine was new in 2019 and wondered if that blast tube was even required. I don't remember having a blast tube or shroud on my 540 plane either but that was carbureted and less PSI.

I was kind of thinking it wasn't necessary, just like it was thought the engine needed the huge air intake at the nose.  But it was easy enough to replace the baffling and re-install the thing, so I put it back in.