IO-360 replacement, what to install off engine before mounting on plane?

[ArtVandelay]

So when I removed the engine the nuts were in the cabin side. It’s been like that for many years with the old engine. Was it installed wrong then?

Hmmm, mine were the opposite as well, having the nuts on the engine side would make them more likely to be inspected. Don’t know if there is any other advantages.


Tom

[Guest]

6 hours ago, jkarch said:

As I recall the nuts were mounted in the cabin and the bolts go through the mount and firewall. That’s how it was installed in 2005. It was hard to thread on the lock washers in the footwell by feel alone. Is it installed backwards?

Normally the upper bolts pass from the cabin to the engine compartment and are secured with steel lock nuts.  If the bolts need to be pulled to correct the installation I would remove the mount and attach it to the engine, then swing the entire assembly into place and bolt it to the firewall.

The IPC says AN363-428 steel lock nuts.

Clarence

[N201MKTurbo]

It is easier to drive the bolts in from the engine to the cabin, but that’s not the right way. If you have new bolts, drive the old bolts in from the engine side and drive them back out with the new bolts. I don’t think there is a requirement to replace the bolts, but why not? They are only a couple of bucks.

[Shadrach]

7 hours ago, jkarch said:

So when I removed the engine the nuts were in the cabin side. It’s been like that for many years with the old engine. Was it installed wrong then?

I think trying to torque fasteners on the cabin side would be an exercise in frustration. There is not a lot of room to manipulate a wrench much less read torque values (they didn’t have snap-on shaker wrenches when these things were built). I don’t think torquing the bolt is an approved methodology but I cud be wrong.  As a side note, if you’re helping your mechanic, it would be a good idea to get a tube of torque seal. I use it when working alone. With two people on a job it leaves no question as to what has been properly tightened.

https://www.amazon.com/Dykem-Tamperproof-Tube-Marker-Orange/dp/B0078RA9FE/ref=pd_lpo_sbs_263_img_1?_encoding=UTF8&psc=1&refRID=Y5D6N3724TXTH446C4R2

[jkarch]

8 hours ago, ArtVandelay said:

I was referring to the engine shock mount bolts, in your picture you have them in place. Editorial comment: I was shocked by the size of the frame mount bolts as compared with the shock mount bolts, they seem grossly undersized in comparison.

 

 

Tom

Scary, isn't it? 2 1/4" bolts plus the ones on the bottom attach the engine mount to the firewall!

[jkarch]

1 hour ago, Shadrach said:

I think trying to torque fasteners on the cabin side would be an exercise in frustration. There is not a lot of room to manipulate a wrench much less read torque values (they didn’t have snap-on shaker wrenches when these things were built). I don’t think torquing the bolt is an approved methodology but I cud be wrong.  As a side note, if you’re helping your mechanic, it would be a good idea to get a tube of torque seal. I use it when working alone. With two people on a job it leaves no question as to what has been properly tightened.

https://www.amazon.com/Dykem-Tamperproof-Tube-Marker-Orange/dp/B0078RA9FE/ref=pd_lpo_sbs_263_img_1?_encoding=UTF8&psc=1&refRID=Y5D6N3724TXTH446C4R2

I ended up holding the wrench in place inside the instrument panel with the nut while my mechanic torqued the bolt instead. I did replace the bolts, but wonder if I should get all new bolts and nuts and try again, i.e. are the bolts like lock nuts, a "one time" install item?

[PT20J]

16 minutes ago, jkarch said:

I ended up holding the wrench in place inside the instrument panel with the nut while my mechanic torqued the bolt instead. I did replace the bolts, but wonder if I should get all new bolts and nuts and try again, i.e. are the bolts like lock nuts, a "one time" install item?

Only a few bolts -- usually in engines -- are one-time use. General purpose hardware can be reused unless it's been over torqued and stretched or otherwise damaged. Lock nuts can be reused unless they run up finger tight. But, hardware is cheap and if you don't know the history of a fastener it's probably best to use new. Years ago during a factory tour someone told me that Al Mooney had calculated that he could use a size smaller on the upper engine mount bolts but thought it didn't look right.

Here's the info on the nuts for for the baffles from the Lycoming IPC. BTW it's best to check all the mounting details with the IPC and Maintenance Manual. Don't just put it back the way you found it without checking because the last person may have done it incorrectly, which is not uncommon on Mooneys I've learned.

Skip

Edited September 21, 2019 by PT20J

[jkarch]

11 minutes ago, PT20J said:

Only a few bolts -- usually in engines -- are one-time use. General purpose hardware can be reused unless it's been over torqued and stretched or otherwise damaged. Lock nuts can be reused unless they run up finger tight. But, hardware is cheap and if you don't know the history of a fastener it's probably best to use new. Years ago during a factory tour someone told me that Al Mooney had calculated that he could use a size smaller on the upper engine mount bolts but thought it didn't look right.

Here's the info on the nuts for for the baffles from the Lycoming IPC. BTW it's best to check all the mounting details with the IPC and Maintenance Manual. Don't just put it back the way you found it without checking because the last person may have done it incorrectly, which is not uncommon on Mooneys I've learned.

Skip

Skip, Thank you for that info. Those bolts and nuts are brand new from LASAR but they’ve been used to hold the mount in place. And the nuts were unscrewed once because my mechanic had to put the LORD mounts in on the bottom. But if they are facing the wrong way I might as well remove them and attach the mount to the new engine.  When reinstalling I assume I align the lower mount and put the bolts in that allow you to pivot the engine right?

[carusoam]

Note on torquing bolt vs. nut...

expect to get different results... probably tiny differences.

Friction between different surfaces can make a difference in the measurement... the aluminum firewall is going to be soft and ‘sticky’ compared to two surface that are intended to slide...

like a nut and a washer

It looks like the same washer is used with the bolt, so similar frictional characteristics may be encountered... if the bolt head is made of the same material and has the same shape as the nut...

Adding to all the friction is the bolt’s stem passing through the hole... adding friction here.

 

so...

torquing a bolt vs. torquing a nut... has the opportunity of not getting it right...

 

This is why we follow the instructions exactly...  

the engine installation instructions were only written one way...

not saying that they could have been done multiple ways, but that would have taken more effort for the people writing the instructions...

And would probably add confusion for the end users...

 

Also... use extra caution on the interior side of the firewall... Mooneys have been known to get insulation and fabrics stuck under fasteners...

Different fasteners are designed for different things... so use extra caution when swapping in new hardware... the bolts going through the firewall are incredibly small in diameter... accidentally getting the wrong bolt type would be surprisingly bad.

PP thoughts only, not a mechanic...

Best regards,

-a-

[jkarch]

8 minutes ago, carusoam said:

Note on torquing bolt vs. nut...

expect to get different results... probably tiny differences.

Friction between different surfaces can make a difference in the measurement... the aluminum firewall is going to be soft and ‘sticky’ compared to two surface that are intended to slide...

like a nut and a washer

It looks like the same washer is used with the bolt, so similar frictional characteristics may be encountered... if the bolt head is made of the same material and has the same shape as the nut...

Adding to all the friction is the bolt’s stem passing through the hole... adding friction here.

 

so...

torquing a bolt vs. torquing a nut... has the opportunity of not getting it right...

 

This is why we follow the instructions exactly...  

the engine installation instructions were only written one way...

not saying that they could have been done multiple ways, but that would have taken more effort for the people writing the instructions...

And would probably add confusion for the end users...

 

Also... use extra caution on the interior side of the firewall... Mooneys have been known to get insulation and fabrics stuck under fasteners...

Different fasteners are designed for different things... so use extra caution when swapping in new hardware... the bolts going through the firewall are incredibly small in diameter... accidentally getting the wrong bolt type would be surprisingly bad.

PP thoughts only, not a mechanic...

Best regards,

-a-

I was thinking the same as you, the nut should have been torqued, not the bolt.  I'm sure the amounts are "within tolerance" but I'll redo it because I want the bolts to stick through the frame as shown in the above drawings.  These bolts came from LASAR a few months ago and they're definitely the correct hardware. Unfortunately it seems the initial mistake was made when the engine was installed by the previous owner's mechanic.  It also seems that mechanic from 2005 dinged the footwells trying to get the engine installed.  So I'll make sure this is done correctly, now that I know.  Plus it will be easier for my mechanic to torque the engine to the mount at such high levels while there's room to do work.  Seems like the best thing is install almost everything that would otherwise be impossible to reach before torquing to the frame (governor, rear baffles, vacuum pump, even possibly oil pressure+ hoses and oil temperature and the 75730 prop control line to replace the one it's coming with).  Noted on the interior of the firewall, yeah I don't want anything but metal to metal contact, no insulation or fabrics, that would ruin my day.  And yeah, I can't believe those two tiny bolts plus the ones installed on the bottom hold the engine to the airplane.  Seems counterintuitive.  Have these bolts ever failed on any airplane and caused the engine and mount to separate from the airframe?

[jkarch]

Even scarier, these bolts are $1.67 each.  I thought these were special material bolts, but they are just AN4-27A standard cadmium plated bolts.

[carusoam]

My M20C broke the welds off the engine mount... disconnecting away from one of the four bolts holding the mount to the firewall...

Doing the math quickly...

That left about $5.01 worth of bolts holding the engine to the fire wall....

And it took a few flights to figure out something was going on...

See if you can find the tensile strength of the bolts...  If you go vertical, Mav... all four bolts are going to hold the MGTW of the plane dangling beneath it.... 

Everything is good, until the tip of a prop blade separates.... a small amount of imbalance turns into thousands of pound of force wobbling around straining those tiny bolts... in a direction that will be more than just tensile...

 

The good news...

i don’t recall any Mooneys that have lost an engine overboard...   

The resulting major change of WnB would be disastrous.

PP thoughts only...

Best regards,

-a-

[Shadrach]

2 hours ago, jkarch said:

I ended up holding the wrench in place inside the instrument panel with the nut while my mechanic torqued the bolt instead. I did replace the bolts, but wonder if I should get all new bolts and nuts and try again, i.e. are the bolts like lock nuts, a "one time" install item?

So two things. Skip is absolutely correct about hardware reusability. However there are certain areas where I think it’s good practice to use new. One of those areas is the engine mount. Using new is the best way to know what you’ve got. All of the corrosion proofing is intact and you know they’ve never been over torqued. 

Secondly, I’ve never seen any guidance regarding the method that you and your mechanic used to torque the bolts. It seems to me that torquing a long bolt that’s running through the mount, the firewall and the boss on the steel cage may not yield the same value as torquing the nut directly.

Maybe it’s fine to do it this way but why do something unconventional on such a critical piece of hardware?

Edited September 21, 2019 by Shadrach

[jkarch]

44 minutes ago, Shadrach said:

So two things. Skip is absolutely correct about hardware reusability. However there are certain areas where I think it’s good practice to use new. One of those areas is the engine mount. Using new is the best way to know what you’ve got. All of the corrosion proofing is intact and you know they’ve never been over torqued. 

Secondly, I’ve never seen any guidance regarding the method that you and your mechanic used to torque the bolts. It seems to me that torquing a long bolt that’s running through the mount, the firewall and the boss on the steel cage may not yield the same value as torquing the nut directly.

Maybe it’s fine to do it this way but why do something unconventional on such a critical piece of hardware?

That’s why I want to repeat it with fresh hardware. I’m going to get new parts and try again, and also torque seal. When I removed the old mounts I was surprised to see the old bolt (of 12 years) had signs of worn threads. Any thoughts on cadmium vs stainless? Spruce has both. Seems Cadmium is standard. The big bolts connecting to the LORD mounts are also brand new, as is the rest of the hardware save for the lower shims.

Edited September 21, 2019 by jkarch

[Shadrach]

19 minutes ago, jkarch said:

That’s why I want to repeat it with fresh hardware. I’m going to get new parts and try again, and also torque seal. When I removed the old mounts I was surprised to see the old bolt (of 12 years) had signs of worn threads. Any thoughts on cadmium vs stainless? Spruce has both. Seems Cadmium is standard. The big bolts connecting to the LORD mounts are also brand new, as is the rest of the hardware save for the lower shims.

The sheer strength of Cad vs Stainless is not the same.  Cad plated steel is much stronger.  I don’t believe you could legally use stainless in that application.

[ArtVandelay]

I remember checking and stainless was much weaker.


Tom

[larrynimmo]

also folks...just for the record the firewall on Mooneys is stainless steel....not aluminum.  The reason has to do with its intended purpose....to serve as a "fire" wall.

aluminum has much too low of a melting point.

[jkarch]

29 minutes ago, Shadrach said:

The sheer strength of Cad vs Stainless is not the same.  Cad plated steel is much stronger.  I don’t believe you could legally use stainless in that application.

Why is stainless so much more expensive than Cad plated? Why would someone use stainless vs cad plated steel? Is it just for corrosion protection properties because it's possible to scratch off the Cad coating?

Edited September 21, 2019 by jkarch

[PT20J]

The reason to torque a bolt is to stretch it a predetermined amount which gives it optimum fastening capacity. The proper way to torque a bolt is to torque the nut if at all possible. Torquing the bolt can result in low torque due to added friction and also wears the cad plating off the shank. Nonetheless, occasionally it’s the only way to do it. For self locking nuts, you are supposed to measure the run up torque and add that to the torque value. 

[Shadrach]

9 minutes ago, jkarch said:

Why is stainless so much more expensive than Cad plated? Why would someone use stainless vs cad plated steel? Is it just for corrosion protection properties because it's possible to scratch off the Cad coating?

Stainless is more corrosion resistant. Non-structural items like panel screws, clamps,  the aforementioned firewall, etc. etc. are not bearing a significant load. Stainless is fine in those applications. What we’re talking about is four bolts that keep your engine affixed to the airframe.They’re kind of important…

[jkarch]

12 minutes ago, Shadrach said:

Stainless is more corrosion resistant. Non-structural items like panel screws, clamps,  the aforementioned firewall, etc. etc. are not bearing a significant load. Stainless is fine in those applications. What we’re talking about is four bolts that keep your engine affixed to the airframe.They’re kind of important…

Exactly my thoughts. I will redo install with fresh never used bolts. The current ones are only 3 months old but already have two torque cycles on them so I might as well just get a new set of cad plated AN parts (bolt,locknut, and washers) and torque it only one time.

Edited September 21, 2019 by jkarch

[jkarch]

17 minutes ago, PT20J said:

The reason to torque a bolt is to stretch it a predetermined amount which gives it optimum fastening capacity. The proper way to torque a bolt is to torque the nut if at all possible. Torquing the bolt can result in low torque due to added friction and also wears the cad plating off the shank. Nonetheless, occasionally it’s the only way to do it. For self locking nuts, you are supposed to measure the run up torque and add that to the torque value. 

Interesting, so if I used my digital torque wrench and my desired final torque is 75 inch pounds, and I measure 3 inch pounds while torquing in steady rotation, I should set my wrench to 78 inch pounds?

Edited September 21, 2019 by jkarch

[jkarch]

Lastly it’s still unclear to me whether or not I would be able to align the mount plus engine combination and press the mount against the firewall where it goes through the holes in the cabin. With the pre J Mooneys it looks like the recommendation is to attach the mount to the engine and reinstall. It seems less clear regarding a J model whether or not to install the engine mount first to the engine before airframe or airframe before engine. Different contributors have said different things! But the manual does seem to insinuate torquing LORD mounts before firewall mounts.

[Guest]

4 hours ago, jkarch said:

Lastly it’s still unclear to me whether or not I would be able to align the mount plus engine combination and press the mount against the firewall where it goes through the holes in the cabin. With the pre J Mooneys it looks like the recommendation is to attach the mount to the engine and reinstall. It seems less clear regarding a J model whether or not to install the engine mount first to the engine before airframe or airframe before engine. Different contributors have said different things! But the manual does seem to insinuate torquing LORD mounts before firewall mounts.

I install all 4 cylinder Lycoming engines in Mooney airframes by attaching the mount to the engine first, then slide the engine and mount into place against the firewall, sliding control cables through the mount as needed. Then install the lower 2 AN 4 crosswise through the aluminum blocks, then push the upper bolts from the cabin torquing all of the nuts.

Clarence

[jkarch]

2 hours ago, M20Doc said:

I install all 4 cylinder Lycoming engines in Mooney airframes by attaching the mount to the engine first, then slide the engine and mount into place against the firewall, sliding control cables through the mount as needed. Then install the lower 2 AN 4 crosswise through the aluminum blocks, then push the upper bolts from the cabin torquing all of the nuts.

Clarence

I'm printing this out and bringing it with me!  Thanks!