Engine alignment with new engine mount

[ShawnR]

Hello all

I noticed a while back that my engine is offset slightly to the left, relative to the cowl. This dynafocal mount is not the original mount. It was replaced a few years ago following a mishap. I am wondering if anyone has removed their engine and mount, replaced the mount and then found a discrepancy with cowling/spinner alignment. I had noticed earlier this year that the innermost nutplate was very close to the ring gear whereas on the right side, there was good clearance, so, I do believe the engine is to the left slightly. The builder is no longer with us so I cannot ask him about the original installation. I consulted with Van's and they felt that, after confirming that all engine mounts and washers are in place correctly, shimming under the mount at the firewall would be acceptable. I was wondering if anyone else has had to deal with a similar issue? I know there can be some variation between mounts, but it seems odd that it can be that much.....

Any suggestions/input?

Having a whopping 6 hours and 32 landings in my first flying RV, I am loving it.

 

[Avanza]

I know there can be some variation between mounts, but it seems odd that it can be that much.....

How much ?
If the previous engine mount was damaged and could not be repaired it´s possible that the firewall took some of the impact.
This would not be the end of the world but I would inspect the firewall very closely.
It´s important to understand where you have the variation, the firewall or the engine mount.
I would liked to have a second opinion from someone that has built the same type of plane.

Good luck

 

[docjjrmd]

If memory serves the original as built per plans has the engine cocked to the right. Could the replacement have been set up straight ? i.e. A & P not familiar with RV "fixed" the crooked engine? I concur look closely at firewall, though to get that much off set I 'd expect to see some other deformation elsewhere if the firewall was bent. Need a 9A builder to pitch in here!

 

[David Lowe]

I would check that the rubber "lord" mounts are:
1. correct for the mount,
2. in the right locations and
3. in good condition.
4. Correctly located in the mount and the engine lugs.

 

[ShawnR]

Thanks. I will take a better look at the engine mounts. I did verify they are installed correctly, but perhaps a better look is warranted.

 

[jrs14855]

You can fabricate some custom washers out of flat steel. 3/32 thick is definitely acceptable maybe a bit more. Loosen all bolts at the rubber mounts. Remove one bolt at a time on the left side and put a washer between the rubber bushing and the mount. Replace the bolt but leave it loose. Remove the other left side bolt and repeat. Making the holes in the shim washers slightly oversize will make re installing the bolts easier. I have two "bullets" , tapered bolts with the head cut off. One is long with a t handle welded to it. The other is only about an inch long and can be pushed thru the assembly all the way to the front.

 

[ShawnR]

You can fabricate some custom washers out of flat steel. 3/32 thick is definitely acceptable maybe a bit more. Loosen all bolts at the rubber mounts. Remove one bolt at a time on the left side and put a washer between the rubber bushing and the mount. Replace the bolt but leave it loose. Remove the other left side bolt and repeat. Making the holes in the shim washers slightly oversize will make re installing the bolts easier. I have two "bullets" , tapered bolts with the head cut off. One is long with a t handle welded to it. The other is only about an inch long and can be pushed thru the assembly all the way to the front.

Interesting. I was assuming I should shim the mount at the firewall but you are suggesting the washers on the engine mounts. That makes sense since there is already a washer there. I have spare washers from the 4 project so easy to do too. Might need longer bolts. Mmmmmm...

 

[Carl Froehlich]

Interesting. I was assuming I should shim the mount at the firewall but you are suggesting the washers on the engine mounts. That makes sense since there is already a washer there. I have spare washers from the 4 project so easy to do too. Might need longer bolts. Mmmmmm...

Adding a big washer between the engine and lower engine mounts is a standard fix for “sagging” engines. Based on your photo a single 1/16” fender washer between the engine and lower left engine mount might do the trick.

Keep in mind you may need to get a 1/8” longer engine mount bolt and put another standard washer under the bolt head to make up the difference.

Carl

 

[jrs14855]

Because of the geometry the washer at the mount rubber bushing will move the engine to the side more than the same washer at the firewall. The washer at the rubber mount needs to be the same diameter as the rubber mount so will need to be custom made. At the firewall a large diameter AN washer is ok but you will probably need two washers at the firewall to more the engine the same amount as one at the mount rubber.

 

[rvbuilder2002]

Thanks. I will take a better look at the engine mounts. I did verify they are installed correctly, but perhaps a better look is warranted.

There are spacer washers (approx 1/8" thick) that are specified to be installed on the 2 lower isolator locations between the engine case and the isolators. Make sure those are installed.

If everything does check out to be correct, adding U shaped shims between the isolators and the engine case is an acceptable way to solve the mis-alignment.
I would recommend starting with an .063 spacer on the lower left and and .032 on the upper left and lower right.

 

[ShawnR]

There are spacer washers (approx 1/8" thick) that are specified to be installed on the 2 lower isolator locations between the engine case and the isolators. Make sure those are installed.

If everything does check out to be correct, adding U shaped shims between the isolators and the engine case is an acceptable way to solve the mis-alignment.
I would recommend starting with an .063 spacer on the lower left and and .032 on the upper left and lower right.

Yes, the 2 center lower washers are in place. Thanks