DIY: 2013 3.8 OEM Poly Engine/Motor Mounts - Hyundai Genesis Forum
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post #1 of 5 Old 10-29-2017 Thread Starter
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DIY: 2013 3.8 OEM Poly Engine/Motor Mounts

I want to start off by first saying that I have not installed these yet but I am putting this up as a place-marker for myself so that I will actually make this DIY (and will update it accordingly as long as everything goes well) as well as the following disclaimer.

Disclaimer: I'm not responsible for any damage you may cause to your vehicle or any injury to your person from attempting this modification as it is only a guideline to DIY. All info shared in this DIY is to the best of my knowledge and I encourage and appreciate any corrections.

Now with that being said, since nobody makes engine mounts specifically for the 2013+ 3.8 (and I don't want to drill holes in my subframe) I decided to fill the top portion of the OEM mounts with polyurethane. My whole desire to do this was that I had previously installed the Megan Transmission mount and noticed improved shifting but even more influential was the "Engine Leash" I had installed. The engine leash drastically improved shifting feel of the car, after these findings my next logical step was engine mounts.

Instead of pulling the old engine mounts off of the car and having a lot of downtime, I decided to purchase brand new mounts. I was quoted from my local Hyundai dealership $225 USD per mount. I decided that was far too much and then sourced them elsewhere. As far as I know the part number for the two mounts is 21812 3N000 with the same mount being used on the passenger and drivers side of the car.

Once you have sourced your engine mounts you will need Polyurethane, I chose 60A Durometer and got it from McMaster Carr, it is part number 8644K24 and can be found under casting compounds . I chose 60A from the recommendation of a few other forum members as a good balance between performance as well as minimal increase in NVH.

When you get your engine mounts they will look like this

To fill the mount you need to remove the top dust cover to expose the holes in the mount, it will then look like this (mount has already been filled)

The dust cover is just glued on around the top and can be removed by carefully taking an razor blade around the area where it is glued and pulling it off. Once that is done I washed the mounts down with soapy water to try and remove any old release compounds left on the OEM rubber mount so that the polyurethane would properly adhere. You could also scuff up any areas where the polyurethane is going with sandpaper to further promote adhesion. Once it is all cleaned up you need to tape off the three slotted holes in the mount so that poly does not leak out. For this I used black electrical tape and it worked fantastic, the poly did not stick to the tape and the tape did not leak at all.

Now time to mix the polyurethane, for this particular polyurethane the ratio was 10 parts liquid base to 1 part activator, if using another product see product description for use. It is critical that you get the ratio correct or otherwise your polyurethane may not harden correctly. To do this I used a cheap digital scale off of amazon, I think it was like $9 but it worked very well for this. I made the polyurethane in ~100g batches, so I weighed out 100g of base and then added 10g of activator. From this time you have roughly 15 minutes of working time before the product becomes too thick. When filling the mount make sure that the mount is level, I happened to have some plastic cups that the mounts fit perfectly in (roughly 3 3/8" diameter). Being in a cup also made it easy to turn the mount with one hand while filling with the other so that I could ensure I would fill evenly with minimal air pockets trapped. To fill both mounts it took a little under 300g of polyurethane. This polyurethane says it requires roughly 7 days to fully cure, additional specs are shown below.

Next its time for install....I will update when that happens, hopefully it will be this coming weekend of 11/4
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Last edited by Hoovie59; 10-29-2017 at 04:33 PM. Reason: Resized Photos
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post #2 of 5 Old 11-04-2017 Thread Starter
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Ok so finally got them installed. Overall took about 5 hours with 2 people but to be fair I had recently hurt my back and was slow to get around under the car, plus I didn't really know how the mounts were supposed to be removed so we spent a decent amount of time figuring out what needed to be removed. Also I want to note that the way I did this may not be the best or most effective way but it worked for me, again do at your own risk.

First I would start by removing the intake, I had an R2C intake and for me it got in the way when I started jacking up the motor.

Once you have the intake off we can remove the top nuts on the motor mounts, for this I had bought some tools to help me reach them, without these tools you may need to remove the heat shields on the headers to reach these nuts. Below I have shown what I used to remove them. Instead of the ratchet I had to use a breaker bar to break them loose. But in all the whole setup consisted of a 1/2 breaker bar, 14" extension, 1/2" to 3/8" adapter, 3/8" universal joint, and a 17mm torque wrench adapter. The torque wrench adapter is something I've never heard of but it greatly aided me in reaching the nuts under the headers.

Once those are off you need to get under the car and loosen the bottom nuts on the mounts. Do do this I had to loosen the power steering rack. What I found that worked good is since the drivers side has longer bolts than the passenger side, fully take out one of the drivers side bolts and swap it out with one of the passenger side bolts. This way you can lower the rack down farther without it hanging by the hoses. I had mine hanging on the last couple threads on the two long bolts from the drivers side, this was enough clearance for me to get my electric impact in using a 19mm socket on a universal joint and then a 6" extension.

Once you get those off you need to jack up the engine. Be very careful jacking up the engine, I jacked mine up by the bell housing with a piece of wood between the jack and the bell housing. You can only jack the engine up so far before the top of the transmission hits the tunnel. Once you have the engine jacked up as far as it will go you can start removing the motor mounts. I started with the passenger side since it is much easier to remove. If you can't seem to get enough clearance to remove the mount studs from the holes you may need to lower the subframe slightly, I had no real problems on this side with that. Once you get it free in the engine bay it needs to go out the bottom near the exhaust. Go back under the car and remove the bracket that spans between the headers and the engine block. Once you do that you can pull the mount out through that hole and put in the new one. (shown below where you can see the blue shirt of my helper under the car)

Now for the passenger side mount...this one is a bit more difficult. Just to remove the studs for the mounting spots on the engine I had to lower subframe slightly to have enough clearance. To do this locate the four subframe bolts and slowly unscrew them so that the whole subframe lowers down without binding. Be very careful to not undo the bolts completely or the whole subframe may fall. Once you get the mount loose in the engine bay it has to come down by the exhaust similar to the passenger side. To make it fit however you have to disconnect the steering column shaft from the steering rack. Push back the rubber cover and undo the one bolt clamping the shafts together. I then had to use a small pry bar to lift up on the upper portion to pull the splined shafts apart. Be careful not to spin the shafts or turn the wheels/steering wheel once the shafts are separated, I did and I need to go fix it because my steering wheel is no longer straight. After that you need to disconnect the sway bar mounting bolts by undoing the 4 bolts on the bottom and swinging it out of the way. Note: you may need to further lower the subframe to get the mount out.

Once you get that out put the new one back in the same way. Reverse installation making sure not to bolt up the power steering before tightening the lower mount bolts and also make sure when tightening the subframe bolts that the motor mount studs line up with the holes and that the small pins on the mounts are in the holes in the subframe.

Overall the mounts make the car feel much more solid. Different noises and play I previously felt in the drivetrain that I had blamed the DMF for are gone. Downshifts feel much better and the engine overall feels much more responsive. 2nd gear is still a little harder to get into than the rest of the gears but shifting as a whole feels more planted. Overall there doesn't seem to be much added noise, maybe a hint more vibration felt in the seat and the steering wheel but it's not a bad vibration, it feels well dampened. I also have a transmission mount, engine leash, all the shifter linkage bushings from ATQ and a cnt v3 cat back and test pipes so the noise my be more noticeable on a stock/quieter vehicle. Overall I would recommend these, and while I cant say definitively, I would almost recommend filling them with 80a poly if you want even that much more performance since these 60a filled hardly changed the NVH at all.
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post #3 of 5 Old 11-15-2017
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Cool write up

A must do for anyone boosting their 3.8.

I went with 75A-80A durometer Urethane from Aero Marine. I'm adding 150 whp, and want her in there solid.

Aero Marine is black and is 1:1 mixing. Very simple.

Here we go again !
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post #4 of 5 Old 11-15-2017
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Man, That rust on your old mount is UNREAL! Sometimes I'm glad I live in CA. When mine came off they looked factory new with just a wipedown. Anyway, thanks for the time and effort of the DIY. Looks like you're doing god's work out there

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post #5 of 5 Old 11-23-2017 Thread Starter
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Originally Posted by Odelagt View Post
Man, That rust on your old mount is UNREAL! Sometimes I'm glad I live in CA. When mine came off they looked factory new with just a wipedown. Anyway, thanks for the time and effort of the DIY. Looks like you're doing god's work out there
I was pretty surprised it had rusted like that. Nothing else in the engine bay has any rust on it. The only thing rusty is the oem exhaust fasteners.

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