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How-to: DIY Urethane-filled right side engine mount

39K views 50 replies 11 participants last post by  amc49 
#1 ·
My passenger motor mount broke. The rubber separated and all the goo is all over my engine bay. Including on my accessory pulleys :(



Tousley has them for $80. There are several cheap brands around $25 but the reviews all say they break within a few months' time. Being that my car has 213,000 miles on it and has officially achieved honest-to-goodness beater/project car status, I needed to fix this as cheaply and reliably as possible. So these options were not going to work.

User mellephants was my inspiration here. He just got done with the same job with the same financial constraint. In fact, somehow all three of our motor mounts have broken at about the same time, despite way different mileage on our cars... Thanks to the internet, we found a couple of options in this area of motormount repair. McMaster sells a few hardnesses of 2-part liquid urethane, the most typical ones being 60A and 80A. Each comes out to about 40 bucks after tax and shipping.

The vibrations in mellephants's car with the 80A is a bit much for me so I wanted to try the 60A. But then I found threads talking about 3M Window Weld, which is 55-60A and supposedly $10. Perfect! But when I went to look for it online, it was $20 or $25 at my local stores. Bummer.

Finally, I found other threads where guys used a Loctite roofing sealant, P/N 1402254. The data sheet on the Loctite website says only 27.5A hardness... but the internet people were saying it is not squishy. And it was $5. So, no brainer!



On with the how-to.

1. Support your engine then remove the bracket and mount from the car (there is another how-to about this, I'm sure) (15mm, deep 18mm sockets). Then remove the mount itself from the bracket (deep 18mm socket).

2. Gently pry off the top plastic piece and cut the rubber seal. If your mount was not broken, there will be a bunch of goo in there you need to get out.



3. Cut and remove one piece at a time the rubber baffle between the two valves. I just slit it once and pulled it out, involuntarily breaking it in pieces as I pulled it through.



Sidebar. This fluid-filled mount works exactly like a shock absorber. The motion of the fluid is controlled by a baffle between two valves. In the upper right of this pic is the orifice that controls "compression" movement of the mount. "rebound" is controlled by the baffle covering the bottom valve.



4. Clean the goo out. A healthy serving of flowing brakleen will help.



5. If your mount was already broken, tape up the edge so the urethane doesnt simply leak out. Take note here of the locating pin on the base of the stud. It is very important to align this properly so it fits back in the bracket. It should be on the opposite side as the motor.



6. Grab plenty of towels you don't care about and wear gloves you are willing to throw away. Cover your workspace with cardboard or something. Warm up the mount and sealant to at least room temperature but no higher than about 90F. I used a male 3" PVC adapter to hold the mount. It fits perfect and I had it lying around from a bushing install on another car, but they are only a couple dollars if you want to buy one.

Steps 7-9 should all be done within 15 minutes to avoid setting the urethane in the wrong position.

7. Cut just the very tip off the tube, and break the inner seal of the tube with a long screwdriver or something. Then, try to jam the tip of the tube down into the side of the mount. Here we are trying to get the urethane to go under a metal ball inside the mount. Sorry, I don't have pics of that but you will see it. Squeeze a bunch in on both of the larger opening sides of the ball. then work in a circle. Eventually it will start to come out the other holes, and you can jam it back in. Just get as much in there as you can, I used about half a tube.





8. If I've learned anything from placing concrete, it's that vibration is your friend if you want to reduce voids. Go around in a circle and tap the mount with a hammer.



9. Load the top of the mount so the bushing part of the mount is compressed. This will give you the best range of motion after everything cures. I used 50lbs. Speaking of curing, the recommendations range anywhere from 1 day to 7 days. Most people wait 2 days. I think I will go 3 days.



So that's where I'm at right now. I'll report back once I get it installed and running.
 
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#5 ·
I "assume" it flowed down there. It took a really long time before I started to see the urethane come up the sides of the ball.

The benefit of this method over the liquid stuff is it is $35 cheaper. And locally available (Home Depot).
 
#6 ·
Agreed on that.

As I said before, worst case scenario, this stuff falls apart, and you have to blowtorch it out and do what I did. Oh I guess a picture of that monstrosity would fit in here.

Passenger mount, all rubber burnt off, and wirewheeled clean. (Ignore the junkyard wheels)


IMG_20111121_100437 by mellephants, on Flickr

After using duct tape and 80A urethane casting compound to create a new, completely solid polyurethane mount:


20111123_30D_3939 by mellephants, on Flickr


I have since whittled it down to a normal looking shape using a common knife, and installed it. I've also filled the driver's side mount, so that the two would be equally stiff. My whole car vibrates with every movement of the engine, but nothing ever hops skips or jumps when driving the car hard, throttle input is incredibly direct, and you can barely notice the vibrations at highway speed.

Drove it for 6 hours straight (o'hare and back) on Wednesday with zero complaints.
 
#15 ·
#8 ·
Not sure on the roof sealant. but I have made them in the past for escorts & the rear lower for our cars. I us 3m windsheild urethane. it has been really good & from all the DIY i found on google it seems to be great to work with & strength.

 
#9 ·
on my old computer i had a chart. i will look to find again. it showed from rubber to poly & the strength of the products. so a person can ake there own as hard as they like or even a bit soft but still better than rubber . this way not rough on a DD car

The mount you are doing I have been planning on. so interested to see how this works out. i never thought of putting weights on it to compress it.
 
#11 ·
12 hours later and the test string I squeezed out is starting to gum up. It's no longer turning my fingers black. I think I will leave the weight on for a full day at least.

The Window Weld is probably better, and it is certainly harder at 60A vs 30A for this stuff, but I wanted to do this for the lowest possible cost. 25 bucks was too much lol
 
#12 ·
i was looking at that to. also urs is good for DD. now i may leave the lower with the windsheild weld. try your idea for the two uppers. this way it is still much better than a rubber one. but sill a bit of flex so not rattle teeth .lol. oh i got my 3M for 13.97. But at 25.00 i think i would have looked around for a lower cost idea myself.
 
#13 ·
Sweet deal for someone that doesnt have the cash or doesnt want the hardness of all 3 mounts with street bushings I know theres tons of vibration I run race bushings 93a any harder it would be delrin or nylon plastic.

Idle is terrible but during regular driving smooth as butter.
 
#16 ·
the lower & the driver side seem simple to fill. the passenger is the one i question. it has fluid to remove & then fill. i am wondering why illinipo decided to add 50lbs to compress his? should I look into compressing mine? his is for 00-04. mine is 05-07. hmmmmm??????
 
#17 ·
The compression was to get the mount to the stock position. My bushing was broken so the whole thing was shifted down about 1/8". The weights just put it approximately back in the right spot.
 
#21 ·
Agree on all points. If I could I would redo mine with weights, just like illinipo, but still use the 80a casting compund

Mine was broken worse though, and I wanted to see what the thing looked like on the inside, so I burnt all the rubber off. The bad thing about doing that is the difficulty to get it aligned and avoid preloading. Mine is radially preloaded pretty significantly. We'll see how it works in the long run. If I have to replace, I will find a high miles / broken mount to fix again.

Sent from my ADR6300 using Tapatalk
 
#24 ·
Mine broke years ago, then replaced and broke some more. The cheap ones only last a year if that. When I replaced it the first time my motor was sitting almost a inch maybe more lower than what it should have been.
 
#25 ·
OMG

WTF

I GOT MY CAR BACK :D

Shifter slop, GONE

Vague clutch engagement, GONE

Torsen once again working as designed.

Now I remember why I used to love to drive this car. I think that mount has been broken for a lot longer than I previously thought. Perhaps 1 year or more. Man, I really missed this car in this form!


Anyway, I broke down and pulled the weights off on Sunday night (~48 hours). The stuff inside was still really, really squishy... So I tossed it in front of one of my heater vents in the house until just a few hours ago (~84 hours). It finally got pretty stiff, and I really needed to put my car together, so I did.

Very minor increase in vibration. I am really sensitive to it so most people would think there is no difference. Driveline is solid. It is raining today, so very very easy to test out wheelspin characteristics. Where it used to just spin up the RF instantly with tons of wheel hop, I am now getting even wheelspin or on occasion the left side actually spinning up a bit, something that has not happened in this car for 2 years.
 
#26 ·
I was worried when you said it was still soft at 48 hours, but sounds like the $5 fix was a total success. Horray!

FWIW the vibrations from my "much more solid" mounts are still not bothering me, I just find them somewhat amusing, and the added firmness and accuracy in all of the areas you mentioned (shifter, clutch, wheelspin control) make it completely worth doing.
 
#27 ·
I remember when I just replaced my stock mounts with more stock ones (beside the lower one of course). The car felt like a brand new car very solid, needless to say it doesn't feel like that right now. Can't wait to try this myself.
 
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