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Discussion Starter · #1 ·
Hi guys,

Over the summer I imagine my engine has started to shake more than usual at idle/warm up. It behaves just like the 351C in this youtube clips where someone states that it's caused by the rubber-ish motor mounts. I have those in my car together with a mild performance 351C. Do these mounts wear in a couple of years? If so, can anyone recommend some heavy duty ones for a 351C cougar -69 setup?

Many thanks!
Hampus

 

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Hi guys,

Over the summer I imagine my engine has started to shake more than usual at idle/warm up. It behaves just like the 351C in this youtube clips where someone states that it's caused by the rubber-ish motor mounts. I have those in my car together with a mild performance 351C. Do these mounts wear in a couple of years? If so, can anyone recommend some heavy duty ones for a 351C cougar -69 setup?


Many thanks!
Hampus



Most like something wrong with the mounts. Could be worn, broken or missing a bolt? Also if its rough at warm up have you checked choke to make sure its working? I had that problem for a while until I realized that my choke cam was hung up. But looking at the video and your engine is doing this, I would look to the mounts for the issue
 

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Discussion Starter · #4 ·
I've tried to inspect them visually as much as possible but I cant really see any obvious issues from outside. Since they seem to be partially covered/made by some kind of rubber mix, I wonder if the wear over time and need to be replaced if/when the rubber gets worn out...? Similar to this: http://www2.cougarpartscatalog.com/67sbmm.html.

The choke works as it should btw.

Thanks.
 

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The purpose of the motor mounts is to insulate the engine vibrations and noises from the rest of the car so a little movement is acceptable. Usually what happens is the drivers side mount tears or separates due to the torque of the engine eventually pulling the mount apart. Add a little valve cover or power steering leak and low quality reproduction mounts lead to short life.
Engine mounts are easy to replace. All you need is a jack and some basic tools. Put the jack under the oil pan (use a piece of plywood to prevent the jack from denting the oil pan), remove the bolts and jack the engine up just enough to remove the old mount and replace it. To add, anytime you work underneath a car use good quality jackstands, never concrete blocks.
I've tried to inspect them visually as much as possible but I cant really see any obvious issues from outside. Since they seem to be partially covered/made by some kind of rubber mix, I wonder if the wear over time and need to be replaced if/when the rubber gets worn out...? Similar to this: http://www2.cougarpartscatalog.com/67sbmm.html.

The choke works as it should btw.

Thanks.
 

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The car could also shake a little on idle if it's not firing on one of the cillinders, just a thought.
Or if your idle is on the low side.

Heavy shaking like on the vid is probably the mounts :)
 

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Is the problem due to the engine mount or the engine? If the engine is bone stock and is running rough the problem lies elsewhere. I totally get the "motor mount" answer as it has happened to me and I have a rough idling engine. But don't overlook the problem as a mount if you have carb, intake, or spark issue :)
 

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One thing you can do to test them is simply have soemebody help you - put the car in gear and then watch for excess movement at those mounts as they give it a little push on the pedal. You will see it if it's shot.....
 

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Discussion Starter · #12 ·
Engine is not stock, mild performance hydraulic roller cam, howards hydraulic roller lifters, 64cc aluminium heads "3V", 3V ported edelbrock intake, edelbrock 600cfm carb. I haven't yet abandoned the potential engine issues, it could very well be some of the issues that you describe dfw*. I have very limited access to my car for the moment, so I've been stacking up some troubleshooting for next time I see her... :)

But since I have the "stock" mounts I'm thinking about swaping them for some heavy duty ones so I can take her to the track and dont have to worry about them.. Maybe I exaggerating my thinking about stock engine mounts here....?

Badcat; Not sure I understand you correctly, "put the car in gear.. push on the pedal", how will I survive that exercise? :)

Thanks!
 

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Engine is not stock, mild performance hydraulic roller cam, howards hydraulic roller lifters, 64cc aluminium heads "3V", 3V ported edelbrock intake, edelbrock 600cfm carb. I haven't yet abandoned the potential engine issues, it could very well be some of the issues that you describe dfw*. I have very limited access to my car for the moment, so I've been stacking up some troubleshooting for next time I see her... :)

But since I have the "stock" mounts I'm thinking about swaping them for some heavy duty ones so I can take her to the track and dont have to worry about them.. Maybe I exaggerating my thinking about stock engine mounts here....?

Badcat; Not sure I understand you correctly, "put the car in gear.. push on the pedal", how will I survive that exercise? :)

Thanks!
Foot hard on the brake, put the car in gear, push the throttle lightly and watch for engine lifting on drivers side.
 

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Discussion Starter · #14 · (Edited)
Lol, thanks for the clarification... Badcat almost got a dead swede on his conscience there.... ;-)

I think it will move around quite a bit, but I'll probably make a vid and put on YouTube so I can get a second opinion.

I'm very thankful for everything you guys teach me on this forum. Without you I wouldn't be able to learn, and enjoy learning, about my nice cougar and cars in general.

Thank you kindly,
Hampus
 

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LOL I like Swiss chocolate - pancakes - not so much!
 

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sweden >>> sweds

switzerland >>> swiss

LOL - I was on a about 30 hours of no sleep! Still feeling like I haven't slept......
 

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From past experience when a motor mount goes bad you know it. The motor will lift up violently from the drivers or left side. Often times hitting the hood and causing damage. When a motor shakes at idle I begin with vacuum. Looking for vacuum leaks is a constant issue with our cars due to the headlights. Then there is misfire as noted earlier. If you can do a burn out and not dent the hood with the motor the mount is not broken. Going bad maybe but not likely the cause.

Using a vacuum gauge hook to any unused (pluged or blocked off) vacuum port on the manifold or remove a vacuum hose and plug it to prevent backward drain then hook where it was. Using my memory I think a constant draw of 15lbs vacuum is normal (please join in guys and correct my number). The important part is constent. If it goes up and down there is for certian a leak at one of the intake manifold gaskets. Usually I start simple. Check or replace the PCV valve and hose. The big one that connects to the back of the carb base if you have it. Look for any vacuum connections that are unpluged or hoses are old and cracked. Spray carb cleaner or another flamable but safe spray with the little straw around the carb base, intake gaskets, power brake booster and hose or any other vacuum related connection. If te motor evens out when sprayed or reves higher you found a leak.

Points in standard mechanical distributor ware over time chanching the fire slightly. This causes shaking. I now use only Petronics modules in place of points. First time starts and great hot fire every time.

There is some stuff to keep you busy. PM me of you have questions.
 

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I hate to throw more wood on the fire but when I first bought my car back in 2008 the engine rocked so hard at idle the hood would shake. Motor mounts checked out fine, cause they were new. Turns out my harmonic balancer was missing a screw and one was loose. Our best guess was that the previous owner hadn't torqued them down properly after he had did a ton of engine work on the car. I was told I was lucky because if the 2nd screw had come out fully my engine could have been damaged severely.
 
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