Signs of Bad Motor Mount?

[How Do I]

What are the typical signs of a bad motor mount? My Blazer has always had a slight miss in it and sometimes at idle it will cling-clang lightly. The exhaust pipe makes contact with the cross-member, right before where it enters the catalytic converter. Now, there is a strap there for a hanger, but for some reason there isn't a hanger attached to the pipe at that point.

I noticed that I only have the miss when the vehicle is in park or in gear. If you put it in neutral, it goes away and the engine idles smoothly. But I was just wondering if the motor mounts or at least one might be bad? When it is in park and the engine is idling and you are looking at the engine, you can see it moving slightly along with the miss. So, what exactly do you look for when you suspect a bad motor mount? Just for future reference, if nothing else.

[tamsam]

Quickest way is put it forward gear and hold the brake and give it a little gas. If the engine raises up on the drivers side more than and inch at the most the drivers side mount is bad. Or you can get under it with a jack and jack the drivers side of the engine up a little to see if the mount sparates. Just don't over jack it and don't put the jack on the oil pan. Hope this helps. Sam

[Wis Bang 2]

And reverse will test the opposite side...This works for any engine mounted north - south, transverse engines will be different...

A miss that goes away sounds more like a vacuum leak or a bad sparkplug/wire...The vibration w/ the miss is the engine rocking on the rubber inside the engine mounts

A Vee engine w/ a bad motor mount usually has the fan making contact as it rises up off the bad mount. The torque makes it rise up the side that is unsecured as you step on the gas so it would get worse as you increase your speed...You would be hearing it as you drive and wouldn't hear it when parked...

Time to get someone to do some trouble shootin'

[sammyd]

when the fan eats the radiator every time you run the snowplow into a big drift you may have bad motor mounts......

[Ray]

a broken motor mount can be expensive in damage if not fixed. some of the sidemount motors will destroy the exhaust manifolds, among other things, any can cause enough movement to damage the radiator and fan. with a console shift stick you can actually see the stick raise a move a great distance more that normal in either direction, and you can hear strange noises under the hood you've never herd before when you hold the brake and torq the engine, (give it gas) while its in gear, forward and reverse, this will cause the engine to tilt and raise up off of the broken mount and put moving parts in places they weren't ment to go, like the fan into the radiator, or after enough times break the cast exhaust manifold. have someone you trust to hold the brake and torq it while you watch under the hood, i'm sure you will see if a broken mount is the problem. you must be extremely careful not to run over someone, or through a wall while doing this test, be most careful it can be dangerous, to torq an engine in gear with a brake on, don't over do it. it don't take too much, best wishes, ray