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Motor mounts and spark plugs

Hello and thank you to anyone who reads this and gives me advice. I drive a 2003 Focus ZX5. Over the last year, it’s run pretty well, but one problem I encountered was that it would not start (occasionally) if I drove in traffic for a while and the engine was warm (not overheated). I mentioned this to my mechanic when the serpentine belt was replaced several months ago, but he was not able to repeat the problem and diagnose it. A couple days ago, the car started to run terribly (vibrating) and struggling when I pressed the gas. I took it to the nearest mechanic (not my normal mechanic) and had the spark plugs and ignition coil replaced. It seems to have alleviated the problem. So . . . a couple questions:

  1. Was the engine’s difficulty starting related to the spark plugs?
  2. On a separate note, the mechanic I just saw advised that some of the vibrations (for instance, in idle) could be resolved with new motor and transmission mounts, which is not cheap. Is it worth it?

Again, thank you for your help.

  1. plugs and/or coil, yes
  2. If it needs them, it’s worth it. Bad motor mounts let the engine rock back and forth excessively, which stresses the things connected to the engine, like the radiator hose. In my case that led to a cracked radiator. But that’s true only if it needs new mounts, you might get a second opinion.
  1. Absolutely.
  2. Follow Texases advice. Get a second opinion.

Question: did you get the coil replaced based upon his diagnosis, or just because you’ve heard or read that bad coils can cause rough operation?

  1. Maybe. How many miles are there on the car? When was the last time the plugs were replaced? If this was the first time, they probably did need to be replaced.

  2. You should only need now motor/transmission mounts if the old ones are broken. Get a second opinion. If you trust your usual mechanic, take it to him and explain the situation. He should give you a straight answer and may even show you the motor mounts and transmission mounts.

You should have a owners manual and it should have a schedule for preventative maintenance (aka scheduled maintenance) that give you the recommended intervals for things like oil changes, coolant changes, filters, spark plugs and timing belts. If you have been following it, and the plugs weren’t overdue, then maybe they weren’t the problem.

Now if you haven’t been following the maintenance schedule and the plugs were overdue, you are paying the price for it. Normally the coil will last the life of the vehicle, but every time a spark plug misfires, it causes and arc fault inside the coil. Eventually these arc faults take their toll and the coil has to be replaced as well.

Some cars have issues with motor mounts, some don’t. And in cases with those that do, it is often only one mount, not all of them. For this you need to talk with someone who specializes in these cars, a dealer perhaps, but always get two or more opinions. You might also google for forums dedicated to you model car and get advice from experience owners.

Some cars have issues with motor mounts, some don’t. And in cases with those that do, it is often only one mount, not all of them. For this you need to talk with someone who specializes in these cars, a dealer perhaps, but always get two or more opinions. You might also google for forums dedicated to your model car and get advice from experience owners.

Some ignition coils fail when they get too hot. Likely the coil was bad, but the plug(s) should be replaced too if they were old and had been misfiring frequently.

Thank you SO much, Keith, UncleTurbo, jtsanders, the same mountainbike, and texases. I decided to wait on the motor and transmission mounts until I speak with my family mechanic (and wise guys like you). We’ve had an excessively hot summer so far, which has necessitated the use of the AC. Forgive me for a possibly silly question, but can regular use of the AC decrease the “life expectancy” of spark plugs?

No.

Thanks for your prompt reply and sorry for the silly question. :slight_smile:

Nope.

Well, perhaps the argument could be made that it changes the life of the plugs an unmeasurable amount only because of the added load on the crank from the AC compressor. Every little bit of added load means a little more power is needed from the engine. That means either a wee bit bigger booms or a bit more booms, depending on the engine’s total load. But that’s a technical argument. Honestly, i doubt of you could measure the difference.

Basically, the idea is to change the plugs based upon the recommended maintenance schedule that comes with the owner’s manual. Although some recommend new plugs every 100,000 miles and I prefer halving that, the recommendation should be taken as an absolute max.

All motors move a bit in the engine bay. Question is what movement is within normal limits and which aren’t? Motor mounts can be visually inspected. Movement of the motor beyond normal limits can result in clunking noises and other things a driver might notice.

A shop that wants to sell motor mounts can show you hairline cracks and make claims the motor is moving too much. These are often the types of repairs where a second opinion is worth the time to obtain.

There are no silly questions, Jenny V, just silly answers. No one knows everything.

theres a chance that a ground wire from the engine to the chassiss will solve the problem.
LEE

It was not a silly question, just a simple one that only required one word to answer.