Quick answer. This 2005 Mercedes C230 came in for engine and transmission mounts. Our tech replaced both. After that, the car would not start. Our tech found a ground issue and repaired it. The record shows 4.5 hours of labor at $150 an hour, $675.
Key Points
- The job was engine mounts and a transmission mount on a 2005 C230.
- After the new mounts went in, the car would not start.
- Our tech traced the no start to a ground issue and repaired it.
- The record shows 3.5 hours for the engine mounts and 1 hour for the transmission mount, $675 in labor.
- An engine sits on rubber, so it needs a ground strap or cable to complete its circuit.
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What Went Wrong
The worst part first. The car would not start after the mounts were done.
That is the kind of thing that makes an owner nervous. You pay to fix one thing and now the car does not run at all. Our tech did not guess at a starter or a battery. The note on the job says the no start came from a ground issue, and that it was repaired.
The record does not say which ground it was or what was done to fix it. So we will not tell you more than that.
What We Did
The owner asked for engine and transmission mounts. Our tech replaced the engine mounts and the transmission mount.
The engine mounts took 3.5 hours on the record. The transmission mount took 1 more hour. The ground repair has no line of its own on the ticket.
2005 Mercedes C230, November 10, 2026
Came in for: engine and transmission mounts.
Our tech found: after the mounts, the car would not start because of a ground issue.
What was done: new engine mounts, a new transmission mount, and the ground repaired.
Cost on record: $525 for the engine mounts and $150 for the transmission mount, $675 in labor.
What Engine Mounts Do
This part is general. It is not what our tech found on this car.
A mount holds the engine in place. It also soaks up shake so you do not feel it in the seat. Some mounts are filled with liquid and work like a shock absorber. The one that holds the transmission is called the transmission mount (Samarins).
When mounts wear out, the signs are noise and shake. One guide lists three. You hear knocks from the engine bay, you feel too much shake, and you see the engine move more than it should (YourMechanic). Another says more engine noise and shake inside the car is the most common sign, and a bad transmission mount can squeak when you shift (Samarins).
Why the Ground Matters After Mount Work
Here is the part most people never think about. An engine sits on rubber mounts. Rubber does not carry current. So the only way the engine is grounded is through ground straps or cables (FCP Euro). Those cables link the starter and alternator to the rest of the car's wiring.
Mounts and grounds are tied together. A parts seller that writes about German cars says badly worn mounts let the engine move more than it should, and that movement puts stress on the ground cables (FCP Euro). The same page says a corroded or cracked ground cable often starts as a long, slow crank and can end with a car that will not crank at all. It even says a bad ground can fail with no warning, and then jumper cables will not help.
That is why a no start after mount work is not a mystery part. The engine gets lifted and moved to swap mounts. The ground path runs from that engine to the body. Our tech checked the ground and found the fault there. The finding is written on the job in Shop Desk, the software our San Jacinto shop built. Any mechanic can use it free.
Check Your Own C230 for Recalls
Our job record does not say whether any recall was done on this car. If you own a 2005 C230, put your VIN into the NHTSA recall lookup. It is free and shows any open recall on your exact car.
Frequently Asked Questions
How much did these mounts cost?
The record shows 3.5 hours of labor for the engine mounts and 1 hour for the transmission mount, at $150 an hour. That is $675 in labor.
Why would a car not start after new engine mounts?
On this car, our tech found a ground issue. The engine sits on rubber, so it relies on ground straps or cables. If one is loose, cracked or corroded, the starter may not get the current it needs.
What are signs of a bad engine mount?
Knocks from under the hood, too much shake, and an engine that rocks more than it should are the common ones.
Is a transmission mount the same as an engine mount?
They do the same job. The transmission mount holds the transmission, and the engine mounts hold the engine.
Can a mobile mechanic replace engine mounts?
Yes. This job was mounts plus a ground repair, and it did not need a bay.
What We Read
- FCP Euro, BMW Ground Strap Failure and Replacement
- YourMechanic, Symptoms of a Bad or Failing Engine Mount
- Samarins, Engine Mount: How It Works, Symptoms, Problems, Replacement
Supercanic tip: If your car cranks slow or will not crank after engine work, ask about the ground straps before you buy a starter. Call us at (951) 904-2477 and we will test before we touch.
Engine Shaking or Clunking?
We find the worn mount, replace it, and check the grounds before we hand the keys back.
