Q: The car idles rough when in drive with the brake applied.

asked by on March 03, 2017

I just had a shop replace the head gaskets because there was an external leak. The car was picked up from the shop and seemed to run fine, the next morning the intake manifold gasket failed and the engine took the coolant into cylinders and quit running. The mechanic replaced the intake manifold gaskets and returned it to me with a rough idle and low compression in one cylinder bank.

My car has 123000 miles.
My car has an automatic transmission.

Engine is misfiring Inspection $79.99 - $89.99 Get a Quote

Hi there. It is quite possible that during the head gasket replacement, a fuel injector or ignition system component may have been improperly installed. It is also highly probable that the mechanic installed the old spark plugs instead of new ones. First, I wouldn’t visit this mechanic again, but I would recommend having a professional mobile mechanic come to your location and complete an engine is misfiring inspection.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

What others are asking

My heater makes a really loud noise when its on.

The level of refrigerant in the air conditioning system would not affect the noise level of the blower motor. If you replaced the motor with an aftermarket (non OEM) motor that could create an issue in terms of the quality...

1996 Ford Crown Victoria overheated and now won't start

Sounds like your Crown Victoria is having a hard time. While being able to turn over but not start is one thing, overheating is another. Overheating in a car is never a good thing. When engine temperatures reach that...

Transfer case making grinding noise

Hello. A grinding sound from the transfer case on this truck is an indication of an internal chain failure. This happens often on this vehicle. I will typically drain the fluid from the transfer case and see if there is...

Water coming out of the exhaust pipe

Hello. Water coming out of the exhaust pipe is usually an indication of a blown head gasket. The head gasket is located between the engine block and the cylinder head. Antifreeze runs over the head gasket and when working properly....

My truck keeps giving me the cylinder #8 misfire code

Hello. A continuing misfire on #8 suggests a bad plug wire, a bad spark plug, or possibly oil leaking down onto the #8 plug, shorting it out. Also, if one plug wire is bad, replace them all. Given your mileage,...

Stuttering with check engine light

If you are having an electrical system problem that is causing the lighting and other systems to have erratic issues then you need to check the alternator wire connections on the back of the alternator for loose or bad connections....

master cylinder is bad, but does it make a noise going down the road. if so what kind. mine is intermittent

Hello, thank you for writing in. The master cylinder may make some noises, however it is rather unlikely that you are going to hear these fluid sounding noises over the engine noise. Start by adding the differential fluid and take...

Car shuts off when the weather is hot

Hello. A bad cam position sensor will cause a Check Engine Light to come on and possibly cause a stall or no start condition for your 2000 Mercury Mystique. Cam position sensors usually develop their problems when hot, so this is likely...

My 2001 Mercury cougar will start just fine but will sputter/ shake then die when not pushing on the gas or stop/idle.

This may be a result of a dirty or failing idle air control valve. The idle air control valve reads the air intake as it is mixed with fuel prior to being injected into the engine at low speeds and...

Related articles

Mercury Certified Pre-Owned (CPO) Car Program
Drivers Drivers who are shopping around for a used Mercury vehicle may want to check out cars under their certified pre-owned program. Many manufacturers have a certified pre-owned (CPO) program, and each one is set up differently. Read on to...
Understanding the Mercury Intelligent Oil Life Monitor and Service Indicator Lights
Car symbols, or dashboard lights, are a car service reminder. The Mercury Intelligent Oil Life Monitor indicates when and what service your car needs.
What Are Brake Pads Made of?
Brake Brake pads are an essential component of the braking system of your car. Every time you press the brake pedal, this force translates by way of a hydraulic system to the caliper. This caliper in turn pushes the brake...