Car won’t start after doing valve cover job.

Once the valve cover gaskets were replaced with new ones and the covers put back on, I put the intake back on without using new gaskets and the car wouldn't start but I did get a pop and a backfire and the intake has become quite warm. I have bought new intake gaskets but have not installed them yet. Can u help

My car has 152000 miles.
My car has an automatic transmission.

Experienced mechanics share their insights in answering this question :
Hi there. From the description you have provided, something was reassembled incorrectly. Not replacing the upper intake (plenum) gaskets should not have caused the vehicle’s no start condition. Once that you have the plenum removed, carefully inspect all the components you disconnected to do the valve cover gaskets. Hopefully you locate the problem. You may want someone else to inspect it, while it’s apart. If you locate the problem, put it all back together with new gaskets and happy motoring. If you did not locate the problem and your vehicle does not start, I recommend having your vehicle inspected by a certified technician, such as one from YourMechanic.

How to Identify and Fix Common car Problems ?

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A bad valve cover gasket can prevent a car from starting by causing a loss of oil pressure. This can happen if the gasket is damaged or if it is not properly sealed. If there is a loss of oil pressure, the engine will not be able to start.
You can do just about anything you want, but running an engine with the valve covers removed is going to make a mess with oil all over the place.
Your valve cover gasket may be leaking for a variety of reasons. It could be shrunken, cracked or rotten, or your valve cover itself may be cracked or broken or one of the valve cover bolts may just be loose, allowing a little leak. Your car may have 1 or 2 valve covers depending on its configuration.
Unfortunately, a valve cover gasket leak can be dangerous if it leads to spontaneous vehicle failure or overheating as you drive. While it doesn`t pose a serious risk of sudden harm otherwise, it can cause extensive internal damage to your engine and related systems, which can cost hundreds or thousands to repair.
When this occurs, the gasket can lose its integrity and leak, potentially causing cosmetic issues like leaking oil, or drivability problems and reduced engine performance. If not replaced by an ASE certified mechanic in time, a bad valve cover gasket can lead to complete engine failure.
Common burnt valve symptoms include the appearance of blue-white smoke, excessive oil consumption, and poor engine performance. If the valve seals on your new or newly purchased vehicle are defective, you may be entitled to compensation under your state`s lemon laws.
A leaking valve cover is a prime issue in a gasket. The common signs of a leaked valve cover are filthy cover, oil burning smell, engine failure, engine knocking, and a lit check engine light. Sometimes you might also see white fumes from the engine.
If you suspect your engine may have bent or broken valves, it is crucial not to attempt to start the engine as this may result in more costly damage being caused to the cylinder head, pistons and cylinder bores. The bent valves above are a result of a fatigued timing belt that has broken.
Technically you can drive without a working EGR valve.

It won`t affect the health of your engine, but it will hurt the environment. The role of your EGR valve is to reduce the number of toxic NOx gases in the air, so if it isn`t working quite right, more toxic gases will be released into the air.

Although valve cover gaskets don`t necessarily need sealers or cements, it`s a common practice to glue the gasket to the valve cover. There are a number of sealant choices, too. For this application, Permatex No. 1, RTVs or Permatex High Tack gasket sealant work well.
Trauma can cause valves to leak, as can infection of the heart valve or damage from rheumatic fever. High blood pressure, pulmonary hypertension, and an enlarged heart can also cause leaking valves. Some heart surgeries to correct heart defects in children may result in leaking valves later in life.
If your valve cover gasket is leaking badly, it could cause a fire. The PCV valve vents pressure from the engine back into the intake manifold and can become clogged and dirty over time.
Another common sign of valve cover gasket failure is engine misfiring or reduced performance. If the gasket is not sealing properly, oil can enter the combustion chamber, leading to engine misfiring or reduced performance. This can manifest as a rough idle, stalling, or difficulty starting the vehicle.

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