Q: My 1971 Plymouth Roadrunner developed a terrible rattle between 1800-4000 rpm. We removed the heads

asked by

Joshua P

on March 17, 2018

We bought a 1971 Plymouth Roadrunner with a 440 engine, and automatic transmission. About 6 months ago a rattle developed that sounds like 50 hammers slamming on a steel table. We suspected the lifters & cam, so I removed the heads, and gave them a perfect reconditioning, along with a new cam & lifter kit, with our non adjustable rocker arms. We checked the engine for clearances with no problem for lift & duration. I turned the motor by hand to observe the lifters & pushrods during the build. It was all clear & beautiful. We closed up the engine & fired it up. Now the car shuddered violently during the cam break in. It idles beautifully & sounds awesome, but if I hold the rpm's at 2000 or higher....the car vibrates violently. Oil pressure is still perfect around 65-75 pounds. That is why I never took the short block apart. Could this problem be the torque converter/ or the flex plate / or the transmission, since it shudders?

My car has 8000 miles.
My car has an automatic transmission.

Save Big on Auto Repairs

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

Get a quote

Experienced Mechanic?

Earn up to $70/hr

Apply Now

What others are asking

What does it mean when the Check Engine Light comes on?

The Check Engine Light is handy tool that will tell you when something is wrong with your vehicle. It does not tell you exactly what is wrong, but a loose gas cap is a common fixable problem. If a loose...

transmission question

The transfer case has its own separate oiling system and does not share fluids with the transmission. The transmission may be having a problem with sucking air from a leak in the valve body or a front pump of the...

Malfunction indicator light stays on, remote start issue

Hello, thanks for writing in about your 11998 Chrysler Aspen. If the MIL (Malfunction Indicator Lamp), also known as the Check Engine Light, is coming on, then there is a hard fault in the engine computer. This fault will need...

Tachometer is not moving at all

Hello. If the fuse is okay, then the next thing I would look at the wiring. Most tachometers (https://www.yourmechanic.com/article/3-essential-things-to-know-about-your-car-s-tachometer) get their signal from the crank sensor or ignition module and will malfunction if there is an issue with the signal....

Car is running crappy sounds like a v8 truck with dual exaust.

If the engine exhaust sounds very loud, there may be a loose or broken component like a cracked manifold or rusted pipe section like on your egr valve. A technician will be able to look over the vehicle listening for...

Engine stalls when the brakes are applied

Hello. From what you describe it would appear that your vehicle may be experiencing possible engine management or transmission issues. The symptoms you describe can commonly be caused by faulty idle air control valve. The idle air control valve is...

I have a 2011 Audi A5 quatro 2.0T, it has 55K miles. Needs an oil change and turn off the service message.

Hello. You are right. Your vehicle does need these filters changed and the oil changed during this service. It will also need to have a complete vehicle inspection as part of this service. A certified mechanic from YourMechanic can come...

Dealership didn't close air filter box. Anything I need to worry about?

If the air filter was not in place, dirt, leaves, you name it can be directly sucked into the engine. If you operated the engine only briefly, the risk of something really indigestable (from the standpoint of an engine) getting...

I was told that Nissan Altima requires synthetic oil and If I use any other it might damage system. Is that true? 2013 Nissan Altima

There are several schools of thought on this topic. While many can attest that synthetic oils can reduce friction and extend oil life, others prefer not to use synthetics in engines that have run on conventional oils for most of...

P0700 OBD-II Trouble Code: Transmission Control System Malfunction

P0700 code definition P0700 is a generic OBD-II code that is indicating a fault within the transmission control system. This code may...

Plymouth Certified Pre-Owned (CPO) Car Program

Many Many drivers who are in the market for a used Plymouth vehicle want to consider a Certified Pre-Owned, or CPO, vehicle. CPO programs allow owners of used cars to drive with confidence, knowing that their vehicle has been inspected...

Understanding the Plymouth Service Indicator Lights

Car symbols, or dashboard lights, are a car service reminder. The Plymouth service indicator lights indicate when and what service your car needs.

Q: My 1971 Plymouth Roadrunner developed a terrible rattle between 1800-4000 rpm. We removed the heads

Get an instant quote for your car

Experienced Mechanic?

Earn up to $70/hr

What others are asking

Related articles

Browse other content