Weird Engine Flywheel Problems

_It’s not often you see engine flywheel problems. But when you do this usually means the vehicle is not going to move anywhere. Whether it’s a worn out ring gear causing a no start or a clutch problem the vehicle is staying put.

Picture 98 ford f150 with manual transmission

95 Ford F150

_Sometimes we see rear main seal leaks work their way onto the flywheel surface causing a slipping problem. But the other day I stumbled onto a good one you don’t see every day. How about an engine flywheel problem that caused slipping of a newly installed clutch.

I was called over to a friend’s house to see what went wrong with his clutch installation side job on his 95 Ford F150 pickup. He installed a complete clutch kit and had the flywheel resurfaced at a machine shop. The truck would move forward slightly when the clutch was let out but it was clear that it was slipping badly with all new parts.


Picture engine flywheel

engine flywheel

_Unfortunately for diagnosis it had to come back apart. As in removing the transmission, which is no fun in the driveway. When we pulled the transmission out I didn’t see anything wrong. We pulled off the clutch and pressure plate and you could see that the resurfaced engine flywheel was already starting to get a purplish color from the slipping clutch.

To make a long story short I truly did get lucky on this one as the cut or resurfaced job on the face of the flywheel didn’t look so good. So we pulled it off and I went and got my micrometer to measure the flywheel. The flywheel was resurfaced in excess. Meaning that the flywheel was well undersized and needed to be replaced. The vehicle owner was not notified by the machine shop and wasted a lot of time and money on his driveway clutch replacement project.

When it comes to clutches and manual transmissions there are not a lot of articles or information on the Internet about the subject overall, compared to other automotive systems. This is why I have built a complete section over at my you fix cars website that talks about manual transmissions and clutches.


_More about the engine flywheel

ring gear flywheel

Flywheel ring gear

_The flywheel is an important part of the engine. It is also the main driving member of the clutch in a manual transmission set up. An engine flywheel is normally made of modular cast-iron which means that it is one of the heavier parts on the automobile. Another important component that sometimes causes problems is the ring gear that is pressed onto the outside diameter of the flywheel.

This is the area that the starter drive meshes with to turn the engine over during the engine start cycle. When a grinding sound is heard when the key is turned this is the starter drive grinding away at the ring gear of the flywheel. This grinding sound is not a good thing. If this happens many times you will probably have an engine flywheel problem and replacement of just the starter will not solve it.


Picture of clutch and pressure plate

Pressure plate and clutch

_In this situation replacing the two components involved being the starter motor and the flywheel is usually recommended and in the end necessary. The rear surface of the flywheel is a friction surface machined very flat to ensure a smooth clutch engagement. As in the above example the flywheel itself can cause a few problems. If it is undersized the clutch will slip. If the surface is wavy you will have a clutch pedal pulsation and increased wear of the clutch disc.

The engine flywheel also provides some absorption of torsional vibrations from the crankshaft. Which is a fancy way of saying that it helps smooth out the engine as it spins it further provides some inertia to help rotate the crankshaft through the four strokes of engine operation.

There is a precision bore at the center of the flywheel that holds the pilot bushing this supports the front end of the transmission input shaft and maintains proper alignment with the engine crankshaft. Sometimes the pilot bushing is a brass insert and sometimes it is a needle bearing set up instead. Excessive vibration in the drive-line can cause problems in this area.

If you need more information about engine flywheel problems you can visit my page about what to do when having automotive clutch problems. For more articles posted here on this website is next link will take you back to the online auto repair blog.


One comment

  1. I generally enjoy DIY car repair but when it comes to diagnosis and repair of things this complex I refer to my mechanic. This gives me encouragement to try more things on my own.

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