Your Chevy Express’s clutch provides a direct connection between the engine and transmission. Without it, it can’t move at all. This connection requires a tremendous amount of pressure. This guide is intended to help you determine why your clutch is slipping on the flywheel.
Note: This article is for manual cars only. Here’s the automatic transmission version of this article.
Slipping Clutch Meaning
The phrase slipping clutch means that when the Express’s clutch is fully engaged there is not enough pressure or contact surface left to transfer the force from the flywheel to the transmission. This can happen for a variety of reasons (the most common being that the disc is worn down).
What Happens When a Clutch Slips
When there’s too much force coming from the engine for the clutch to handle, it slips. Slipping feels like you’ve pressed the clutch in a bit and the RPM’s shoot up, even though you haven’t pressed the clutch at all. The natural reaction is to let off of the gas, and the RPM’s will go back down and the clutch will re-engage.
This problem will first start showing itself in the later gears when driving your Express at higher speed. That’s when the clutch has the most force on it. As the clutch burns up from slipping (and it will) the problem only gets worse. It’ll happen at slower speeds and in gears closer to first. Eventually it’ll just stop grabbing altogether and your car or truck will no longer be able to move.
Clutch Slipping Symptoms: Chevy Express
There are a few symptoms associated with a clutch slipping.
- RPM’s Rise– With a manual transmission, the RPM should only change when the gears change, or the vehicle’s speed increases/decreases. When the RPM goes up when you push the Express’s gas (but the other factors haven’t changed) that is evidence that the clutch is slipping.
- Smell– The smell of a burning clutch smell like rotten eggs or burnt carpet. It depends on what the disc is made of.
Express Slipping Clutch Causes
1. Worn Clutch Disc
Think of your clutch like a giant brake pad. While it is very likely that it will outlast a set of normal brake pads, it still does wear down. When it wears all the way down to there is no friction surface left. At this point, the clutch can no longer grip the flywheel properly, even though it still has pressure put on it from the pressure plate.
The friction material wearing down is far and away the most common reason that a clutch slips.
2. Oil or Grease
If there is oil or grease that is leaking from your Express’s engine or transmission, it can cause the clutch to slip. Unlike a clutch disc that has worn out, an oily or greasy disc will usually grab again without you letting off the throttle (the slipping burns it up).
Oil on your clutch disc is likely to be caused by:
- Engine that is leaking oil
- Transmission leak
- Leak in the clutch lines or clutch slave cylinder
- Too much grease put on the pilot bearing or input shaft during installation
3. Clutch Disc Not Making Full Contact
This can happen when you replace the clutch but not the flywheel (or you don’t have the flywheel resurfaced). The clutch disc will only cover a fraction of the available flywheel surface, and it won’t be enough to handle a high amount of torque.
4. Overheating
If the clutch disc overheats, it can slip. This can happen when you have to slip the disc constantly (think traffic jam). When this happens it can do a lot of damage to the clutch and pressure plate.
New Clutch Slipping
A new clutch can slip for a variety of reasons. The most common one is that the old flywheel was reused. It can also be due to a fault in the release system.
Conclusion
We hope this article helps you better understand how and why your Express’s clutch may be slipping. If you can leave anything to help the next person diagnose their vehicle, please leave a comment below. Thanks!