A question asked by many homeowners: Why doesn’t my string trimmer bump head last?

People seem to accept that the bump feed mechanism on their string trimmer needs to be replaced a few times a year. This should not be the case if you maintain your string trimmer. There isn’t much to it once you know what to do.

You should check all the nuts, bolts, and screws regularly. On some models, this may be required every time you use your string trimmer, as vibrations can cause bolts and screws to work loose. Even if you have a really good string trimmer, you should check all the fasteners every few months.

Replacement Bump Heads on Amazon

Check Your Bump Head Regularly

There is one common string trimmer complaint that has been mentioned by our readers, as well as on popular forums and customer reviews on sites like Amazon. Bump feed heads don’t seem to last. This is the component on your string trimmer that most needs regular maintenance.

The first time I bought a bump feed string trimmer, I found that the head only lasted a few hours before I needed to replace it. Admittedly, this was a Ryobi string trimmer, not the best brand. Though it was one of the better, professional-grade Ryobi models and not all that cheap.

As a rule, I don’t buy Ryobi tools as they are usually junk. However, the salesclerk at the hardware store explained to me that Ryobi also manufactures better tools than the cheap stuff you find at Home Depot. Basically, if the warranty is more than 1 year, it is a better-quality machine.

Since the Ryobi string trimmer in question had a 2-year warranty, I took the chance. As it turns out, my Ryobi string trimmer has lasted many years. This was after I learned the importance of bump head maintenance. Though the machine I bought was a little different.

The bump head on this particular model is protected using twine wound inside the spindle housing. Once I discovered this, I replaced the original twine and compacted it into the top of the bump head. Since then, it’s been plain sailing. I’ve been using the same bump head for about 5 years without any hassles, apart from checking the bump feed head twice a year, to ensure that the twine is still doing its job.

Fortunately, most string trimmer bump heads are easier to maintain. Clean the bump head after every use to remove grass and debris and lubricate the head at least once a year.  

Lubricating Your String Trimmer Bump Head

Most String trimmers have a lubrication port on the gearbox, just above the bump head. If you don’t keep your bump head lubricated, it will overheat, causing damage. I’ve seen melted plastic components resulting from heat damage.  This can all be avoided by keeping the bump head properly lubricated.

To lubricate your string trimmer bump head, simply remove the bolt on the gearbox housing and insert a tube of grease into the opening. I recommend, using good-quality a multi-purpose weatherproof compound, like AGS Sil-Glyde. Squeeze in enough grease until you feel resistance on the grease tube, indicating that the cavity is full. Then fasten the bolt.

This video provides a step-by-step guide on how to lubricate your string trimmer bump feed head:

If you keep your string well-maintained, it will last for years and remain reliable. There really is no need to constantly replace the bump feed trimmer head if keep it lubricated and clean.

If you’re not careful, the bump knob on your string trimmer may be easily damaged. This isn’t such a big deal because these items are cheap and easy to obtain. Amazon has a huge selection of bump knobs for most string trimmer models.

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