Track Adjuster Seized or Blowing Seals? Reseal or Replace Safely

Your track won’t hold tension, the adjuster won’t take grease or won’t back off, or grease keeps weeping past a blown seal. Before you strip anything, remember the unit behind the idler holds a lot of stored energy.

This guide helps you find the likely cause, stay safe and choose between a reseal and a new assembly. PartsForMachines lists 387 track adjuster assemblies, tensioners, spring groups and yokes for excavators from makes including Hitachi, Caterpillar and Komatsu: browse the track adjuster range.

Grease Goes In but the Adjuster Won’t Move: Is It Seized?

Probably, if the nipple and gun are fine and the rod still won’t push the idler out or let it back. The adjuster is a short grease-filled cylinder: grease drives the rod forward, which pushes the idler and compresses the recoil spring behind it. If grease reaches the cylinder but nothing moves, something inside is stuck or has failed.

Stop pumping at that point. The grease inside is already under high pressure; pumping harder adds to it. Don’t try to force it free either. If it doesn’t respond the way your manual describes, make the machine safe and have a fitter assess it, or plan for a replacement.

Why Does My Track Adjuster Keep Blowing Its Seals?

Often because something keeps driving the pressure inside the adjuster too high. A track run tighter than the maker’s figure leaves the grease that holds the idler out under very high pressure. Stones, mud or set concrete packed into the chain tighten the track as you work and push that pressure up again.

So before fitting new seals, find out why the old ones went. Check the tension against the operator’s manual, clear any packing, and look closely at where the grease is escaping. Otherwise the new seals are likely to go the same way.

Can I Strip the Recoil Spring Myself, or Is It Too Dangerous?

Not safely: treat the spring group as a job for a specialist workshop with the proper equipment and the maker’s procedure. The grease cylinder works by compressing the recoil spring, so the spring is held under compression, and that energy has to be released under control.

The grease side is dangerous too, as pressurised grease released from an adjuster can cause serious injury. If the procedure in your manual reaches the spring nut or the bolt through the spring, that is the point to hand the job over.

Reseal or Replace: When Is a New Adjuster Assembly the Better Buy?

A reseal can make sense when a workshop confirms the rod, bore and spring are sound. A new assembly is the cleaner fix when they are not, or when downtime costs more than the part. Choose a replacement rather than a reseal if the cylinder or a weld is cracked, the spring is suspect, or the workshop finds the rod or bore too damaged to reseal.

For many machines you can order the complete unit, such as the ID27489 track adjuster assembly for the JCB JS200 LC. Match it to your machine’s exact model and variant.

What Should I Check Before I Order?

• the machine make, model and exact variant (LC, NLC, SR or series number), as fitment can differ between them
• which part has failed: the complete assembly, the tensioner, the spring group or the yoke
• any part number stamped on the old unit or shown in the parts book
• why the old one failed, so the new one isn’t overloaded the same way
• photos of the old unit from the rod end to the yoke, showing its length and fixings

Browse the track adjuster range, or contact the PartsForMachines team by WhatsApp, telephone or email with your machine model, the old part number and your photos.

Product options, delivery options and returns terms are shown on each product page. A 30-day return policy applies to eligible items.

Frequently Asked Questions

Assembly, tensioner or spring group: which part do I need?

It depends on what failed and how parts are listed for your machine. Some are sold as one complete assembly, others as separate parts, such as the ID08918 tensioner and ID08917 spring group for the Case CX130. Order the part that matches the failure.

Can I buy the yoke on its own?

Yes, for some machines, such as the ID23708 yoke for the Hitachi ZX75UR. If yours is bent or cracked, quote the machine model and compare the new yoke with the old one before fitting.

Can I find a new adjuster from the number on my old one?

Sometimes. A few units are matched to the machine maker’s part number, such as the ID26747 assembly that replaces JCB 234/70145. Otherwise, send our team the number, your machine model and a photo.

Who should tension or slacken the tracks?

Someone trained to do it, working to the machine’s manual. The grease in the adjuster is a high-pressure fluid, so release it only by the maker’s method and never stand in front of, or in line with, the nipple or valve.

Grease is weeping from a weld, not the seal: can it be repaired?

New seals won’t cure it, because a crack in the cylinder or its welds isn’t a seal fault. The cylinder works under high pressure, so replace the tensioner or the whole assembly rather than trying a weld repair.

Can I take the adjuster out without splitting the track?

It depends on the machine, so follow the workshop manual for your model. If the procedure means dismantling the spring group or removing its nut, hand that stage to a specialist workshop with a spring press.

Does a new adjuster need setting up after fitting?

Yes. Once it is fitted, set the track tension to the sag figure in the operator’s manual, with mud and stones cleared from the chain first.

Do your track adjusters come with a warranty?

Yes. Every track adjuster, tensioner, spring group and yoke in this range is covered by a 12-month warranty as standard. Keep the old unit and your machine details handy in case of a query.