Home › Car clip guides › Cable ties, hoses and washers

Hose joiners: straight and T joiners for small lines

3 min read · Cable ties, hoses and washers

Small rubber and plastic lines in a car, such as windscreen washer hoses, vacuum lines and breathers, often split near a fitting or need a branch added. A plastic hose joiner is a quick fix.

Straight or T?

A straight joiner connects two lengths of hose, for example to repair a split. A T-piece joins three, for example to run a washer line to two jets. See our hose joiners.

Matching the size

Barbed joiners go inside the hose, so match the barb to the hose's inside diameter. A barb that is too small will leak or pull out; one that is too big will be hard to fit and may split the hose. Each product lists the barb and body sizes shown on its photo.

Fitting tips

1. Cut the hose square and remove any damaged section.
2. Push the hose fully over the barb.
3. Add a small clamp or a cable tie where the line could pull off.
4. Check for leaks or loss of vacuum after fitting.

Where not to use them

Plastic joiners are for low-pressure lines. Do not use them on fuel, brake, power steering or coolant lines unless the part is rated for that use. Those lines need the correct fittings.

How to measure the hose

The size that matters is the inside diameter of the hose, because the barb goes inside it. If the hose end is still good, measure across the inside of the opening with a ruler or the tips of a vernier. If you only have the outside size and the wall thickness, the inside diameter is the outside size minus two wall thicknesses. Write the size down before you order, and compare it with the barb size on the product page.

Common jobs

• Washer hose split near the bonnet hinge: cut out the split part and join with a straight joiner.
• Adding a second washer jet: split the line with a T-piece.
• Cracked vacuum line: replace the cracked section and join it, then check that the engine idles normally.
• Breather hose that has hardened: replace the hose, using joiners only where the original design had a join.

Common mistakes

• Joining a hose that has gone hard and cracked along its length. Replace the hose instead.
• Using a joiner with a barb that is too big, which splits the hose end.
• Leaving the line unsecured where it can rub on a sharp edge or a hot part.

Need something stronger?

For higher pressure or hydraulic lines, look at proper fittings such as our hydraulic swivels, and follow the vehicle or equipment manual.

Hose joiners in our range

The "ends" figure is the barb size that goes inside the hose. Stepped barbs (for example 9.1, 5.8 and 4.0) fit more than one hose size.

Sizes are approximate, read from the measurement marks on our product photos. Always compare with your original part.

Frequently asked questions

Do I need a clamp on a hose joiner?

On small washer and vacuum lines a firm push fit is often enough, but a clamp or cable tie stops the hose working loose.

Sizes and fitting steps in our guides are general. Check your vehicle's manual for anything specific to your car. Questions? Call 0499 001004.