---
product_id: 176580041
title: "New Leak Down Tester Tu-21 Engine Cylinder Leak Tester Leakage Detector Engine Compression Tester Gauges Set"
brand: "ondy"
price: "€ 73.67"
currency: EUR
in_stock: true
reviews_count: 9
category: "Ondy"
url: https://www.desertcart.nl/products/176580041-new-leak-down-tester-tu-21-engine-cylinder-leak-tester
store_origin: NL
region: Netherlands
---

# Fits 4-stroke gasoline engines Accurate cylinder leak down & compression readings 12mm & 14mm spark plug compatibility New Leak Down Tester Tu-21 Engine Cylinder Leak Tester Leakage Detector Engine Compression Tester Gauges Set

**Brand:** ondy
**Price:** € 73.67
**Availability:** ✅ In Stock

## Summary

> 🔍 Diagnose like a pro, avoid costly repairs—don’t let engine leaks catch you off guard!

## Quick Answers

- **What is this?** New Leak Down Tester Tu-21 Engine Cylinder Leak Tester Leakage Detector Engine Compression Tester Gauges Set by ondy
- **How much does it cost?** € 73.67 with free shipping
- **Is it available?** Yes, in stock and ready to ship
- **Where can I buy it?** [www.desertcart.nl](https://www.desertcart.nl/products/176580041-new-leak-down-tester-tu-21-engine-cylinder-leak-tester)

## Best For

- ondy enthusiasts

## Why This Product

- Trusted ondy brand quality
- Free international shipping included
- Worldwide delivery with tracking
- 15-day hassle-free returns

## Key Features

- • **Compact & Durable Design:** Carbon steel build with compact dimensions fits tight engine bays—ideal for trucks and late-model cars.
- • **Precision Leak Detection:** Pinpoints worn piston rings, cracked cylinder walls, and blown head gaskets with professional-grade accuracy.
- • **Universal Spark Plug Fit:** Works seamlessly with 10, 12, or 14mm spark plugs across most petrol engines—no adapter hassle.
- • **User-Friendly Calibration:** Quickly calibrate the leak gauge with your shop air supply for instant, reliable diagnostics.
- • **Comprehensive Cylinder Comparison:** Easily compare suspect cylinders against healthy ones to isolate engine issues fast.

## Overview

The ONDY TU-21 Leak Down Tester is a precision diagnostic tool designed for gasoline 4-stroke engines with standard spark plug sockets (10-14mm). It accurately measures cylinder leakage and compression, helping identify engine faults such as worn rings, valve leaks, cracks, and blown head gaskets. Featuring easy calibration with shop air and a durable carbon steel build, this compact tester is perfect for professional mechanics and DIY enthusiasts aiming to maintain peak engine performance.

## Description

desertcart.com: New Leak Down Tester Tu-21 Engine Cylinder Leak Tester Leakage Detector Engine Compression Tester Gauges Set : Automotive

Review: A handy diagnostic tool - I read most of the reviews. It seems that if this tool arrives undamaged then it should work. Yes, I had to change the regulator air fitting. And, yes, it's cheaply made. If you think you need a better quality tool than this, you better just pay up for one. But this tool helped me diagnose both broken compression rings and which valves were leaking. For the price, if I used it only one time, it's worth it. And to clear up the confusion, if you run 60-100 psi air TO the regulator then you should have plenty of volume to calibrate the leakdown gage, which should read 25-30 psi AFTER the regulator. Yes, the directions provided are not as clear as they could be. But these were probably written by someone with limited skills in English language.
Review: Tester quickly identifies all types of head gasket failures - OEM makes a great line of reasonably priced, reasonably well made and reasonably accurate tools for the DIY automotive mechanic. Their Cylinder Leakage Tester is no exception. This tester has two different connection, Input air and Output air to cylinder. The Input connects to your 90-100psi shop air compressor with NPR Quick connect couplers and the Output connects to the cylinder under test a special Test Hose. The test hose has 14mm male threads to screw into the spark plug hole (hand tighten only) and a NPR Quick connector to connect to the Tester's Output port. Disconnect the Test hose to quickly calibrate the tester, then reconnect the Test hose and you will immediately see and hear results. Keep the ignition OFF. You may need to manually rotate the engine crankshaft with a wrench to bring the cylinder under test toward the TDC of its Compression Stroke so that the valves will both be shut and a "Good Cylinder" should not leak high pressure air being fed through the spark plug hole. Under this test condition, a blown head gasket will let high pressure air leak to either or both coolant passages or oil passages. Coolant expansion tanks may overflow as a result. Pressurized air may leak (and whistle?) from oil filler caps and /or Air-Oil separators. This tester can readily locate a blown head gasket that a Compression Test will completely miss.

## Features

- FITS YOUR VEHICLE -- It is compatible with gasoline 4-stroke engines and 12mm or 14mm spark. As long your vehicle has a standard spark plug socket, this set will work for you.
- COMPARE CYLINDERS -- It best tests cylinder leak down and compression when comparing a suspect cylinder to a known good cylinder on the same engine.
- EASY TO USE -- Remove the Schrader valve and turn the regulator off before applying shop air. Install the hose to the cylinder, the unit to an air supply, calibrate the leak gauge, and connect the unit to the cylinder hose. Diagnosis is made by observing the amount of leakage indicated on the cylinder leakage gauge and listening for leakage at various points of the car system.
- Designed to detect a variety of common engine faults. including: Worn piston rings, worn valves, cracks in cylinder walls and blown head gaskets.
- Suitable for use on any petrol engine with 10, 12 or 14mm spark plugs. Tester checks the amount of leakage in an engine cylinder & helps determine the source. Ideal for testing trucks & late model cars where clearance is minimal.

## Technical Specifications

| Specification | Value |
|---------------|-------|
| ASIN | B08225M7VC |
| Best Sellers Rank | #183,174 in Automotive ( See Top 100 in Automotive ) #2,374 in Diagnostic, Test & Measurement Tools |
| Brand | ONDY |
| Date First Available | November 26, 2019 |
| Item Weight | 3.12 pounds |
| Item dimensions L x W x H | 11.81 x 11.81 x 1.97 inches |
| Manufacturer | ONDY |
| Material | Carbon steel |
| Product Dimensions | 11.81 x 11.81 x 1.97 inches |
| Thread Type | Npt |
| UPC | 016071508109 |

## Product Details

- **Brand:** ONDY
- **Item dimensions L x W x H:** 11.81 x 11.81 x 1.97 inches
- **Material:** Carbon steel
- **Thread Type:** Npt
- **UPC:** 016071508109

## Images

![New Leak Down Tester Tu-21 Engine Cylinder Leak Tester Leakage Detector Engine Compression Tester Gauges Set - Image 1](https://m.media-amazon.com/images/I/81hp0zGvQsL.jpg)

## Questions & Answers

**Q: This says for compression and leak test.  compression testing requires a gauge to at least 180 psi but gauge shown is far less. is picture wrong?**
A: I would not use a leak down tester as a compression tester. A leak down test is very specific and gives complementary data to a compression test. If you want to do a compression test get the proper tool. When testing an engine of unknown quality I always do both tests since the testers are not expensive.

**Q: Where is this made?**
A: China

**Q: Can anyone tell me if the attachments will fit down the spark plug well of bmw r1200 gs motorcycles, 2010-2012?**
A: Suitable for use on any petrol engine with 10, 12 or 14mm spark plugs.

**Q: Will this work on a jeep 4.0l? (2000 grand cherokee wj)**
A: Suitable for use on any petrol engine with 10, 12 or 14mm spark plugs. Tester checks the amount of leakage in an engine cylinder & helps determine the source. Ideal for testing trucks & late model cars where clearance is minimal.

## Customer Reviews

### ⭐⭐⭐⭐⭐ A handy diagnostic tool
*by P***L on August 12, 2023*

I read most of the reviews. It seems that if this tool arrives undamaged then it should work. Yes, I had to change the regulator air fitting. And, yes, it's cheaply made. If you think you need a better quality tool than this, you better just pay up for one. But this tool helped me diagnose both broken compression rings and which valves were leaking. For the price, if I used it only one time, it's worth it. And to clear up the confusion, if you run 60-100 psi air TO the regulator then you should have plenty of volume to calibrate the leakdown gage, which should read 25-30 psi AFTER the regulator. Yes, the directions provided are not as clear as they could be. But these were probably written by someone with limited skills in English language.

### ⭐⭐⭐⭐⭐ Tester quickly identifies all types of head gasket failures
*by D***H on July 29, 2020*

OEM makes a great line of reasonably priced, reasonably well made and reasonably accurate tools for the DIY automotive mechanic. Their Cylinder Leakage Tester is no exception. This tester has two different connection, Input air and Output air to cylinder. The Input connects to your 90-100psi shop air compressor with NPR Quick connect couplers and the Output connects to the cylinder under test a special Test Hose. The test hose has 14mm male threads to screw into the spark plug hole (hand tighten only) and a NPR Quick connector to connect to the Tester's Output port. Disconnect the Test hose to quickly calibrate the tester, then reconnect the Test hose and you will immediately see and hear results. Keep the ignition OFF. You may need to manually rotate the engine crankshaft with a wrench to bring the cylinder under test toward the TDC of its Compression Stroke so that the valves will both be shut and a "Good Cylinder" should not leak high pressure air being fed through the spark plug hole. Under this test condition, a blown head gasket will let high pressure air leak to either or both coolant passages or oil passages. Coolant expansion tanks may overflow as a result. Pressurized air may leak (and whistle?) from oil filler caps and /or Air-Oil separators. This tester can readily locate a blown head gasket that a Compression Test will completely miss.

### ⭐⭐⭐⭐ Works good but no orifice adjustments.
*by G***G on May 15, 2025*

Works good, but would be nice to replace the orifice size for different diameter cylinders.

## Frequently Bought Together

- New Leak Down Tester Tu-21 Engine Cylinder Leak Tester Leakage Detector Engine Compression Tester Gauges Set
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*Product available on Desertcart Netherlands*
*Store origin: NL*
*Last updated: 2026-03-07*