---
product_id: 176580041
title: "New Leak Down Tester Tu-21 Engine Cylinder Leak Tester Leakage Detector Engine Compression Tester Gauges Set"
brand: "ondy"
price: "292 zł"
currency: PLN
in_stock: true
reviews_count: 9
category: "Ondy"
url: https://www.desertcart.pl/products/176580041-new-leak-down-tester-tu-21-engine-cylinder-leak-tester
store_origin: PL
region: Poland
---

# 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:** 292 zł
**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?** 292 zł with free shipping
- **Is it available?** Yes, in stock and ready to ship
- **Where can I buy it?** [www.desertcart.pl](https://www.desertcart.pl/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

Product description High Precision Leak Down Tester for Car Inspection and Maintenance Tu-21 Engine Cylinder Leak Tester Leakage Detector This tester can readily locate a blown head gasket that a Compression Test will completely miss. Their Cylinder Leakage Tester is reasonably well made and reasonably accurate tools for the DIY automotive mechanic. 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. Tester checks the amount of leakage in an engine cylinder & helps determine the source. Best used when comparing a suspect cylinder to a known good cylinder on same engine. Ideal for testing trucks & late model cars where clearance is minimal. Equipped with 2-1/2\" input pressure gauge for proper leakage test setup and accurate results. Package Size (LWH): 37cm x 27cm x 8cm/14.56" x 10.62" x 3.14" Designed to detect a variety of common engine faults including: Worn piston rings, worn valves, cracks in cylinder walls and blown head gaskets. Available with either single gauge or twin gauge manifold. Gauges show % of cylinder leakage or cylinder leakage and cylinder pressure. Suitable for use on any petrol engine with 10, 12 or 14mm spark plugs. TU-21 Cylinder Leak Detector Pinpoint the source of compression problems by doing cylinder leak-down tests Works with domestic and import engines Input and leakage gauges with rubberized housing. Air pressure: 0-10 BAR, 0-140 PSI Measures leak percentage from 0-100% 1/8\" NPT manifold ports Package Content: 1 x Cylinder Leak Detector Set. Air Supply The recommended hook-up is shown below ensure that the air valve regulator is in the "off" position before connecting to the air supply will require an air pressure of 45 to 100psi WARNING! ensure the air supply is clean and does not exceed the pressure quoted. too high an air pressure and/or unclean air will shorten the life of the tester due to excessive wear and may be dangerous, causing damage and/or personal injury. drain the compressor air tank daily. water in the air line will damage the tester. clean compressor air inlet filter weekly. line pressure should be increased to compensate for unusually long ari hose (over 8 meters). the minimum bore for hose and fitting is 1/4" keep hose away from heat, oil and sharp edges. Check hos es for wear and make certain that all connections are secure. FAULT DIAGNOSIS Low compression reading on some cylinders Use oil in cylinder to see if rings are worn if compression increases, rings and/or cylinder wall are worn if compression does not rise, do a cylinder leakage test to determine source of problem high relative compression readings and relatively equal cylinder readings. but, if excessive exhaust emissions, lack of power, poor performance, or poor fuel consumption do a cylinder leakage test to determine source of problem. lower relative compression readings. one or more cylinders lower than others do a cylinder leakge test to determine source of problem. Cylinder Leak Tester •use Cylinder air leakage measuring instrument is suitable for detecting whether the air-tightness of automobile engine cylinders is within the allowable air leakage range; it can further determine the air leakage location and cause from the analysis of the failure phenomenon, so as to take measures to eliminate the failure. •principle The inspection principle is to inject a certain amount of compressed air into the cylinder when the engine is static and the piston is at the top dead center position of the stroke. The time it takes for the air pressure to drop to a specified value reflects the size of the air leak. The shorter the time, the larger the air leakage. 3 On the contrary, the smaller the air leakage. If the constant pressure air is continuously supplied, the main parts causing the air leakage can be judged, so that the engine can be maintained in a targeted manner. •Instrument structure The instrument consists of a pressure regulator, an intake pressure gauge, a measuring pressure gauge, an air duct, a quick-change connector, etc. the main technical parameters Pressure measurement range: 0—1 MPa Inlet pressure range: 0-l.6 MPa Working air pressure: 0.6—0.8 MPa •How to use 1. Remove the spark plugs of the engine, use the handle to turn the crankshaft to make the piston at the top dead center, engage the direct gear, and tighten the parking brake to prevent the compressed air from pushing the piston to move during the test. 2. Screw the air supply connector on the first cylinder at the compression top dead center, connect the quick-change connector end of the air duct to the output end of the measuring instrument, and at the same time, connect the air compressor to the input end of the test instrument . Close the pressure regulating valve of the instrument (pull out the pressure regulator knob when in use). 3. Start the air compressor to inflate, and close it when the charging reaches 0.8MPa, prepare the stopwatch, quickly start the pressure regulating valve, press the stopwatch at the same time, record the pressure holding time, observe the change of the pressure gauge, when the gauge pressure drops When it reaches 0.4 MPa, press the stopwatch to record the time it takes for the gauge pressure to drop from 0.8 MPa to 0.4 MPa. Use this length of time to compare similar machines to diagnose the degree of damage to the cylinder air leakage. The longer the maintenance time, The better the air-tightness of the cylinder; if the pressure holding time is very short, usually less than 10 seconds, it indicates that the air redness is serious and the air leakage must be repaired. In order to facilitate the test, the test sequence of each cylinder is carried out according to the firing order of the cylinders. One cylinder can be tested for every half revolution (180°) of the crankshaft. 4. Judgment of leaking location Simultaneously actuate the air compressor to deliver air to the cylinder at the top dead center. Use the pressure regulating valve to control the pressure at 0.6MP3. Listen carefully to the sound of air leakage to determine where the cylinder is leaking. If you hear the sound of air leakage at the intake manifold, it means that the intake valve is not sealed; if you hear the sound of air leakage at the muffler port of the exhaust pipe, it means the exhaust valve is not sealed; if you hear it at the oil filling port, Generally, there is a sound of air leakage, and a slight small sound is normal; if you hear a loud sound and feel that there is air flow, it is a serious air leakage, indicating that the cylinder-piston pair is not sealed: If you see air bubbles at the radiator filling place Emerging from the water indicates that the cylinder head gasket is burnt out, causing the cylinder and the water jacket to pass through; if you hear the sound of air leakage at the spark plug port adjacent to the cylinder, it indicates that the cylinder head gasket is burned out between the two cylinders and a cylinder flush occurs.

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 | #461,715 in Automotive ( See Top 100 in Automotive ) #3,681 in Diagnostic, Test & Measurement Tools |
| Brand | ONDY |
| Brand Name | ONDY |
| Customer Reviews | 4.2 out of 5 stars 448 Reviews |
| Item Dimensions | 11.81 x 11.81 x 1.97 inches |
| Item dimensions L x W x H | 11.81 x 11.81 x 1.97 inches |
| Manufacturer | ONDY |
| Material | Carbon steel |
| Material Type | Carbon steel |
| Number of Items | 1 |
| Part Number | 29-0629 |
| Thread Style | Npt |
| Thread Type | Npt |
| UPC | 016071508109 |
| Unit Count | 1.0 Count |

## 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)
![New Leak Down Tester Tu-21 Engine Cylinder Leak Tester Leakage Detector Engine Compression Tester Gauges Set - Image 2](https://m.media-amazon.com/images/I/81+O9WPDreL.jpg)
![New Leak Down Tester Tu-21 Engine Cylinder Leak Tester Leakage Detector Engine Compression Tester Gauges Set - Image 3](https://m.media-amazon.com/images/I/81AZ4cs2FsL.jpg)
![New Leak Down Tester Tu-21 Engine Cylinder Leak Tester Leakage Detector Engine Compression Tester Gauges Set - Image 4](https://m.media-amazon.com/images/I/81hB2ImneDL.jpg)
![New Leak Down Tester Tu-21 Engine Cylinder Leak Tester Leakage Detector Engine Compression Tester Gauges Set - Image 5](https://m.media-amazon.com/images/I/71uhoqf2ILL.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 Poland*
*Store origin: PL*
*Last updated: 2026-05-27*