can you use this as a compression tester?

No. With a compression tester, the engine is cranked over with the spark and fuel systems disengaged. The compression stroke is what generates the pressure that is read on the gauge. It's used to see if the cylinder can produce adequate pressure during a stroke or if air is escaping somewhere (like past piston rings, or through non-sealing valves, for example). It will not, however, help you locate a leak.With a leakage tester like this one, compressed air is supplied through the spark plug hole into the cylinder through the use of an air compressor. One meter will read you the amount of air pressure you put in, the other will read you the amount of air that stays in the cylinder. This will show you a percentage of air that is leaking. With a constant supply of air going into the cylinder, you can then look and/or listen for leaks. Sometimes the air is escaping past the rings into the crank case, sometimes past an intake valve or exhaust valve that is not closing for some reason, and in some case the air might be leaking past the head gasket into another cylinder.Different tools, different process. I'd buy both.

What would be a good compressor to use with this?

Any compressor that has a tank. And an built 120psi. I would say probably atleast one of the pancake compressors with the 1.5 gallon tank you need the volume from it to sustain the 100 psi in the cylinder. And enough to were if it does lack it doesn't have to turn on to build preasure. But I have a 3 gallon tank and it works great. I have resently put a bigger tank on it becuase of my impact guns. They needed more volume so I hosed in a 15 gallon tank and tied it into my hose. The compressor takes a little longer to fill ip the tanks know but I multiplied the tank size by 5. It is a realy nice tool. I use it all the time. I did let it sit for a while once and you should apply a light coat of oil to the rubber hoses or they will start to get stiff. But that's what rubber does.

audi 4.2l v8 how do you tighten the fitting into the very deep well spark plug hole? Is finger tight by twisting the hose good enough?

Just snug the fitting into the cylinder hole by gently twisting the hose if you can't snug the fitting in with a wrench. If needed, put a rag on the hose, to protect it, and tighten just a little bit more with a slip-joint pliers. Over tightening the fitting will just ruin the o-ring. Apply a small amount of silicone lubricant to the o-ring to lube it before use. The o-ring will then make a "wet" seal and won't bind-up as it's being tightened . DO NOT use any petroleum-based lubricant to lube the o-ring because it breaks down rubber over time. I also do all this when using a compression tester. Have fun!

can you use this tool AS IS to presurize a cylinder to change vavle springs on an engine?

I believe you can use this tool to hold the valve closed while removing the valve spring if you unlock the valve stem keepers first. I do it all of the time and use 100 PSI of air pressure. The piston has to be at bottom dead center. You can also remove the spark plug, insert a flexible rope (cloth drying rope) in the cylinder when the piston is at the bottom of the stroke, rotate the crankshaft to squeeze together near top dead center to hold the valve up while the valve spring is taken off and put back on. It takes longer this way but you do not need the tool or air pressure.

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Description

🔍 Uncover the Truth Behind Your Engine's Performance!

BUILT TO LAST - Rugged protective outer boots on gauges ensure longevity and reliability.
DURABLE ORGANIZED - Blow molded storage case keeps your tools safe and organized.
USER FRIENDLY DESIGN - Comes with a detailed instruction chart for effortless operation.
DIAGNOSE WITH PRECISION - Quickly identify engine issues like bad rings and leaking gaskets.
VERSATILE COMPATIBILITY - Includes adapters for 10mm, 12mm, and 18mm threads for most applications.

The OTC5609 Cylinder Leakage Tester Kit is an essential tool for diagnosing internal engine problems, featuring dual gauges, a pressure regulated manifold, and a comprehensive set of adapters, all housed in a durable storage case.

Reviews

R**E

Quality leak down tester

Please avoid all the cheap Chinese leak down testers on Amazon. This is a proper leak down tester and diagnostic tool. If use correctly, it will give you accurate readings and help you diagnose blowing head gaskets, cracked blocks, cylinder and valve leakage amongst others. Compared to the cheap sets polluting Amazon, that are all the same by the way, this one uses quality air hose fittings and gauges. It is built very sturdy to withstand life in a shop. Included are m10, M12 and M18 adapters and the hose is hidden within the case. There is operating instructions and a handy chart to read the percentage of leakage on the right hand gauge. If you need to perform a leak down test, you cannot afford to have inaccurate readings. Buy a quality tool that allows you to get the job done right the first time and save yourself a ton of frustration. You're already going to be spending enough replacing the head gasket so don't cheap out on your leak down tester

11.03.2024

H**1

Excellent tool good quality good price

OTC makes the best mechanics tools excellent leak down tool works well easy to diagnose a problem, good price and delivery Honest dealer thanks from down under 🇦🇺🇦🇺

13.09.2025

R**Y

Extremely good quality

Works fantastic. I absolutely love it. Don't buy cheaper imitations if u want 100% accuracy. Buy once cry once. U will be 100% satisfied

5.08.2025

T**S

Very Good Tool

This worked great. I first ordered a $35 one that is sold under lots of different names, and it was totally non-functional. This one did exactly what I needed it to do, helping me to diagnose a car. Notice that it does not have the green, yellow, and red zones in the leakdown gauge readings. I prefer it not having that, because every vehicle has different specs about the % of leakdown that is acceptable. You have to do a small bit of math, but you get much more reliable results.

7.03.2025

C**G

Really good quality.

After messing around with the AMAZON cheap brand leak checkers, and having no luck with consistency (nor was the thing built correctly) I bought this OTC brand for my sprint car engine. It is perfect! Reliable and consistent. Plus it looks cool too. Buy this instead of the cheap brands. At least you will know what you have.

27.11.2024

R**O

Almost perfect

Gauges work and feel like a snap on brand quality. Being picky, the case build quality is the cheapest thing I've seen, and the gauge back plate design is just nonexistent.

14.09.2025

S**1

A must have in any shop!

This OTC leak down tester and diagnostic tool is essential in any home garage or shop. If used correctly you can diagnose blown head gaskets, cracked blocks cylinder and valve leakage. No more guessing around what the problem could be. The OTC Brand is know for quality products at great prices. I would recommend this to everyone.

28.03.2024

J**C

Great diagnostic tool!

My classic car was smoking on startup and I needed a leakdown tester to help me determine where the problem was. I read the reviews for this tester and decided to give it a try. The quality of this unit appeared to be very good, and with the test hose not connected both pressure gauges read spot on. The tester was fairly simple to use, although a certain amount of mechanical skills are needed to get the best results. The tester clearly showed me the condition of my engine, and what repairs were needed. All in all a good quality product I would purchase again.

18.09.2023

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