This is a high quality TU-21 cylinder leak detector, including double gauge system, 2-1/2" input pressure gauge, snap-on quick connect male connector, gauge scale 0-100PSI, 12mm, 14mm spark plug adapters, air regulator and carry case. After the short block is assembled I install the head WITHOUT the cams, or the followers, or the pushrods, or without whatever operates the valves. If you are on the hunt for a leak down tester, chances are you have a serious engine problem or are trying to isolate one.

Tip: Insert a long screwdriver or extension into the spark plug hole and turn the engine by hand with a socket on the crankshaft. Equally likely is the fact that this is one purchase where quality and accuracy are essential elements. This is simply pressurizing a cylinder to check both the amount of leakage and where it is leaking from.

The use of a controlled, regulated compressed air source makes a leak-down test much more consistent and repeatable. Depending on your budget and how much power you are willing to give up, you will probably want to rebuild the engine when leak-down reaches somewhere around 10% to 15%. Usually head gasket issues also come with overheating, white clouds of smoke that dissipate quickly (steam).

These types of scenarios are accounted for in our ranking process to ensure every option is truly the "best of. Although a compression tester alone won't give you a detailed picture of your engine's health, it can (and should) be used first if there is any reason to believe that a problem might exist.You can test both of these at one time without rotating the engine at all as the cam position is NOT part of the equation. comes with 12mm and 14mm fittings, and must be calibrated before each use by manipulating the Schrader valve for the regulator. It DOESN"T mean you have fixed your valve problem by this method when you achieve good readings using this trick, merely that you have for sure found your problem.

At low and modest leakage percentages, there is little or no difference between single and dual gauges.Others may not be clamped on to the hose and allow air to escape during a test, thereby causing a false reading. A locomotive engine which gives a leak-down of 10% on a leak-down tester is virtually perfectly sealed while the same tester giving a 10% reading on a model airplane engine indicates a catastrophic leak. If the timing mark is off more than 1/2 degree a free engine (no plugs and not in gear) will spin 180degrees when 100PSI is applied to the cylinder at TDC compression.