leak down test

First you will need the gauges and a air compressor. I got mine from Summit Racing. The direction are very simple. The leakdown test tells alot.:biggrin:
 
The gauges will show how much leakdown you have. Could be valves, piston rings, ect, ect. One gauge will hold steady pressure the other will show how much leakdown you have. It seems complicated but once you do one cylinder you will fly through the rest. It really gives you a good idea of engine health.
 
You keepa you digits away from the accessory belt or you coulda loosa a digit or two.:eek:

When you plug the shop air into the leak down tester, the engine may rotate FAST, causing fingers to depart your hand if they as anywhere near the belt. Be careful.

As stated above just follow the instructions in the box. Listen to the throttle body for intake valve leaks by the sound of rushing air, then listen to the tail pipe for a leaky exhaust valve, then listen to the valve cover breathers for a leaky ring or head gasket. You will hear the sound of escaping air if it is leaking.
 
Summit, Jegs or even Harbor Freight has them. Not sure how accurate they are but there's not much to them. I have a Snap-On one, but one from Summit/Jegs would be fine for the money.
 
Not sure what you are trying to find inside your engine, but to get the best results from a leak down test you should loosen all the rockers so none are touching the valves when rotating the engine. They MUST be completely seated for accurate results.

If you suspect a cylinder or 2 does not have good compression, doing a simpler compression test will find that.

With a low compression reading on a cylinder, you may not be able to determine the exact problem, but if it is low due to head gasket, valve or something else, the head has to be removed for repair reguardless, good luck on what your are doing! :)
 
Here's a WIKI article explaining it's use, and a link to the Jeg's version.


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what readings are ok with turbo engine % leakage , my engine has 7% on all cylinders , is that acceptable ? What does a normal engine have thats been built and broke in have ?
 
I just finished putting a new set of heads on an 87 that had some cylinders in the 15% range and others in the 39% range. Valves were not seating very good. Compression check said 100 across the board. After heads, 130 and 4-6% leakage. New timing set also while it was all out and apart. Car runs like fresh from the dealer now. Typical rule of thumb is 8% is ok. Anymore and you start to look to where the compression is going.
 
Not sure what you are trying to find inside your engine, but to get the best results from a leak down test you should loosen all the rockers so none are touching the valves when rotating the engine. They MUST be completely seated for accurate results.

If you suspect a cylinder or 2 does not have good compression, doing a simpler compression test will find that.

With a low compression reading on a cylinder, you may not be able to determine the exact problem, but if it is low due to head gasket, valve or something else, the head has to be removed for repair reguardless, good luck on what your are doing! :)

X2. A leak down test is not completly acurate unless you loosen the rockers and get each cylinder at TDC. Doing a leak down on a new engine after it is broken in gives a baseline for future tests. Besides testing the valves for leakage, it is a great indication of ring seal as the engine wears.
 
Well if you have a score in your cylinder lets say below your ring package at TDC a leak down test is not going to catch that. That's why you really need to do both. The fact is they are both a pain in the ass to do in the car that's why I like to do em on an engine stand lol. Hope it checks out ok for ya.
 
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