What is a leak down test? What does it measure?

My car is burning oil like a **** but it still fells nice and strong. The only thing bad with my car is that the oil temp guage on my GSR doesnt work at all.

So with all this oil burning Im told I should get a compression and leak down test.

 

oops i hit the send button too quick

Compression test - basically you stick a compression tester into the spark plug hole and crank the engine 5 times or so. The gauge will give you a reading of the compression of your engine...if there are no leaks, the pressure will be around 200 for a GSR. There is no specific number your looking for. A good engine will have a small difference between the highest compression number, and the lowest. A reading of lets say...200 205 203 201 is good.....but if its 200 203 204 120 ...there is clearly somthin leaking out of the last cylinder. Reason why no specific number is given is because there are a lot of variables, like battery power and what not...*Do a search on how to do this because i did not describe it in detail sufficient enough to accomplish this task.

Leakdown test - The more conclusive test . You need a compressor and a leakdown test kit to do this. Basically it's similar to the compression test in that it also looks for leaks (duh, look at the name). However, the method of looking for the leaky cylinder is different. Instead of cranking the engine and using the piston to compress the air, and measuring the amt of compression, the leakdown tester pumps air into engine. Lets say 100psi. the gauge in the leak down tester will show you how much pressure is actually there. From this information you can tell how much is leaking. The reason why it is more conclusive is because in this test there are less variables. Here your looking for all the cylinders to be 100(if you are using 100psi), that is a tight sealed engine..whereas in compression your looking for somthing around 200, and all the numbers to be close to each other +/- X%
Also, the benefit of the compressor pumpin air in is that you can locate the leak.

If it's the exhaust valve is leaking, sounds will be comming from the exhaust
If the intake valves are leaking, the sound will be emerging from the intake
If it's the head gasket, the coolant will have bubbles in them
If the rings are bad and you have blow by the sound will be emitting from the oil filler cap.

Hope this helps




[Modified by Ricehornet, 10:37 PM 8/25/2001]

 

Excellent, thanks!!

 

BTW there is no factory oil temp guage on the GSR. You wouldnt happen to be referring to water temp would you?

 

hmmmm I thought that picture was a pic for oil. Its the guage on the left side.

temp,tach,speedo,gas

Im thinking the temp guage not working is not affecting anything at all on my car. Theres plenty of fluid in it, so it should be fine.

 

The temp gauge that comes stock is a water temp gauge