leak down test

yalipito

New member
Hi guys, I setup my gauge/regulator to 100psi and connected to the engine and I'm losing 5 psi. Is that too much, normal or border line? It is getting past the rings by the way. Thanks
 

DynoDon

Member
Your best way to determine how your own personal tester is doing would be for you to test an engine that you know is a strong engine. Many times a leakdown is like a dyno depending on the type of unit you have. so take a reading on your best engine that you know is a good engoine and document from there. 5% in my book is not a good leak. Make sure the engine is warm to touch or hotter if ya can stand it. Listen to the exhaust, carb, and breather to determine where the leak is.
 

yalipito

New member
Your best way to determine how your own personal tester is doing would be for you to test an engine that you know is a strong engine. Many times a leakdown is like a dyno depending on the type of unit you have. so take a reading on your best engine that you know is a good engoine and document from there. 5% in my book is not a good leak. Make sure the engine is warm to touch or hotter if ya can stand it. Listen to the exhaust, carb, and breather to determine where the leak is.
Don, I know that the leak is at the rings as I already did the "listen" test, the engine was cold though. 5% not good in your book, what do you mean? Too much of a leak? If so what is acceptable from a "competitive" point of view? Thanks for your input.
 
Not all testers are created equal. They come in a wide variety of prices. I use a cheapo Harbor Frieght unit. It never shows less than 5% leak down. Heck I even capped the end and put air on it and it showed 3 to 4% leak. Ive checked enough with it to know that anything less than 6% is GREAT and less than 8% is Ok. Thats on my gauge. We all have to decide what OK means to us. Those that require less than say 3%, have a real good gauge. I feel like Im shooting for abot 3% but my gauge simply wont show that number. %5 may be really good from your gauge. It may be just on the edge of worn out too. Thats why Don said to check a known good engine. Campare to your buddys gauges too. In all reality, I should just get another gauge. Just old and set in my ways I guess.(AKA cheap and lazy).Good luck
 

sCREamnClones

New member
Hi guys, I setup my gauge/regulator to 100psi and connected to the engine and I'm losing 5 psi. Is that too much, normal or border line? It is getting past the rings by the way. Thanks
If you have 'loses' at the valves, engine temp will not have 'much' (if any) any effect with your reading(s). However, leak-down loses via 'rings' is critical in the need of engine heat! If you are 'seeking' too identify a problem, you 'must' test with the engine being as heated as possible. If, you are 'monitoring' the condition of your engine...you can develop a 'number' that works-4-U under room-temp conditions.
 

Kart43

Member
Also remember a head gasket can leak into the oil galley or push rod tunnel which would be heard through the crankcase and rings may not be the culprit.
 

astrowrench

New member
A squirt of heavy oil in the cylinder will pretty much seal rings, to help isolate oil galley or pushrod area leakage
 

DynoDon

Member
Don, I know that the leak is at the rings as I already did the "listen" test, the engine was cold though. 5% not good in your book, what do you mean? Too much of a leak? If so what is acceptable from a "competitive" point of view? Thanks for your input.
5% is good in my book when the engine is cold by "MY" leakdown tool
 

bigcat6

New member
Not all testers are created equal. They come in a wide variety of prices. I use a cheapo Harbor Frieght unit. It never shows less than 5% leak down. Heck I even capped the end and put air on it and it showed 3 to 4% leak. Ive checked enough with it to know that anything less than 6% is GREAT and less than 8% is Ok. Thats on my gauge. We all have to decide what OK means to us. Those that require less than say 3%, have a real good gauge. I feel like Im shooting for abot 3% but my gauge simply wont show that number. %5 may be really good from your gauge. It may be just on the edge of worn out too. Thats why Don said to check a known good engine. Campare to your buddys gauges too. In all reality, I should just get another gauge. Just old and set in my ways I guess.(AKA cheap and lazy).Good luck
I would take this to the bank...
 
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