Leakdown test procedure info needed
02-07-2015, 11:42 AM
#31
Registered
I have a tool that I am improving upon that screws into the spark plug hole and is spring loaded that has a measuring stick that moves when the piston moves. It is very accurate for finding TDC and on the compression stroke of course. I should have this tool completely on the market in about 3 or 4 months. Takes all the guess work out of finding true TDC.
Believe it or not a lot techs in the marine industry do leak down tests on 2 stroke outboards engines as well and you have to lock down the flywheel when filling the cylinder(s) with air. The tool I am bringing to market will be a hit for the outboard tech using it on 2 and 4 stroke engines as well..
Also I sell digital leak down testers for 200 bucks and the analog ones for 100 bucks and they are not cheap quality ones like HF or Northern tools. HF are not accurate by no means. FYI
Believe it or not a lot techs in the marine industry do leak down tests on 2 stroke outboards engines as well and you have to lock down the flywheel when filling the cylinder(s) with air. The tool I am bringing to market will be a hit for the outboard tech using it on 2 and 4 stroke engines as well..
Also I sell digital leak down testers for 200 bucks and the analog ones for 100 bucks and they are not cheap quality ones like HF or Northern tools. HF are not accurate by no means. FYI
02-07-2015, 12:43 PM
#33
Platinum Member
Platinum Member
It makes sense that when the crank throw and rod are fully extended in the bore TDC that it wont try to rotate, good read
Last edited by F-2 Speedy; 02-07-2015 at 12:49 PM.
02-07-2015, 12:53 PM
#34
Banned
And I will add as people will ask how can you make it easier to find your leak source. ie: ring seal -cylinder - piston or valves intake or exhaust or even the head gasket.
What I do is tape Kleenex one side of it only over the exhaust tips and another kleenex over the intake = carb or throttle body then add the air in the cylinder - if leaking watch for the Kleenex blowing if not blowing then stick your mechanics stethoscope way down the oil dip stick tube to hear air leaking past the rings / piston / cylinder. Also Kleenex tissue over the oil cap hole in the valve cover works also.
If it is a head gasket and you have closed cooling watch for air bubbles in the coolant - if no closed cooling use a real doctors stethoscope and use it to listen around the head area. You will hear the air leaking past the head gasket by useing the docs scope. I use this as a tool all the damn time. It is great for finding bad bearings in pulleys, lifter noise, crank bearing noise as well, when you can not figure out what and where is that noise coming from.
FYI Volvo Penta pulleys do not last that long and this how I can find out exactly what the noise is. I can not tell you how many times shops and owners think they have an internal engine problem but it is just the darn bearing in the pulley..
What I do is tape Kleenex one side of it only over the exhaust tips and another kleenex over the intake = carb or throttle body then add the air in the cylinder - if leaking watch for the Kleenex blowing if not blowing then stick your mechanics stethoscope way down the oil dip stick tube to hear air leaking past the rings / piston / cylinder. Also Kleenex tissue over the oil cap hole in the valve cover works also.
If it is a head gasket and you have closed cooling watch for air bubbles in the coolant - if no closed cooling use a real doctors stethoscope and use it to listen around the head area. You will hear the air leaking past the head gasket by useing the docs scope. I use this as a tool all the damn time. It is great for finding bad bearings in pulleys, lifter noise, crank bearing noise as well, when you can not figure out what and where is that noise coming from.
FYI Volvo Penta pulleys do not last that long and this how I can find out exactly what the noise is. I can not tell you how many times shops and owners think they have an internal engine problem but it is just the darn bearing in the pulley..
Last edited by BUP; 02-07-2015 at 01:01 PM.
02-07-2015, 10:40 PM
#35
Registered
Pretty good leakdown thread . If you want to get it done fast and effective hyfive had it down . It will take some practice . I vote remote starter , a quality dual gauge gauge (google what the faa specs for leakdown tests and call it a day ) let it spool at 30 psi stop hold pressure to 100 with breaker bar and good short socket .remember what smoky yunic said , all the important stuff happens at the top 2/3of the piston stroke .a go for the gusto buildwill return 3% or a late obd2. If your not that guy get a reading from the 2nd gauge at 30 move the breaker bar while tecnician b manipulates the air pressure to 100 psi and get a feel of whats happening in the engine .if you have a leakdown tester that reads in percent , toss it and get one that reads psi.
02-08-2015, 01:42 AM
#37
Registered
so just tape a tape measure around the balancer with 0 inches at tdc. see the number where it hits tdc again? 7 inch balancer will be 21 and some inches. 11 inch balancer 34 or so. divide that number by 4 and that is your 4 tdc marks on the balancer.
02-08-2015, 03:31 AM
#38
Registered
I have a tool that I am improving upon that screws into the spark plug hole and is spring loaded that has a measuring stick that moves when the piston moves. It is very accurate for finding TDC and on the compression stroke of course. I should have this tool completely on the market in about 3 or 4 months. Takes all the guess work out of finding true TDC.
Believe it or not a lot techs in the marine industry do leak down tests on 2 stroke outboards engines as well and you have to lock down the flywheel when filling the cylinder(s) with air. The tool I am bringing to market will be a hit for the outboard tech using it on 2 and 4 stroke engines as well..
Also I sell digital leak down testers for 200 bucks and the analog ones for 100 bucks and they are not cheap quality ones like HF or Northern tools. HF are not accurate by no means. FYI
Believe it or not a lot techs in the marine industry do leak down tests on 2 stroke outboards engines as well and you have to lock down the flywheel when filling the cylinder(s) with air. The tool I am bringing to market will be a hit for the outboard tech using it on 2 and 4 stroke engines as well..
Also I sell digital leak down testers for 200 bucks and the analog ones for 100 bucks and they are not cheap quality ones like HF or Northern tools. HF are not accurate by no means. FYI
02-08-2015, 09:30 AM
#39
I have a feeling i am about to get slamed but here is my thoughts anyway.
As usual with technical threads, this thread has come to the corner of neophyte and pedant, and made a hard left at pedant.
If we go down neophyte instead, this is an easy test to perform and if not done exactly perfect no harm no foul. This is a great way to assess the condition and isolate falts of the upper end of the engine. (lots of good info on this thread).
By the time you get it done the first time you will have devised your own tricks for success. It does not take long.
If you are doing it for the first time do it twice to verify repeatable results. Now document all readings and observations ie. Leakdown numbers, where the air is excaping engine overall performance etc.
Do this every time you change or read your plugs or having performance issues, document and compaire to previous reedings and you can get a good idea of any degration in your top end and plan accordingly.
This test, if done as a scheduled maintenance is kind of an engine top end barometer and indicator of things to come. Coupled with a compression test (heck the plugs are out already) and you know what is happening over time within the cylinders.
Most of us are not race engine builders and are doing this test to verify all is ok. Exact percission is not essential for valid results or trending.
Not trying to offend anybody, there is a need for perfection in the professional world but if you are asking how to and seaking advice you are not at the professional level, just trying to help.
Just my 2 ct. Go ahead and slam away.
As usual with technical threads, this thread has come to the corner of neophyte and pedant, and made a hard left at pedant.
If we go down neophyte instead, this is an easy test to perform and if not done exactly perfect no harm no foul. This is a great way to assess the condition and isolate falts of the upper end of the engine. (lots of good info on this thread).
By the time you get it done the first time you will have devised your own tricks for success. It does not take long.
If you are doing it for the first time do it twice to verify repeatable results. Now document all readings and observations ie. Leakdown numbers, where the air is excaping engine overall performance etc.
Do this every time you change or read your plugs or having performance issues, document and compaire to previous reedings and you can get a good idea of any degration in your top end and plan accordingly.
This test, if done as a scheduled maintenance is kind of an engine top end barometer and indicator of things to come. Coupled with a compression test (heck the plugs are out already) and you know what is happening over time within the cylinders.
Most of us are not race engine builders and are doing this test to verify all is ok. Exact percission is not essential for valid results or trending.
Not trying to offend anybody, there is a need for perfection in the professional world but if you are asking how to and seaking advice you are not at the professional level, just trying to help.
Just my 2 ct. Go ahead and slam away.
02-08-2015, 10:55 AM
#40
Banned
To further add some say 10% leak and under U are good - some say 15% and under leak and you are still good, some say 20% and under leak and you are still good. Merc lists in one of their service manuals 30 % and under is still good for leak.
Really if you are good at reading spark plugs and good with a vacuum gauge in which really is a forgotten test these days, you can determine a lot. Also a cylinder drop test using a digital rpm gauge set to a 1000 rpm scale is another good test.
Really if you are good at reading spark plugs and good with a vacuum gauge in which really is a forgotten test these days, you can determine a lot. Also a cylinder drop test using a digital rpm gauge set to a 1000 rpm scale is another good test.
