leakdown assistance plz.

[s13drob]

2day i tried to do a leakdown test on my 1993 jdm sr20de motor. every cylinder i tested i heard air coming out either the exhaust or intake ports of my motor. i had the valve cover off and made sure the rocker arms were at their highest point (visual 2 make sure timing was right and to make sure valves were closed) plus made sure the cam lobes werent pushing them down. i put a little oil in the cylinder via spak plug hole.

could this mean i have major headwork ahead? could there be multiple valves bent or could it be bad springs? or could it be dried out hydraulic lifters? any help is appreciated.

[sr20det drift]

before you screwed in the guage, did you make sure that the clyinder you where testing was at TDC ? othere then that your valves arent sealing, which you probably already know

[s13drob]

before you screwed in the guage, did you make sure that the clyinder you where testing was at TDC ? othere then that your valves arent sealing, which you probably already know

thanx 4 a quick response. yea i even put a long screw driver in the spark plug hole and made sure it went all the way up and made sure the cam lobes werent opening the valves.

[Gjohnson7]

Are you sure your timing is set correctly. Does the engine run??? I would set the engine at TDC and make sure the cam marks line up with the FSM and then retest.

[s13drob]

engines a no go. im working on rebuilding it and i wanted 2 do a good leakdown 2 figure out what ima need.

any1 got that info off the FSM? is it for each cylinder the exhuast lobe and the intake lobe supposed 2 be 90 degrees of eachother? i.e. (intake down - ex. up)?

[s13drob]

never mind tha 90 degress BS. i found out its intake 12o'clock and ex. 10 o'clock. but if my cams are set right and i have the engine locked at TDC what could be causing my leakage? or any tips?

[brndck]

if you are 100% sure that the cyl ur testing is at tdc when you test it, first thing to make sure of is that your crank isn't moving when you apply air pressure to that cyl. if its still leaking down then most likely you have a valve that isn't seating properly. maybe burned or may have damage to the seat. but at that point you'd need to remove the head to inspect further, unless you have access to a boroscope. (iirc you shouldn't need to add oil to the cyl unless ur doing a compression test, not a leakdown test, but i may be incorrect).

[s13drob]

yea when i test a cylinder i lock it at TDC via chain from flywheel bolt 2 bolt on block. i guess ima have to remove the head but if it is a valve problem how could it happen to basically all 4 cylinders. 2morrow ima check timing.

can some1 confirm that the cam sprocket gears have to be 12 o'clock for intake and 10 o'clock exhaust when the cranks at TDC? any links that could help me. other than the "set CAS timing" writeup off FRsport? thanx guyz

[aNskY]

no you are wrong, its not the sprocket gears that have to be 10 and 12, its the cam key on the front of the actual camshaft. intake should be 10 o clock and exhaust 12oclock. this is straight out of the fsm page EM-27

[s13drob]

where can i find the cam key exactly? i dont have a fsm. i cant even find 1 to DL

[s13drob]

Nm found a FSM. thanx ima check the timing later

[s13drob]

timings correct. im in process of removing the head... waiting to get a 10mm allen socket 2 remove headbolts. cams and cam journals look pretty good. no bad wear.

[Z U L8R]

yooooooooooooo, hold up.

are you using a real leak down tester? or just shooting compressed air into your engine?

4% leak is allowable, a real leak down tester will give you the % of leakage. anything in the 10% is still driveable, anything more than that is a tired or busted the fuck up motor hahahhaha

before you get all happy dissassembling ur motor cause you heard 150+psi of compressed air swooshing around ur motor.....do u know what % leakage the cylinder has?

Dave

[s13drob]

yea i used a summit racing dual gauge leakdown tester running at 100psi. somethings has 2 be wrong with the valves. when i did the 1st cylinder air was comin out only 1 of the intake valves and air was leaking through the exhaust too.

n by the way i am happy because im breakin it down :naughtyd: :naughtyd: ... u gotta love it. n i was goin 2 have 2 remove the headgasket anywayz when i buy a gasket kit

[gotta240]

I think you may be making the same mistake i did when i first did a leakdown test. If you are getting LOTS of air from the intake or exhaust sides, rotate the motor one full rotation untill the cylinder is at the top again.

I was 180 degress out when i first did it, and got similar results as you.

[s13drob]

shiet. 2late. i already removed my cylinder head. i planned on replacing the HG n e wayz. ima get the head machined for 160 at a local shop (valvejob, clean resurface and pressure tested) which i think is a good deal. thanx 4 the info tho... ill remember that nxt time.

heres a pic of my cyl. head. let me kno what u guys think or can see.
http://i2.photobucket.com/albums/y21/csalgangsta/4-7-08003.jpg
http://i2.photobucket.com/albums/y21/csalgangsta/4-7-08002.jpg
http://i2.photobucket.com/albums/y21/csalgangsta/4-7-08001.jpg

[gotta240]

LOOKS normal too me. Not too much carbon and no steam cleaned spots from water. A pressure test will tell all.

Was the HG intact when pulled?

[s13drob]

yea... it was doin its job.

[s13drob]

ok 1 question. what can i use 2 remove the rest of the HG residue off the shortblock? i read in a post somewhere where a guy used laquer thinner. is that a good choice and then just flush it with oil?

[jspaeth]

Why is this poor guy so deep in the red? Good luck with your rebuild.

[project_s13]

at TDC you have overlap= both valves are open slightly. if your doing a leak down especially on small engines that will have more overlap. you would rather be on BDC or on compression stroke. if both valves are riding on the base cirlce of the cam lobes you know those valves are closed. on that note valve lifters dont usually stick open they usally colapse. if ones was stuck open youd notice a misfire in your exhaust or through your intake underload. if you need any more help PM me

Your friend the mechanic
Project_s13

[project_s13]

FYI laquer thinner tends to eat fine metal. you probably could. I (a person who build engines on regular basis) take long way around I eaither use plastic blade or if i have to a steel one. but with sharp blade be carful not to gouge the aluminum block. another technique that works extremely well for me is find a large flat low grit file. one thats about 2 inches wide about 8-12 inches long. run it along the top of the bloek being carful to stay flat on the block and dont file the edges. go back and forth on the block not legth wise. and dont use a whole lot of pressure. it will do its job. spray some deep creap or some fluid film on there with it. it will help. maybe some gasket remover aswel. clean it up then use the file. thats the way i go. the file will also remove and burs and what not from the block. which is nice for a new headgasket then you know you have nice sealing surface. ALSO make sure your dont file in one area for long period of time. ALWAYS keep mooving as a steal file will eat aluminum quickly. IF IT CONTINUES to be stuborn go buy a 3m pad from paint store or parts store there about 4x5 sheet i use red grade. it works well also. but again being sure to not press to hard as it will eat aluminum. when its shinny ish its done PM me if u need further help

[s13drob]

sweet. great help. when i was doin the i made sure both cams were on the base circle of the lobe. ill find out whats up with the head from the machine shop when i send it in.

great advice tho. just about the best i got from this thread. thanx every1 esp. P s13. i will contact u if i need any more help.:bowdown: :bow: :bowdown:

[project_s13]

oh and FYI when u put ur head back on before you start it make sure u clean out the cylinders and before u bolt the head down pour abour a teaspoon of any type of ATF (auto trans fluid) in each cylinder. lubs the rings and prevents dry start which is death to many engines. for the 2 sseconds it takes and 5 dollars it worth can save u blown rings or major repairs down the road :P. just a little secret i learned doing engines. i do it every year after car has been sitting for 2-3 months of winter. and change ur oil after ur heads back on and change it gaain after about 100 kms dunno what that is on miles. and enjoy lol

[s13drob]

:angel: :kiss: haha no homo. thanx again s13. ur tha shit