On this type of test can you take off all your spark plugs then perform the test or do you have to take each spark plug off one at a time.

 

 

one at a time is fine

-Brian

 

ok say if i took out all the spark plugs should any air be coming out of the other spark plug holes. I dont think it should just trying to determine if i have a bad headgasket or somthing

 

i dont think there should be any air coming out of any of the other holes but from my experience Ive always only taken one out at a time and even the shop that i go to they do the same

 

first set the leak down tester.
put #1 at top dead center
take plug out and do a leakdown
then do number 3, 4, 2-- make sure each cylinder is at top dead center before you do a leakdown.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by IH82LOSE &raquo;</TD></TR><TR><TD CLASS="quote">ok say if i took out all the spark plugs should any air be coming out of the other spark plug holes. I dont think it should just trying to determine if i have a bad headgasket or somthing</TD></TR></TABLE>

if that's what you're doing it for, there's no need to take off all the spark plugs at the same time. just pop off the radiator cap and look for bubbles coming out of the radiator.

 

the reason he is doing it is because one of the cyl has a low compression number and we are trying to figure out whats going on.

he took out all the spark plugs and then did the leak down test. air came out of the spark plugs holes when doing the test.

he's wondering, should air come out of the spark plug holes when testing one cyl? shouldn't the head being bolted down prevent air from going into the other cyl when doing the leak down test?

you see what i'm saying?

 

any other idea

 

did you do the leak down the way i suggested?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by IH82LOSE &raquo;</TD></TR><TR><TD CLASS="quote">ok say if i took out all the spark plugs should any air be coming out of the other spark plug holes.</TD></TR></TABLE>
No

 

you CAN take all the plugs out, it doesnt matter.

don't believe the hype. (chuck d)

 

Thats how i did the leakdown test by removing all of the plugs. Now what happen when i did that air was coming out of the other spark plug holes. My question is is that suppose to happen. thanks

 

yeah, its blowby. dont worry. your leakdown results will still be correct.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by IH82LOSE &raquo;</TD></TR><TR><TD CLASS="quote">Thats how i did the leakdown test by removing all of the plugs. Now what happen when i did that air was coming out of the other spark plug holes. My question is is that suppose to happen. thanks</TD></TR></TABLE>
No, if your doing the leakdown test right, that means there is a leak. Valve or headgasket.

 

I would think no air should be leaking out of the other spark plugs right. So a bad headgasket or bad valves will leak air threw the other spark plugs right. Well i took the head off gonna have the valves check to see if any are bad if not i guess i had a bad headgasket then.
Another question to anyone that knows when i had the piston at top dead center in order to know whether i had a bad valve should any air come out of the exhaust or intake. Lots of air was coming out of cyl 1-3 except for cyl four it held 100 plus psi of air with no leakage. thanks

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by IH82LOSE &raquo;</TD></TR><TR><TD CLASS="quote"> Lots of air was coming out of cyl 1-3 except for cyl four it held 100 plus psi of air with no leakage. thanks</TD></TR></TABLE>
You put each cylinder you were testing to TDC on the compression stroke right?

 

yes thats how i perform the test in each cylinder piston set to the highest point

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by IH82LOSE &raquo;</TD></TR><TR><TD CLASS="quote">yes thats how i perform the test in each cylinder piston set to the highest point</TD></TR></TABLE>
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Chiovnidca &raquo;</TD></TR><TR><TD CLASS="quote">
on the compression stroke right?</TD></TR></TABLE>

 

the pressure will stay separate in each cylinder.

 

so no air should be leaking out of the other spark plug holes. all the air should stay in each cylinder right the air should not be leaking to the other cyl. So say i put the compress air in cyl 1 no air should be coming out of the other cyl 2,3,4 right

 

you SHOULD remove all spark plugs. if you dont and you have a leak between cylinders it will give false readings.

leakdown and compression tests have this same procedure.

 

you take one plug out at a time when doing a compression test.

when doing a leakdown test, how would air come out of the other cyl when your just putting air in one cyl? shouldn't the head being bolted down prevent that from happening? i would think air wouldn't be able to get from one cyl to the next unless the headgasket is worn or something.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by hondaeg8 &raquo;</TD></TR><TR><TD CLASS="quote">you take one plug out at a time when doing a compression test.

when doing a leakdown test, how would air come out of the other cyl when your just putting air in one cyl? shouldn't the head being bolted down prevent that from happening? i would think air wouldn't be able to get from one cyl to the next unless the headgasket is worn or something. </TD></TR></TABLE>
no you dont! you remove ALL PLUGS, if you have a cross cylinder leak it can give a false compression reading!

the air comes out the other cylinder if you have a blown headgasket.

 

according to the c-speedracing directions...i believe you take one plug out at a time.


so since this guy has air coming out of all cyl when spraying air in one cyl, the headgasket is blown?