head cracked? cylinder 4 compression low

[affy]

wow been a long time since i got my hands on a starlet, cant run the gt4 now petrol is too expensive lol, but because i love the bov sound i got a ep82 again :haha:

only problem is cylinder 4 compression was low, i guessed it would be the piston ringland as i have had this problem few years ago with both starlets as there is a breather filter on the rocker cover and its letting out oil, (similair to catch can)

only problem is i took off the the sump, got the piston out (no.4) but it seems fine? no cracks or anything, could it be the head? can that be causing oil to get up to the blow by, maybe seals or valves?

since head is off was thinking of getting it tested, this is confusing as before in the past when oil was coming through the blow by it usually resulted in piston ringland failure?

compressin test results:

155, 160, 150, 100

no.4 is low

any help much appreciated

affy

 

[gtadvmike]

Might just be me mate but I have heard lots of people talking about putting a breather filter on the rocker cover and a little oil comes out it that aint due to piston ring failure that just happens lol

 

[Skalabala]

The rings could be tired?

 

[affy]

Might just be me mate but I have heard lots of people talking about putting a breather filter on the rocker cover and a little oil comes out it that aint due to piston ring failure that just happens lol

i really hope so lol easy problem to solve, but now i've opend her all up have to make sure,

The rings could be tired?

yeah even though theres no visible damge was thinkng to replace the rings?

is it possible there may be a hair line crack sumwhere? not visible to the eye?

 

[weeJohn]

Pour about 5ml of oil (teaspoonful) into number 4 and see if compression goes up, if it does it could be rings or a cracked piston. To check for leaking valves, turn the head over (watch the buckets and shims) and pour some petrol into the combustion chamber when both valves are closed. If it runs through then its the valves. If the heads not off the car, turn the cams until number 4 cylinder valves are closed, pour a little oil in the bore then blow an airline in the spark plug hole, it will need a decent seal down there but if an exhaust valve is passing then air will blow out the exhaust ports, intake valve then it will blow out the inlet ports.

 

[affy]

Pour about 5ml of oil (teaspoonful) into number 4 and see if compression goes up, if it does it could be rings or a cracked piston. To check for leaking valves, turn the head over (watch the buckets and shims) and pour some petrol into the combustion chamber when both valves are closed. If it runs through then its the valves. If the heads not off the car, turn the cams until number 4 cylinder valves are closed, pour a little oil in the bore then blow an airline in the spark plug hole, it will need a decent seal down there but if an exhaust valve is passing then air will blow out the exhaust ports, intake valve then it will blow out the inlet ports.

thanks for that dude

hmmmmmmmmmmmmmm this gona sound daft but how do i do all that as my head and psiton no.4 is out the car? if its mentioned above i do apologize, think am losing the plot lol either that or my eye sight

 

[Skalabala]

A hair line crack wont make the compression go down so much.
How does the bore look? Does it still have some of the original bore marks?
I will say it is tired rings. Give the block a hone and fit new rings and inspect bottom end and fit new big ends.

 

[affy]

A hair line crack wont make the compression go down so much.
How does the bore look? Does it still have some of the original bore marks?
I will say it is tired rings. Give the block a hone and fit new rings and inspect bottom end and fit new big ends.

bore marks are original like you said, theres no sign of unsual wear or marks, i inspected the bearings they are good too, just hoping its the head, will give it in tmrw hopefully for a test, say the head gasket was leaking at cylinder 4 would that cause oil to go up blow by?

 

[toyotagt]

bore marks are original like you said, theres no sign of unsual wear or marks, i inspected the bearings they are good too, just hoping its the head, will give it in tmrw hopefully for a test, say the head gasket was leaking at cylinder 4 would that cause oil to go up blow by?

id say its more then likely rings like he said,
have a very good look for cracks in the ringlands in the intake side, it the psitons are ok then just give quick hone and new rings, there only €101 off speedvision..


if the head gasket was gone it would be using water or if it was gone between cylinders no 3 would have had bad comp too. but you have it stripped now so you cant check all that..

 

[toyotagt]

did u check to see if there was oil in water? or water in oil? make sure u dont mix up the shims if you take them out.,
check ur valves aswell incase they need re seating,

 

[affy]

cheers guys, will go shortly to check the oil and water if its mixed, will update tmrw, or tonight, yeah have to be careful with the shims as last time i totally messed up they got mixed lol,

i was told by freind cant get single rings, would i have to buy full set?

right the plan for tmrw then is:

give head in to engine specialists
get it checked for pressure leak, valves and seals

hopefully then i can eliminate the head if its not that, hope its not costly, am already low on budget, dam taxes, low wages and fuel prices lol, cant even enjoy my gt4 no more myte just come back to the ep world again,

 

[weeJohn]

thanks for that dude

hmmmmmmmmmmmmmm this gona sound daft but how do i do all that as my head and psiton no.4 is out the car? if its mentioned above i do apologize, think am losing the plot lol either that or my eye sight

No you can only check the valves and combustion chamber is not cracked by filling it with petrol now. Maybe just take a note of it before ripping the engine apart next time lol.