90 tsi has no compression in one cylinder

[Digitronical]

i just bought a 90 tsi awd and brought it home to do a compression test and found the first cylinder ( passenger side ) had a compression of 10-20. I added a cap full of oil into the first cylinder and nothing changed as far as psi. also when i pulled the plugs and wires that first cylinder had oil on it. the others were fine clapping around 150-160 psi. what is wrong with my new dsm and whats it gonna take to fix it.

 

[half-cocked]

I would say valve stem seals. If you did all the labor but out sourced the head work it would run you roughly $500. This is a VERY rough price off the top of my head. It includes new head gasket, ARP studs, new valve seals and a machine shop doing an R&R on the head reusing all other hardware.

 

[Digitronical]

can anyone comfirm this statment. I'm ready to start taking things apart to fix the car but i wanna know what i'm getting myself into first.

 

[Michael Z.]

With compression that low, I would say that you may have a of couple bent valves. I would say that the best bet is to remove your cylinder head, and get a valve job done. A 3-angle valve job, new seals, and possibly two new valves should run you about $400 to $500, if you re and re the head yourself. Otherwise, you could get a used head for about half the money, but you don't know what kind of compression you're going to see, or if it has issues too.

 

[FullyBuiltDSM]

definatly check the valves and seals, but also check to see if your timing belt has been replaced. if it has theres a chance that the previous owner could have jumped timing causing bent valves and maybe even chipped pistons. If theres an oil build-up in one of the cylenders you can try and suck it out then run the compression test again. it should go up some

 

[gunna's dad]

You need to do a leak down check first. You don’t need to go out and get a leak down tester unless you have a large need for one. Nice to have tool but ... a hose from a two part compression tester is all you need ( refer to JPG below for example) remove needle valve from hose and hook the hose to compressor. Install comp. gauge hose in spark plug hole. Roll piston for that cylinder to top dead center and apply air regulated to about 40-50 psi. Listen at exhaust and intake for leaks in the valve system. Listen at oil cap/pvc valve for ring blow by. This will help you determine if just the head has to go or the whole engine need to be removed for repairs.

BTW the Sears tool is $24.00

http://content.sears.com/data/product_images/009/02171/00902171000-dlv.jpg

Below links are for illustration only!

http://buy1.snapon.com/catalog/item...&group_ID=1424&store=snapon-store&dir=catalog

http://buy1.snapon.com/products/dia...atalog&pix=objects/28300/28257.JPG&email=true

 

[half-cocked]

Low compression and oil in 1 cylinder, a bad valve seal can lower compression and it prevents oil from getting into the cylinder. Is there any reason the valves might be bent, or is micheal z just shooting from the hip?

 

[92awddsm]

Low compression and oil in 1 cylinder, a bad valve seal can lower compression and it prevents oil from getting into the cylinder. Is there any reason the valves might be bent, or is micheal z just shooting from the hip?

Do you have any clue about what you speak of? Valve seals have no affect on compression what so ever. the compression is sealed by the pistons, rings, and valves. The valve seals are only there to keep the oil from running into the combustion chamber and cause a smoking problem. Do a little research before you start giving false information.

Digitronical, like stated before, do a leakdown test. Also, with the plug out, rotate that cylinder to bottom dead center and shine a light into it and visually inspect the piston. With 10-20 psi, the most likely causes are either bent intake valves or a burnt (melted somwhere around the edge) piston. Since it is only one cylinder and it has oil in it, I am leaning towards the burnt piston.

 

[half-cocked]

Do you have any clue about what you speak of? Valve seals have no affect on compression what so ever. the compression is sealed by the pistons, rings, and valves. The valve seals are only there to keep the oil from running into the combustion chamber and cause a smoking problem. Do a little research before you start giving false information.

Digitronical, like stated before, do a leakdown test. Also, with the plug out, rotate that cylinder to bottom dead center and shine a light into it and visually inspect the piston. With 10-20 psi, the most likely causes are either bent intake valves or a burnt (melted somwhere around the edge) piston. Since it is only one cylinder and it has oil in it, I am leaning towards the burnt piston.

Yeah actually I do, if you have a bad valve seal you will lose compression. Do you have any idea of what you speak of?

 

[gunna's dad]

If you have a large enough overlap in your cam, it is possible to pull oil/air past the intake seals and push exhaust gas past the exhaust seals. For this to happen you have to have worn guides and valves not seating properly. So in effect you already have a compression/vacuum leak to start with. That's not the problem here. If you reread his post he did a wet test also with the same results.

 

[Defiant]

Yeah actually I do, if you have a bad valve seal you will lose compression. Do you have any idea of what you speak of?

What in the hell are you talking about? Valve seals regulate oil supply to the valve guides along the valve stems. They have shit-all to do with compression.
If you're trying to talk about the valve and valve seat faces, use the right language.

 

[Defiant]

i just bought a 90 tsi awd and brought it home to do a compression test and found the first cylinder ( passenger side )

That's the last cylinder. #4. Motors count from the end opposite the flywheel (although there is some debate amongst V engines as to whether they count along the crank or along the heads)

had a compression of 10-20. I added a cap full of oil into the first cylinder and nothing changed as far as psi. also when i pulled the plugs and wires that first cylinder had oil on it.

You probably have an incinerated piston, although it may be a burned valve. It's extremely unlikely to have been a timing accident which bent a pair of valves, as that's almost impossible to do on a DSM motor- you'll take out at least two cylinders, and virtually always all four.

 

[gunna's dad]

What in the hell are you talking about? Valve seals regulate oil supply to the valve guides along the valve stems. They have shit-all to do with compression.
If you're trying to talk about the valve and valve seat faces, use the right language.

That's what I really wanted to say but being a rookie here.... Good pics, prime example of lean mixture, detonation, and valve seats being beat to death.

Dave

 

[half-cocked]

I'm an idiot, you guys are right. I was out ot lunch, I apologize to the micheal z, 92awddsm and Digitronical.