Is it possible to tell if a smoking motor is being caused by leaking valve seals with the head off? Possibly checking the valve stems to see if theyre off color compared to the rest? Any certain color they should be?

d16a6 already apart, blew smoke when it ran, no compression test before pulled, head gasket seems fine, just trying to find a way to tell without having to replace them and the rings if I can narrow it down.

 

should've done a compression test before hand, but I think you figured that out. I don't think you can reallly tell by what the headgasket looks like or anything, There is a way to test without it on the block though, I think?

 

Yeah, I didnt really plan on using the motor for anything, had 195k on it anyway, I just wanted the shell for my ZC. When I decided to wire up my DX for mpfi I figured I'd just throw the whole a6 head on and bam. Maybe I'll just use the dx head, swap the cam and that'll be it....


Modified by blah13 at 11:03 AM 1/15/2004

 

you might be able to take the head to a machine shop and see if they can find anything with the head. Depending on how many miles are on the motor, you might want to just change the seals since you have the head off anyways.

 

How about its behavior when it was running... Valve seals will leak more when the vacuum is strong, like engine braking with the throttle closed.

A compression test won't tell you much because the valves are closed during the compression stroke. The valve stem seals don't see that pressure.

Edit for MeanB18:
Yeah, that's what I meant. The compression test wont say the valve stem seals are bad; but you're right, it'll show bad rings or bad sealing at the valves seats.



Modified by JimBlake at 9:14 AM 1/15/2004

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JimBlake &raquo;</TD></TR><TR><TD CLASS="quote">How about its behavior when it was running... Valve seals will leak more when the vacuum is strong, like engine braking with the throttle closed.

A compression test won't tell you much because the valves are closed during the compression stroke. The valve stem seals don't see that pressure.
</TD></TR></TABLE>

A compression test won't tell you about the valve seals, however the rings could be another reason the car is smoking. If it's not holding compression, that could be a tell tale sign that it's the rings, not just the valve seals.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by MEANB18 &raquo;</TD></TR><TR><TD CLASS="quote">A compression test won't tell you about the valve seals, however the rings could be another reason the car is smoking. If it's not holding compression, that could be a tell tale sign that it's the rings, not just the valve seals. </TD></TR></TABLE>

Exactly, I just wish I had done one so I know its not the rings and can narrow it down elsewhere. I guess really my only 2 options are to replace the seals (cheap, not hard) and throw it in and see what happens. Or go ahead and do the seals and the rings but then I'll need a hone and a breakin period to seal the new rings...I appreciate the help though.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JimBlake &raquo;</TD></TR><TR><TD CLASS="quote">How about its behavior when it was running... Valve seals will leak more when the vacuum is strong, like engine braking with the throttle closed.</TD></TR></TABLE>

More smoke under load then decel, but it ran fine, chirped 2nd, pulled pretty good. I'm really just leaning towards using my b2 head instead which I know is good and just swapping the cam...I've just heard the a6 springs etc were a bit stronger.