93 940: New head, loud valves

e777 · Post by **e777** » 20 Mar 2013, 20:23

Hello,

I recently completed fitting a new head onto my 93 940 (non-turbo). The previous one had warped from overheating when driven by the previous owner.

I pulled a head from my parts car and had it machined, at which time they did a complete head job (valve seals, stem guides, etc.). Looked like new by the time I got it back.

Anyway, I proceed to drive the car for some weeks and I notice the valves (I believe it is the valves, mind you) were clicking quite a bit more than in my other Volvos. I figured it was because I had not done the valve adjustment.

Today I check the clearances between tappet and cam lobe and they are all perfectly within specified range!

What gives? I do actually have one theory, and this is also a cautionary tale.

When they did the head, they painted it with head paint (here is the cautionary tale part: do not let them paint your head, for reasons explained below). The problem is that the small cylinders in which the shim caps slide up and down are machined surfaces, I later discovered. Now they had paint in them. This made the shim caps slide with greater difficulty, as there was more friction. I figured driving the car a bit would wear down the surface. Anyway, I thought this could be the culprit for the loud valves....

Thanks for any insights you might have!

Post by **jimmy57** » 20 Mar 2013, 20:50

Did the seals between the valve tops and bottom of tappets get put in?
There is a seal there that makes the tappet "stick" to the valve so it doesn't get stuck to cam and then get slammed against valve top when lobe of cam starts to depress tappet.

e777 · Post by **e777** » 20 Mar 2013, 21:20

Thanks, jimmy 57. Yes, I put those in myself.