My '91 740 (8 valve, 90K) has started ejecting oil from the filler cap since an oil change last week. Mechanic cleaned flame trap 3k miles ago, and changed the seal on the filler cap, with no results. Said this morning that it could be the flame trap box? What is that?

Also, car is losing about 1/2 to 1 quart of oil between 3k oil changes. It's definitely not leaking. How do I rectify this? Thanks in advance for your help!

I had a slight oil weep from my filler cap that did not respond to a new gasket. My tech told me to SLIGHTLY bend the cap tabs toward the top of the cap to make it fit tighter. It worked!

If you suspect the cap at all, try swapping caps with a buddy. If the problem follows the cap, your problem is found.

BTW the cap on my 95 850 looks just like the caps on my 740s.

Thanks for the replies! I'll check out all these suggestions, and hope fully it will be taken care of!

my wifes '91 745 N/A did same thing, I did replace flame trap and oil fill cap seal but what helped the most was this - trace top hose off flame trap > to upper intake > brass threaded fitting that hose connects to may be plugged shut. I removed this fitting & drilled ! out the baked on crud. Have not seen a drop of oil on valve cover since.

You should personally check the flame trap. Look at the 700/900 faq via the features pull down menu for instructions.

Yup, replaced the gasket...no luck. Any other ideas?

The oil trap is just under the flame trap. They do plug. Cost is about 30-35 from Volvo. Some folks clean them. Be sure to get a new O ring for it. Two bolts hold it to the engine block, approx under # 3 intake manifold runner. a little frustrating to change, but not that bad. Clean the area around it before removing so dirt doesn't fall in. Also, check all your vacuum connetions on the manifold---these plug up. Cleaned mine by using coat hangers etc to get a better flow.

Hope this helps,

dick

Have you changed the filler cap gasket? They do deteriorate. Cheap to replace in less than a minute.

dick