Hi everybody,
The rear camshaft cap of my B200F 240 Polar popped out and the engine bay (firewall side) is now flushed with oil :-(
I saw that the main culprit can be a clogged flame trap/barrel, but I changed both barrel and flame trap some 18 months ago.
My car has 570k km. and it's very well kept and carefully serviced.
Can somebody give me a hint about a different possible cause to search for?
And then: is it enough to just replace the lost cap with a brand new one or should I change something else (gaskets etc)
Thanks a lot!

Mimmo

You can make a retainer for the rear seal if you have the right scrap metal.

Hell, you could probably use an aluminum can.

See this back post.




(Image by Don Foster, uploaded to Brickpix by rstarkie)


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'79 242, '84 DL 2 door, '80 DL 2 door, '89 DL Wagon, '15 XC70 T6 AWD

Yes
go to Hardware Store---preferably Not HD or Lowes---ACE at least has 'owned' stores (by real people)

Yes this happened to me once for no reason as it just fell out.

Could be just age if your PCV system is clear.

IPD sells a strap that will hold the plug in place.

Dan

Thanks Dan!
Do you mean this? https://www.skandix.de/a/1020909/ Can I add it without boring the two holes?
I knew it was for 7xx/9xx only.

When do you say "age", do you refer to pressure in the block or just the cap becoming brittle/deformed with age?

If they go to the lengths of making a bespoke plate and sell it, it must be a common problem (and sure enough, it happened to me on my very first test drive of a 245, I didn't buy that one).

If I look at the additional info Skandix provides, it says this:
"Prevents derailing of the camshaft cover at gauge pressures."
English is not my native language, but it sounds strange to me.

If I look at it in German (also not native to me, but I can read and understand a lot of it) it says:
"Verhindert das Herausspringen des Nockenwellendeckels bei Überdruck im Kurbelgehäuse."

Google translates it as this:
"Prevents the camshaft cover from jumping out if there is overpressure in the crankcase."

And to me that's a much more correct translation. Close enough.
In other words, overpressure is expected...hmmm....

Yes these cars are 30 years old now. The strap can keep this plug in place and not cause massive oil leak. You can make the strap yourself but will need the distance between the two existing mounting holes.
Dan

700/900 red blocks don't have that half moon disc as they have rear cam distributors. If your flame trap and all attached PCV hoses are clear then suspect a plugged oil evaporator box (that big black thing that the main PCV hose attached to down at the base of the block). You could try attaching a hose and blowing into it with the oil filler cap removed to see how badly it's blocked, but if it hasn't been cleaned/replaced before then just assume it's getting plugged after all these years.

Do not try cleaning it in place. Removal and cleaning (rodding and flushing) often suffices, but many will simply replace it, also it does get brittle with age. Rather awkward and messy to get to, especially if an EGR valve is in the way. Be careful not to poke the plastic drain tube in the block below it down into the oil pan. If an EGR valve is preventing access (such as attached to the front bolt), you will need penetrating oil, larger wrenches using counter hold methods and patience to get it out of the way, maybe a couple of band-aids for your knuckles. It's often simplest to disconnect the outlet tube at the intake manifold.

If your PCV system is clean you shouldn't need a metal retaining strap (otherwise Volvo would have put one there), but it's always safer to have one. You can easily make your own strap, you just need to get appropriate metric bolts for the unused distributor holes at the back of the block, likely 10mm if I had to guess. You should be able to find what uou need in decent hardware stores, often in the bulk small fastener bins, and as well in auto supply stores. An aluminum strap works well as it's easy to drill and won't rust, thickness doesn't really matter, 5 layers of a foil pie plate would probably work in a pinch, no one will see your cheap handiwork.

I never had one blow (as I always maintain my PCV systems), but I've witnessed a couple of people who have, one where the plug was found and one where it was lost on the highway.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now

The bolt heads may be 10mm but the shank is how bolts are i.d.'d. A bolt with a 10mm head would have a 6mm shank with either fine or coarse threads. The thread size should be the same as the valve cover studs. - Dave

PCV and evaporator box have been installed brand new less than 2 years ago.
This worries me (where does this overpressure come from???)

Arranging a proper strap for the new cap will not be an issue (metric bolts) since I live in Italy! I'll do it for sure!
thanks!

On the one hand, it could just be that the plastic has shrunk enough to have it pop out. On the other hand it might be overpressure.

If the PCV system is clean, it seems unlikely that overpressure from that is the cause. At this mileage (kilometrage) it might be that the piston rings are past their best, especially when driven in an Italian driving style ;-) . The B200F isn't the fastest engine with 111 bhp and 158 Nm or torque (my 245 has one too).

A simple test for overpressure in the crankcase is to idle the engine, remove the oil filler cap and hold your hand over the hole. You may feel pulsating air, but it must not be forced past your hand. A plastic bag over the oil filler hole should show the pulsation but not be blown away.

Double check the flametrap element. They don't take long to plug back up on an old engine (especially the ancient waffled copper design, no longer used on your 1992, but someone could have put one in later as they can still be found). Also check the little hose PCV brass port on the throttle body (you can remove it and carefully rod it out with a small drill bit), but there's almost no way that should cause your plug to blow out. You could also double check your oil box by blowing back through it with the oil filler cap removed, but I'd be very surpised if a relatively new one was plugged again so soon.

To confirm that it may be excessive crankcase pressure, you could check for evidence of oil leaks at the front engine seals (cam, auxiliary shaft, crankshaft) collecting at the bottom of the timing cover. Failing all that, I'd just put the strap on and wait for further evidence.

There's always the chance it's the beginnings of a blown head gasket, but again I'd wait for further evidence. The oil on the dipstick and under the valve cover looks nice and clean, not at all milky? Unexplained coolant loss? You could do a compression leakdown test if you remain concerned.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now