Hi All, I have a 79' 242 GT. I was cleaning my engine and doing routine maintenance and noticed some oil inside of the intake tube. Is this normal for these cars? The flametrap has been replaced recently. Thank you.

My 81 B21F does the same thing. After cleaning everything and checking for leaks, I think its true that the oil is coming through the vacuum line from the flame tap.

The breather box is probably too small to do a good job of catching and returning oil to the crankcase. I have noticed that oil accumulates on the air meter plate also. This could change the balance of the plate just enough to cause a minor mixture issue also.

Perhaps installing a catch tank in that vacuum line would help.

You mention cleaning your engine - you really do not want to wash it.

I have seen many posts about sad results after washing a Volvo engine - damaged sensors, etc are expensive.

I use WD40 on rubber parts and kerosine on metal parts. I save old socks to put over my hand to get into nooks and crannies.

One thing that has helped me to reduce small issues is to disconnect electrical items, clean the contacts, then seal them with dielectric grease and zip tie any that you can.

BTW - look over the 700/900 FAQ - Many, many of the items in there relate to your car also.

Years ago, one of my dealers techs told me that our '88 745 had a 240 engine and should run forever.

Thank you for some great tips. I wonder if the vslve cover has an internal bafflw to reduce the amount of oil going through the flame trap.

As far as oil collecting in the tube - it may have taken 100 thousand or 200 thousand miles to build up that much.

If you like to experiment, carefully clean and dry the inside of the hose and check it after 5000 miles - I wager that you won't much, if any oil.

If you are talking about the black corrugated tube after the air filter, we had oil in that tube of our '88 745 GLE.

When an engine is running under various conditions, the cycles and opening of valves, etc are not neat digital off and on things - the gas flows stop and start in a sloppy manner and things overlap - also things called standing waves get set up and there are back flows and other stuff.

These vagaries account for gunk in the throttle body - that is why it needs to be cleaned on occasion.

This oil or whatever it may be will possibly soften the tube, and you might check the bottom of it at each oil change for failure.

The flame trap is meant to stop flames, oil vapors pass right through it.

Hi,

That's a very good explanation for most of the conditions that go on inside an engine.

You are saying its basis is thermodynamics in action.
Heat goes or travels to cold. It is the action of equilibrium as the energy in molecules is seeking to be at rest and would do it, at absolute zero!

Ever noticed ice cubes in your freezers ice bin and that the oldest are a lot smaller over time.
There is still heat in the water that makes up ice.
The evaporator in the refrigerator/ freezer is still colder than the ice will ever get by a few degrees. You see heat is always trying to get in that space.
In order to remove heat that gets in there, there has to be a temperature gradient maintained.
So as we try to keep heat out of the ice, that is really evaporating that water as a portion of that heat energy moves to absence of heat energy.

I worked on an experimental contraption for the Air Force many moons ago. The company I worked for made cryogenic vacuum lines for rocket fuel transfer.
This was an encasement with several sets of helium pumps arranged in cascade order to reduce a chamber within to absolute zero in temperature.
We got really really close according to a scientist from the Vandenberg Air Force base. I was later told by him that in a conclusion that energy was still getting in no matter the amount of vacuum, lead shields or some thin fiberglass sheets, made like wagon wheels to conduct less heat in from the shell. I drilled down through the narrow spokes to carry in some very thin power conductors.

This was one of many experiments to find what we are now calling today ... a Neutrino!
The last I knew, they are working in a deep mine shaft up in Idaho or Montana to detect them going through the earths center. Using optic sensors for radiation.
Figures to me, it was radiation, after rubbing elbows with those scientists.

Those many kinds of Hot vapors in our engines will be attracted by a colder space to go reside.
That accordion tube or hose in question is really thin and can quickily attract those vapors from the crankcase blow by.
Especially, since the flame trap hooks right at the top portion of this engine. There the thinnest or least amount of oil vapors are transmitted by piston motion and heat convection. It then condenses into the volutes of that long hose. Maybe some goes back in over time?

Believe it or not there are cold spots in an engine. Mostly the inside corners that will get an extra coating of sludge, varnish or coking. We see more of this as our engines are get older with build up despite the best detergent oils.
In many cases these looks like very light stains in the oil caps bottom side.

It's life, that with all we build and learn, there is something more to learn or ponder!
Phil

Thank you both for the detailed explanation. Yes, I'm talking about the corrugated tube from air filter box to the throttle body. Why not just put a pcv valve in place of the flanetrap or inline to the hose that is connected to it like most newer cars? Wouldn't that keep the oil from moving down the tube?

Hi,

That is a good question and maybe the answers are in the “patent laws.”
Of course one would have to say the check valves might work a whole bunch better on a four banger? I personally have never seen them on foreign cars but I don’t own or see many others either.

On my Ford of 1974 vintage truck, has check valve was in the top of the valve cover. A high point inside the engine but vapors were routed to the inside of a round air cleaner housing.
In theory, it gets sucked back into the engine and burnt.

Only trouble Ford was smarter. They put a scratch pad material in a pocket holder to hold the hose onto the housing.
Now, with this setup going on, here was their wisdom smacks you in the head.
It dumps all those big V8 vapors, from a crappie engine, right on the outside of your paper air filter! No way to keep it clean long and that in itself sold more air filters! So much for Ford’s advertising slogan back then “Ford has a better idea!”
At least Volvo put in behind the air cleaner on the K-Jet and up by the throttle plate on the LH series.

I turned out their “light bulb” when I went looking for a passenger car.
I have been with Volvo ever since! Never another brand new vehicle either, just to lose money while driving it off the lot!

Maybe they should route those vapors through cows urine (Blue Def) like the diesels exhaust?

Phil