What is this and why is it full of oil?

[TexasDreamer]

The engine is a 1700 Crossflow. The first image is a catch tank for oil. There is a clear vertical tube to show how much is in the canister. The tube is now full of oil. It was empty for a long time. The other end of the tube connects to a sort of box which connects to the crankcase. You can see the other end of the tube in the second picture going down beside the dipstick. I may have overfilled the crankcase. It loses oil pressure when the dipstick shows half a quart below "H" so I keep it above the max mark on the dipstick.  May or not be related, but the oil filler cap on top of the valve cover disappeared. What part do I order to replace it? I'll be away for a few days, looking forward to any info I can get.

[MV8]

1)      Overfilling causes additional crank case pressure from the spinning crank being closer to the dynamic oil level in the pan. You can add a 1.5qt accumulator and solenoid to cope with pressure loss to the crank and top end during hard cornering, which will also lower your dynamic oil level in the pan and pre-lube the engine at cold start while adding extra capacity that only overfills during low oil pressure events, then the level comes back down as the pressure rises. Heavier weight/viscosity than necessary oil aggravates the problem. If your hot idle pressure is less than 10psi with a new filter, I would not change to the next thinner weight oil since your bearing clearances and pump wear are probably excessive. Custom oil pan improvements are another option.

2)      This catch can configuration must be periodically drained as it cannot empty back to the crankcase after engine shut down. There should be a valve or plug on the bottom of the catch can. The attachment to the engine sounds good for a gravity drain, but the position and type of can is lacking. Post more pics (engine breather attachment area and an overview showing engine and firewall on the left side) if you'd like to upgrade and want a recommendation.

3)      If the valve cover cap is the only other breather and is a push-on type, a full catch can could be enough restriction for the crankcase pressure from being overfilled to force the cap off but you'd also have oil all over the top of the engine. A pic of the valve cover area could help determine which cap needs to be installed.

Edited February 5 by MV8

[TexasDreamer]

Thanks for the info. Normally oil pressure at idle (100 rpm) is 2 bar = 30 psi so that sounds good. This situation came to my attention when I saw a small amount of smoke coming up through the louvers on the bonnet. There was oil sprayed around the engine bay and apparently some found its way to the exhaust manifold. I found the plug on the bottom of the catch can, so emptying it will be easy. My plan is to replace the oil filler cap, empty the catch can and see what happens. I've attached a pic of the valve cover so someone can tell me what oil filler cap to get. the diameter of the oil filler is about 1.5".

[IamScotticus]

Your oil overflow system is too complicated, low capacity and getting plugged up.

Oil separation box with PCV valve needs cleaning out.

The Ford cap has a mesh vent thar should have released pressure,  but oil mist makes the engine bay dirty.  There are caps with breather nipples to run a hose to the catch tank.  Burton has a metal one and I got a plastic one for a 70s AMC Javelin.  It fits!

I will try to find a catch tank better for you.

 

 

Edited February 5 by IamScotticus

[MV8]

One source: https://www.burtonpower.com/oil-filler-cap-x-flow-pinto-etc-fp630.html

[wdb]

3 hours ago, MV8 said:

One source: https://www.burtonpower.com/oil-filler-cap-x-flow-pinto-etc-fp630.html

Good heavens! I'd be tempted to change the valve cover just to get a cap that is more securely attached.

 

From what I've learned so far while trying to stop oil leaks on my twincam, Kent engines are well known for blowing oil out of the crankcase. Twink folks even add a breather on the valve cover to give the pressure someplace to go (catch can). Doesn't seem to matter how well the piston rings seal because even the top engine builders will add that breather. Or I guess they could be building intentionally loose engines...

 

All that said, if this car has PCV it should at least be giving all that pressure someplace to go besides the catch can, which leads me to believe there is something wrong with the PCV side of things. 

Edited February 5 by wdb
not pipe, dope!

[IamScotticus]

This more like it

https://www.summitracing.com/parts/jzp-600-025-05

Better:

https://www.summitracing.com/parts/jzp-605-125-05

 

The capacity could be bigger,

The top hole would go to a a Filtered vent or air intake.  The top would need holes cut to accept crank case vent hose and rocker cover vent hose.  The tank should be checked after every drive.

Why this type of tank?  It's translucent,  you can SEE the oil level.  No sight tube to clog up or leak.

 

Sorry, I can't post pictures. I exceeded data limits.

Edited February 5 by IamScotticus

[MV8]

No pcv on this one. There are caps with spring clips that also vent but they would hit the bonnet. I've not seen that type of oil hose in many years. I expect it may crack if you bend it. Offy used to make these add on breathers. Also an example of how they fit.

[CBuff]

Here was a thread from last year. I was looking to stop blow thru on my 420R which was shooting directly thru the plastic breather bottle and down the bottom and side of the car. As a stop gap fix I adjusted the tubes into the breather bottle and that stopped it (pretty much). Track days are really the only problem.

 

I might upgrade to one of the iridium units for some bling under the hood.  They are pricey and some alts are cheaper but do not have any first hand knowledge on them. I think some of them can be configured to have a return or just vented to the outside. 

 

 

[bball7754]

My Crossflow spit out oil like crazy when I bought it.  There was a hose from the crankcase fitting (no PCV) to the catch can, and a hose from the cap to the catch can.  The catch can was, and still is, a second windshield washer fluid container with two holes drilled in the side.  I had to empty the catch can, and add oil, after every session of a track day.

 

I eliminated most of the oil venting by implementing the Roger King (of Blatchat fame) venting solution.  I added a hose fitting in the middle of the side of the valve cover, and another at the rear corner.  The crankcase hose was then routed to the middle of the valve cover, and the corner valve cover fitting to the catch can.  Huge difference in what was landing in the catch can.

 

I ultimately had the engine rebuilt, and I’m not sure if there has been any oil in the catch can since.

 

 

 

 

[MV8]

Borrowed BBall7754's pic to draw a system that adds one port to the neck of the valve cover (or no mods if using a ported filler cap), compact, self draining, with minimal oil hose.

[joe7]

The orientation of the brass elbow is a great way to fill the catch can. Turn it up at least above horizontal. Experience on that!!

[IamScotticus]

@bball7754 have part number for that filler cap?

[bball7754]

11 hours ago, joe7 said:

The orientation of the brass elbow is a great way to fill the catch can. Turn it up at least above horizontal. Experience on that!!

As soon as I actually see some oil in the can, I’ll change the orientation.  But essentially nothing there in 10 years, including track days.

[bball7754]

5 hours ago, IamScotticus said:

@bball7754 have part number for that filler cap?

I don’t, but will see if there are any numbers on it over the weekend.

[MV8]

Oil filler cap: With enough bonnet clearance or shortening of the neck, a 10070 cap with vent port should fit the neck and be secure.

A link to one: https://www.classicindustries.com/product/st10070.html

 

For a cap without a port, 10098.

A link to one: https://www.ebay.com/itm/276744538767?var=0&mkevt=1&mkcid=1&mkrid=711-53200-19255-0&campid=5338590836&toolid=10044&customid=e0b98187185a17df5ccae62106723d6a&gclid=e0b98187185a17df5ccae62106723d6a

Edited Friday at 02:57 PM by MV8

[IamScotticus]

This is the AMC Jeep cap I know fits.  Common part number 8084. Most auto parts stores should have one.

But I want to get a blue one like bball's.  You know, color = power.

 

Actually, I want to know if bball's blue cap has a longer neck than the yellow 8084, which is only 15mm deep and could pop off with little effort.  I think too thick a breather hose could walk it off with enough vibration.

here's a link to one:

https://www.oreillyauto.com/detail/c/masterpro-select-caps/masterpro-select-caps-crankcase-breather-cap/omp0/8084/v/a/1201/automotive-car-2002-mini-cooper?q=8084&pos=1

Edited Saturday at 04:32 AM by IamScotticus

[bball7754]

On 2/6/2025 at 4:27 PM, IamScotticus said:

@bball7754 have part number for that filler cap?

I do!  Ford part 79IF-6K614-AA

 

Hmmmm.  I just googled the part number, and I think they modified the original part.  I didn’t take a pic from the side, but it’s essentially the same as the yellow one you posted.  They must have split the part and gotten rid of all the stuff on the bottom.  Not what I expected!

 

 

Edited Sunday at 06:29 PM by bball7754

[IamScotticus]

4 hours ago, bball7754 said:

I do!  Ford part 79IF-6K614-AA

 

Hmmmm.  I just googled the part number, and I think they modified the original part.  I didn’t take a pic from the side, but it’s essentially the same as the yellow one you posted.  They must have split the part and gotten rid of all the stuff on the bottom.  Not what I expected!

 

 

Thanks.

[IamScotticus]

On 2/9/2025 at 12:23 PM, bball7754 said:

I do!  Ford part 79IF-6K614-AA

 

Hmmmm.  I just googled the part number, and I think they modified the original part.  I didn’t take a pic from the side, but it’s essentially the same as the yellow one you posted.  They must have split the part and gotten rid of all the stuff on the bottom.  Not what I expected!

 

 

Yea, you got a unicorn there