In addition to flame trap what else could be causing excessive pressure?

My 1990 240DL (143k miles) started with a front crankshaft seal leak. My mechanic cleaned the frame trap, clean the connector hoses and replaced the crankshaft seal (see note below). A short while later I blew out the rear camshaft seal and had that replaced. The oil fill cap next started leaking and oil cap and cap seal has been replaced - now just starting to seep past the cap seal again. Logic tells me I still have a problem with too much pressure. When the engine is idling my hand gets gently sucked into the oil fill opening which to me indicates that I some flow through the flame trap system. When I first replaced the oil fill cap I only did short trips (2-3 miles) - no leak. Today I did a 15 mile trip and that is when the oil fill cap started leaking again. Is something partially clogged? That would explain the negative pressure I feel at idle and may not relieve enough pressure when engine is hot and run harder/longer. Suggestions?

(Crankseal note: During the course of the front crankshaft seal, my mechanic put just the belt pulley back on and ran the car to check for crankshaft seal leakage. After a short time, it started slowly weeping oil past the seal. That's when his eye caught the pulley displaying end movement. He estimated a 1/16" of end play and that movement would tend to unseat the crankshaft seal, allowing the weeping. I assume that the crankshaft bearings or bearing surfaces are worn which is allowing the excessive end play. I included this crankshaft info in case it is a clue to the excessive pressure problem.)

 

The oil separator box could be plugged up. Two 13mm bolts (I think). The oil return tube goes into the oil sump -- don't mess with it. That's 'E' in the diagram, if the diagram gets uploaded.

 

That diagram is for '87-. On '88+ the oil separator box is taller.

 

Thanks for suggesting where to look. Do you think it may be partially clogged - passes pressure OK at idle but too clogged for higher flows?

 

Correct. Not much air flow at idle. The flame trap housing has two hoses, a large one to the input side of the throttle body and a small one to the output side. You also have a metal nipple on the intake manifold where the small hose connects. The different size hoses is to regulate the air flow at idle and at high RPM. The mech may have replaced the two upper hoses and the hose from the flame trap down to the oil box -- good. What about the little nipple? It gets clogged up. Use a 3/32" drill bit and a pipe cleaner to ream it out.

The way to tell for sure what the crankcase pressure is is to use a gauge connected to a modified oil filler cap. Not really necessary unless you've cleaned the whole PCV system and you're still leaking oil past the seals.

Or -- it could be simply bad oil seals.

First -- clean up the entire PCV system. The breather box (oil separator box) can be removed without removing the intake manifold, with patience and dexterity.

 

I had issues with crankcase pressure, replaced entire PCV system, including hoses, still leaked past brand new filler caps.
Put 250ml of kerosene in the oil and just drove the car. Whether it was stuck/clogged rings, glazed bores or whatever, the problem dissapeared after a few thousand kilometres.
So, don't assume the PCV system is bad, look at the engine as well.

Regards, Andrew.

 

Please help my feeble mind. Are you saying that you think combustion pressure was slipping past the rings and adding to the crankcase pressure? In that scenario, wouldn't you get an indication of oil getting into the combustion (smokey exhaust and/or excessive oil consumption)? You know, if gases can seep past the ring on combustion, then wouldn't oil be passing on the return stroke? I don't know, just thinking....

 

Not necessarily. Combustion and compression pressure is way greater than suction on overrun, especially on a turbocharged engine and an automatic. It's quite possible to get crankcase pressurisation issues at low/idle speeds too and have it go away somewhat with higher engine speeds, due to the greater volume the PCV system can draw, plus often some extra cylinder pressure can help seal rings once the engine loads up.
The crankcase is also not as well sealed as the combustion chamber, any excess crankcase pressure can be forced out the PCV or oil seals.....cylinder pressure can only go past rings or valves.
Sucking oil into the combustion chamber is terminal piston/bore wear (piston clearance too great for rings to seal), not usually just rings.

Regards, Andrew.

 

Seems like you use inferior oil. You do also have the thin tubes for the oil cooler.
I had sand in my engine. You on the other hand are using a 10w30 or a 5w30, which means that normal operating temperatures are doing what they are supposed to do to your oil. cooking it.
Sorry I don't access a computer much, but the flush could have been done with a bottle of Gunk, and I would look into a higher temp rated oil.
Just to get this one off of my chest and not have to start a new topic, I got rid of the 1/2 inch plastic tube going to the oil trap and replaced it with 1/2 inch flexible copper tubing. No I don't have a camera. Also the plastic vacuum line going to the plenumb, I used a brake line.
On oil, try using a 10w40 or better and synthetic is helpful but not a required with diligent oil changes.
I am learning just as well.

 

If you are referring to my post, you could not be more wrong about everything you assumed and wrote.

Regards, Andrew.

 

I don't think I have been doing anything neglectful in regards to oil and filtration, also. I have had this car for over 10 years, changed the oil every 3000 miles with a name brand (Pensoil, Valvoline, Havoline) non-syn 10W30 and Purolator oil filters. (Previous owners were an uncle and then my father - both not known for NOT taking care of their vehicles.)

Regardless, I am waiting arrival of parts via UPS. In order to eliminate one potential problem at a time, I decided to replace the entire flametrap system before looking elsewhere. Since this includes replacing the oil trap, I thought it best to remove the intake manifold and get "spacious" access to the oil trap. I do not want to risk damaging the oil return tube. Should I be wary of anything else?

When ordering parts I noticed that the flame trap is available in plastic and in metal. Is one design/material superior to the other?

 

Okey Dokey.

I had to get a used oil trap and soaked it in Kerosene to clean it out and used that one, my oil trap had sand and oil. I like metal, though I couldn't afford a new oil trap, metal or plastic.
Well, I hope you get it back on the road soon.

 

Here is an update on this thread. I am writing this in hopes that it may benefit someone else who might find themselves with similar issues.

Recapping: My 1990 240DL developed a front crank seal leak. My mechanic cleaned the flametrap, adjacent hoses and replaced the front crank seal (noting that he thought I might have excessive crank play - he tried three seals, finally using an OEM seal, but it still leaked - but much slower). About 500 miles later I blew out a rear cam seal. The front crank seal leak had also been increasing in volume. My mechanic replaced the rear cam seal and noticed that it looked like one of the seals under the timing belt cover was also leaking - oil was slowly seeping around the middle cover screw. This is where I started this thread - looking for sources other than the flametrap for excessive crankcase pressure. Blue Goose suggested to look at the oil separator so I decided I might as well replace the entire flametrap system as a way to eliminate that as the potential source of my problem.

I got a good deal on the parts at FCP Groton and my mechanic did the dirty work. Looking at the old parts I see I had the old metal style flametrap and that it was already pretty well clogged with a oily, sooty mess - only 700 miles after it was cleaned. The new flametrap is the plastic style - I would have replaced the metal one when it was previously cleaned but did not know better at the time.

Posts are alway much better when there are pictures so here are a couple of pics I took of the old oil separator that I cut into two pieces.



The left picture is looking at the bottom of the separator. The hole to the left leads to the crankcase return tube, the hole second from the right is the "in" from the top of the crankcase. Notice that the "in" hole is a separate small, curvy section. The flow of pressure goes from the left side, thru the squeezed-down curvy area and to the right side where it flairs alittle bigger. The other two holes are for mounting. The picture on the right is top section. Remember the flaired area I just mentioned, well, although you can't see it in the picture, there is a passage way thru the wall from the flaired area that leads to the large center cavity. The passage way is fairly small and only goes thru the wall near the top of the separator. You can see all the surfaces are covered with a decent layer of oily-sooty, gritty grime. Although I did not see anything clogged, that layer of grime looks like it restricts the squeezed-in area of the curvy section. But then again, the separator is quite tall so I really don't think that flow was appreciably restricted here.

Immediately after the flametrap system replacement I saw no oil seeping from the timing belt cover bolt and that ground-droppings from the splash pan (collection point for the leak from front crank seal) had become extremely small. A couple hundred miles later, seeping did return to the timing belt screw and the ground-droppings have slightly increased. I pulled the new flametrap to see if something had already started to clog it, but it was still very clean. I still have not eliminated piston ring blow-by as a source for excessive crank pressure - if it's still there. I am thinking that if I was getting compression blow-by, then I would see evidence of carbon or some kind of build-up on the flametrap. Does anyone support or disagree with this thinking? Maybe I just need to replace leaking seals.

 

Carbon buildup is oil that has broken down. If you have excessive blowby, you will have lots of excess crankcase pressure and that will force the oil mist and combustion chamber gases into teh crankcase and into the trap.
Carbon takes a loooong time to build up like that, the oil tends to wash it away fairly well for a long time.
Trust me on this, on a high mileage redblock, you have blowby, how much is the issue. You need to do a leakdown and compression test. If you have lots of leakdown, you are fighting a losing battle with crankcase pressure and will need to use alternatives.
I still think you have nothing at all to lose running a pint of kerosene in your oil till the next change, it'll free stuck rings if they are an issue and will also help deglaze cylinder bores a small amount.

Regards, Andrew.

 

Gosh, I guess I'm a wimp - I can't bring myself to adding kerosene to the motor oil. I think my plan of action is to add Seafoam, run it for ~100 miles and change the oil and filter. If I think I still have a problem after that, then I will find someone to do a cylinder leakdown test.

Please help me be less ignorant: What's a "redblock" and how did it get that name?

 

You could also have a Volvo dealer perform an engine flush and it shouldnt cost much or you can buy products at auto parts stores that will do the job as well. It could be as simple as a partially clogged pickup screen in the oil pan I have even seen a badly dented oil pan restrict flow and cause excess pressure. Or it might just be some oil return gulleys partially or fully clogged. either way a good engine flush and a visual inspection of the oil pan would be good low cost places to start in my opinion.

 

I do the Auto-RX treatment on all my cars at 100k mi:

http://www.auto-rx.com/

 

Just so you know, my 740 Turbo has had about a pint of kerosene in it since the last oil change and my engine's blowby/leakage out of every orifice issues have gone away. I chased flame traps, new oil filler caps etc and decided I was fixing symptoms rather than the problem.
Seafoam is an upper cylinder cleaner, it won't generally free up rings or deglaze.
I've heard good things about AutoRX and there are also some good commercial diesel products that are excellent for deglazing and freeing rings, but they're about $100/pint.....kerosene however is cheap and proven to work for decades.
Redblock is the name given to Volvo's inline four engines, simply because they have a red cylinder block. It's an all emcompassing term for the whole engine range.

Regards, Andrew.

 

I personally had a good experience with Auto-RX on a car that really needed it. The worst thing for an engine is to make a bunch of short trips when the engine has never fully warmed up.

 

I just wanted to add something to this thread.

My 93-245 with 183k on it leaks a bit out of the oil cap,...I have cleaned most of the engine, especially wiping around the oil cap. There is NO leakage from the front cam seals (none what so ever, it is dry), but after about 15 miles of driving...I notice that there is fresh "mist" (if I can call it that) leaking from the oil cap.

I just replaced the flame trap and 1/2in hose from IPD, but that didn't seem to help. (the old trap was dirty..but not actually "clogged")

The car doesn't smoke as far as I can tell, but I have to put in about 1/2 quart every 1500 miles or so. It doesn't drip any oil on the ground either..so I'm sort of stumped.

From what I've read, the oil trap could be clogged,...or I might have another leak somewhere else?

Should I try the Kerosene trick?