A PCV on an engine just takes any pressure in the crank case (bottom end, under pistons), and feeds it to the vacuum system, or intake (top end, above pistons).
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thanks. dopey questions i know. so the valves (and valve seals) are below the cam - with something inbetween - and the combustion chamber below that? and the spark plugs and tube seals are inserted somewhere in relation to all of that?The valve cover, covers the valves
Jk, not really. You will see the cams and the timing chain when you take it off.
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Not dopey questions. Someone will explain this better than me I’m sure.
The plugs don’t really factor into it, they just thread through the head into the combustion chamber, there is no oil sitting on top of them. There should be vacuum under the valve cover not pressure, if there is pressure then the valve seals could leak onto intake and exhaust valves. Look up a cylinder head animation on YouTube, might help.
The plugs don’t really factor into it, they just thread through the head into the combustion chamber, there is no oil sitting on top of them. There should be vacuum under the valve cover not pressure, if there is pressure then the valve seals could leak onto intake and exhaust valves. Look up a cylinder head animation on YouTube, might help.
yeah. my only point of reference is a horizontally opposed boxer engine so i think i am looking at it sideways or something!
i forget it is /valve/ seals that leak not spark plug tube seals which tricked me up.
so does blocked baffles leading to high oil consumption also mean your rings/cylinder walls or valve seats or valve seals also have to be bad? i mean. the OP seemed to indicate cleaning baffles could solve oil consumption...
In general you could lose oil in an engine from the top down (valve stem seals), or from the bottom up (past the rings). The two would not be related, other than that they could both be made worse by un-vented case pressure.
mudgudgeon
Resident galah
If you have excess oil consumption due to high crank case pressure, it doesn't necessarily mean rings or valve stem seals are bad. Is more a case of the problem (crank case pressure) creating assumptions that look like another separate problem (oil consumption is a symptom, not the real problem)
This is not to say that your oil consumption is definitely due to crank case pressure.
The trick is doing some diagnosis and sorting the wheat from the chafe and getting to the real problem.
This is not to say that your oil consumption is definitely due to crank case pressure.
The trick is doing some diagnosis and sorting the wheat from the chafe and getting to the real problem.
can you determine which side by doing a compression test and a leak down test and an oil sample analysis from blackstone telling you if or what kind of metal is or is not in the engine?(!).
and why or why not please?
I agree with mudgudgeon. Need to start narrowing it down. All of those tests you mentioned are useful for getting an idea of how tight the motor is (rings, cylinder walls, valve seats). But I don’t think any of them will help find out the condition of stem seals, bc they don’t seal in any compression, just oil.
Look for leaks, replace the pcv, run heavier weight oil, do the simplest stuff first. See how that does. If consumption dosnt improve maybe get a compression, leak down test, etc.
Look for leaks, replace the pcv, run heavier weight oil, do the simplest stuff first. See how that does. If consumption dosnt improve maybe get a compression, leak down test, etc.
OK. thanks. APPRECIATE IT. i’ve been narrowing it down.
i think i am on to a compression and leak down test at this point.
and do another blackstone report. first one came back great (no metal and no coolant) but it was not mine at that point.
not sure why land cruiser shops don’t seem to have much interest in doing a compression or leak down through. they all seem supremely uninterested in this. i guess they figure you need to take it in and drop the cash and let them do whatever they find they need to do? and on a pre-purchase they figure you buy it and they would have a shot to do the work anyway? i don’t get it.
maybe i need to buy a kit and learn to do it myself...
also. seems to me if i can spend an afternoon eliminating the baffles and the PCV and do a valve cover gasket prior to going in for full head gasket (plus whatever) i should plannon this too. no?
can it be blowing out the bottom end while i drive?
so. one thought. does the fact that i was throwing a p0410 code and just did an EGR delete thinking i would clean out the throttle body and the passage in the air intake or whatever mean anything related to this?
I can see your engine block fu is weak, so I'll give this a shot. The head is a thick slab of aluminum on top of the the engine block that covers the tops of the cylinders. The bottom surface of the head is where the spark plugs and valves protrude into the combustion chambers where the pistons go up and down. The top surface of the head is where the spinning camshafts live that open and close the valves. The top surface of the head where the valves are needs a lot of oil to handle the friction and heat and when it's done being used, the valve drains down large holes all the way to the bottom of the engine where the oil pan is bolted to the bottom of the engine block.
So, the space on top of the head (under the valve cover you're asking about) is connected by large passages to the oil pan on the bottom. When normal piston blow by of compression gases pressurizes the oil pan, it also pressurizes the space under the valve covers. So an engine has to have a vent up top in the valve cover to allow this pressure to escape. If we didn't care about spewing polluted air, the vent would just vent air into the engine bay and the driver behind you would get to smell it. Because we care, the oily air is sucked into the throttle body and burned in the engine instead.
If the baffles are clogged, oil can sit atop that baffle pan where the Positive Crankcase Ventilation (PCV) valve can suck solid oil right out of the engine (vs its job of sucking oily vapor). Open baffles let oil splashed up there drain quickly instead of building up and being sucked out by the PCV valve. Hope that helps. You can also look at the Engine section if you have a factory manual or google a drawing of the FZJ80 4.5L engine.
So, the space on top of the head (under the valve cover you're asking about) is connected by large passages to the oil pan on the bottom. When normal piston blow by of compression gases pressurizes the oil pan, it also pressurizes the space under the valve covers. So an engine has to have a vent up top in the valve cover to allow this pressure to escape. If we didn't care about spewing polluted air, the vent would just vent air into the engine bay and the driver behind you would get to smell it. Because we care, the oily air is sucked into the throttle body and burned in the engine instead.
If the baffles are clogged, oil can sit atop that baffle pan where the Positive Crankcase Ventilation (PCV) valve can suck solid oil right out of the engine (vs its job of sucking oily vapor). Open baffles let oil splashed up there drain quickly instead of building up and being sucked out by the PCV valve. Hope that helps. You can also look at the Engine section if you have a factory manual or google a drawing of the FZJ80 4.5L engine.
Oh wow. And I see you just posted again. You need some guidance here. You just mentioned you are going in for a HG as well?? Why? What else is going on. It makes absolutely no sense to pull the valve cover and do the PVC, remove the baffle (huh - why are you doing that?), then install a new valve cover gasket, and reassemble. Then go in for a HG. So why don't you slow down, take a breath and explain what is going on here if you're looking for advie.
so a local LC shop here in town said they simply put in a new valve cover instead of cleaning the old one when they do an engine service. they seemed to think it is not even worth cleaning them.
so before paying for a full HG job to do seals i figured i would hot tank my valve cover gasket over the course of two days off and on work.
not sure i want to spend cash on a local shop doing a head gasket job right now. figured to see if the OP’s suggestion to clean the baffles would help.
so before paying for a full HG job to do seals i figured i would hot tank my valve cover gasket over the course of two days off and on work.
not sure i want to spend cash on a local shop doing a head gasket job right now. figured to see if the OP’s suggestion to clean the baffles would help.
I don't know what to tell you here. I specifically asked you to explain symptoms and you gave me gobbledygook about hot tanking your "valve cover gasket" because the shop you're going to pay to do a HG doesn't want to re-use your valve cover. So you're going to save money by apparently doing a few hours work and then reassembling and then you oddly plan to pay the shop to again disassemble what you just assembled and the reason for the HG appears to be "seals" and you threw in the "baffles" question just to give the post a full 360 degrees of coverage of several completely unrelated things without answering my question so I could create the longest run on sentence of my life in honor of this bizarre post. My summary comment? A shop that wants to replace my valve cover because they're too lazy to clean and reuse a permanent part like that and they want me to pay for the new one is a shop whose doorway I'd never darken again.
mudgudgeon
Resident galah
Start with the low hanging fruit.
Remove the PCV and hoses, make sure they are clear. Refit the PCV and drive it for a few weeks see if it makes any difference. It'll cost nothing but an hour or two. Replace the PCV if you're someone who likes to throw parts at a problem.
Next, you could try removing the valve cover and check the baffles. I think it's very unlikely they are the problem, but it'll only cost you a few hours on a Saturday if you do it yourself. There's a good chance you can reuse the valve cover gasket and button it back up after checking it.
Try and borrow, or buy a compression gauge and do a compression test, you can also do a leak down test at the same time. Again, easily done in a few hours.
Just go one step at a time.
I wouldn't rush to do a head gasket until after doing a compression test, and oil analysis.
Remove the PCV and hoses, make sure they are clear. Refit the PCV and drive it for a few weeks see if it makes any difference. It'll cost nothing but an hour or two. Replace the PCV if you're someone who likes to throw parts at a problem.
Next, you could try removing the valve cover and check the baffles. I think it's very unlikely they are the problem, but it'll only cost you a few hours on a Saturday if you do it yourself. There's a good chance you can reuse the valve cover gasket and button it back up after checking it.
Try and borrow, or buy a compression gauge and do a compression test, you can also do a leak down test at the same time. Again, easily done in a few hours.
Just go one step at a time.
I wouldn't rush to do a head gasket until after doing a compression test, and oil analysis.
it’s burning oil doug. a lot of oil. i’m trying to see if i can get a handle on whether it needs more than valve seals before i have someone go in.
if it needs more than valve seals i may want to sell it or see if i can somehow get a second set of hands and eyes and do it myself over the course of a month parked under a carport.
THANKS mudgudgeon and @IdahoDoug
so PCV is done. oil sample, compression and leak down and valve cover baffle cleaning in no particular order is that right?
This is what you will see when the valve cover is removed.
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thanks zack. appreciate it. seems straightforward enough and something i will do.
