and it's not the piston rings (freshly rebuilt) or the turbo (freshly replaced)and I don't think the physical valves have been damaged, I cleaned them up when the motor was torn down.
Here's the problem. Whenever the car comes to a stop and I let it idle, it will be fine for a few seconds and then an embarrassing amount of blue/white smoke (oil of course) will come billowing out the tailpipe. On startup it will not smoke. It usually takes it a little while before it would start to smoke. I've pulled the plugs several times, they don't appear to be burning oil.
If I had to guess I would say that I have blown at least one or two valve stem seals on the exhaust side. But I really am just guessing, any opinions?
If it would be the valve stems, do I need to pull the head or can they be replaced with the head still installed?
KA24DET smokes at idle
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Checkered-Member
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PMan_S13
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First off, I just rebuilt this motor. So I've only been driving it for about 400 miles. It has smoked ever since I got it running again. I have a new o2 sensor. 370cc injectors are controlled by afc2. By the looks of the plugs, it is running a little lean if anything...
The smoke is pretty much white but you can see a blue tint to it.
And I have to add oil all the time just to keep up with the burning.
I am at a loss. I was so sure that it was just the turbo exhaust seal having gone bad. But I replaced it and while it is somewhat better (not so dark and not so thick) it is still smoking. At this point I just want to get it fixed and get done with it; not even fun working on this car anymore..
The smoke is pretty much white but you can see a blue tint to it.
And I have to add oil all the time just to keep up with the burning.
I am at a loss. I was so sure that it was just the turbo exhaust seal having gone bad. But I replaced it and while it is somewhat better (not so dark and not so thick) it is still smoking. At this point I just want to get it fixed and get done with it; not even fun working on this car anymore..
it may be valve guide seals as you say then. it can be done without pulling the head but have only seen very skilled mechanics do it. it requires the use of a leak down tester to fill the cyl with air so it holds the valve against the head. but you cant have more then 10 % leak down or the valve will drop down into the cyl when the spring is released.
you mention the lower end was just rebuilt. where the ring gaps stagered properly?
you mention the lower end was just rebuilt. where the ring gaps stagered properly?
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PMan_S13
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Yeah, when I rebuilt the bottom end I had the rings in the exact position the fsm shows. So that should not be a problem.
Is there a way I can put a finger what's wrong? I really am getting tired of replacing things that don't fix the problem..
Maybe there is a way to tell if a valve stem is blown?
This also is important but I forgot to point it out.. the reason this motor was rebuilt was because it had a fuel leak and it hydrolocked upon trying to start. (yeah, it destroyed all 4 pistons pretty nicely).
Is there a way I can put a finger what's wrong? I really am getting tired of replacing things that don't fix the problem..
Maybe there is a way to tell if a valve stem is blown?
This also is important but I forgot to point it out.. the reason this motor was rebuilt was because it had a fuel leak and it hydrolocked upon trying to start. (yeah, it destroyed all 4 pistons pretty nicely).
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Q45tech
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Did you measure the bore taper at 3 locations, how did you select the appropriate ring sizes? What were the ring clearances cold?
Obviously a leak down test will point the location of the problem if you are careful and measure at differening piston locations.
What is the dry cranking compression, what is the running compression at idle [shut of injector and spark on one cylinder at a time and measure while idling or use Consult for power balance.
Obviously a leak down test will point the location of the problem if you are careful and measure at differening piston locations.
What is the dry cranking compression, what is the running compression at idle [shut of injector and spark on one cylinder at a time and measure while idling or use Consult for power balance.
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PMan_S13
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well I finally got around to testing my compression, (working nights really sucks) and the results look good..
The comp was all over 200psi in every cylinder. I'm not quite sure how the compression is that good, but I'm not complaining. (No, these are not pistons from a ka24e. They came from another DE)
So anyway, does that mean it's a fair shot at being the valve stem seals? I tried looking up how to remove them in the fsm but it doesn't even list them. From top to bottom it lists shim, lifter, cotter, retainer, spring, spring seat, and the valve. Any help?
I thought of something else when I was watching my car idle.. in daylight the smoke is pretty white and not so bad.. it's when you start driving it and then come to idle that the smoke is horrible. So the oil might be pooling up somewhere?
Thanks for the patience.. I always type too much
The comp was all over 200psi in every cylinder. I'm not quite sure how the compression is that good, but I'm not complaining. (No, these are not pistons from a ka24e. They came from another DE)
So anyway, does that mean it's a fair shot at being the valve stem seals? I tried looking up how to remove them in the fsm but it doesn't even list them. From top to bottom it lists shim, lifter, cotter, retainer, spring, spring seat, and the valve. Any help?
I thought of something else when I was watching my car idle.. in daylight the smoke is pretty white and not so bad.. it's when you start driving it and then come to idle that the smoke is horrible. So the oil might be pooling up somewhere?
Thanks for the patience.. I always type too much
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PMan_S13
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Well I've been trying to put a finger on the problems I'm having. Here's what I've done...
I pulled the turbo off at the turbine housing. I left it connected to the oil inlet and return lines. It's pretty much just sitting there. I reconnected the air filter and front intake to the rest of the intake. (So I pretty much just took the turbo out of the system; except for oil that goes through it of course) Then I started it up to see if anything different happens.
It is slightly different. At idle, there is nearly no smoke coming out, just enough for it to be visible. but if I jab the gas a bit it will blow a kind of whitish, grayish smoke (maybe bluish, but it's hard to tell).
I don't know what to make of this. Just a theory, but what if the valve timing is off? Could that give the results I am seeing? Could that possible explain the high compression?
I pulled the turbo off at the turbine housing. I left it connected to the oil inlet and return lines. It's pretty much just sitting there. I reconnected the air filter and front intake to the rest of the intake. (So I pretty much just took the turbo out of the system; except for oil that goes through it of course) Then I started it up to see if anything different happens.
It is slightly different. At idle, there is nearly no smoke coming out, just enough for it to be visible. but if I jab the gas a bit it will blow a kind of whitish, grayish smoke (maybe bluish, but it's hard to tell).
I don't know what to make of this. Just a theory, but what if the valve timing is off? Could that give the results I am seeing? Could that possible explain the high compression?
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Larry Pengilly
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So let me get this straight you rebuilt your engine because of a hydrolocked condition with used pistons and rods from another motor....... Im sorry to say that, that is your first problem. when a set of pistons wears into the cylinder it was first put into they become a matched set. if you change that who knows what you will get..... Did you use new rings at liest? Wow talk about a ghetto rebuild.
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PMan_S13
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Yeah, I rebuilt the motor with used rods and pistons with new rings. And guess what, I'm making over 200psi of compression per cylinder, so go ahead and explain how my "ghetto" rebuild is pushing more than standard... If you would have bothered to read my posts, I said that the spark plugs are not fouled, so it's not burning oil in the combustion chamber.
If you are gonna try to flame, at least make a decent attempt...
If you are gonna try to flame, at least make a decent attempt...
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Larry Pengilly
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If it is going out the exhaust it is going in the combustion chamber, as for the 200 psi compression test, I would point at the user of the gauge or the gauge itself, if you didnt change the profile of the combustion chamber, I would look at that being the reason. And rember it is possible to have too high of pressures in a cyl on the down stroke and it will actually pull oil through the valve seals.....
so think about that , and yes i still call that a ghetto rebuild.
so think about that , and yes i still call that a ghetto rebuild.
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PMan_S13
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larry, you obviously have no idea what you are talking about. I have already stated facts in the posts above that make your statements completely irrevelevant. If you want to post, try to make it helpful..
Richard, yeah I actually just got one at autozone today. The only thing still eluding me is the way the spring actually seperates. All the manuals seriously only say "remove spring with tool" and no pictures or anything. Just have to feel my way through I suppose
Richard, yeah I actually just got one at autozone today. The only thing still eluding me is the way the spring actually seperates. All the manuals seriously only say "remove spring with tool" and no pictures or anything. Just have to feel my way through I suppose
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Larry Pengilly
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Quote »larry, you obviously have no idea what you are talking about. I have already stated facts in the posts above that make your statements completely irrevelevant. If you want to post, try to make it helpful..[/quote]
Gee, lets examine this, hmmmm you have smoke coming out of the exhaust. Where does this smoke come from. lets see, on the ground, no that wouldn't make it in the exhaust, cooling system, oopse still no smoke in the exhaust,
but what is this, the combustion chamber is "one of the two" ways oil can burn and get sent out the exhaust. The other is the exhaust valves themselves. But being you are a master technician or some crap you know it all
and maybee my being a technician for Nissan north America Proving grounds means I dont know anything so be it...
Another think to consider, did you even remotly consider your PCV valve might be stuck open and when you decelerate to a stop sign, you make the most vacuum. It is possible that you are sucking some oil out of the crankcase and sending it in the intake side to be burned and NO That will not foul a sparkplug. That same occurance that you orginally described is a common trait in Mitsubishi DSM 4G63 turbo engines and it is always traced back to the PCV valve on those cars, Nissan uses a similar system. It takes a lot of oil to foul a sparkplug and the car would be smoking all the time if that was the case.
but then again what do I know I have only been fixing these cars for years now.
Gee, lets examine this, hmmmm you have smoke coming out of the exhaust. Where does this smoke come from. lets see, on the ground, no that wouldn't make it in the exhaust, cooling system, oopse still no smoke in the exhaust,
but what is this, the combustion chamber is "one of the two" ways oil can burn and get sent out the exhaust. The other is the exhaust valves themselves. But being you are a master technician or some crap you know it all
and maybee my being a technician for Nissan north America Proving grounds means I dont know anything so be it...
Another think to consider, did you even remotly consider your PCV valve might be stuck open and when you decelerate to a stop sign, you make the most vacuum. It is possible that you are sucking some oil out of the crankcase and sending it in the intake side to be burned and NO That will not foul a sparkplug. That same occurance that you orginally described is a common trait in Mitsubishi DSM 4G63 turbo engines and it is always traced back to the PCV valve on those cars, Nissan uses a similar system. It takes a lot of oil to foul a sparkplug and the car would be smoking all the time if that was the case.
but then again what do I know I have only been fixing these cars for years now.
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PMan_S13
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Larry Pengilly wrote:Gee, lets examine this, hmmmm you have smoke coming out of the exhaust. Where does this smoke come from. lets see, on the ground, no that wouldn't make it in the exhaust, cooling system, oopse still no smoke in the exhaust,
but what is this, the combustion chamber is "one of the two" ways oil can burn and get sent out the exhaust. The other is the exhaust valves themselves. But being you are a master technician or some crap you know it all
and maybee my being a technician for Nissan north America Proving grounds means I dont know anything so be it...
Another think to consider, did you even remotly consider your PCV valve might be stuck open and when you decelerate to a stop sign, you make the most vacuum. It is possible that you are sucking some oil out of the crankcase and sending it in the intake side to be burned and NO That will not foul a sparkplug. That same occurance that you orginally described is a common trait in Mitsubishi DSM 4G63 turbo engines and it is always traced back to the PCV valve on those cars, Nissan uses a similar system. It takes a lot of oil to foul a sparkplug and the car would be smoking all the time if that was the case.
but then again what do I know I have only been fixing these cars for years now.
Yes, I did consider it might have been the pcv valve. But then I remembered that I had a catch can installed and have it ventalated to the atmospere. I even checked the can just to be sure, no oil.
When it smokes, it smokes a whole lot. Plenty to foul plugs, yet they are all clean. But I went against that simple test and checked the compression. If anything was messed up, I wouldn't be getting those kind of numbers.
So it had to be something further downstream. I thought it might be the turbo, but it wasn't. The only real thing left is the valve stem seals on the exhaust end.
If you can come to some other conclusion, please share for the greater good
Larry Pengilly wrote:
and maybee my being a technician for Nissan north America Proving grounds means I dont know anything so be it...
Interesting:thinker I dont wanna thread jack so email me.[email protected]
P_man as stated earlier with the compression your runnin the valve guide seal are most likely your problem.
But I have to really agree its a poor choice to use used internals in another engine due to the piston grade matching. even if you put new seals in you may still suck oil into the cyl. on the down stroke.
But I have to really agree its a poor choice to use used internals in another engine due to the piston grade matching. even if you put new seals in you may still suck oil into the cyl. on the down stroke.
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Larry Pengilly
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lets stop bickering here it isnt doing any good every body has a point of veiw on this its obvious. I have one as well. but as the moderator of this forum I wont let it continue. If one more post goes up slamming him for his decision or one more insult toward anothers point of veiw on it. As much as I dont like doing it I will go back to the beginning of the insults and start wacking posts off till it is cleaned up. Appoligies a this point would be nice,but if its not in you to do it dont. just knock off the bickering.
Scott
Scott
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PMan_S13
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I have no problem with apoligizing, sorry dude =)
Yeah, this wasn't so much a problem with money. I had a time limit that was starting to close in on me and I did't have 6 weeks to sit around waiting for forged internals. I had the pistons, they measured up well, and I had no other choice really.
But that can't be changed now.. now I need to find a solution. As soon as I get done with this post I am going to start tearing down to replace all the stem seals. If that doesn't work and it is the piston pulling too much air in, I guess it will just have to be worn in more before it will stop.
Yeah, this wasn't so much a problem with money. I had a time limit that was starting to close in on me and I did't have 6 weeks to sit around waiting for forged internals. I had the pistons, they measured up well, and I had no other choice really.
But that can't be changed now.. now I need to find a solution. As soon as I get done with this post I am going to start tearing down to replace all the stem seals. If that doesn't work and it is the piston pulling too much air in, I guess it will just have to be worn in more before it will stop.
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Larry Pengilly
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