# Oil Smoke!!! Arrrrggggggg!!!



## tsnow678 (Feb 22, 2011)

My son has a 95 HB with the 2.4 engine. It has quite a few miles on it and runs great. I wanted to go through everything to make sure this truck stays reliable so I started at the rear and worked my way forward. The problem is this, the truck would smoke a little after it was idling for a while but then would clear up. Now after the maintenance I performed it smokes all the time. There are two things I did that could possibly affect this. The first one I doubt has anything to do with it but I will mention it for you to see what you think, I removed the catalytic converter and straight piped it to a new muffler. I wouldn't have taken it off but it was about to fall of anyways and since this is a young driver, who knows!!! The other area of concern and the spot I am concentrating on is the PCV baffle attached to the timing cover. When I pulled the cover off to do the timing chain, gears, tensioner, etc I noticed it was clogged full of oil sludge(the baffle). Me being me I pulled it off of the truck and cleaned it like new and also cleaned the valve itself. After running the truck through several hot cold cycles it still smokes like crazy. Here is a list of the items serviced just in case I am over looking something.
Drained and refilled the rear diff, all three u-joints replaced, center driveshaft support replaced, trnas mount replaced, trans fluid drained and refilled, new release bearing, pressure plate, clutch disc, pilot bearing, rear main seal, timing chain, gears, guides, and tensioner replaced, new oil pump, new main and rod bearings, front cover seal replaced, cleaned and reinstalled the pcv and baffle, radiator was repaired, new oil pan gasket, new clutch master and slave, fresh oil, oil filter, and new antifreeze. That is just about everything I did and now have a great running and reliable vehicle but the smokes like a freight train. What do you guys/gals think? Should I reroute the pcv to pull crank pressure out the top? catch can? new pcv baffle? does the pcv baffle have anything in it other than a divider or should there be some sort of baffling material in there? I made sure the pcv was moving freely before reinstallation but may try a new one to see what happens. I may make a restrictor to go between the baffle and the timing cover to divert the oil back to pan rather than climbing up through the intake system. I need to get under there and see exactly where the line goes to once it leaves the pcv. Any help with this issue would be greatly appreciated. I know my son would appreciate it too!!! Thanks


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## TheRepairMan (Jun 30, 2009)

See how it does after you swap out the PCV. Hopefully a new one will take care of the whole problem.

-R


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## tsnow678 (Feb 22, 2011)

TheRepairMan said:


> See how it does after you swap out the PCV. Hopefully a new one will take care of the whole problem.
> 
> -R


Thanks repairman for the reply!!!

I did just that today. Here is a list of things I did to help correct my wrong doings. I changed the PCV, changed the oil (contaminated with the gear oil I used to prime the oil pump), new oil filter, used a little Seafoam in the oil-gas-and suctioned it into the intake. Everywhere I looked says to add 4.1 qts of oil with a new filter just as I did and found that with 4 qts I am actually over full. So once again I drained the oil out and added 3 qts (oil filter was previously saturated on last oil fill). At 3 qts I am reading dead middle of the cross hatch on the dipstick. I naturally fill it to the top of the cross hatch in anticipation of some loss between oil changes but with my current issues I thought it best to put it in the middle. Last but not least I punched a hole in the new muffler at the lowest point to allow any condensation/oil to drain out after the truck is shut off. I run the ever livin dog shit out this truck for about 10 miles and when I pulled back in, no smoke. I was so proud I about beat on my chest. The wife rolled up and asked if it was fixed and I was like "of course". I fired it up for her and guess what, a cloud of smoke, damn!! I am going to drive this truck the rest of the week back and forth to work and see what happens. This might be residual from all of the other problems. If anyone can think of anything I might have missed fee free to post it up your help or suggestions would be greatly appreciated. Thanks


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## TheRepairMan (Jun 30, 2009)

Okay, so you mentioned the truck would show signs of oil burning after idling a while prior to removing the cat? When a cat reaches normal operating temperatures it will start burning off any unburnt oil, fuel, coolant or whatever, and at some point it gets hot enough to convert high amounts of pollutants into much smaller chemical particles that usually can't be seen coming out the tail pipe... therefore, taking the cat out of any vehicle's exhaust system can, and usually does, allow more of those gasses to visually be detected for much longer periods. Can ya smell where this is going?

Normally a cat creates a second, and even third combustion stage that tends to eliminate most of those unwanted byproducts. That's exactly what it's suppose to do, but that can mask some moderate to serious engine conditions. So if you do have an oil burner, it's almost always going to look worse with no cat in the system. That's just the way it works.

It's quite possible that you have some internal engine problems from normal wear and tear that just haven't been addressed to this point. Whats's more, even cleaners like Seafoam "can" end up removing enough carbon and gunk from around worn rings and hardened valve stem seals to make a problem worse rather than help. Not at all trying to be the doomsayer here, but you are probably going to have to do some further testing to determine what's going on. 

You can run a simple crankcase vacuum test of the PCV system to start with. Hopefully this is just a case of a vacuum hose connected to the wrong place or something simple like that.

If that didn't paint a clear picture, I'd also run a compression test, measure intake vacuum, as well as take a close spark plug comparison reading from cylinder to cylinder. Those can be good indicators of the basic health of the engine and its internals before assuming the worse.

Depending on the results, that may lead to doing and individual cylinder leak down test, and if she passes all those with flying colors you may just end up doing a valve stem seal replacement, but it's too early to call that shot yet.

I had a car years ago that passed all the tests but continued to burn oil at a rate of a quart per 500 miles. I couldn't drive it like that, so not knowing what else to do I tore it down and found everything looked pretty clean inside, but then I discovered it had one burnt piston land, and one piston ring broken. I determined some one (previous owner) had evidently run the car very hard with the ignition timing advanced too far. How that didn't show up in earlier tests was shocking to me, but it can happen. Not that that's what's going on with your truck, but I'm just saying... 

Remember, you have to take into account exactly how many miles are on this engine, how hard it was used... was it ever overheated at any time in its life, and how well was it maintained? Those can be tough questions to answer.

-R


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## tsnow678 (Feb 22, 2011)

Wow!!! Thanks Repairman for the thorough reply. And I agree with you 100%. I am sure this truck was neglected prior to our family owning it. I knew she had some blow-by but didn't think it was this bad. The new PCV actually slowed down the amount of oil smoke coming from the exhaust. I am just wondering with the PCV now working correctly, could the oil smoke that I am seeing be from the oil that is residing in the exhaust/muffler? I was so close to pulling the head and doing a rering on this truck when I did the timing set but hated to do that to a good running engine. Hind sight is always 20/20. I may, for the short term, weld the cat back on and wait till I can pull the engine to do a complete rebuild. You think I could pull the breather box(pcv) off of the timing cover and fab up a restrictor between it and the cover to limit the amount of oil that can be sucked into the intake tract? I thought about a catch can for the time being at least it will slow down the amount of oil that gets expelled out of the exhaust? It would only be a bandaid but she runs so good!!! Damn she runs good!! Thanks once again Repairman!!!


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## tsnow678 (Feb 22, 2011)

Oh yeah, one more weird situation that tends to make me believe its residual oil trapped in the exhaust that caused the majority of the smoke. Not to say I am not dealing with blow-by or a bad something or nother!!! But when I fire this truck up cold, no smoke! Let it warm up a minute or two and the smoke increasing gets worse. I didn't see near as much smoke today as yesterday. I am going to drive this thing as is till the weekend and see whats what. If it is still huffing and puffing the cats back on and I am going to limit the oil flow from the timing cover to the intake tract somewhat. Opinions? Since TheRepairMan seems to be the only one to take the time to reply to this thread, what do you think TRM? Your knowledgable opinion is welcomed with open arms and that is not being sarcastic, you truely are a great guy!!! :thumbup:


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## TheRepairMan (Jun 30, 2009)

tsnow678 said:


> Oh yeah, one more weird situation that tends to make me believe its residual oil trapped in the exhaust that caused the majority of the smoke. Not to say I am not dealing with blow-by or a bad something or nother!!! But when I fire this truck up cold, no smoke! Let it warm up a minute or two and the smoke increasing gets worse. I didn't see near as much smoke today as yesterday. I am going to drive this thing as is till the weekend and see whats what. If it is still huffing and puffing the cats back on and I am going to limit the oil flow from the timing cover to the intake tract somewhat. Opinions? Since TheRepairMan seems to be the only one to take the time to reply to this thread, what do you think TRM? Your knowledgable opinion is welcomed with open arms and that is not being sarcastic, you truely are a great guy!!! :thumbup:


Thanks, but mine IS just an opinion based on what I've seen on many other vehicles. There are other guys on here with lots more Nissan experience, but the HB forum is has a pretty small population these days.

Have you tried easing the oil fill cap off while the truck is smoking? You have to be careful, but if you just crack the cap a bit and see if smoke blows out the valve cover or not, that might give an indication of how bad the internals are. I've seen some that you could remove the cap after shutting the engine off and smoke would come out of the engine for several minutes... just as one would expect from combustion pushing past the rings in a worn or damaged engine. If your motor tries to blow that cap off with any force while running then your half way to finding the problem.

Sometimes on engines that have a blockage in the crankcase breather system (PCV) they will start out okay cold, but shortly build up too much pressure in the block and start pushing oil into the intake. A valve cover itself can become so coked up with carbon that it will no longer allow the crankcase to breath. You've already seen strong signs of the carbon build up, so this may be causing some symptoms.

Here's a good general definition of how the PCV system works, but they fail to recognize that carbon can clog up the rest of the system, and not just at the PCV valve itself. http://www.agcoauto.com/content/plugins/p2_news/printarticle.php?p2_articleid=197

And, you are right about oil accumulating in the exhaust and then burning off once it all gets up to temp, but there is still the other problem of that much oil getting to that point. I'd lean toward a possible PCV system circulation problem while looking at the whole picture, but the PCV system can only handle a limited amount of blow-by. 

There's a very small and simple tool that momentarily takes the place of the oil cap to measure crankcase pressure/vacuum. I'll see if I can find out where one is available. We've got one at my work, but I'd like to have one for my tool box, too. I'm sure you could tee into the PCV system with a regular pressure/vacuum gauge and take a reading, but I haven't done it that way.



-R


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## tsnow678 (Feb 22, 2011)

I have stalled in returning an update to make sure what I found was truely a fix and not just a band aid. After several days of driving this truck the smoke has become almost non-existent. I am going to have to assume the PCV was defective and allowed oil to freely be sucked into the combustion chamber. This in turn allowed the oil to build up in the exhaust, creating the smoke as it burned off. Once the PCV was changed and the exhaust got hot enough for a length of time the smoke literally disappeared. It still will huff every now and again like it did before. This smoke I can live with as it does have 225,000+ miles on it. Thanks goes out to TheRepairMan as he was the only one to step up to the challenge!!!! Actually he was the only one to reply at all! Thanks again TRM!!!!


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## TheRepairMan (Jun 30, 2009)

You're quite welcome, t. Glad I could be of some help. There are lots of great guys here helping from time to time, but just like me they may not have a lot of spare time so if they see someone has it covered they help elsewhere.

-R


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## tsnow678 (Feb 22, 2011)

Your right TRM about the "got this one covered" and I agree. Sometimes it is nice to limit the amount of responses as it tends to divert from the original issues. I guess I am spoiled from using LS1Tech for so long. I am sort of used to the amount of feedback I get over there. Thanks again for all of the help!


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