Jabel Posted September 28, 2009 Report Share Posted September 28, 2009 Been getting a lot of oil in the air cleaner. My mechanic diagnosed it as blow-by and the only remedy is a rebuild or swap. The truck only has 150,000 miles, so I'm considering it. Are engines available for this truck? Can you upgrade to a newer engine with more HP? I love this truck, but not made of money. Thinking about doing the swap myself with friends and their shop. Quote Link to comment
izzo Posted September 28, 2009 Report Share Posted September 28, 2009 (edited) Been getting a lot of oil in the air cleaner. My mechanic diagnosed it as blow-by and the only remedy is a rebuild or swap. The truck only has 150,000 miles, so I'm considering it. Are engines available for this truck? Can you upgrade to a newer engine with more HP? I love this truck, but not made of money. Thinking about doing the swap myself with friends and their shop. a full rebuild is not needed. If you have blow by, you could just have the head rebuilt or put another one on. Engines are still available for these. Fill out your profile and put your location on there, and put in a wanted ad someone might have one thats local (head or whole engine). I just threw a good one in the garbage. If you are mechanically inclined you could pull the head yourself and have it rebuilt by a shop. Edited September 28, 2009 by h2theizzo Quote Link to comment
datsunaholic Posted September 28, 2009 Report Share Posted September 28, 2009 Blowby has nothing to do with the head. Blowby is rings. Answer to question: Any carbbed NAPS-Z engine can be swapped in rather easily, though a Z22s from another 720 would be the easiest. They were used '81-early (VERY early) '83. The Z24s will swap in with very minor mods to the plumbing (if any), and were used '83-midyear 86. You can put a newer engine, but anything after midyear '86 is going to be fuel injected which means there's some work to do (modifying tank/lines for high-pressure fuel, and adding in the wiring and ECU for the EFI system). Plus it also involves welding up new motor mounts. Quote Link to comment
izzo Posted September 28, 2009 Report Share Posted September 28, 2009 (edited) Blowby has nothing to do with the head. Blowby is rings. Answer to question: Any carbbed NAPS-Z engine can be swapped in rather easily, though a Z22s from another 720 would be the easiest. They were used '81-early (VERY early) '83. The Z24s will swap in with very minor mods to the plumbing (if any), and were used '83-midyear 86. You can put a newer engine, but anything after midyear '86 is going to be fuel injected which means there's some work to do (modifying tank/lines for high-pressure fuel, and adding in the wiring and ECU for the EFI system). Plus it also involves welding up new motor mounts. what if the valve seats are worn out? bad rings, wouldnt that cause smoking as well? Edited September 28, 2009 by h2theizzo Quote Link to comment
datsunaholic Posted September 28, 2009 Report Share Posted September 28, 2009 Non-sealing valves will have lots more symptoms, but oil going into the air cleaner isn't usually one of them. A lot of backfiring and extremely low compression is the normal symptoms of valves not seating. You can have worn rings and not get smoke. The oil rings are independant of the compression rings. Plus, a functioning catalytic converter will mask the smoke, at least until it fails due to the amount of hydrocarbons getting run through it. Blowby so bad that it's forcing oil up the breather tube is caused by it being so bad that the PCV can't handle the amount of pressure. You can't get that much pressure up a valve guide. To get pressure up into the valve train, a leaking valve would have to force pressure up the valve stem/guide. That would cause a lot of soot (on an exhaust valve) but it's nearly impossible to force gasses up an intake valve guide because there's vacuum in the intake manifold- pressure is going to go that way, not up to the valve cover that has positive or neutral pressure. Quote Link to comment
datzenmike Posted September 28, 2009 Report Share Posted September 28, 2009 (edited) If the valve guides were severely worn oil will be sucked into the intake port side and burned in the cylinder. A badly worn exhaust guide will leak a small amount of exhaust up under the valve cover but not near enough to push oil spray from the rocker arms out the vent past the baffles. The clearance between the valve stem and the valve guide should be between 0.008" and 0.0021. That's two thousandths of an inch or about half the thickness of newsprint. Max wear allowed is just under 4 thousandths of an inch. Worn guides, and sometimes rotten valve seals, tend to 'leak down' oil when shut off, creating a big puff of blue smoke on the next start up. Fill out your profile location. There was a guy on here giving away a Z24 and tranny this summer. Would help to know where you are. Edited September 28, 2009 by datzenmike Quote Link to comment
Jabel Posted October 2, 2009 Author Report Share Posted October 2, 2009 Thanks for the all the help so far. I went ahead and filled out my profile. I am pretty sure I'm going to do a whole engine swap. I found a z24 with a good warranty and price tag. I have a z22 installed now. Anything I should watch out for with a switch to a z24? I'm also looking for buckets seats and window crank (i snapped the knob off trying to crank the window up, should have fixed the regulator when I noticed it the first time :( ) Quote Link to comment
izzo Posted October 2, 2009 Report Share Posted October 2, 2009 man if you were closer i would love to have that z22 Quote Link to comment
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