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Car Forum / Driving, Maintenance, Tuning / Maintenance and Repair / December 2007engine noise help needed!
Hello, I have a 1985 Nissan Pickup (4cyl carburated engine) and it has started to make a very bad sounding noise and I am wondering what it might me. The noise is like a metal on metal knock and it occurs to a small degree whenever the gas is pressed. There is no noise when I start it up and its in neutral. It is at it's worst when you are just getting going and as the RPM's increase it increases in quickness but it doesn't sound as loud. When the noise is loud there is noticable vibration in the body as well as lots of vibration in the shifter. Is my engine a cooked goose? Anything I can do? although I am not very experienced working with cars, I am willing to try things as this truck is worth next to nothing if the engine isn't working right. Ever since this noise started there is also a noticeable lack of power. All help in diagnosing this is much appreciated. Thanks LOL! We got it the first 7 times man, relax you are on google and you might not see your post or any answers for a couple days. That is normal for them. I would be looking at the driveshaft u-joints. You could be describing a blown one that is about to fall apart. If it falls apart the wrong way, the driveshaft can hit the ground flipping the vehicle over. If that happens at highway speeds.... Mike 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's > Hello, > I have a 1985 Nissan Pickup (4cyl carburated engine) and it has started [quoted text clipped - 10 lines] > this noise started there is also a noticeable lack of power. All help > in diagnosing this is much appreciated. Thanks Mike; Not to cut you down, but sounds more like an ignition problem. OP noted that the truck has experienced a loss of power since the knocking appeared, and knock becomes worse under acceleration. Sounds more like the engine is knocking and the ignition is being modified but not sufficiently enough to eliminate the knock. OP should look at getting the ignition and engine controls checked out. > LOL! > [quoted text clipped - 26 lines] >>this noise started there is also a noticeable lack of power. All help >>in diagnosing this is much appreciated. Thanks Could be. A bad u-joint can load up pretty bad though, worth having a fast look. > Mike; > [quoted text clipped - 37 lines] > >>this noise started there is also a noticeable lack of power. All help > >>in diagnosing this is much appreciated. Thanks Sorry for so many beginning posts, thanks for the replies. A couple of more things I have thought about. The problem came on very suddenly- from no knocking to knocking. Although the knocking did worsen slighly it has seemed to plateau. I know this becuase I drove it 100 miles with this knocking, very gently! About the loss of power, I am not totally sure about that, the engine has always been a little weak and because the noise gets bad I just tried to drive it very gently. When I am in neutral I have to rev the engine pretty high before I can get even the shadow of the knocking I hear while driving. I have tried high octane gas and this helped not at all. Thanks Sorry for so many beginning posts, thanks for the replies. A couple of more things I have thought about. The problem came on very suddenly- from no knocking to knocking. Although the knocking did worsen slighly it has seemed to plateau. I know this becuase I drove it 100 miles with this knocking, very gently! About the loss of power, I am not totally sure about that, the engine has always been a little weak and because the noise gets bad I just tried to drive it very gently. When I am in neutral I have to rev the engine pretty high before I can get even the shadow of the knocking I hear while driving. I have tried high octane gas and this helped not at all. Thanks >Sorry for so many beginning posts, thanks for the replies. A couple of >more things I have thought about. The problem came on very suddenly- [quoted text clipped - 6 lines] >shadow of the knocking I hear while driving. I have tried high octane >gas and this helped not at all. Thanks Well since you hear the noise when it is in neutral and the drive train isn't engaged, maybe the problem is in the engine area only. I'm thinking connecting rod problems, but then, who knows? To bad you can't look into these things without taking them apart. What about a broken valve stem? I would buy one of those engine stethoscopes at an auto parts store, and try to get it down to where the noise is the loudest, and go from there. Lg nevertheless, knocking even in neutral sounds like a busted lifter or valve but defintely something in the engine's internals. Depends on whether its a clanking or just a chattering. Thanks for more replies. I just went and had another look and, yes I can hear the noise when I rev the engine in neutral and it seems to be coming from the rear of the engine, toward the cab. I took it for a very short drive and it is definately weak with power. In fact I had to give it alot of gas to keep it from stalling as I went from a stop. The vibration in the cab is pronounced, even in idle everything seems to be moving. thanks >Thanks for more replies. I just went and had another look and, yes I >can hear the noise when I rev the engine in neutral and it seems to be >coming from the rear of the engine, toward the cab. I took it for a >very short drive and it is definately weak with power. Well that's one clue. > In fact I had to >give it alot of gas to keep it from stalling as I went from a stop. Because you're only running on a few cylinders. Literally. >The vibration in the cab is pronounced, even in idle everything seems >to be moving. thanks Good luck, keep us posted ( well, keep me posted. You'll get a line of horse sh.t from these other nitwits, like your U joint is going out ). Lg >>Sorry for so many beginning posts, thanks for the replies. A couple of >>more things I have thought about. The problem came on very suddenly- [quoted text clipped - 6 lines] > > Lg A piece of dowel, or a broom handle works pretty well too.. Has the Oil Pressure light come on, or the gauge read low?? Could be main bearing? or a dead cylinder....caused by broken rocker or something like that.  SignaturePaul '91 XL1200 '77 GL1000 (W.I.P.) "I feel more like I do now than when I got here" >>>Sorry for so many beginning posts, thanks for the replies. A couple of >>>more things I have thought about. The problem came on very suddenly- [quoted text clipped - 12 lines] >Could be main bearing? or a dead cylinder....caused by broken rocker or >something like that. That's what I'm thinking. If he pulls of his valve cover(s) without doing any more than that, he might see a whole lot of where the problem is. Otoh, could it be an ignition problem? Bad wires / plugs / timing, and such? Right now, we don't know. Lg Ok, well I took off the spark plug wires one by one and gave the engine a good rev each time and I could hear the noise each time. It in not something like typical valve noise but something more knocking, defiately created with metal hitting metal. There is no extra noise in idle but there is alot more vibration than there was before this problem. I am new with cars and have only done the basic- changing belts, brakes, fuel pump, etc. What would I be looking for when I took the valve cover off? >Ok, well I took off the spark plug wires one by one and gave the engine >a good rev each time and I could hear the noise each time. It in not [quoted text clipped - 4 lines] >belts, brakes, fuel pump, etc. What would I be looking for when I took >the valve cover off? Hi, just got back from errand. Well, you can use a very good light ( high power ) and look for anything that is different from everything else , that is, bent or broken. Broken valve stem should be immediately apparent. That would also cause lack of pressure in cylinder, and power loss. Also make clinking clacking noise when engine is running. That is very easy to see and check. First thing I would do. I would take the valve covers off and check for broken or bent parts without any further disassembly. Taking valve covers off takes only a little time, and very little time. Lg >Ok, well I took off the spark plug wires one by one and gave the engine >a good rev each time and I could hear the noise each time. It in not [quoted text clipped - 4 lines] >belts, brakes, fuel pump, etc. What would I be looking for when I took >the valve cover off? OTOH, if you have a broken piston rod, you will know this if you pull your spark plugs. Put a dowel rod down the hole to hit piston head. Crank engine, and see if rod goes up and down. If you find a cylinder where wooden rod does NOT go up and down, oh you have broken piston rod that connects the piston head to the crankshaft. Lg Thanks alot for all the good help- I will be checking it out today or tomarrow and will get back to you. Thanks again, jason jasvidas@yahoo.com wrote in news:1102371129.624937.207180 @c13g2000cwb.googlegroups.com: > Ok, well I took off the spark plug wires one by one and gave the engine > a good rev each time and I could hear the noise each time. It in not [quoted text clipped - 4 lines] > belts, brakes, fuel pump, etc. What would I be looking for when I took > the valve cover off? Jasvidas, One really important question here..... Is the knocking in time with the revolutions of the engine, or is it half-speed? If it is a connecting rod, you should hear it basically every revolution, whereas, if it is in the valvetrain, you will hear it every other revolution of the engine. This can help to narrow the problem considerably. SignatureAnthony You can't 'idiot proof' anything....every time you try, they just make better idiots. Remove sp to reply via email Just a thought but has anyone suggested you look at your torque convertor bolts to see if any are loose or missing. For that matter all of these responses and nobody even asked if the transmission is auto or manual???? If you have an auto trans inspect the flywheel and convertor bolts. >jasvidas@yahoo.com wrote in news:1102371129.624937.207180 >@c13g2000cwb.googlegroups.com: [quoted text clipped - 13 lines] >revolution of the engine. This can help to narrow the problem >considerably.
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