hi everybody, i have a 93 dodge dakota 3.9 liter that has been making an odd knocking sound that lasts about 10 seconds after the motor is shut off. the fan isnt hitting anything, as the noise continues after the fan has stopped. i think it may be the lifters, but im not sure. also, the truck has 222k miles on it, so if anyone has any suggestions of other items to check, please tell me. im pulling the left cylinder head this week to drill some sheared off exhaust manifold bolts, so ill already be pretty far into the motor. thanks.
knocking noise after motor is shut off
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I don't see how there can be any noise after the engine stops moving; and 10 seconds later? :huh:
i just listened again, it lasted almost a minute slowly slowing down until the end. it alternates which side of the motor it comes from, left to right. sounds like its in the upper portions of the motor, the same place on both sides. it confuses me too because nothing should be moving anywhere, and i know it isnt a thermal ticking either. it also sounds like most of the lifters are frozen. how much kerosene should i add to the oil to free them up? this vehicle sat for years before i got it, so i dont really know whats going on in it. it did pass a compression test though. on a side note, i think the timing chain is worn out too.
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This makes no sense to me at all. I'm going to suggest that something is broken internally, though I'm not sure what.
Are you counting from when you turned the key off, or when the pulleys stopped turning? If an engine is dieseling, it still turns after it's shut off, but all noise stops once the engine stops moving.
Are you counting from when you turned the key off, or when the pulleys stopped turning? If an engine is dieseling, it still turns after it's shut off, but all noise stops once the engine stops moving.
I'm starting to think that this may be thermal ticking i haven't noticed before, it didn't sound like it to me the last time because it alternated sides perfectly, but i listened again, and it didn't alternate perfectly at all. it didn't make sense to me that it would last that long after running the motor for only a few seconds. so maybe i just heard it wrong. on the other hand, that wasn't the only noise. the lifters are still rattling and it sounds like the timing chain is shot, which isn't surprising considering the mileage. what should i do for the lifters and how difficult is it to swap the timing chain out? Are there any particular parts on the 3.9 you would recommend checking at this mileage? also, so you know, i have relatively little experience in motors. I've torn a few apart, but that's the extent of it.
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Thermal ticking would be the only thing that made sense if the engine is motionless. Broken exhaust studs could aggravate the noise.
1993 was the 1st year of the Magnum engine offering. It was an option or running change until all V6 and V8 engines were Magnums later in the year. It would be characterized by a high profile aluminum intake manifold.
The Magnum cam was roller-type with roller lifters which were fairly durable.
You ask about servicing lifters with kerosene? I wouldn't do that. Are they noisy when running?
I would more suspect timing chain rattle which Chrysler offered a tensioner package for and distributor/oil pump drive (auxillary) shaft bronze bushing premature wear, although at this mileage it would have to be forgiven. The special installer tool reamed and spread the new bushing into place inside the distributor hole.
Do a general health check of the engine like oil pressure check and compression check. If you drop the pan for inspection and cleaning, you may want to plastigage the rod and main bearings. Any fault codes?
The intake manifold could develop vacuum leaks at the base pan bolted to it and that could cause higher oil consumption. The gasket is replaceable.
1993 was the 1st year of the Magnum engine offering. It was an option or running change until all V6 and V8 engines were Magnums later in the year. It would be characterized by a high profile aluminum intake manifold.
The Magnum cam was roller-type with roller lifters which were fairly durable.
You ask about servicing lifters with kerosene? I wouldn't do that. Are they noisy when running?
I would more suspect timing chain rattle which Chrysler offered a tensioner package for and distributor/oil pump drive (auxillary) shaft bronze bushing premature wear, although at this mileage it would have to be forgiven. The special installer tool reamed and spread the new bushing into place inside the distributor hole.
Do a general health check of the engine like oil pressure check and compression check. If you drop the pan for inspection and cleaning, you may want to plastigage the rod and main bearings. Any fault codes?
The intake manifold could develop vacuum leaks at the base pan bolted to it and that could cause higher oil consumption. The gasket is replaceable.
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I had 150K on my '95 3.9 when I freshened it up when I did an engine swap, installed new oil pump timing chain and camshaft. My cam was pitted worse than I cared for, but the roller rockers were still in perfect shape, not a scratch on them, so I do tend to agree with ImperialCrown, keep the kerosene out of the mix it just isn't necessary. Now, historically, timing chains are about a 250-300K item at best, low oil pressure is about the same, bearings may be worn due to the lower oil pressure. A mechanical or new electrical oil pressure gauge where you can see what the oil pressure is at different points or time, like idle cold and hot, after a cruise then idle, may give you a better idea as far as bearing quality goes. If you look at the 200,000 miles club, there are dozens, literally, of Dakota trucks with the 3.9s, they are one tough motor no matter what anyone says, high miles wear and simple component replacement (bearings, timing chain, etc), usually has them keep going with rare actual machining to repair.
The noise started off as sounding like something was hitting, then went upwards in tone to more of a tinging, so im guessing that i simply heard it wrong.it is a 3.9 magnum so it has the roller lifters, and they are noisy from what i can tell. I'm going to take it to someone i know who is more experienced to tell me for sure if it is them, as i only know what I'm listening for from internet descriptions of the sound. the timing chain is under a lot of suspicion at this point, due to the mileage and i think i can hear it, but its hard to tell with all the other noises. also, i don't think the previous owner would have bothered to check something like that.i haven't checked the distributor cap, but I'm going to when i go to pull the head off. the intake manifold is also going to get a new gasket when i tear the motor down, so any vacuum leaks will be taken care of. I'm going to check it for fault codes on Monday. thanks everyone for the help so far.
"timing chains are about a 250-300K item at best, low oil pressure is about the same"
not sure what you mean here, how is low oil pressure connected to the timing chain?
"timing chains are about a 250-300K item at best, low oil pressure is about the same"
not sure what you mean here, how is low oil pressure connected to the timing chain?
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Sounds right that it's just 'thermal ticking', the sound of the metal contracting as it cools.
And actually, 1992 was the first year for the Magnum engines, not 1993.
And actually, 1992 was the first year for the Magnum engines, not 1993.
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What I mean is this is about the length of time these two components start to wear out, not related to each other, just that they both last quite a while, but they do wear out over time, so you are coming up on the time they could become an issue and should consider replacing them, given the depth you are getting into the engine.
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After pulling the intake, you can examine the lifters. They are held in by brackets.
Check rocker arms and pushrods for wear or damage.
Check rocker arms and pushrods for wear or damage.
I'll be sure to pull the lifters out and look at them. I'm assuming that to check then for seizure you attempt to compress them, and if they dont compress they are frozen. I'm going to inspect everything I can from pulling the left head off, and depending on what I find, I may pull off the right head as well. I probably won't plastiguage anything, but I may later on. If the lifters do turn out to be frozen, how would you guys recommend fixing them?
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The lifters shouldn't compress. Hydraulic lifters 'pump up' with oil to make a zero-lash condition for the valve linkage. They can be leaked down in a vise.
The roller that rides on the cam lobe should be free, but not worn or stuck.
If they compress relatively easily (spongy, collapsed) then that is a problem and they will be noisy (ticking, clatter, etc).
They are not serviceable. Replacement only. Determine that they are a problem first.
The roller that rides on the cam lobe should be free, but not worn or stuck.
If they compress relatively easily (spongy, collapsed) then that is a problem and they will be noisy (ticking, clatter, etc).
They are not serviceable. Replacement only. Determine that they are a problem first.
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