Neon engine Knock
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From: Dupo, Illinios
Neon engine Knock
Ok I have a 98 plymouth/dodge neon. It has an engine knock. I'm not sure what it is though. I've been told the head gasket, push rod, lifters, bad valve spring. But I want to try to figure out what it is before I go ripping into it so I can start pricing parts. The knock can be heard through the exhaust. So is there anyway to figure out?
Also the classic burning oil problem that most 1st gens have. Anyway to fix?
Also the classic burning oil problem that most 1st gens have. Anyway to fix?
Captain
Joined: Mar 2009
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From: Hazel Green, AL
A knocking oil burning engine usually indicates bad ring wear and worn out bearings (main and rod).
How many miles? Have you done a compression and leak down test? They are cheap and/or free to do and will give you a good indication of what may be wrong with your motor.
These motors do not have lifters or push rods, but are overhead cam'd (SOHC or DOHC), and if you have a lot of miles on your car, then yes, you may need to have a good head job done to put the system back to nominal (within specs) operation.
Do the two tests above and let us know. But I am guessing that it may be time for an engine rebuild.
How many miles? Have you done a compression and leak down test? They are cheap and/or free to do and will give you a good indication of what may be wrong with your motor.
These motors do not have lifters or push rods, but are overhead cam'd (SOHC or DOHC), and if you have a lot of miles on your car, then yes, you may need to have a good head job done to put the system back to nominal (within specs) operation.
Do the two tests above and let us know. But I am guessing that it may be time for an engine rebuild.
Captain
Joined: Mar 2009
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From: Hazel Green, AL
With 170K on the car, a quick compression check and leak down test will give you a good idea how well your rings are as well as how good/bad your valves are. Your core engine may well be fine, but you still may need a head job to quiet the noise and here's why:
When your engine gets quieter as it warms up tell me that you don't have a rod or main bearing knocking sound but a valve rattle sound - which is a top end vs. bottom end noise. You can easily detect the difference if you have a mechanics stethoscope. Put it on the valve cover and your ears will hear it rattle like rolling rocks in a tin can - even at idle and will only get faster if rev'd. Put it on the oil pan and if you have knocking rods or mains, it will sound like someone pounding an anvil with a hammer (it is really distinctly different from a rattle) and get louder and sound worse when rev'd.
When your engine gets quieter as it warms up tell me that you don't have a rod or main bearing knocking sound but a valve rattle sound - which is a top end vs. bottom end noise. You can easily detect the difference if you have a mechanics stethoscope. Put it on the valve cover and your ears will hear it rattle like rolling rocks in a tin can - even at idle and will only get faster if rev'd. Put it on the oil pan and if you have knocking rods or mains, it will sound like someone pounding an anvil with a hammer (it is really distinctly different from a rattle) and get louder and sound worse when rev'd.
A valve rattle is extremely common on Neons as they age in miles. There is no valve lash adjustment disc to muck with for the rockers, but the "automatic" lash adjusters on the ends of each rocker (which is hydraulically powered by engine oil pressure) will wear down and need to be replaced as time wears on. Bad oil pressure can also wear them down sooner.
The beauty of the Neon engine is that it is oh so easy to check and replace bad rockers just by taking off the valve cover and a couple of bolts, and the whole thing just pops off toot sweet! The Haynes manual tells you how to check and replace any that are bad.
When I rebuilt my engine, I had to replace some obviously bad rockers in the #1 cylinder, but chose to replace the others as the wear out. Right now, my engine does the same thing as yours - rattles a little louder when cold, but shuts up when fully warmed, and my car is running great! The rattle can be annoying (and if they really are wore out, very loud too), but at $55 to $75 dollars each for SOHC intake and exhaust rockers, it can quickly cost a boat load of $$$ to replace all of them.
I don't believe anyone sells just new lashes anymore - if they ever did - but if you (or anyone else) knows someone who does, or where I can get some whole rockers WAY cheaper then what I put above, then I would love to hear it as I will be in the market for some in about 50000 miles.
The beauty of the Neon engine is that it is oh so easy to check and replace bad rockers just by taking off the valve cover and a couple of bolts, and the whole thing just pops off toot sweet! The Haynes manual tells you how to check and replace any that are bad.
When I rebuilt my engine, I had to replace some obviously bad rockers in the #1 cylinder, but chose to replace the others as the wear out. Right now, my engine does the same thing as yours - rattles a little louder when cold, but shuts up when fully warmed, and my car is running great! The rattle can be annoying (and if they really are wore out, very loud too), but at $55 to $75 dollars each for SOHC intake and exhaust rockers, it can quickly cost a boat load of $$$ to replace all of them.
I don't believe anyone sells just new lashes anymore - if they ever did - but if you (or anyone else) knows someone who does, or where I can get some whole rockers WAY cheaper then what I put above, then I would love to hear it as I will be in the market for some in about 50000 miles.
Captain
Joined: Mar 2009
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From: Hazel Green, AL
Zanko, again, with 170K on the car, you may want to spend a few minutes running the two tests as why just fix the head when the rings and bearing may be getting weak and you will be pulling the head again inside of 10K miles, but this time, putting rings and bearings in too? If you find they are weak, you may want to just go ahead and fix all of it at one time.
Now if a leakdown test indicates excessive valve wear, then when you do pull the head, send the head off to get it cleaned, square checked, pressure checked, magafluxed, etc. and maybe even let them do the work cleaning/honing the valves, springs, replace seals, cam and bearing checks, etc. and even put new rockers as needed on.
Get the local machine shop to give you a total job price estimate on it and make sure you ask not only how long it will take to do the work, but ask when they can actually start working on it. The two dates may very well be very different. The work may only take 2-3 days to do, but 3 weeks to get to it.
In other words, don't get head-pull happy. Run the checks first. That way you can at least say, I ran the diagnostic checks, here is the results, so I pulled the head to begin fixing it.
With 170K you may want to replace the timing belt, tensioner pulley, water and maybe even the oil pump too. I say this because I don't know when you did them - if ever.
Now if a leakdown test indicates excessive valve wear, then when you do pull the head, send the head off to get it cleaned, square checked, pressure checked, magafluxed, etc. and maybe even let them do the work cleaning/honing the valves, springs, replace seals, cam and bearing checks, etc. and even put new rockers as needed on.
Get the local machine shop to give you a total job price estimate on it and make sure you ask not only how long it will take to do the work, but ask when they can actually start working on it. The two dates may very well be very different. The work may only take 2-3 days to do, but 3 weeks to get to it.
In other words, don't get head-pull happy. Run the checks first. That way you can at least say, I ran the diagnostic checks, here is the results, so I pulled the head to begin fixing it.
With 170K you may want to replace the timing belt, tensioner pulley, water and maybe even the oil pump too. I say this because I don't know when you did them - if ever.
All Star
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From: Cullman,Al
check your rod bearings my car has the same problem, i took my car to a mechanics shop and that is what they told me.and a head gasket isn't going to cause your car to knock if it was your head gasket it would make your oil milky and it will overheat eventually
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From: Dupo, Illinios
im gonna run the tests first be for i take the head off. and streetracer88 the head gasket may not be the problem but, i will need to put a new one when i put the head back on
All Star
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From: Cullman,Al
I was just trying to save you some time and headaches because i think you are going to be disappointed when you find out you wasted your time tearing your motor down and you still have the knock thats all but i no you would have to replace it after you take the head off