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Eric does answer here, so he should be along maybe later in the day. Meanwhile, check your coolant level, as barneyb mentioned above. Is there any overheating or signs of coolant dripping underneath the vehicle?
Eric does answer here, so he should be along maybe later in the day. Meanwhile, check your coolant level, as barneyb mentioned above. Is there any overheating or signs of coolant dripping underneath the vehicle?
Sounds a bit like something loose is rattling at that particular RPM.
What year/model is the vehicle? I saw it’s a Jeep but can’t tell much more from the video.Can you tell where the noise comes from? Up in the engine bay or further back from under the floor, etc?
Does the noise change under load vs revving in neutral?
Does the noise change when the engine is cold? hot? while it’s warming up?
Sounds a bit like something loose is rattling at that particular RPM.
What year/model is the vehicle? I saw it’s a Jeep but can’t tell much more from the video.Can you tell where the noise comes from? Up in the engine bay or further back from under the floor, etc?
Does the noise change under load vs revving in neutral?
Does the noise change when the engine is cold? hot? while it’s warming up?
Someone please correct me if I’m wrong, but the way I learned was that the heat of combustion breaks down the metal-containing molecules of octane improvers and oil additives and vaporizes the metal. The vaporized metal then condenses on the relatively cooler exhaust parts, including the surfaces of the catalytic converter.
While the exhaust pipe doesn’t care about a few atoms thick layer of extra metal, the catalytic converter relies on direct contact with the exhaust gases. Once it gets coated with condensed metal vapors, the catalyst is sealed off from the exhaust gas and can’t function anymore. Soot burns off at typical catalytic converter operating temperatures but since most metals have a pretty high boiling point, the exhaust system can’t get hot enough to burn them off. If it did, the exhaust system and the ceramic in the converter would probably have issues as well.
Tap water doesn’t contain that much metal (it would be deadly if it did), and for the most part minerals tend to stay dissolved. Over hundreds of thousands of gallons, some of the minerals can solidify and cause problems with old pipes and fittings, but that is very unlikely with the amount used for rinsing in the video.
Someone please correct me if I’m wrong, but the way I learned was that the heat of combustion breaks down the metal-containing molecules of octane improvers and oil additives and vaporizes the metal. The vaporized metal then condenses on the relatively cooler exhaust parts, including the surfaces of the catalytic converter.
While the exhaust pipe doesn’t care about a few atoms thick layer of extra metal, the catalytic converter relies on direct contact with the exhaust gases. Once it gets coated with condensed metal vapors, the catalyst is sealed off from the exhaust gas and can’t function anymore. Soot burns off at typical catalytic converter operating temperatures but since most metals have a pretty high boiling point, the exhaust system can’t get hot enough to burn them off. If it did, the exhaust system and the ceramic in the converter would probably have issues as well.
Tap water doesn’t contain that much metal (it would be deadly if it did), and for the most part minerals tend to stay dissolved. Over hundreds of thousands of gallons, some of the minerals can solidify and cause problems with old pipes and fittings, but that is very unlikely with the amount used for rinsing in the video.
Interesting that the Cougar uses a more complex electronic level sensor, and good that it failed positive. At least you now know to check often, though a problem like mine may go undetected for enough time to cause damage.
I’m not familiar with the way it sends a signal to the dashboard to turn on the warning light, but there might be a way for you to retrofit a different expansion tank/overflow tank with a working sensor. If you’re electrically inclined it would make for a cool project to see if that would be possible.
Good luck keeping it on the road 🙂Interesting that the Cougar uses a more complex electronic level sensor, and good that it failed positive. At least you now know to check often, though a problem like mine may go undetected for enough time to cause damage.
I’m not familiar with the way it sends a signal to the dashboard to turn on the warning light, but there might be a way for you to retrofit a different expansion tank/overflow tank with a working sensor. If you’re electrically inclined it would make for a cool project to see if that would be possible.
Good luck keeping it on the road 🙂As far as I’m aware, nearly all automatic transmissions use a separate mechanism to lock the output shaft when the gear selector is placed in the Park position. A pin engages with a toothed or slotted section on the shaft, locking it in place. Normally this is meant to be a supplementary means of holding the vehicle, with most of the holding power coming from the parking brake/handbrake.
Excessive stress can wear out the mechanism, such as parking on hills without using the parking brake. Extreme stress such as the vehicle being struck while parked or accidentally shifting into Park while moving can break the pin and/or the teeth it engages.
What may have happened on your car is that the mechanism got damaged or wore out from use. Every time you park, the vehicle rolls a bit, and all that energy must be absorbed by the mechanism when it does catch, causing further stress and wear. Eventually it may not catch reliably at all.
Applying the parking brake and letting the car settle by releasing the brake pedal before putting the transmission into park may prolong its life, but you should probably look into getting it repaired.As far as I’m aware, nearly all automatic transmissions use a separate mechanism to lock the output shaft when the gear selector is placed in the Park position. A pin engages with a toothed or slotted section on the shaft, locking it in place. Normally this is meant to be a supplementary means of holding the vehicle, with most of the holding power coming from the parking brake/handbrake.
Excessive stress can wear out the mechanism, such as parking on hills without using the parking brake. Extreme stress such as the vehicle being struck while parked or accidentally shifting into Park while moving can break the pin and/or the teeth it engages.
What may have happened on your car is that the mechanism got damaged or wore out from use. Every time you park, the vehicle rolls a bit, and all that energy must be absorbed by the mechanism when it does catch, causing further stress and wear. Eventually it may not catch reliably at all.
Applying the parking brake and letting the car settle by releasing the brake pedal before putting the transmission into park may prolong its life, but you should probably look into getting it repaired.[quote=”randalusa” post=99492]
1999 Mercury Villager (Nissan Quest clone)
3.3L V6
…
There is a rapid, fairly light knocking sound (probably not a rod) that reminds me of what is often heard when first starting older engines that have sat at least a few days. The kind that generally goes away after 3-5 seconds.[/quote]
A quick search turned up that the engine has hydraulic tappets, which supports your description and recording of the noise. My car has hydraulic tappets and I remember the owner’s manual stating that the noise may take several minutes to go away if the engine hasn’t run in a long time.
Your first set of short runs got oil to the top of the engine, so you can probably raise the RPM a little or just let it idle and warm up normally, keeping an eye and ear on it. If the noise fades after 10-15 minutes and everything checks out, you’re probably all set for a test drive. I would also recommend changing the oil & filter soon, along with a general inspection of other fluids and systems if you haven’t already. If the noise doesn’t fade or gets worse, it might be time to seek a mechanic.
Best of luck to you 🙂
[quote=”randalusa” post=99492]
1999 Mercury Villager (Nissan Quest clone)
3.3L V6
…
There is a rapid, fairly light knocking sound (probably not a rod) that reminds me of what is often heard when first starting older engines that have sat at least a few days. The kind that generally goes away after 3-5 seconds.[/quote]
A quick search turned up that the engine has hydraulic tappets, which supports your description and recording of the noise. My car has hydraulic tappets and I remember the owner’s manual stating that the noise may take several minutes to go away if the engine hasn’t run in a long time.
Your first set of short runs got oil to the top of the engine, so you can probably raise the RPM a little or just let it idle and warm up normally, keeping an eye and ear on it. If the noise fades after 10-15 minutes and everything checks out, you’re probably all set for a test drive. I would also recommend changing the oil & filter soon, along with a general inspection of other fluids and systems if you haven’t already. If the noise doesn’t fade or gets worse, it might be time to seek a mechanic.
Best of luck to you 🙂