Tapping noise after sitting 5+ hours
#1
12-13-2010, 10:41 PM
Tapping noise after sitting 5+ hours
OK, I know this is very little to go on, and I have not had a chance to thoroughly investigate yet, but here goes:
For the past few days, upon backing out my driveway and driving up the street in front of my house, my Landy has been making a somewhat disturbing tapping sound for the first several hundred feet. After this distance, the nosie quits. This is first thing in the morning, after being parked in a built-in garage (split level house). The temperatures have been in the teens-20s since this has been going on. I also notice the noise (less loud though) when I leave work to come home for lunch (after it has been parked for 5+ hours outside). At lunch, the noise is significantly lower volume, and doesn't last as long.
It's really hard to describe the noise exactly, but I know what rod knock sounds like (it was making that sound when I bought it, knowing I would have to replace the engine), and it is not as deep. I know what lifter ticking sounds like, and it's not as light as that. It almost sounds like plastic fan blades striking something stationary. The noise is not present while reversing out of the driveway, and only appears under load driving up the street, for the first few hundred feet. The noise only happens when the vehicle has been sitting for more than 5 hours. Park it for an hour or two, and I can drive away with no noise.
Lower end noise typically comes on when the engine is warm, not cold. Valve train clatter or ticking I would never think to describe as this "tapping". The front drive shaft has been rebuilt and greased religiously, plus would be making the noise continuously while driving. Nothing appears amiss under the hood the several times I have quickly checked the past few days before realising how cold it is outside and fleeing indoors. Oil is full (Valvoline MaxLife 10w30 with 4,000 miles on it, to be changed this weekend). Coolant level looks good, but may have dropped 1/8-1/4" in the reservoir in the past few months (have not had to add since flushing a few months ago).
Any ideas? I have a few thoughts, but wanted to get your expert opinions before venturing mine, so as not to skew your answers. Thanks in advance!
For the past few days, upon backing out my driveway and driving up the street in front of my house, my Landy has been making a somewhat disturbing tapping sound for the first several hundred feet. After this distance, the nosie quits. This is first thing in the morning, after being parked in a built-in garage (split level house). The temperatures have been in the teens-20s since this has been going on. I also notice the noise (less loud though) when I leave work to come home for lunch (after it has been parked for 5+ hours outside). At lunch, the noise is significantly lower volume, and doesn't last as long.
It's really hard to describe the noise exactly, but I know what rod knock sounds like (it was making that sound when I bought it, knowing I would have to replace the engine), and it is not as deep. I know what lifter ticking sounds like, and it's not as light as that. It almost sounds like plastic fan blades striking something stationary. The noise is not present while reversing out of the driveway, and only appears under load driving up the street, for the first few hundred feet. The noise only happens when the vehicle has been sitting for more than 5 hours. Park it for an hour or two, and I can drive away with no noise.
Lower end noise typically comes on when the engine is warm, not cold. Valve train clatter or ticking I would never think to describe as this "tapping". The front drive shaft has been rebuilt and greased religiously, plus would be making the noise continuously while driving. Nothing appears amiss under the hood the several times I have quickly checked the past few days before realising how cold it is outside and fleeing indoors. Oil is full (Valvoline MaxLife 10w30 with 4,000 miles on it, to be changed this weekend). Coolant level looks good, but may have dropped 1/8-1/4" in the reservoir in the past few months (have not had to add since flushing a few months ago).
Any ideas? I have a few thoughts, but wanted to get your expert opinions before venturing mine, so as not to skew your answers. Thanks in advance!
#2
01-08-2011, 05:15 PM
Update: I finally got my wife to help me this morning. I had her start it cold and back out of the garage. The tapping noise came on once in the driveway, about 15-20 seconds after start up. It sounded like it was coming from below, so she left it in reverse, foot on brake, and I got underneath. The sound definitely sounded louder underneath the vehicle, but it disappeared completely within 5 seconds before I could trace much.
It has only been happening since the weather has gotten much colder. Since I am the only person awake when I leave for work in the morning, I can't check it myself, because when the noise is happening, if I put it in park, the noise disappears.
Could this be piston slap? Since it only happens on a cold engine, and only lasts for 5- 30 seconds?
Anyone?
It has only been happening since the weather has gotten much colder. Since I am the only person awake when I leave for work in the morning, I can't check it myself, because when the noise is happening, if I put it in park, the noise disappears.
Could this be piston slap? Since it only happens on a cold engine, and only lasts for 5- 30 seconds?
Anyone?
#3
01-08-2011, 05:34 PM
#4
01-08-2011, 05:50 PM
Spike: Failing cat...
Are you thinking the honeycomb material has broken apart or something similar? If that were the case, I should be able to replicate it with a rubber mallet on a cold cat, correct?
If it is converter damage, I could only presume any causes were from a PO, since in the 3+ yeas I've owned it, the SES light has only flashed for a few seconds after a Sea-Foam cleaning last spring, and solid for 1.5 days after that, until it cleared itself.
Tonight and tomorrow will be about the same temperatures as today. Tomorrow morning, I will let it idle for a minute or so before backing out. (normally, it is start vehicle, put in reverse immediately, and begin moving)
Are you thinking the honeycomb material has broken apart or something similar? If that were the case, I should be able to replicate it with a rubber mallet on a cold cat, correct?
If it is converter damage, I could only presume any causes were from a PO, since in the 3+ yeas I've owned it, the SES light has only flashed for a few seconds after a Sea-Foam cleaning last spring, and solid for 1.5 days after that, until it cleared itself.
Tonight and tomorrow will be about the same temperatures as today. Tomorrow morning, I will let it idle for a minute or so before backing out. (normally, it is start vehicle, put in reverse immediately, and begin moving)
#5
01-08-2011, 05:59 PM
Yes you should beable to tap on the cat with a mallet and hear the rattle while cold if that is what it is.
Also keep in mind that when it is really cold starting it and driving straight away like that is not good for the engine.
The oil need time to circulate, and depending on the oil filter, the weight of the oil and the condition of the oil will all make a difference.
You really need to give it a full min to let the oil circulate to every part of the engine.
Worn out oil will not flow as well, adding "friction" or "viscosity" modifiers will also reduce oil flow.
Cheap oil filters with poorly designed anti drain valves will also make a difference.
But you really need to start by stopping with the starting and then dropping into gear thing.
Give it a full minute before dropping it into gear when it has sat for several hours.
Also keep in mind that when it is really cold starting it and driving straight away like that is not good for the engine.
The oil need time to circulate, and depending on the oil filter, the weight of the oil and the condition of the oil will all make a difference.
You really need to give it a full min to let the oil circulate to every part of the engine.
Worn out oil will not flow as well, adding "friction" or "viscosity" modifiers will also reduce oil flow.
Cheap oil filters with poorly designed anti drain valves will also make a difference.
But you really need to start by stopping with the starting and then dropping into gear thing.
Give it a full minute before dropping it into gear when it has sat for several hours.
#6
11-25-2011, 02:59 PM
Rock Crawling
#7
11-25-2011, 06:34 PM
I never did figure out the cause. Either it was temperature related, my allowing the engine to idle for 30 seconds before driving, or switching to 15w40 Rotella oil fixed it. I will let you know at some point this winter if it returns. November 25 and 60 degrees today! Hopefully this late fall doesn't result in snow on the ground in June...
#8
11-25-2011, 07:27 PM
Super Moderator
Also consider if SAI system might be part of the puzzle:
It happens on a cold start, it goes away in a short time, it does not repeat again until engine has been cold for hours.....
from RAVE:
55°C (131°F).
It happens on a cold start, it goes away in a short time, it does not repeat again until engine has been cold for hours.....
from RAVE:
The catalytic converters only start to provide effective treatment of emission pollutants when they reach an operating
temperature of approximately 250
temperature of approximately 250
°C (482°F) and need to be between temperatures of 400°C (752°F) and 800°C
(1472°F) for optimum efficiency. Consequently, the heat produced by the secondary air injection “afterburning”,
reduces the time delay before the catalysts reach an efficient operating temperature.
The ECM checks the engine coolant temperature when the engine is started in addition to the elapsed time since the
engine was last started. The engine coolant temperature must be below 55°C (131°F) for the SAI pump to run.
(1472°F) for optimum efficiency. Consequently, the heat produced by the secondary air injection “afterburning”,
reduces the time delay before the catalysts reach an efficient operating temperature.
The ECM checks the engine coolant temperature when the engine is started in addition to the elapsed time since the
engine was last started. The engine coolant temperature must be below 55°C (131°F) for the SAI pump to run.
NOTE: The ambient air temperature must also be above 8
°C (46°F) for the SAI pump to run.
Also, depending on the long term 'modelled' ambient temperature determined by the ECM, the minimum elapsed time
required since the last engine start can be up to 8.25 hours. The period of time that the SAI pump runs for depends
on the starting temperature of the engine and varies from approximately 96 seconds at 8
required since the last engine start can be up to 8.25 hours. The period of time that the SAI pump runs for depends
on the starting temperature of the engine and varies from approximately 96 seconds at 8
°C (46°F) to 30 seconds at
55°C (131°F).
#10
11-25-2011, 07:41 PM
Super Moderator
Open your copy of the RAVE, workshop manual, emissions controls. It has an electric pump, some solenoid and vac operated valves, and is a known source of "the tick" (but not the only source). Also, if you have a 97, it is not a D2, so it won't have one and you may not find what you seek in this part of the forum. More likely you have oil pressure / oil pump problem, or flex plate cracked (tranny to flywheel interface).
Last edited by Savannah Buzz; 11-25-2011 at 07:45 PM.