crackle from s3c engine sump
Discussion
hi,
I have got this sound since 2 weeks or months now, drove at least 2000 km with it. Car/engine has done now 97 000 km total, S3C.
The sound is like a mild electric spark. Like shorting out at, say 12 V, 10 A. But like several per second. Did not think it is electric, nothing on the radio, nothing looking at it during the night. Sound is on anytime the engine is on, revs seem not to alter it (except the exhaust sounds drowning it out).
Location underneath the seats, so not so accessible.
Service was coming up, so I asked the dealer to look at it. They did not find anything, let me listen at it on the bridge. They took the startermotor of, that was OK.
They think it is inside the engine sump, recommend taking the oil sump off. I did not expect it to be inside the engine. It runs perfect. I thought of something like a heatshield, engine mount, catalyst bits rattling inside the exhaust. Anything else in there should make big noise, rpm proportinal, and should be disastrous within 2000 km! The exhaust pipes seemed a bit bent, no circular crosssection anymore, not serious.
I asked if they listened with a stethoscope, they did not have any, and I did not bring mine.
- anybody had this sound? I cannot think of a cause. Anything in there should be submerged under oil. Looked tonight abit in a manual. There is mention of a weak oil pump driveshaft coming down vertically from the (camshaft?) to the submerged pump. Replace when you have a chance it says. Would not like that to snap.
- people at the dealer think they can take the sump off without taking the engine out. Looks difficult to me. I doubt that the oil pump driveshaft can be exchanged this way.
Do you guys (or girls, excuse me) have any ideas?
The dealer has time Monday for this.
I was thinking of returning there Mondaymorning, with my stethoscope, to make sure the sound is in there. Sticking it on the exhaust as well.
mvg Boudewijn
PS the forum confirmation e-mail was seen as spam by my Bayes type filter!
I have got this sound since 2 weeks or months now, drove at least 2000 km with it. Car/engine has done now 97 000 km total, S3C.
The sound is like a mild electric spark. Like shorting out at, say 12 V, 10 A. But like several per second. Did not think it is electric, nothing on the radio, nothing looking at it during the night. Sound is on anytime the engine is on, revs seem not to alter it (except the exhaust sounds drowning it out).
Location underneath the seats, so not so accessible.
Service was coming up, so I asked the dealer to look at it. They did not find anything, let me listen at it on the bridge. They took the startermotor of, that was OK.
They think it is inside the engine sump, recommend taking the oil sump off. I did not expect it to be inside the engine. It runs perfect. I thought of something like a heatshield, engine mount, catalyst bits rattling inside the exhaust. Anything else in there should make big noise, rpm proportinal, and should be disastrous within 2000 km! The exhaust pipes seemed a bit bent, no circular crosssection anymore, not serious.
I asked if they listened with a stethoscope, they did not have any, and I did not bring mine.
- anybody had this sound? I cannot think of a cause. Anything in there should be submerged under oil. Looked tonight abit in a manual. There is mention of a weak oil pump driveshaft coming down vertically from the (camshaft?) to the submerged pump. Replace when you have a chance it says. Would not like that to snap.
- people at the dealer think they can take the sump off without taking the engine out. Looks difficult to me. I doubt that the oil pump driveshaft can be exchanged this way.
Do you guys (or girls, excuse me) have any ideas?
The dealer has time Monday for this.
I was thinking of returning there Mondaymorning, with my stethoscope, to make sure the sound is in there. Sticking it on the exhaust as well.
mvg Boudewijn
PS the forum confirmation e-mail was seen as spam by my Bayes type filter!
I left the car there so cannot check now. I was so convinced it was something external to the engine (like your much appreciated sugg's), that I suddenly was into unknown terrain at Friday evening ezxpecting to just pick up my car. I never had any mechanical problem in any of my cars with engine or drivegear, like to think I am nice to engines. Maybe 1e6 km's.
Looking at the engine innards in carbooks, I found one candidate for the sound: the camshaftdrivegear (or should I write this as four words?).
In a 70's (M-series) description it is defined as "fibre" and to be replaced anytime you can get your hands on it.
In an 80's version they describe how to assemble it, but do not mention fibre. They have a similar story on the oilpumpgearshaft (from distributor to pump), so the ommission perhaps means it is a metal gearwheel now.
Now, if my gearwheel would be fibre, I can imagine reinforcementstrands coming loose and whipping the sides of the distribution lid. More or less like a grass strimmer. And not dampened inside carteroil.
I am going there Mondaymorning with my stethoscope.
and let you know. And be late at work.
Looking at the engine innards in carbooks, I found one candidate for the sound: the camshaftdrivegear (or should I write this as four words?).
In a 70's (M-series) description it is defined as "fibre" and to be replaced anytime you can get your hands on it.
In an 80's version they describe how to assemble it, but do not mention fibre. They have a similar story on the oilpumpgearshaft (from distributor to pump), so the ommission perhaps means it is a metal gearwheel now.
Now, if my gearwheel would be fibre, I can imagine reinforcementstrands coming loose and whipping the sides of the distribution lid. More or less like a grass strimmer. And not dampened inside carteroil.
I am going there Mondaymorning with my stethoscope.
and let you know. And be late at work.
The camshaft drive gear is at the front of the engine behind the pulleys. It is chain driven between two cogs with a self adjuster. No fibres or anything to become loose or worn. If the noise was from the engine internals, then it would certainly alter with increased engine revs. You say it doesn't. I cant see what taking the sump off would do.
Certainly sounds external to the engine to me. Not sure what though, other than whats already been said. Good thing is----it doesnt sound expensive
Certainly sounds external to the engine to me. Not sure what though, other than whats already been said. Good thing is----it doesnt sound expensive
OK,
put the stethoscope on, no trace anywhere on the sump of crackling. Just the bearings sounding perfect. Cancelled pulling off the sump.
The crackling was fully symmetrical with the engine axis.
Absolutely impossible to find anything emmitting the crackling.
Dealer found it to be a loose nut inside the clutch. Now that is at least a dry place. And perhaps you have to put a steth right on the spot where the nut impinges to hear the sound.
put the stethoscope on, no trace anywhere on the sump of crackling. Just the bearings sounding perfect. Cancelled pulling off the sump.
The crackling was fully symmetrical with the engine axis.
Absolutely impossible to find anything emmitting the crackling.
Dealer found it to be a loose nut inside the clutch. Now that is at least a dry place. And perhaps you have to put a steth right on the spot where the nut impinges to hear the sound.
, or something in the bellhousing is dismantling itself? ijbd said:
OK,
put the stethoscope on, no trace anywhere on the sump of crackling. Just the bearings sounding perfect. Cancelled pulling off the sump.
The crackling was fully symmetrical with the engine axis.
Absolutely impossible to find anything emmitting the crackling.
Dealer found it to be a loose nut inside the clutch. Now that is at least a dry place. And perhaps you have to put a steth right on the spot where the nut impinges to hear the sound.
Strewth.....Still, nothing too horrendous then. Thank goodness eh?
OK, fetched the car today, Delayed, job has been abit busy.
Crackle is gone, cause was a loose nut in the clutch housing. Apparently being kicked up by the rotating plates whenever it tried to settle on the bottom of the housing.
Part of the clutch springload stuff.
No damage, except some burrs inside the clutchhousing.
Thanks for thinking along.
mvg Boudewijn
Crackle is gone, cause was a loose nut in the clutch housing. Apparently being kicked up by the rotating plates whenever it tried to settle on the bottom of the housing.
Part of the clutch springload stuff.
No damage, except some burrs inside the clutchhousing.
Thanks for thinking along.
mvg Boudewijn
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