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Droning sound under heavy acceleration
http://www.international2cvfriends.com/forum/viewtopic.php?f=7&t=5981		 Page 1 of 1
Author:  turbofiat124 [ March 28th, 2017, 1:30 am ]
Post subject:  Droning sound under heavy acceleration
So today the misses and I went for a little drive. First time I've had my 2CV out since October.

Anyway I was going down the road and for no apparent reason, under high RPMs just below the shift mark (in any gear), the engine or exhaust suddenly get's louder. I checked all the bolts on the saddle clamps. None were loose.

I was afraid the clamp that exits the crossbox came loose (or fell off) like it did once.

I have a new "rear" silencer to go on the car. The one after the crossbox. It's breaking up inside (rattles). I can't find any adapters small enough to fit it at any auto part stores so I'm just going to take it to a muffler shop since they have all the parts to do it.

The noise sounds like it's around the driver's side cylinder (LHD) when I rev the engine up with the bonnet open. You know where the exhaust makes an elbow off the cylinder? Is this joint sealed with a gasket? Unlike the other ones which are beveled? I'm wondering if the gasket has blown out.

Tomorrow (hopefully) I'm going to take it to the muffler shop and have the new silencer installed. I'm hoping it's just the silencer that has given up the ghost and not another damn saddle clamp leak.

Another thing. I ordered a new air cleaner (foam element and lid). The lid piece was broken and the foam element was distorted.

Anyway I can't seem to keep this thing in place. It keeps popping off. It's got an arrow on the lid and two arrows on the housing. I press down on the lid and rotate the lid trying to line up two of the arrows but doesn't seem to jive. I don't know if that makes any sense. What's the trick to keeping the lid in place?

I'm wondering if this droning sound is the lid popping off and I am hearing intake noise. Is that possible? Can a 600cc create that much intake noise under heavy acceleration?

I installed a pipe in place of the silencer on the intake system of my Subaru and it creates a loud droning sound under heavy acceleration but nowhere near as loud as on my Citroen.
Author:  chevrons2 [ March 28th, 2017, 2:22 am ]
Post subject:  Re: Droning sound under heavy acceleration
It does get quite loud when the air filter lid comes loose. If you take it off and look at the bottom of it, and in the bottom of the housing, you'll see that it locates in 3 places around the lower edge. If you can't get the arrows to line up, then it's not fully located.
Author:  turbofiat124 [ March 28th, 2017, 5:32 am ]
Post subject:  Re: Droning sound under heavy acceleration
chevrons2 wrote:
It does get quite loud when the air filter lid comes loose. If you take it off and look at the bottom of it, and in the bottom of the housing, you'll see that it locates in 3 places around the lower edge. If you can't get the arrows to line up, then it's not fully located.


I aligned those three tabs and assumed I need to push down then twist? I hope that noise is the air cleaner now that I have a stereo in my car.
Author:  samfieldhouse [ March 28th, 2017, 2:17 pm ]
Post subject:  Re: Droning sound under heavy acceleration
Given you haven't used it in five months I'd probably go easy before subjecting it to 'heavy acceleration.' I'm lucky in that I live about 20 mins from the motorway, so I mine get a 20 minute warm up before they start having to work hard. Even so, It feels like it's at least an hour before they reach that happy thrumming point and will bottle quite happily above 70.
Author:  Jonathan [ March 28th, 2017, 6:49 pm ]
Post subject:  Re: Droning sound under heavy acceleration
I'm 300 miles from the nearest motorway :lol:

The plastic air filter box fitted to most 1980's 2CVs is quite simply (to use a French term) merde! One 'fix' you can do is remove the top, put good old fashioned insulation tape around the rim, building up a few layers to get a good seal and fit. That should last a good amount of time, but will eventually need to be screwed down. You've mentioned buying the top part, complete with new foam filter, but you may find the main body of the air box has worn, so the new lid may well not stay in place. Has happened to me in the past.
Author:  turbofiat124 [ March 29th, 2017, 12:01 am ]
Post subject:  Re: Droning sound under heavy acceleration
I did some investigating as to why the air cleaner lid keeps popping off and I think I found out why. When I put the lid on and press down and try to rotate the lid counterclockwise, this is as far as the arrows align:

Image

I noticed three notches in the "bucket" that the tabs in the lid fit into and another notch which is supposed to hold it in place. Then discovered that part of the bucket where the securing notch goes is broken.

Image

I put some Gorilla tape on the lid for a quick fix to see if this affects the droning sound near red line. It seemed to fix the problem. In the meantime my plan is to cut a couple of strips of metal and used some sheet metal screws.

I took the car to my favorite muffler shop today. They did not have any pipe clamps or pipe adapters small enough for this exhaust! I think I measured 1 3/8". The smallest pipe they have was 1.5".

But the guy is pretty good at his work and managed to make it work. He welded the rear silencer to the pipe that exists the crossbox and used 1 1/2" pipe after the rear silencer.

The verdict: No more "train horn in the distance" sound under deceleration but the engine is still a bit louder than I'd expect it to be. But this is the first 2CV I've ever owned so I don't have anything to compare it to.

I know VW Type 1's are loud as hell no matter what so is that the nature of the beast with 2CVs?

I can't smell any exhaust fumes so I guess that's all that really matters.

During tickover, I can barely hear the engine running, it's only near redline that the engine starts making more exhaust noise than I would expect. But I do suspect the air cleaner lid was the source of the droning noise.

However I have been driving my Subaru since October so maybe I did not realize how loud the car actually is? I drove the car about every day for three months after I got it and maybe just got used to it.
Author:  ken [ March 29th, 2017, 1:23 pm ]
Post subject:  Re: Droning sound under heavy acceleration
Is it worth mentioning that the lid should be rotated clockwise in order to lock it in place? :roll:

Also, once the interlocking parts have been damaged, fitting screws around the edge of the lid is a waste of time.
A length of 6mm studding/allthread plus some nuts and penny washers are all that's needed for a better solution...
Author:  turbofiat124 [ March 29th, 2017, 3:17 pm ]
Post subject:  Re: Droning sound under heavy acceleration
ken wrote:
Is it worth mentioning that the lid should be rotated clockwise in order to lock it in place? :roll:

Also, once the interlocking parts have been damaged, fitting screws around the edge of the lid is a waste of time.
A length of 6mm studding/allthread plus some nuts and penny washers are all that's needed for a better solution...



I'll double check but seems like I couldn't get the lid to rotate clockwise. Why is their two arrows on the housing? Which one is supposed to align with the arrow on the lid?
Author:  AZL57 [ March 29th, 2017, 4:57 pm ]
Post subject:  Re: Droning sound under heavy acceleration
Yes the two arrows are aligned when the cover is locked.
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