Just a query on 20 cam belts. I had a noise from the front and thought a bearing had gone so I removed the various belts from the crank drive and listened but no abating in noise. It sounded like a distributor seizing and got louder with revs. So I pulled off the cam belt cover and listened, still noise. I pulled off the cam belt and examined the belt and "cogs" and the auxilliary shaft, no apparent problems, the belt had been replaced 20K earkier. I thought must be the tensioner bearing so it was replaced to no joy. My mind now says must be the cam seizing so out it comes and, you guessed it, no sign of seizure. The auxilliary shaft was turning fine so what was left the distributor (was the sound coming down the shaft and appearing at the other end?) and the cam belt it self. I changed the belt and noise was gone, so my question is how does the belt make so much noise? Is it the "chords" inside the belt? or "what"?
R20 cam belt noise????
- Thread starter Sherman
- Start date
A "Whirring" sound comes from an overtight cambelt.
Cambelts in the main are also directional & if yours was on assabout it wouldn't be the first. Whether this would cause the noise or not I can't say but it is possible I suppose. Wise move sorting it & fast!!
Alan S
Cambelts in the main are also directional & if yours was on assabout it wouldn't be the first. Whether this would cause the noise or not I can't say but it is possible I suppose. Wise move sorting it & fast!!
Alan S
Alan S said:
Wonder if anyone has ever had it off since it was fitted & refitted it the opposite direction? 
I have been told that steel ply radials will do some very strange things if the rotation is reversed & I don't mean directional tyres either.
Just a thought.
Alan S
I have been told that steel ply radials will do some very strange things if the rotation is reversed & I don't mean directional tyres either.
Just a thought.
Alan S
was the belt tensioned correctly? I have seen a few Douvrins with the spring/plunger missing (from a water pump change no doubt) and poeple just tension it by hand. It should be as tight as the spring will make it, no tighter.
The oil pumps are quite noisy on these motors, especially when cold. The steel sumps magnify this noise (a lot quiter on my alloy sumped R21 and R25 than my Fuegos) Sort of makes a whirring/rattly noise.
Does the R20 run a mechanical fuel pump ala Fuego?
The oil pumps are quite noisy on these motors, especially when cold. The steel sumps magnify this noise (a lot quiter on my alloy sumped R21 and R25 than my Fuegos) Sort of makes a whirring/rattly noise.
Does the R20 run a mechanical fuel pump ala Fuego?
Haakon said:
All of above was OK. Yes a mechanical pump. The noise reminded me of a seizing distributor shaft. A mechanic friend said cam belts will "delaminate" internally if reversed after being used. Spooky. I have the "original" which was a replacemnt some 20K ago and it looks perfect. I am not going to put it back on to see if the noise comes back but that would be a good indicator. The noise just "appeared".
Sherman said:
Our 306 had a noisy belt (#2 of 3). I've always presumed that a slight difference in profile between worn driving cogs and new belt would account for it - ours was fitted by a man I trust so I'm fairly sure it was correctly tensioned.
Regarding the "original" belt, it's none of my business but I'd cut it in half so it is a strip not a circle, so no-one could accidentally fit it!
Cheers
JohnW
new belts make a little noise when first installed (the huge belt on my friends DOHC mitsubishi certainly did), but should quieten down once bedded in. Chuck a new one on - they are very cheap from Carrevelle. I replace them if I take them off even if they only have a year on them.
Check the little mesh oil filter in the back of the rocker shaft - they rarely get cleaned. it may be blocked starving the rocker gear of oil?
Check the little mesh oil filter in the back of the rocker shaft - they rarely get cleaned. it may be blocked starving the rocker gear of oil?
FWIW, it was fairly common knowledge overseas that the "Gates" belts on the PSA (Cit/Pug) 16V engines had a faulty or incompatible profile & I understand the majority of failures were Gates belts.
I know of one guy here in Oz who had such a failure on a fairly new cambelt & upon checking it was found that it was also a Gates belt.
It's logical to think that if a belt has a slightly different profile to the teeth it's sitting in that as time goes on the teeth will tend to bed in as a "V" belt does with age & could conceivably bottom out on the teeth which could explain the noise after a period of time. It could also begin delaminating as had been suggested due to friction and flapping caused by this bottoming out so a combination of these things I feel could have been the cause.
Be interesting to know the brand of belt that was noisy & see if anyone else has had similar problems. It would also be a good idea to keep a record of the belt fitted & see if it does the same in time & if it was the same brand as the one replaced.
Alan S
I know of one guy here in Oz who had such a failure on a fairly new cambelt & upon checking it was found that it was also a Gates belt.
It's logical to think that if a belt has a slightly different profile to the teeth it's sitting in that as time goes on the teeth will tend to bed in as a "V" belt does with age & could conceivably bottom out on the teeth which could explain the noise after a period of time. It could also begin delaminating as had been suggested due to friction and flapping caused by this bottoming out so a combination of these things I feel could have been the cause.
Be interesting to know the brand of belt that was noisy & see if anyone else has had similar problems. It would also be a good idea to keep a record of the belt fitted & see if it does the same in time & if it was the same brand as the one replaced.
Alan S
Alan S said:
The belt that came off is a QH and the replacement an AE.
Just an update. It turns out the problem was "compound", bent valves and a big end. Cam belt was probably OK.