Cambelt replacement intervals

[classic2cv]

A local bodger (read garage owner) tried to convince me that Citroens intervals for changing the cambelt were rubbish

and that it could be left until 60,000 miles

I’ll be changing mine at around 45,000 even though the recommendation is 48,000

[Stinkwheel]

rubbish indeed, but if you like the extra work it brings his way in head rebuilds

Id be happy to change the belts at 30k mile intervals personally.

Still got that BX then mate?

Hows the Berlingo going?

[AlanS]

The mechanic is correct up to a point.
According to the belt manufacturers now, the current generation 3 belts are made from a nitrile and fibreglass base and are now a non stretch variety.
Here is a posting I made on another forum a while back that details it all.

A while back, I did a cambelt on an engine and in the process, sent a pic across to a friend in the parts industry overseas. I was somewhat surprised to be told that the belt I had was a "48,000 mile belt but the new ones are a 72,000" which was explained to me as the materials they're made from these days and that the belt I had on the car (supposedly changed as routine service) had been out of production for at least 8 years.
We often get new owners enquiring about how and when to change a cambelt and in the process also often hear theories about cambelts "skipping a tooth" or recently an owner who was told by a repairer that some belts whine when changed; neither are practical and the only ones that whine are the ones set too tight. It is usually always suggested by the manuals (which remember are now possibly best part of 20 years old so will contain info referring to older style belts) that the belts need "retensioning" after a short period.

I've just done a cambelt on an 8 valve PSA engine and noticed a bit of interesting info printed on the box the belt came in that I feel is relevant to anyone wanting to do a belt change.

1st Generation:

(NEO) = Neoprene, fibre glass cords and nylon tooth facing.

2nn Generation:

(HTN) = High-Temperature Neoprene, fibre glass cords and nylon tooth facing.

3rd Generation:

(HSN) = Highly Saturated Nitrile. Aramid fibre or fibreglass cords and non stretch nylon facing at higher temperatures with greater horsepower.

A graph showing the heat resistence comparison is also interesting with Gen 1 showing at 105 degrees C which is increased to 130 for the Generation 3 belt.

Having done at least 3 cars in recent months that have been up on mileage for a cambelt change, past the recommended intervals mileage and age wise and then discovered belts that seemed to have never been off the car, (particularly the instance of the long out of production belt) it has to be wondered if some of the service people are using this higher specs belt as a reason to not do a belt change but to "take a punt" that it will go long enough for the current owner to get rid of the car before there's a catastrophe; maybe I'm just a bit cynical based on my own recent findings. It may also explain why the 16V engines were supposedly prone to snapped cambelts and how these days we rarely ever hear of a belt snapping in comparison to back when they were much younger.
I'm not suggesting that a new belt bearing the HSN specs is the be all to end all and that one cambelt change will see the rest of your days of ownership out, but I do believe that if cambelts are genuinely changed at the recommended intervals, using these newer high spec belts, then chances are you may never have to wear a busted engine due to failure; it lowers the risk considerably.
It must also bring into question a belt whirring or whining after change being a a very risky proposition as having now a "non stretching nylon facing" is an advantage in a properly set up cambelt situation but walking through a minefield if overtightened. The upside of course is that being a non stretching type means it should really be a case of once it's set it should be left rather than risk stressing the non stretch facing.

If nothing else, a well fitted belt of Gen 3 specs should give any owner of a car with an interference engine a bit of peace of mind.


Alan S

Having said all that, I just did a belt on my 16V that had seen the 4 years but not the 80K klms and as far as I was concerned, I'm glad I didn't leave it go any further, so whilst the chances for the belt to go the extra may exist, I think a check even if it's only on the top section of the belt to see if it's going a bit soft, may be a handy precaution. Mine was looking very secondhand but again, it wasn't a Gen3 belt either.



Alan S

[docchevron]

I'm REALLY anal about belts. The valver gets a new belt and tensioners every 10K miles. The diesel gets a new belt every year before the MOT, which is usually about 12K miles.
Over the top it may be, but I've never had one break, and a belt is WAY cheaper than a top end rebuild! The diesel takes me about 45 mins these days (allowing for smokes and the such), and the valver takes about an hour and a half (again, smokes, beer etc).

Even customers / mates cars get belts every 30k miles...

[AlanS]

Mate, honest; if you saw my cars internals, you'd know what a fanatic I really am.
I just had the sump off the 16V and internally I kid you not, it is so clean you can almost see your face on the inside of the sump. The guy who did the TIG job on the air/con brackets was dumbstruck, so I keep a close eye on my belts.
I think one of the reasons our belts may last longer than yours is that you have rain and snow whereas we get hot and dry. It also has to be remembered that our maximum speed is 110 kph but the majority is 100 and we also get long distances with my average drive from here is a round trip of 700 - 800 klms, but the thing to remember is that if for any reason circumstances may dictate that you can't change when you'd like to, there is now a bit of playing room until you can get round to it, something we didn't have before providing the belt is changed properly and providing it was a 3rd generation belt that was used.


Alan S

[DLM]

Interesting info on the new cambelts, Alan - and I'm not surprised to hear of you attitude to belts, Doc, considering you've done enough to probably do one in your sleep by now .

The main inhibiting factors for cambelt changes are the cost (if done by a garage/mechanic), the time factor (particularly important on your first attempt), or just the fear factor. I recently had a masterclass in it from Tom from the grease-monkey angle (cambelt and waterpump change in a carpark on my latest BX to get it home after purchase).

The cambelt is undoubtedly a mental hurdle for many of the semi-competent like myself, though I can also see it's a relatively straightforward job. It's a shame I didn't get the DIY bug while I still had petrol BXs, as they're so much easier to work on (16v and Gti excepted) than the diesels, so I could have got my hand in on the XU-engined cars that I owned. I do feel for anyone taking on a TD as a DIY car if they have little prior experience of mechanics, due to the unpacking involved for simple tasks, and not a lot of access to some vital bits.

A cooking petrol BX is a great DIY learners car - if anyone is considering a BX for the first time, it's where I'd advise them to start. All of which has gone a bit off-topic...

[Geoffrey Gould]

Hello all Having had the benefit of Doc,s help on many ocasions then changing the belt before each MOT seems to be not a bad thing , mine being a diesel it gets the 'benefit' of having the hell reved out of it. Admittedly the mileage I do is not a lot but I find the water pump and idlers lasting as long as the belt is cause for some caution.
A belt and bits are a lot cheaper than an engine.
Cheers.
Geoff.

[AlanS]

As I mentioned in the earlier post, I feel climatic conditions play a part in belt life too.
When I first had BXs, there was a guy from Malaysia, a friend of Brij Dogras who reckoned over there they changed belts at 40,000 klms due to high humidity & wet weather causing them to fail prematurely.
They also had a lot of problems popping strut tops through the bonnet a la' XM & Xantia style. Whether that has changed due to different materials or not I'm not sure but they may have run out of BXs by now anyway as they're pretty hard on them over there.
The downside of changing the belt unnecessarily I suppose is the potential for a mishap in the process a.k.a. human error which is why they say "If it ain't broke, don't fix it"


Alan S

[tim leech]

From somoene who knows, its best to be over careful with cambelts!

[docchevron]

I'd never thought about climate playing a part before, but you could be right there Alan, makes sense if you think about it.

Human error is always a possibility, but I just feel happier knowing the belt in the engine is new, peace of mind kinda thang!

I think driving style has something to do with it too, I know a guy who has broken a belt more than once well inside recomended change intervals, but he drives EVERYWHERE like Michael Shumacher on Acid!

IMHO, however much cheaper and quieter belts are over chains, I'd still rather have a chain keeping things turning than a lump of rubber....

BTW Alan, I have no doubt whatsoever about your engineering prowess mate, I've seen enough on AF to satisfy myself that you know what your talking about. Not trying to be condescending, but theres a few people I will always listen to and take advice from, it's a small list, and you're on it, just dont tell Shane, he'll get pi$$y!!!

Cheers
Chris G

[AlanS]

The reasons I am so uneasy on the human error angle is that there have been a couple of 16Vs that have had problems like this that spring to mind.
One had a set of high tensile steel locating pins made that were a work of art from all accounts.
I questioned the material used and mentioned how the race car engineers had made me a set out of a really crappy aluminium material, but he reckoned it was no problem for him as he'd done them before.
Day of the change, he is 90% finished and wifey calls him for a cuppa and bikkies Upon his return, an hour or so later, he's ready to test so spins the key and.................................bang, clunk........valves striking pistons and .....bugga,bugga,bugga,bugga,bugga,bugga,bugga,bugga a head off job.
Another about 12 months ago where an owner took his car to a recommended workshop for a belt change and it came back "sounding like a turbo." I suggested to him he gets it back there pronto and get the belt adjusted. He took it back where he was told it was a tensioner failing. They replaced it. It still whirred, so next time it was a pump. Still no difference, so after a couple more attempts, he took it to another garage who came to the same conclusion, so slackened it off and it was right.
When he went back to the original garage screaming refund, he was eventually told the guy had used a couple of 16 year old work experience/wannabe apprentices to do the job to give them the experience.
So I suppose the morals of the stories are to be extremely careful if you intend to DIY or use a proven honest repairer if someone else is doing it.


Alan S

[classic2cv]

rubbish indeed, but if you like the extra work it brings his way in head rebuilds

Id be happy to change the belts at 30k mile intervals personally.

Still got that BX then mate?

Hows the Berlingo going?

Hi stinky

the BX & Berlingo are doing fine

the both of them have gone through the MOT and both passed on the second visit

the BX’s Cambelt has done 42000 miles so it's due for a change about now and so is the clutch maybe i'll have the motor out and do lots of bits at the same time

BTW how’s that green drummer doing?

[simonineaston]

Did the cam-belt on mine Saturday and was a bit miffed to see the old one looked "brand new", but am reassured by these posts that seem to say "you can't be too careful" so I don't feel I wasted my time
Further to that, I agree that the job doesn't seem too bad once you've done it once, in fact so confident am I that I chose to skip changing the tensioners until a later date after I have asked you guys a couple of Q.s, which are:
Is it straightforward to replace the tensioners with the engine in? The tensioner nearest the front of the car appears to be held at 3 points, the top left of which is behind a casting situated between the cam and pump wheels - does this casting have to come off? Is the sprung tensioner under huge spring tension - am I going to lose the spring as soon as I remove the 2 nuts, is it going to hard to get enought tension on it for replacement??
PS if you're good at diagnosing problems from the descriptions of noises (!) have a look at my other, more worrying, posting "Wierd noises from the turbo-charger department..."
Yours nervously

[simonineaston]

Have just read a couple of other posts about tensioners and spring-pressure, so unless you guys feel you have anything new you think I ought to know, please consider my Q.s suitably answered