V70: Engine What is the longest surviving cam belt?!?!

[V70greg]

I am asking as I brought my car as a 4 year old high mileage ex fleet car which had not been on the road for 1 year. In its first 3 years it covered about 155k miles don't remember exact now.

It had full main dealer history up until my ownership. I went to my local dealer who had not seen the car and as such did not have the history but said cam belt is due changing at 90k my and their assumption was that as it had full history as a fleet car (with out details I only had dates and mileage) the cam belt was changed.

Well I have just driven to Poland with family to see the wife's family, her brother is a mechanic so we called the dealer who's stamp is in the book out of interest and they had no record of the belt ever being changed. My brother in law kindly changed it with my help and the date stamps on all the old idlers, water pump tension pully etc confirmed that they were manufactured in 2014 (car first registered 01/01/15) so we are pretty sure that after 5 years and 162,571 miles my original cam belt lasted with out failure.

I really wish I had checked it with more enthusiasm when I first got the car, as it would have been changed much earlier and probably wouldn't have attempted a 1,000 mile none stop journey, but I am happy it didn't fail.

[Tatsfield]

Objectively the car must have done lots of long journeys to have covered that mileage in that time. It probably had remarkably little use of the starter. The main cause of stress on the belt is the punch when the engine starts and the belt is at it's coldest and stiffest. You don't say which engine, but if it is the D5 diesel that imposes extra stress when the engine is started and the fifth cylinder unevenly applies extra stress on the first revolution. The change times and mileage are calculated on assumed average usage and the deterioration rate of the belt material. The original Volvo spec belt, I believe, is reinforced with Kevlar so it is a strong piece of kit. It spent most of it's usage time in your car running and kept warm and flexible. If you have this extreme mileage and continuous use you can virtually double the mileage that the belt can cope with. The deterioration over time in your case would not apply in 5 years as the belt is time lifed at 10 years.

So while at first sight your belt history looks extreme, actually it isn't really very stressed compared to a car that does 20 x 2 mile journeys spread over the day. I only hope that you used a genuine Volvo belt as a replacement because belts made to a lower spec, and most after market belts are, will not give you the sort of protection that the original did and could fail under far less stressful conditions. On a D56 some spare parts are not as critical as others but the timing belt really needs to be genuine Volvo.

[Martin Cox]

Assuming it's the D5 engine, I believe most timing belt failures on the D5 not due to the timing belt itself failing.

What usually happens is that the Aux belt fails, often as a consequence of its tensioner failing. Unfortunately the remains of the Aux belt then often finds its way into the path of the timing belt wreaking expensive havoc.

Changing the Aux belt and tensioner is probably more critical than changing the timing belt, which is relatively bombproof.

I believe the recommended interval for changing the Aux belt and tensioner is 54,000 miles but I can't recall the time interval.

I understand that Tatsfield's comments regarding stresses on the timing belt apply similarly to the Aux belt too.

Motorway miles are by far the kindest.

However sometimes one is just plain unlucky. The cambelt on my 1998 V70 failed for no obvious reason, despite being comfortably within time and mileage limits. Timely belt changes do stack the odds in your favour though.

Hope this is of some help and interest.

Martin

2008 V70 2.4D auto 117,000 miles
1998 V70 Tdi auto 226,000 miles

Martin

[Olaf Els]

Originally Posted by Tatsfield

... the D5 diesel that imposes extra stress when the engine is started and the fifth cylinder unevenly applies extra stress on the first revolution.

I'd like to understand the theory behind this statement. I believe the cranks are distributed evenly around the crankshaft. So why should the fifth cylinder apply extra stress? Isn't the stress exactly the same as from the other four?

[V70greg]

Originally Posted by Olaf Els

I'd like to understand the theory behind this statement. I believe the cranks are distributed evenly around the crankshaft. So why should the fifth cylinder apply extra stress? Isn't the stress exactly the same as from the other four?

To be honest I would think more than 4 cylinders would have made the engine smoother as the firing angle on a 4 cylinder will be on 180 degrees of the rotation, a 6 cylinder for example will have 3 firing points around the rotation (rather than 2) making the engine smoother so 5 would have a similar affect (same thinking as super cars have with their V12s as they provide may points of firing around the rotation meaning a silky smooth engine)....

But I don't have enough knowledge to disagree as this seems to be a continuous thread through this Volvo forum that the fifth cylinder adds an impact to an engine, I would be interested to know also, hopefully someone with knowledge of the engine geometry will help??

In regards to your statement I believe additional cylinders would make it smoother rather than make no difference.

[Olaf Els]

Originally Posted by V70greg

.....

In regards to your statement I believe additional cylinders would make it smoother rather than make no difference.

Agreed. I would expect an inline 5 to be smoother than an inline 4 but less smooth than an inline 6, all things being equal. I found this clip on the subject, which is informative and well-presented: https://youtu.be/VBUyR7xQvhY

I'd also read about the extra stress from the 5th cylinder on another thread. I am sure that Tatsfield will shed some light on the subject in due course.

[V70greg]

Very useful video and explains what I was thinking better than I could.

Possibly it is the lack of plain balance which causes the issues with the belts??

[Zebster]

Originally Posted by V70greg

I am asking as I brought my car as a 4 year old high mileage ex fleet car which had not been on the road for 1 year. In its first 3 years it covered about 155k miles don't remember exact now.

It had full main dealer history up until my ownership. I went to my local dealer who had not seen the car and as such did not have the history but said cam belt is due changing at 90k my and their assumption was that as it had full history as a fleet car (with out details I only had dates and mileage) the cam belt was changed.

Well I have just driven to Poland with family to see the wife's family, her brother is a mechanic so we called the dealer who's stamp is in the book out of interest and they had no record of the belt ever being changed. My brother in law kindly changed it with my help and the date stamps on all the old idlers, water pump tension pully etc confirmed that they were manufactured in 2014 (car first registered 01/01/15) so we are pretty sure that after 5 years and 162,571 miles my original cam belt lasted with out failure.

I really wish I had checked it with more enthusiasm when I first got the car, as it would have been changed much earlier and probably wouldn't have attempted a 1,000 mile none stop journey, but I am happy it didn't fail.

Would be useful if you could confirm what engine this is. The 90k mile cam belt interval might suggest a 4-cylinder VEA... if so, the change interval was originally specified as 144k miles but was revised downwards about a year or so ago. This may explain why it appears to have slipped through the net?

Did the old belt, etc look significantly worn?

[V70greg]

Hi

Thanks for all the insight never considered the warmed up motorway driving gives you more miles on the timing belt, knew about a lot of the other advantages.

The engine is a D4 4 cylinder which probably explains the long life and the updated change interval explains why it was missed I thought the previous owner was just taking the chance/scrimping (why would you though on a fleet car??)

The belt was noticeably longer than the new one, when we got the cam shaft timing mark lined up the fuel pump and crank shaft were slightly out. Once the new belt was fitted it all lined up perfectly. As for condition the outer black rubber looked used but no significant damage, the teeth looked good to be honest almost like new. I wish I had taken a photo of them together didn't think about it at the time, I still have the old belt I can post some photos here.

We used genuine Volvo parts for the timing belt, so assuming this life I don't expect to ever change these parts again.

[V8XCV]

Just changed my V70 D5 cambelt, no record of previous change and looked pretty old, so that's 117,000 & 12 years!