XC70: Engine S29451 hydraulic belt tensioner

[Jocke011]

Hi Volvo experts 😁

I’ve for like one month ago bought my first Volvo, XC70 D5 from 2011, with 317.000 km, and I am the owner nr. 2.

I decided to change the timing belt set, water pump and also the multi belt set.
But while changing the parts my mechanician saw that old hydraulic belt tensioner still was in the motor block, and when he removed it he also saw that someone tried to change to a new mechanical tensioner, but he couldn’t and that person also damaged the one of holes where the screws of the upgraded version of tensioner should fit, so there is no way the car can get the tensioner upgrade.

I did a research and found out that the previous owner got factory re-call for that change in 2014, but still the old tensioner haven't been replaced (or upgraded to a mechanical one).


My question is can I still drive the care because that hydraulic tensioner had a factory failure and Volvo did a re-call for all those tensioners? I couldn’t neither found the part number of the old one tensioner…

What do you recommend me to do in this case?


Appreciate your help 😊

[GrahamBrown1]

So the hydraulic tensioner was changed to the mechanical type as it was putting to much pressure on the belts and causing them to fail. So the fix was the back to a mechanical tensioner. The problem was that some engines built in the range when the hydraulic tensioner was fitted did not have the mounting hole drilled for the mechanical type.

A special jig is required to drill the block to accept the new tensioner. It is a one shot operation. Now seeing as from what you say someone has tried and failed it means you are a little stuck. Access is limited to say the least.

Lowering the engine would be the only way to access the damage and see if it can be repaired, however it is crucial good threads can be put into the block. The likes of a helicoil could be required or a thread insert however the block materiel is soft. It all depends on how much materiel is left. Bolt torque for the new tensioner is 24nm so not massive but the threads need to be solid.

A machine shop may be able to help though they may want the engine out the car. Machine shops fit thread inserts into cylinder heads for exhaust manifold bolts for example no problem so I’m sure this wouldn’t be much different.

Least invasive is keep the tensioner you have and change the belt more frequently. You will struggle to buy a replacement and it is not available from volvo. There will always be the risk of failure however.

[Georgeandkira]

Is the old hydraulic tensioner in service?
You must be able to source one in a tune up kit.
Post some photos of it. Someone here likely will recognize it.

You might want to keep an eye out for a replacement engine if, down the road, a failed timing belt destroys your engine.

Try to get a new tensioner and drive the car to learn how much you like it.

[Jocke011]

Thanks a lot for quick answers, appreciate that!

I really like the car and would like to keep it if I can eliminate the risk of getting the engine damaged by this old tensioner.


Putting out some photos.

Thanks a lot guys! 😊

[GrahamBrown1]

That is a bit of mess, tho it doesn’t look that deep? Looks like the surface is badly damaged tho. Perhaps the wrong tools were used. It may be possible to still drill through that as from memory it is a fairly deep hole and the bolt is a decent length but I don’t think there’s much materiel left at the surface for decent threads.

I’d maybe have a chat with a machine shop first and show them the pictures. See if there’s anything they can do.

The correct tooling is needed to ensure that any threads are exactly 90 degrees to the block otherwise the tensioner will obviously not sit correctly and the belt will not run true.

[Jocke011]

Originally Posted by GrahamBrown1

That is a bit of mess, tho it doesn’t look that deep? Looks like the surface is badly damaged tho. Perhaps the wrong tools were used. It may be possible to still drill through that as from memory it is a fairly deep hole and the bolt is a decent length but I don’t think there’s much materiel left at the surface for decent threads.

I’d maybe have a chat with a machine shop first and show them the pictures. See if there’s anything they can do.

The correct tooling is needed to ensure that any threads are exactly 90 degrees to the block otherwise the tensioner will obviously not sit correctly and the belt will not run true.

Thanks GrahamBrown1, appreciate your answer!


I think that putting the engine out due to fixing the damaged hole will be a big investment for me. I am more interested in other possibilities like finding the new tensioner (if there is an aftermarket part that’s not from Volvo, and ofc what’s the possibility that this one tensioner get failure. As I mentioned before I have just changed all belts with tensioners and also water pump. Yeah everything except the old hydraulic tensioner. Is it safe to drive the car?

[GrahamBrown1]

Originally Posted by Jocke011

Thanks GrahamBrown1, appreciate your answer!


I think that putting the engine out due to fixing the damaged hole will be a big investment for me. I am more interested in other possibilities like finding the new tensioner (if there is an aftermarket part that’s not from Volvo, and ofc what’s the possibility that this one tensioner get failure. As I mentioned before I have just changed all belts with tensioners and also water pump. Yeah everything except the old hydraulic tensioner. Is it safe to drive the car?

I have never come across an aftermarket hydraulic tensioner and there is the possibility you could end up with one that’s worse than the original. From what I remember it was never the hydraulic tensioner that failed just the belt due to the forces on it. So you could refit the original tensioner which will get you going for now. I’d keep a very close eye on the Belt and go from there. Least you will have a mobile car.

[Georgeandkira]

Does "owner nr. 1" have anything to offer in the way of history? Did a Volvo dealer do this retrofit?

[Daim]

My D5 had the old hydraulic tensioner and one of the previous dealerships claimed to have 'done' the swap, but that was never done. My dealer did iflt for me free of charge as I supplied the tensioner (original part). They neither had to drop the engine nor anything else. It didn't cost me a cent (other than the other repairs I had done).

[Jocke011]

I don’t have nor I can get in a contact with owner nr. 1.
But today I came with a contact with a Volvo dealer and got info that replacement was done by also but another one Volvo dealer.
When I got in contact with the dealer who ‘did’ the reparation so they said that we are talking about reparation that have been in 2015, and the car is after that was on several tension-changins at another dealers so they can’t guarantee that it was their fault.
Weird also that other dealers wrote that they have changed the tensioner, have no idea what have they done.

Also no idea what to do at the moment, I am driving the car everyday to work and home so started to thinking to change it for something else. But started to love the car and will try to invest to do a reparation, but so far got recommendations ti change the whole engine…