164 12V V6 cambelt tensioner...

[CorseChris]

....bearing. Does anyone know what the bearing spec is and if it's possible to buy just the bearing? This is for the old-style hydraulic tensioner. I know the Alfa part umber for the entire bearing/carrier but if it's possible to get just the bearing, it has to be a lot cheaper! I managed to remove the 'hub' piece from one no trouble but can't make out the markings on the edge of the outer race.

I don't much fancy converting to the Alfa thermostatic tensioner if I can avoid it - seems they can be problematic way beyond the oil leak one typically gets with the old-style item. Maybe just find a suitable roller from a Ford or wherever and mod it to fit could be a way forward.

TIA

[stableblock]

Hi Chris
I'd take care doing this. The wheel surface that bears on the back of the belt does wear and this could well damage your new belt if you don't replace the whole thing. This would tend to shorten its working life unpredictably.

Peter

[CorseChris]

Hi Peter,

On the one I'm looking at, the belt runs on the outer surface of the bearing itself, so it would be replaced. It has a removable centre piece that has an offset bore running through it and a couple of M6 holes - this is the bit I took out and am hoping to fit into a new bearing. I take your point about types that have an outer body with an inner bearing though.

I've been reading some horror stories about the later spring type tensioners but as is usual with these things it seems, there is a lot of confusion surrounding it. The 155 V6 uses the later thermostatic spring type tensioner system and I'll take a chance by saying it's not been a problem. Probably regret that statement......

As I understand it, whichever type is used, part of it's job is to de-tension the belt as temperatures rise to accomodate block expansion. There seem to be 3 types in common use. Standard oil pressure type, later and allegedly fragile spring thermostatic type and a modified hydraulic unit that works with fixed tension.

[stableblock]

Yes, I dare say that is what the complication is for. I've no experience of reusing these bits but I have seen some non bearing outers with lots of pick up that would quickly ruin a new belt.

I take your point that as the belt runs on the bearing this shouldn't be a problem here.

I guess re-use of the other bits is more or less risky depending on how over engineered they were. Fancy spring tensioners may have finite cycle limits esp if based on "memory" metals rather than conventional springs.

How much would you save? Is it worth the risk?

Peter

[CorseChris]

Indeed - the spring type are a fully disposable item with a plastic outer surrounding a much smaller bearing than the hydraulic type. The 'standard' replacement parts for the hydraulic unit are seals, all internal parts & spings (normal ones) as well as the bearing itself with it's 'core'. The thing I'm trying to avoid is paying over £100 for a standard ballrace with an extra chunk of steel that can be re-used from the old unit. If it turns out the bearing is a special then I'll not have any choice. At that point I may be forced to go for the new type as I suspect the older one has been superceded.

I'll see what I can find first but I'm tempted to try and find an alternative bearing that will work. Can't be that hard (I hope).

The disposable type is about £75 complete I think. Cheaper than a scrap engine of course. I'll not be reusing anything that isn't suitable for re-use. I have an old disposable type of unknown history for example - that's only being kept out of interest. I'll take it apart when I have some time just to satisfy my curiosity.

So...anybody have a new one in stock that they can read the numbers from please?

[Paul164]

There is a tensioner on ebay atthe moment ? £46

[CorseChris]

Hi Paul,

Thanks for that..and the PM...but I can't find it now :( Only one that is for an Alfa is the wrong sort.

[Bob]

Hi Chris, you could try a guy called Steve at Alternative Autos on 01484 865086. I had a conversation about tensioners recently with him as I was going to send my hydraulic (leaky) one to Lionel Gooch as apparently he converts them to mechanical on an exchange basis. Steve did offer to source the proper hydraulic replacement part (he runs a FIAT specialist parts company near me) so he might be able to sort out a number for you.

Cheers

Bob.

P.S he has the most concourse pale green Pantera for sale in his workshop, with about 400 bhp!.

[CorseChris]

Thanks Bob, I'll give him a call and see if he has the info (or even a bearing). I did consider Lionel's mod and may still go that way as opinion seems to be that the modded hydraulic is the best option. First step is a sound bearing though.

[CorseChris]

OK, moving along....I've managed to find out that the bearing is an SKF 633254 and looks like this image...


..but after talking to Lionel I think I fancy one of his modified hydraulic types. As I understand it, it's based on the hydraulic original but uses a new fixed mechanical bearing with oilways blocked off. It's not like the later Alfa types with use the thermostatic de-tensioner.

[Swamprat33]

Hi Chris, I have been running one of those for the last 12months or so.

I will have to swap it over onto the new engine.
* Reminder to myself * ;)