Which tensioner should i use?

[superloaf]

so i'm getting to the point of having to decide on a tensioner for my 2.5 and just wanted to get some opinions. what tensioner are you guys using? i've heard all the arguments and just can't decide which way to go.

i like the idea of the mechanical tensioner until i hear things about the engine rolling backwards and the belt skipping. also, the mechanical seems risky just for the fact that you're limited to one tension which then has to work for both cold temps and hot engine temps so that means you're either running too tight or too loose at one temp.

the grease filled hydraulic seems to have merit but i don't know much about that one so if you're running that please post your experience.

i was going to just rebuild the hydraulic when the kits were a measly $40 but now i guess they've gone up so i'm not so sold on that method anymore. how long does the hydraulic rebuild last? why does it leak? can that be fixed so it doesn't leak?

ok, any info here appreciated although i know we're split into 2 camps here so let the fighting begin.

[AR4me]

Quote:

Originally Posted by superloaf also, the mechanical seems risky just for the fact that you're limited to one tension which then has to work for both cold temps and hot engine temps so that means you're either running too tight or too loose at one temp.

[superloaf]

Quote:

Originally Posted by AR4me Not correct. The mechanical tensioner from Alfa does account for temp. You are probably thinking of some home-made fixed tensioners that various people experiment with. Jes

[AR4me]

I use the Alfa mechanical tensioner on both street car and race car. But, each to his own.
Jes

[superloaf]

also, regarding the grease filled hydraulic: does it change tension according to the engine temp? not sure if the raising temp of the grease would de-tension the belt that much or more accurately, de-tension the proper amount? if the detensioning amount is accurate, that would seem a very good way to go. but i'm sure there's not enough study on this to say for sure.

any grease filled folks out there?

[kredden]

Quote:

Originally Posted by superloaf also, regarding the grease filled hydraulic: does it change tension according to the engine temp? not sure if the raising temp of the grease would de-tension the belt that much or more accurately, de-tension the proper amount? if the detensioning amount is accurate, that would seem a very good way to go. but i'm sure there's not enough study on this to say for sure. any grease filled folks out there?

[superloaf]

Quote:

Originally Posted by kredden No, the way the hydraulic detensioner detensions is via the oil pressure. If you block off the oil passage then my understanding is that it is more like the Zat. The rebuild kits are just a bunch of seals, no bearings or springs. I bought a few some months ago from Trail Auto in Michigan and I think they were less than $40 ea. I've haven't used a hydraulic to date but am building a hopped up 3.0L where I plan to use one. I haven't decided yet whether I'll plug the oil feed or not yet. Kevin

[kredden]

Every time it revs higher due to the pressure, as you surmised.

Kevin

[superloaf]

Quote:

Originally Posted by kredden Every time it revs higher due to the pressure, as you surmised. Kevin

[Craig]

The thought was probably based on higher pressures when cold

[ToonRboy]

superloaf, you might wanna try a search on this subject. There have been many - not that there has been any solid conclusions... Here's one: Timing belt tensioner

I have tried to find you the "official" description of how the de-tensioner is supposed to work, but I can't find it, even in the shop manual. Just disassembly, re-assembly. Try here: Craig's Place, Alfa 75 Manuals and Information

A couple of things.
1) It's not filled with grease. If that's what you found in yours, it's no doubt old azz caked-on oil sludge dude.
2) The de-tensioner (called a "belt stretcher" in the english manual) basically does it's job via spring tension. When installed properly, the belt should be "tight as a drum". The purpose of the oil gallery feature is to allow a little de-tensioning of the belt as the engine expands from heat (this is where all the argument is - whether the heads expand away from each other at all). Oil being what it is, changes viscosity in the various heat ranges. Thus you'll have higher oil pressure when cold and when revving, less when hot and idling.

The de-tensioner is supposed to make up for these conditions - and does when installed properly. Which is the real problem since most dinkel-berries can't even install the mechanical one right.

Here's the basic choices, Zat style notwithstanding. Alfa Heaven closed that side of their business.
a. $47.00 de-tensioner Rebuild kit - Hydraulic Tensioner Rebuild Kit
or
b. $145.50 Mechanical de-tensioner - Timing Belt Tensioner (Mechanical) (Don't forget, you also have to remove the existing oil tube, drill and tap the oil gallery and install a plug as well) International-Auto and others are $20-30.00 more.

[vml]

Quote:

Originally Posted by superloaf ok, then here's the million dollar question: why? i mean why the hell would a belt need to be loosened everytime the rpm's increased? temperature makes perfect sense but rpm?

[superloaf]

Quote:

Originally Posted by ToonRboy A couple of things. 1) It's not filled with grease. If that's what you found in yours, it's no doubt old azz caked-on oil sludge dude.

[superloaf]

Quote:

Originally Posted by vml I doesnt need to be loosen with RPM's, that's just a non-needed feature. The point is that the difference in pressure between cold and hot is higher than between low and high RPM's so the detensioning technique works where is supposed to.

[vml]

Quote:

Originally Posted by superloaf so why not just make a temperature controlled detensioner and eliminate the whole oil pressure factor?