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Discussion Starter #1
I have a Tom Zat timing belt tensioner for my "new to me" 164S. It's about 1/3 the price of the Alfa mechanical tensioner. Any reason not to use it? Any reason not to use the Alfa tensioner?
Any input one way or the other?

Anyone...................

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Mark,
Just got your message. I would use the Zat tensioner because it will keep the belt from slipping if someone lets the car roll back in gear or the stupid spring breaks in the new style tensioner. It just needs the belt tension to be checked occasionally. I had one on Kates old silver GTV-6 and it worked without fail through a buttload of abuse. That engine was run at or above supposed redline (9,100 rpm when I destroyed the trans at an auto cross) and was flawless. Just make sure thta you have a good old style bearing to use with it. I would PM Jason to see if he would repack it for you with the magic grease.

Paul
 

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Discussion Starter #3
Thanks Paul.........that was my question and my plan!

We got the last two tensioners from Tom last week. Still looking for an old style hydraulic bearing to send to Jason!:cool:

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If you got the last two save let me see it before you install it on a car. I need to copy it to make one for the 164:D

Paul
 

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Thanks Paul.........that was my question and my plan!

We got the last two tensioners from Tom last week. Still looking for an old style hydraulic bearing to send to Jason!:cool:

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This is the bearing you need: Click here: Alfa Romeo, Fiat and Lancia Serpentine Belt Tensioners - Serpentine Belts and Tensioners Alfa Romeo, Fiat and Lancia Serpentine Belt Tensioners - Serpentine Belts and Tensioners

Item 02754 tensioner bearing The same bearing is used on 24v engine.

I never felt comfortable with Zat belt "tensioner". I still have two of them but always found belt to tight hot or to loose cold since it is a fixed design. I took them off my Milano and 164.
 

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I would NOT use a Zat tensioner. It requires the use of old, outdated hydraulic tensioners that will fail. There is no automatic adjustment for the Zat tensioner.
I have had the new style mechanical unit from Alfa on two of my V6's for almost 50,000 miles each with zero problems.
 

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There are many many cases of failed Alfa mechanical failures. I don't know of any failures with the ZAT unit.
Beat me to it greg.
I will be using on the track car as well for that same reason, its so simple, nothing to fail. As long as you keep track of it and make sure it doesn't go loose on you its flawless.
 

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Greg,

You hit the nail on the head. I had one of the new mechanical tensioners fail the same day I installed it. Fetta78's father in-law installed a Zat tensioner on my old Milano after THREE mechanical tensioners failed. He told me "I have a barrel full of those old mechanical units that have failed".

I haven't done the math but, the coeficient of thermal expansion for Aluminum should calculate to a very small dimensional change for pieces the size of Alfa V6 engines. I think the tensioner / detensioner was a redundant piece of overkill. The Alfa designers should have spent their time eliminating the insufficient cam belt wrap on the 12 valve engine passenger side cam pulley. Thats why the belt slips.


There are many many cases of failed Alfa mechanical failures. I don't know of any failures with the ZAT unit.
 

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George, you are exactly right! The lack of belt wrap on the passenger side cam pulley is a contributing factor to this whole problem.

Greg
 

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I think Alfisto Steve makes a good point, the mechanical tensioner has to be installed correctly, meaning give it some help via the two small holes on it while setting tension. I have had two now on my car with no issue, but others here have. I think its a tossup, the old oil preassure units are probably the best, but I think the mechanical ones work well given proper installation. Its amazing how much a motor can expand when warm when its all aluminum.
 

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Can someone post pictures of the different types of units available?

I only have experience with the old hydraulic type units. I am interested in seeing what Alfa and others did to try and cure it.
 

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OOOOHH:eek:

One more thing I forgot!! Make sure that the e-brake is working properly! If you have a weak e-brake there is the chance that the car could roll backward and the tensioner could cause the belt to slip. A couple of new/reman calipers or a set of cables can save you a lot of headaches in the future. Make sure that it is adjusted properly and that BOTH sides work. I try to remember to put the car in neutral every time I park it but the wife leaves it in gear occasionally:mad:

Paul
 

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I never felt comfortable with Zat belt "tensioner". I still have two of them but always found belt to tight hot or to loose cold since it is a fixed design. I took them off my Milano and 164.

Hi Steve: Do you want to sell one of them to me?

Ed Prytherch
 

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I have thought about doing this for a long time, so here's my quick & dirty science project for the morning: determine expansion / contraction range for Alfa V6 cam belt

From "Machinery's handbook" Linear expansion for Aluminum, unit length per degree= .00001244

Assumptions:

1. A 12 valve Milano engine, 15 inches between the cam pulleys and from cam pulleys to crank pulley (estimate only, no engine or cam belt to meaure). So assume the expansion / contraction takes place along a linear path of 45 inches. This is very conservative and doesn't accomodate the "V" dimension between cylinder banks.

2. A nominal temperature of 70 degrees F. raised to 180F for warm engine, and lowered to minus 20F for a winter time cold start. From nominal, 110F increase and 90F decrease

3. For simplicity, assume expansion / contraction takes place for solid aluminum

Dimensional increase from nominal:
.0001244 x 45 in total expansion distance x 110 degrees temperature increase= .062 in.

Dimensional decrease from nominal:
.00001244 x total expansion distance x 90 degrees temperature decrease = .050 in.

Preliminary conclusion: If the belt is set correctly on a 70 degree day, the overall dimension increase it must stretch to accomodate will increase by .062 inches, or .021 inch per pulley. For a minus 20 degree F day, and cold engine, the overall dimension shrinkage or looseness it must accomodate will decrease by .050 inches, or .0167 per pulley

So... if the belt will stretch overall by 1/16 inch when hot, and not slip when the fit over each pulley is loose by just over 1/64 inch for a wintertime cold start, a ZAT tensioner should be just fine.

OK, BB'ers, there's my preliminary story. Either flame away, refine my dimensions and assumptions, or agree with me...

(Additional thoughts after posting [don't we all have these?]. I didn't make any accomodation for cam belt growth or other change...do I feel the warmth of flames licking at my feet?)

Greg,

You hit the nail on the head. I had one of the new mechanical tensioners fail the same day I installed it. Fetta78's father in-law installed a Zat tensioner on my old Milano after THREE mechanical tensioners failed. He told me "I have a barrel full of those old mechanical units that have failed".

I haven't done the math but, the coeficient of thermal expansion for Aluminum should calculate to a very small dimensional change for pieces the size of Alfa V6 engines. I think the tensioner / detensioner was a redundant piece of overkill. The Alfa designers should have spent their time eliminating the insufficient cam belt wrap on the 12 valve engine passenger side cam pulley. Thats why the belt slips.
 

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Thanks Paul.........that was my question and my plan!

We got the last two tensioners from Tom last week. Still looking for an old style hydraulic bearing to send to Jason!:cool:

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I have never used it but have had customers use the hydraulic as a fixed tensioner with 0 problems.
I do have the tensioner bearings if you need one. I think the krytox is not a bad idea but that bearing is a tough one to fill as there is a seal and a cage. I suggest using it the way it is as they do last a long time.

Belts will also not stretch as much as they use to. There is very minimal to no stretch from heat or cold with the new t-belts.
I would not worry about it. try it. Check the tension from time to time.

What are the methods people are using to tension this correctly? I have looked at VW tensioners in the past, such a simple thing to do on the old 4 bangers 16V's. Just put on the belt and tighten up the tensioner. That car was a hot running car as well and never had belt issues.

At over $130 per tensioner now, I myself have always been weary of the mechanical and rather use the hydraulic and rebuild every belt change or find something else.


Jason
 

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Jason, how much is a new bearing for the hyd. tensioner?

Paul

By the way Mark.............. I have a good bearing that your Dad in law gave me that you actually handed me! BWAHAHAHA!!!

FOOL!
 

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Jason, how much is a new bearing for the hyd. tensioner?

Paul

By the way Mark.............. I have a good bearing that your Dad in law gave me that you actually handed me! BWAHAHAHA!!!

FOOL!
IAP asking 82.50 for just bearing without pivot eccentric inside it. but states to call for availibility. FYI this is same bearing that is used on 24v engine but if you order 24v version with eccentric pivot pressed inside it you have to press it out and install 12v eccentric pivot into it to use bearing with Tom Zat tensioner or original alfa oil fed tensioner.
 

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Discussion Starter #19
By the way Mark.............. I have a good bearing that your Dad in law gave me that you actually handed me! BWAHAHAHA!!!

FOOL!
Katie wants the beer back now!!:eek:

Hmmmmm, after reading the good and bad I am going with the Zat tensioner. I'm the sort of person to actually pull the inner shield out of the wheelwell a few times a year to check the tensioner and clean stuff up anyway.......

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Jason, how much is a new bearing for the hyd. tensioner?

Paul

By the way Mark.............. I have a good bearing that your Dad in law gave me that you actually handed me! BWAHAHAHA!!!

FOOL!
I'll beat IAP:
$78.00

Oh BTW, think we are the only ones that suffer from this tensioner problem? I was doing some research on a VW site and there are tons of posts that talk about these same issues, hydraulic tensioner to Mechanical, thermal mechanical, timing belt failures due to crappy mechanical thermal tensioners etc... Even the Germans get it wrong.

Jason
 
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