Replacing Timing Belts

The search function will be very gentle with your ass. I promise

Sent from my DROID RAZR

 

What do you warn to know?

 

Right here! I've been asking questions, and so far nobody has bothered kicking my ass. I'm right in the middle of my DIY 30K service, have finished replacing the water pump, thermostat, coolant hoses in the V, and will be moving on to cam seals, valve clearances, and belts after the Monterey Historics weekend.

The search function isn't all that bad, either - Here's a bunch of very helpful threads I've bookmarked on the belt change subject:

http://www.ferrarichat.com/forum/308-328/445982-started-cam-belt-change-today.html
http://www.ferrarichat.com/forum/308-328/363421-valve-cover-seal-gasket-replacement.html
http://www.ferrarichat.com/forum/308-328/200520-water-pump-removal.html#post138107579
http://www.ferrarichat.com/forum/308-328/302756-water-pump-step-step.html#post140101259
http://www.ferrarichat.com/forum/308-328/416575-timing-belt-help.html
http://www.ferrarichat.com/forum/308-328/312304-308-engine-bay-hose-reference-thread-sizes-lengths.html
Birdman's Replacing Ferrari 308 Mondial timing belts
http://www.ferrarichat.com/forum/308-328/289560-robzworkz-3-328-basic-timing-belt-service.html

And there are a few more great reference threads listed/linked in http://www.ferrarichat.com/forum/308-328/281516-interesting-3x8-technical-diy-threads.html

 

with 9000 posts and you are afraid of a little Azz Kicking ?

 

If you start with their early albums, the Police aren't too scary.


As far as belts - you can change one at a time or both at once. I doubt there's a technical reason to do either way. One at a time means you will be more focused, and perhaps less likely to miss a step.

Jonathan
The FiatRN

 

I have to admit that in all the belt replacement threads I've read, I've never seen that technique suggested. Recognizing that I haven't completed my first belt replacement job yet, but...

The QV Workshop Manual specified procedure is to install the belts with the engine and cams lined up at the TDC marks, install the tensioners, loosen the tensioner lock nuts. Rotate the engine two turns in the direction of rotation until returning to TDC, keeping the belts stretched (ie don't back off on the rotation), lock the two nuts of the tensioners.

With the clamp the cams and tension the belts technique, how will you know how much tension to apply before tightening the tensioner bolts?

 

You Tube video and associated FChat thread:

https://www.youtube.com/watch?v=rn-bpUziJag

http://www.ferrarichat.com/forum/308-328/456523-how-change-3-way-tension-cambelt-video.html

This describes/discusses the various methods of tensioning the belts

 

If I understand your question, the answer is one at a time.

I can only speak from my own experience, but I chose to do it as follows:
1) Change both belts (after marking the old and new, and locking the cams in place)
2) I then work on one belt at a time to set the tensioner.
3) Rotate the crank while letting the tensioner float, observe the point where the tensioner extends the furthest and lock in place at that point (when still applying tension/pressure to the wrench on the crank so the belt is taut).
4) Repeat with the other belt/tensioner.

 

If you want to go to the trouble of rotating the engine to TDC and locking the cams down and marking belts, that's certainly OK but not really necessary and provides no added precision to the job. All you have to do is mark the two cam gears prior to removing the old belt and then ensure the cam gear marks are still aligned when you install the new belts.

Obviously if you have some concern that the valve timing is incorrect, then to check everything you WILL need to go to TDC/check the cam positions.

 

True Mike, but isn't it safer just to find TDC it takes 2 mins.
Firstly because the cams are stamped with bench marks for a TDC position which on some cars are easily viewable, also cam pulleys will probably be marked for TDC anyway from previous belt changes, although you should always mark your own.
And finally if you were to loose position you could be a tooth out and not know.
TDC gives a proper factory starting point, stick to that and you don't run any nasty risks.
And let's face it nobody should risk their lovely pride and joy unnecessarily buy cocking up a cambelt change...and I've seen it done.

 

+ 1 , it's all here! Lost

 

I'm not disagreeing that TDC/marking everything/locking the gears in place is a fine way to do it. And certainly, folks should do whatever they are most comfortable doing. I have just never personally had any need to do that on any engine for a normal timing belt or chain replacement.

It is is true that the cam gears can shift out of position after the belt is removed due to pressure on the cam(s) from the valve springs. They won't shift more than a few teeth and it's easy enough to just rotate it (them) back to the marked position. One cam on my 328's recent change did exactly that but I just reached up, turned it back to the proper position and installed the belt. I have a couple of pics of that somewhere...I'll see if I can find/post them.

But, again, folks should do whatever they feel mechanically comfortable doing. If that means doing the TDC/marking of gears/belts/locking them in place then that's what they should do.

 

Just to be a colossal pain in the ass I'm curious... Why don't you guys tension the belts IAW the directions in the factory shop manual? Are you all smarter than Ferrari? I've done the belts on my gt4 twice in the eight years I've owned the car and both times I followed the shop manual procedure. I regularly turn the engine 6500 rpm and 7500 isn't unknown if I'm showing off or in the tunnel... Never had any belt related issues.

 

I totally agree personally that the factory way is the way to to tension the bearings. But apparently some folks have found that other methods seem to work for them just fine. I would not be comfortable adding additional tension as some folks do or recommending a method other than that specified in the shop manual but that's just me...

As I said earlier - all aspects of this stuff is based on what makes the individual comfortable with his/her procedure...

 

I think regarding belt tension the Ferrari/Verrell method is totally reliant on the condition of your 20 year old tensioners which means tension can vary if they are partly seized or spring is bad. Other Way can get round this, but do have issues of their own h's ha.

 

You are right about the tensioners but they are very simple to clean and re-grease and if you have any doubts about the springs, Superformance sell them for £12.95 each:

Cam Belt Tensioner Spring 104148 £12.95

But I'm still dubious about the important of the tension on such a very short belt run (i.e. the distance between the various cogs).
You'd really have to go some to get so much slack in the belt that it could cause problems?
I suspect that over tensioning them is a bigger concern.

 

Search using Google. MUCH better results.

My Google searches start out: "Ferrarichat 308" then subject words like "worst car ever to work on" "over priced" "resale red" "how to pick up girls" or "carb cars rule"

You get the idea.

 

H. Glassman, in my video I show you I hope clearly how to change both belts.
In it you will see that there is only one TDC that is set for both sides of the engine at the same time.
In other words you find TDC in the crank, check that your cam marker is lined up through the oil filler.
IF CAM MARKER NOT LINED up then rotate the crank +360 degrees to the TDC mark again uuntil the cam mark appears. BOTH MARKS MUST LINE UP perfectly.
Then draw a line through the centre of your cam pulleys..... And off you go

 

I heard that you were never, never, ever supposed to do that ---- wait..... maybe I'm thinking of something else