How to change 308 timing belt?

If you do a search all your questions have been covered in great detail.

 

Dennis I dont mean to disuade you from doing any work on your car but personally if you have to ask these questions then probably this type of work might be above you.If you get it wrong it could be very costly.Again I dont know what mechanical capabilities you have so I mean no disrespect here

 

You’ve asked a bit of a trick question since you’re not removing the cam covers and the distributors. It really wouldn’t matter whether you were correctly at the end of the compression stroke when the flywheel PM1-4 mark is at the pointer, or you were wrongly at the end of the exhaust stroke, since you’ll effectively be making your own set of external “reference marks” (and the distributor-to-camshaft relationships will still be “correct” if you don’t disassemble them) -- but if you look down the oil filler cap opening at the #1 cyl intake lobe, it would be the first occurrence of the PM1-4 mark on the flywheel to reach the pointer after the intake valve closes when rotating the crankshaft CW as viewed from the crank snout end (remember the cams will rotate CCW when viewed from the crank snout end because of the gears between the crankshaft and the belt driving sprockets).
Try a search on “308 cam bearings” – these are two of the best:

http://ferrarichat.com/forum/showthread.php?t=28437

http://ferrarichat.com/forum/showthread.php?t=103998

and there are plenty more . I would agree with the others that doing the outer ball bearings and seal of the drive ends is a step up in difficulty from just doing the timing belts and the tensioner bearings (and doing the inner bearings too is another level of extra difficulty).

What are your print references? Do you have the OM, SPC, and (carbed 308) WSM?

Most PM1-4 marks on the flywheel edge are not this clear :
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There are certain repair jobs on a Ferrari that shouldn't be done on the cheap...and if you try to replace the cam drive gears without pulling the cam covers and making sure the flywheel TDC and cam TDC marks are in alignment, you are risking other mechanical and timing issues.

Once you disassemble the engine to the point you will need to to get this fixed properly, it only makes sense to go the extra effort and retime the engine, change the tensioner bearings, and replace the belts...all of the belts. Consider this a perfect opportunity to get a 30K major under your belt. But please, don't rush this. It takes time and a lot of patience...but the time investment if done properly is worth every second.

 

This is a bad idea. First off, you cant even be sure its correctly timed now, before you do this work, without pulling the cam covers. Further, you have the possibility to gain some added performance. If you degree wheel the cams, you may in fact find the factory marks are off a tad here or there. This could be a minor difference, or a dramatic one, possibly worth 10-30 HP. I also found, by checking the TDC mark on this second 308, that the timing mark pointer (the part held with two small bolts in 91tr's picture) was retarded 3 degrees. Imagine what retarding your valve and ignition timing 3 degrees might cause. Also, I found some rather loose exhaust valves and a few tight ones. Tight can burn a valve, loose can whack HP and overall drive quality.

Secondly, I dont know why all the fuss. It is not that hard to remove the cam covers. In maybe an hour or so you can have the covers off. Depending on how you tackle it, the AC pump can be off in 20 minutes or so. Now you can get to work. Pull the plugs to inspect/change them, and to possibly check compression and or leakdown. Re-torque the heads (they will most likely be loose), drain the oil, change all your filters, fix your bearing trouble, teardown your distributors, and begin putting it back together. I think everyone who has done this will agree your car will run different. A lot different.

 

MEGA ditto's! Your enthusiasm to do your own work will go to hell in a hand basket if you screw this job up! Find a mechanic that you can pay an extra couple of hundred to let you help on this job. I did it with my first QV and I took a LOT of pictures along the way (30K Major). I learned three things:

1) This job was worth paying a mechanic to do.
2) I drove away with more appreciation for the knowledge of a good mechanic!
3) A good mechanic will spot other items that need attention Vs a novice doing it.

 

i'm going to throw in my 2 cents. i'm more of the in for a penny in for a pound type. if the lower drive bearings are shot and the seal is leaking what other problems are lurking around?

all this can be done while in situ however the extra time and money to pull the motor and freshen up the bay and replace the hoses makes it worth it to me. whats the milage from the last service? what was done at the last serivce?

i spent around $2000 in parts to replace all the hoses, injectors and seals. cam belts and bearings. and new gaskets. retimed the cams, cleaned and degreased the engine and bay. and alot more work. the advantage for me is that i can turn a wrench so it was my time vs a mechanics. took about 2wks of nights and 2 weekends start to finish. i have peace of mind i couldn't buy anywhere and now know that engine like an old shirt.

if the most you've ever done is change oil and don't know how to service engines in the least, this job can from bad to worse real quick. the thought of paying a shop and paying a little more is great becouse you'll learn alot. or if you can afford it, pay a good mechanic and sleep well.

and you will have to pull the cam covers for this job. the lower drive pulleys are geared to the crank. once that cover comes off and the assymbly comes out. the timing is now in need of being re-set. to do it will require the cam covers off so you can set the factory marks up. each tooth on the pulleys represent 12* of timing, so putting them back on without it being set will throw the timing off.

don't worry we'll help as best we can around here.

 

I disagree. You do not need to take off the valve covers to do this job, that is if you are happy with the timing as it is. There is no more reason to take the covers off whilst changing the outer drive bearings, than when changing only the belts. Just make sure the belt teeth are marked up on the drive gears and the cam gears so that their orientation can be found again. You don't even need to know if you have TDC or if its TDC firing.

91TR's 2nd link looks like an excellent description of the job.

You will need some special tools though:
- air impact hammer to remove the damper bolt, (no need to prevent the engine turning)
- the spanner to remove the crown nut on the drive gears (90$ from Baum tools?)
- the famous Sykes bearing extractor kit,
- some means of preventing the cams from rotating although this is not so critical with the 2 valve as they tend to stay put.


AS 91TR says it is one step up from changing the belts alone, but it is easier than taking the engine out which is what many garages will insist on doing.

 

if it was just a leak then i'd agree, however i'm pulling from info he posted on the other 'f' site. he mentions a wobble in the drive gear. my concern at this point is to re-check timing. look i know it's not fun to change the cam cover gaskets and re-time the cams but at this point i'd highly recomend it. a little more time and money spent here will save $$$$ later. and as you know the 308 2v does not have any timing reference on the outside like the later 3.2's or Qv's so how would he know for sure it's still timed right?

just my opinion ofcourse

 

Change the belts with the covers on? Hmmm. Yes, you can do it. Yes, it will run, probably the exact same way it does now. That is if you mark the pulleys exactly and dont screw anything up. But I do not believe it is a good idea. First of all, you have NO idea if its correct right now, so once you do this, and sign it off, you could simply be relagating the car to run just as screwed up tomorrow as it is today.

My car had marks on the pulleys, and it was very easy to line them up and see that the mark on the rear intake cam aligned through the oil cap, the ignition rotors aligned, someone marked things really good. The motor ran great, idled great, no complaints. So, because I only wanted to drive the car a few months and fully intended to tear it down this winter, I simply slid on new belts. Car ran just as before, no change. But a front cam seal oil leak forced me to go back and pull the cam covers, and then do the full deal on it. I am glad I did. I found several exhaust valves with over .022" inch of clearance, some intakes over .018". I found the timing mark for the flywheel to be retarded 3 degrees, and I found one cam to be off about one tooth retarded.

When I timed the cams, I set them with a dial indicator and a degree wheel, and set them for max lift (lobe centers) at 100 BTDC on the intakes, 90 ATDC on the exhaust. Mk e and others sent me off in that direction. Timed this way, the front intake and rear exhaust cams scribe marks are just about exact. The front exhaust mark is about 1/16" off, the the rear intake is about an 3/32" off its marks. The two that are "off" got double checked as I wanted to be sure I wasnt fudging anything. Does any of this BS matter?

The US carbed car had the exact same cams, with the intakes timed 4 degrees more advanced. The Euro cars produced 35 more HP than the US cars, and except for valve timing they are virtually identical engines. A one degree change of valve timing would move the mark of the cam in relation to the cam cap index mark .004" inch. The marks are probably about .035" inch across, so if your off half a mark you could be off over 4 degrees, and that could be losing you 30 HP or more. But if the very marks them self are only "in the ball park, and if the flywheel mark is off some as well, well maybe 185 HP or less will work just fine for you. All I know is this car runs and idles far better than before, and has a very noticeable increase in power. On the injected cars the exhaust is closing far later, and coupled with the early opening intake, cuts all the overlap out. I would probably time the cams on the injected cars simularly, with 90 to 100 degree lobe centers.

 

BAD NEWS, REAR BEARING IS PROBABLY BAD:
Unfortunately, IMHO, based on these symptoms, you're now past the point that you can just replace the front bearing.

The rear bearing has had it's off-axis spec exceeded by about an order of magnitude! If you just replace the front bearing, you're running the risk of the rear bearing failing fairly soon, if it hasn't been badly damaged already.

Replacing the rear bearing requires replacing the timing cover. So you won't need a sykes tool.

MUST VERIFY TIMING:
There is also the possibility that the wobbling drive gear has permitted one or both of the cam gears to jump a belt tooth & loose timing.

While you can make a confidence check of the intake cam's timing thru the oil filler hole, the only ways to check the exhaust cam's timing are:

a) Pull the cam covers
b) Use the tiny timing check marks on the rear of the cam gear mounting flanges and a tool with reference marks to compare them to.

Ferraru used to supply a tool for this, but they've been NLA for many years. For a picture of one in use, see post #10 in this thread:
Cam Gear Locking Tool for quick belt changes
http://ferrarichat.com/forum/showthread.php?t=40071&page=4

However, I've designed my 2V cam locks so that they can be used to perform the check. This is discussed later in the same thread.

As others have mentioned, using the marks is not as accurate as dialing in the timing, but they are adequate to verify that you haven't jumped a tooth.

 

With any luck the gasket has glued itself to the cover and the block over the last 20 or 30 years. You are probably going to have to pry it off, so be VERY careful

 

Paul,
Thanks for this post - my car runs "good", but my gut feel tells me that the cam timing is off, in spite of what the service records and last mechanic say. First sign of nasty winter weather I am pulling the cam covers and checking things for myself!

 

Ive done this twice, to geet the cover off you need to
remove dip stick
remove dip stick inset tube with finger
remove oil temp sender
drop the oil pan
remove the oil pick-up tube, hard but can be done.

I agree this should be done with the valve covers off, and you should replace inner and outer bearings, seals, tensioner bearings and belts, cam seals also, while your there1

Rob
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I hope you were at PM1 and marked everything good?

previous pics courtesy of Ric R.

 

Good job- so far!! Those big case studs are a real b****.

You also need to remove the studs (3) that hold the oil pick-up tube to the bottom of the front case- at least on a QV. I'm sure your cover is just being held up by these three studs.

The second photo shows them after the pick-up tube is removed- photo taken from under the engine looking up through the oil sump. It's VERY tight in there.

Is that what the outer bearings looked like (in your photo) after you removed the cam drive gears? That is a real mess.

Good luck, and please keep us posted.
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Welcome to FerrariLand!

There's a reason Step 1 is usually "Remove the engine with a chain, and throw it on the floor"....

That evens up the odds in our favor.....hang in there, there's VAST knowledge on this board...

 

In your honor the thread really should be:

"Fearless New Guy leaps off DEEP on first engine problem..."

*salute*

 

Robert, having done this job twice, I was curious if you would have a reasonable idea of the time involved in doing this job. I seem to recall Jwise ran into a broken stud problem and in the end was forced to remove the engine anyway. I would almost think that the amount of time involved doing this job in situ would about equal the time it would take to R&R the motor, drop the gearbox, and R&R the cover on a engine stand. Just an FYI, I had the motor out of my other car (77 GTB) in about 6 or 7 hours, and believe I could beat that time the next time. Once out of the car, I had it pretty stripped down in a few hours. Sure is a lot easier to clean it all up once its out. IOW, if this job would exceed 10-15 hours, might it be best to just pull the motor?