Timing Belt Drive Sprocket Bearings - Boxer

This question might be a little late, as my engine has been put back together and will be back in the car soon, but another post concerning a 308 has given me pause.

Should I have replaced the belt drive bearings? The car has 29k on it and the records show it was done ten years ago. I did not specifically ask the mechanic who reassembled the engine to check them, but I know they blow out on the 8 cylinder cars and don't see why the 12 would be any different.

How often do you guys do these? When they go or as a preventative measure while doing majors, perhaps every other time? If tensioners are replaced as a matter of course, shouldn't these be as well?

Thanks

 

I have never seen the cam drive bearings go bad on a boxer nor leak any oil. Maybe I just haven't done enough of them though. I'm quite sure the mechanic would have mentioned somthing to you, if he felt they needed attention.

 

Sorry Tom I'm going to disagree. I have seen more problems on those than I ever saw on the 8's. They are doing 1 1/2 times the amount of work with exactly the same parts. While you may think they are OK now, will they go for another set of belts? I take more BB motors out to repair those bearings than I do for belt jobs because the last guy didn't do them. Age is not an issue, how many miles do they have, and how many miles will you go before the next set of belts? If it was my car I would do them now.

 

Excuse the ignorance, what are cam drive bearings?

 

The crankshaft gear drives a pair of gears that actually drive the timing belts. The bearings we are talking about are the bearings that support those gears.

 

Thanks.

 

Thanks for the info Brian!...Like I said..I don't think I have done enough of them to get a good enough base line on the failure rate. I will definatly be looking much closer at these components from now on. Again thank you!

 

Thanks all. I kinda figured that was the case and like the tensioner bearings, should be changed as a matter of preventive maintenance. I would hate to get everything back together only to have to pull it apart again to replace those, not to mention what might happen if one fails on a longer trip.

Naturally, I will be sure to change the belts, although brand new, as they have now been tensioned and cannot be re-used.

Much appreciated....

 

Even though the belts are cheap (sort of) no need to replace. Ferrari's position is that some number of miles have to be run (I don't remember, 1000 or so) before they make their initial stretch. It is at that point that they should not be retensioned, yours have not even been run.

 

Good advice...

In looking at the parts schematic, I cannot tell if there are two bearings per sprocket shaft or just one. Could there be an inner and other bearing per shaft? The book calls for a sealed bearing and a ball race bearing but it is not obvious to me how that works.

Are there special pullers required to get the old ones out, or do they pop out of the case once the circlip is removed?

Thanks

 

There is an inner and an outer bearing. If all you are doing is the outer (all that is needed in most cases) you need a special tool. It is not made by Ferrari but a couple of other specialty tool makers offer it and is rather expensive. I just bought a nice one in a set with adaptors to do several different size bearings for $500.00

If you want to do inner and outer bearings or just don't want to buy the tool you need to lift the motor off the trans and remove the front engine cover.

If you lift the motor off the trans the sealing surface between the two will probably be sealed with silicone. Do not whatever you do reseal it with silicone. Ferrari lost quite a few motors that way and switched to Prematex 518, an anerobic sealant.

 

What are the signs of failure with this bearing and what happens if not repaired other than the bearing seizing and coming apart as the end result?

Noise? Wobbly timing belt sprockets?

 

As you said. Noise, then wobbly sprocket, then wrecked gears, then slipped belt and bent valves. The problem in waiting for the noise to cue you to make a repair is that the motor makes so many noises that many people are unable to pick out the bad ones.

 

On my 308 the noise was loud enough for passengers to remark on it, but it had not reached the wobbly stage. If you get that far I'd have thought they'd be really noisy. Maybe TR's are generally noisier

Rifledriver, what was wrong with Silicone? I thought it was good for 150°C or thereabouts.

 

The BB's were built in rather small numbers so if they (Ferrari) experienced the problem they did not seem to worry about it. In 85 when the TR's were rolling out as fast as they could build them motors were blowing up. No a lot of them but enought to get attention and cost lots of money. The silicone used to seal the pan rail was oozing into the main oil gallery that passes through the pan rail. The excess would break off in the oil flow (post oil filter) and clog the small oil passage from the block to the head depriving the cams of lubrication. Cams would sieze, break the belt bend the valves and damage the pistons. It was a very expensive repair. Permatex 518 will not turn hard in that environment, I have tested it. It will travel through the oiling system until it gets collected in the oil filter. That is why Ferrari uses it.

It is also a good example of Ferrari cost conciousness. They know 518 is a superior product in appropriate applications but it costs more in large quantity buys. They persist in using silicone for sealing many areas of the cars (like oil pans on many but not all 360's) and continue to have leak problems as a result. At one time I asked directly a factory engineer why they did that and he assured me it was simply a cost related decision. That was what maybe $1.00 per car? That's Ferrari.

 

Is 518 the blue halomar stuff? When I use it (or silicon), I never run a bead but instead just use enough to tack the gasket on both sides.

 

IMO Hylomar is one of the worst sealants known to man. Every auto maker that used it has been famous for oil leaks. Every use of it I have seen on a Ferrari has been a mess. In the application I am speaking of as well as the applications that 518 and Hylomar are designed for, no gasket is used.

518 is red and made by the Locktite Corp and has been packaged in both Locktite and Permatex containers. I don't care how you apply silicone, your method is the same they used and it still blew up lots of motors.

 

When my 308 bearing started to go, it sounded like a coffee grinder.

 

Change the lower drive bearings, Rifledriver is BANG ON!

 

I had a look at the cam drive pulley's and they are buried behind the crank pulley and the front cover looks like a b!tch to get off. What would be more cost effective - taking the whole unit to a shop that has the special puller and just replace the outer bearings (how many hours is that job), or split the cases, pull the whole front apart and take out the shafts and do both bearings per side, which I can probably do myself?

Is there a place where I can just rent the puller and only have to remove the crank pulley to get to the outer bearings?

How difficult is it to remove the crank pulley and are the cam drive shafts marked at the gears to easily put them back in the same orientation assuming I go in that deeply? Any words of advice besides using the red permatex when doing this job?

Thanks in advance.

 

Is there a good reason to change them when they are OK?

 

Once the crank pulley bolt is out the pulley should just slide off, it may take a little persuasion but it will not be a big deal. It will take a special ring nut socket to get the lower drive sprockets off which need to come off no matter how you do the job. If you elect to lift the motor off to take the entire front cover you need to pull the left transaxle output flange to remove the bolt hiding in there. That will require a simple puller of some type to extract it (the drive flange). You will have to pull the flywheel to pull the 2 nuts hiding behind it. Around the front of the motor several of the nuts will be hard to get a wrench (17mm box) on. I have one I modified just for the purpose. Then once you are in, you will need a blind hole bearing puller to get the inner bearings out of the block. The bearing puller you will need to pull the bearings out the front if you elect to just do the outers,is a very specialized tool and you will not have an easy time finding one just laying around. Either way you do it, despite what it sounds like, it is a very easy job if you are equipped, if you are not you will be swearing at me for days for ever bringing it up.

As for the timing if you put it at TDC and mark everything with touch up paint and put all the pieces back to their original locations you will be OK.

 

Reread post #3. And I will add to that.

If it was my car and I did the prior belt service. If I knew it had new high quality bearings and seals last time, If I knew the timing belts had not been installed too tight and I did not put a lot of miles on the car and I was just doing the belts for age, I would let them ride until the next belt service. Thats a lot of if's. I would also be inspecting them regularly.

 

Wow - I am sure it is easy with the proper tools but I don't have them.... Since you had indicated that the outer bearings are the ones that usually require replacement, I think I will call the local dealer/shops and get an estimate to pull the drive spockets and change out the bearing with the special puller. With some luck, they will have the tool and can do the job without telling me they have to yank apart the whole front case, in which case I would be inclined to do it myself or at least under my mechanic friend's supervision.

I take it the special puller is one that can slip in and grab the outer bearing and pull it off the shaft as a complete unit and not leave the inner race behind. Is it a Snap-on tool, or something even more specialized than some of their stuff?

Thanks for all the advice.