More problems... part Deux!

Isn't it possible that the broken shoe from the tensioner was moving around inside the sump and got whacked by the crankshaft or connecting rods and knocked off the sprayer nozzles?

The rev limiter built into the Motronic should keep the engine from over-revving, and I doubt if over-revving would cause this kind of damage anyway. Metal fatigue? Again, I doubt it.

Curious damage. Thanks for the update.

 

These cars never cease to amaze me. Roll up your sleves time for some hard work sorry to say. No way around it. You get to work or it will just sit there and rot.

 

Sorry for your troubles especially during the holidays, if you want you can use the spider I wont mind. Much....... lol Roberto.

 

Not the time to cut corners when you are this far in. The sprayers are held in quite snug by a waffered ring around the OD and will not just fall out. The broken sprayer nozzles have bounced around inside the engine and pulling it the rest of the way down at this point will allow you to inspect and clean everything. Look closely at the belt drive gears as I have seen broken nozzles raise hell with those in the past.

Broken nozzles are an indication of serious vibration issues. Find the source of the problem before reassembly.

Dave

 

unfortunately this is incorrect.

If you miss a shift and go from 3rd to 2nd instead of 3rd to 4th like you wanted, the engine is being accelerated by the rear tires, drivetrain, and transmission. The rev limiter simply cuts fuel, but since the crank is being turned by the wheels, not the combustion process, your only hope is that the tires or clutch slip before the car revs to over 10k rpm.

This is what's known as a mechanical overrev, and rev limiter can do nothing to stop it.

 

This last post is correct about over-revving due to a missed shift, but he didn't say anything about a missed shift.

I take it from Dave's post that he has seen this problem with broken nozzles at some point in the past, and he attributes it to the possibility of engine vibration. That made me think. Since Franck didn't mention a problem with engine vibration, just the rattle from the bad oil pump chain tensioner (I think this is correct), do you suppose it's possible that the Voith flywheel was faulty? We know that it's possible for the engine to refuse to start if the sensors detect imbalance in the flywheel (the famous hot start problem). Maybe, just maybe, at some rpm's the flywheel is going out of balance, and giving the engine a good shaking.

Dave, have you encountered a source of engine vibration?

Franck, do you know the history on your flywheel? Has it ever been opened up for inspection/repacking?

 

I have seen the broken nozzles a few times and have seen them wedge into the belt drive gears and blow the front cover apart. Each engine that I found nozzles like this either had a bad flywheel or a flywheel over worked trying to compensate for other engine issues.

I have yet to see the "hot start" issue you speak about and I have had some that shook bad enough that we thought all the engine mounts were missing.

Time for a complete and proper inspection.

Dave

 

How could the nozzles get outside the crankcase into the timing belt cover area?

There have been numerous instances reported here, including my own 348, that had very difficult hot start problems which were totally cured by repacking a leaking flywheel. I don't know exactly how the ECU's read this, but it must be off the crank sensors.

I'm very interested to hear what Franck would find if he opened up his flywheel.

 

"Belt Drive Gears". Pardon me, I took that to mean the gears for the toothed timing belt. You must mean the gears/chain from the crankshaft to the driven gear. Wow. Those little nozzles can cause that kind of damage? Scary!

 

Yup, they dont compress very well when run through fine tooth gears. I just wonder if airborn ballistic nozzles had anything to do with the tensioner failure.

Not doubting your theory with the hot start, I just havent seen it and cant make sense of it right off.

Dave

 

Don't worry, he's using the 456 right now.
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Dave the hot start problem is a dumb theory but its all we have. It also is more fact than theory. When the grease gets wet with oil and thins out the part inside the flywheel rattle and the cars have hot starting issues. When cold the grease solidifes and the cars start. This is classic 348 and has happened on few 355's. I think but do not know that the 355 has the same triple seals on the input shaft that rides in the hollow clutch shaft. This is where the 348's leak. They all do it with time. It is a poor design. If the 355's are not doing it there must be something different in their design. Outwardly I see no difference. Interestingly the 355 I think does have supports on the gearbox on the crossover frame brace. The 348 does not have them but does have the gearbox drilled and threaded from the factory in the same 355 location on their gearbox. I wonder if but have never tried (I use a solid flywheel so it is a non-issue for me) adding a similar gearbox support to the 348. My thinking is that maybe the 348 gearbox is actually lower or not supported in the chassis and the oil is encouraged to wick down the shaft and end up in the flywheel greasepack just by gravity. All that would be needed is a few degrees and oil would be on those triple seals all the time and cause leaks. It is an easy test and an easy experiment but I have never taken the time. But if it works you could be the manufacturer of 348 gearbox plates , make a fortune ,and discover the solution to the 348 greasepack failures.

Well maybe not make a fortune....LOL

 

Oh and to get the thread back on track.


I have never played with the sprayers nor looked at them closely. I did not even know they could grenade a motor. IF those nozzles are just swagged into the bosses and expect to stay but obviously do not then I would take a scrap one and see if I could tig weld a spotweld to the body so they could not come off. If tig is possible I would then tig a spot weld on my new ones so this would not happen again. If you have an old one you could send me I could try to weld on it and give you back a report. I'll cost you nothing except a stamp to mail it. Then you could take the new ones to your local welding pro and tig it. If I destroy the old ones then you'll know to just buy new ones and live with the OEM design. What do you think?

 

Why? What does it cause to happen?

Dave

PS I am all about this fortune making thing... Tell me more

 

The tubes are brazed / silver soldered into the bodies. Vibration causes the tubes to fracture near the body.

I cant recall right off if it was on the IMSA car Sprint or Enduro engine but I was in the middle of building one of them when I came across the nozzle Vs front cover engine from a street car. The race engine ended up getting a billet machined aluminum nozzle I designed to eliminate the tube as I was building it with that flywheel / clutch you saw and vibration was a concerned.

That said, I have yet to see it happen on a car running anything near smoothly.

Dave

 

Hi Dave,

I do not know what is really happening because I have no equipment to test the theory. I posted on this issue way back when we had the old Fchat site or maybe even as far back as the old Flist. Now in 348 circles it is considered common knowledge as the cars get older and more DIY’ER’s buy the next entry level Ferrari. Greasepack issues are the first thing to check for when there are hot starting problems on these cars. When a hot 348 flywheel with “hot” oil thinned grease spins up during startup the flywheel pack rattles. The theory is that this rattle sends funny impulses to the TDC sensors and the car will not start. If you keep the starter activated and the 30 rpm centrifical force makes all the parts move outward and stop making noise sometimes this will be enough and the car will studder to a start. The only other immediate fix is to wait until the grease solidifies as it cools. The classic sign of thin grease in the flywheel is a rattle like rocks shaking in a bag upon engine shut down when hot. Once the grease pack cools the parts are stuck in the grease and the car will cold start just fine. Imbalance on start-up is not an issue. It is the rattle of parts inside that seems to cause the trouble. In the past I have suffered from the problem and put many miles on my car so I suffered it often. I experimented with several grease types which all worked but all eventually thinned due to the oil leak past the triple seals. I could never get the triple seals to really seal. I thought about the angle of the two shafts relative to horizontal being an issue but never pursued the issue since I gutted my OEM flywheel and built it solid so grease would never again be an issue. I dropped out perhaps 6-8 lbs I forget of rotating mass. Some thought I would harmonically destroy my engine but in reality 5+ years of racing have seen no engine damage. I thought of the need for the voight dampened flywheel as more for driver comfort and driver perception more than any real function. We see this with Porsches and so I made the analogy to Ferrari with zero evidence to back me up but now I have time and miles under harsh conditions to prove my case on this one data point. To tie this back to the original thread…I can’t imagine what kind of brutal vibration would snap the sprayer nozzles off. They have such a low mass a very unusual harmonic vibration would need to do the bad deed. So to solve the oil leak problem which is the source of the thinning flywheel grease we need to either come up with better seals or tip the gearbox to zero degrees horizontal or even a few degrees above horizontal to keep passive oil pressure off the seals. That’s why if I was still running a greased flywheel I would experiment with a gearbox support a la 355 to maintain the shafts horizontal position. I wonder if there is some advantage to making such a support also for racing making a more rigid structure of engine to chassis and I am thinking of running my wing supports to the gearbox rather than off my bumper. Aerodynamics is more significant than I ever thought even at my slow speeds of under 140 mph. Oh there is one other trick and I used to use it diagnostically. I don’t do it anymore because once I hear the hot shut down rattle of the flywheel vs rattle from say loose exhaust I know it is the flywheel. You just need to hear a few and then it will be instant for you too. If you are not there quite yet one trick is to look though the square cutout vents in the back of the bellhouse. You will see if you turn the flywheel pack 2 allen plugs. I think they are 8mm but I can’t remember. Anyway you can screw a grease gun into one hole and pump in grease until it comes out the other hole. I have been able to instantly solve the hot start problem doing this for at least a short time. The OEM fix is replacing the triple seals on the input shaft and then cleaning out and regrease the flywheel. It is a messy job.

 

Cool solution to an interesting and thankfully rare problem. I wonder if the problem is in the initial brazing where we see a similar problem with 4130 chromoly welding fractures of roll cage tubing. I am sure little thought from Ferrari went into the OE design. I wonder if a slow cool or anneal process would toughen up those little tubes. Welding 4130 for cages the general thought is weld over 70 degrees F ambient temp, slow weld to build in heat but not locally overheat and go for slow cool to prevent weld fractures and brittleness. Could be same thing?

 

I have used O-rings for four thousand miles without a problem .They are luibricated by the gearbox oil during operation . Give it a try .
carl has the best fly wheel . No grease at all . Brilliant.

 

Hmmm, Just havent seen a hot start issue that could not be traced to a FI / Wiring / Ign component, again not to say it doesnt happen, I just havent seen it YET.

I have had that damn flywheel grease covering the workbench many times going back to when they were still under warranty. I would rebuild them when Ferrari would nix the warranty claim. Must be a regional thing with all the miles you are able to put on year around as I just dont see reoccuring problems once the triple seals are replaced properly. I think a solid flywheel is fine on a race car, just not sold on using it for the street with the wide RPM band seen.

I dont think the vibration has to be brutal to break the tubes, just abnormally heavy and constant. Mix that with turning the restricted oil flow 90 degrees while under high pressure.... I am sure you are right in that embrittlement is also a key player in the failures. Hey, I too am guessing as I havent found enough of this problem to warrant looking deeper. When I started to see this the 355 headers, liners.. were starting to fail and I had my hands full. It did scare me enough to modify the one race engine but not enough to tear the other down.

I am in the middle of designing the dual element wing mounts for the IMSA car now. I would love to see what you are thinking on your mount idea. Ahhh here I go taking this way off track but I gave up on the PC crap a while back. I am going to try to find clear roads and yarn tuft the car to see how high I have to mount the wing for clean air. Any ideas? Have you researched that yet? Getting a 100MPH burst (on the street) without waking the dead and alerting every officer in the county with this car is tough and we have no tracks near anymore. Now the car has been shod with the Forgelines and an alignment setting that I think will work (was at odds with the past owner on how the chassis should be set up) properly I look forward to getting it sorted with the wing in place. As the car has a blade type front sway bar I am also fabing a cockpit adjuster so I can deal with the changing loads due to the fuel cell up front. That proved a problem in the limited time I have had it on a track. Got it running again just the other day, was sitting for a couple years in a hanger. Time to pull this engine, freshen and install something a bit more civilized while working on the slide valve throttles.

http://youtube.com/profile?user=**************** (Doing a couple of short run ups in the shop) I wanted to take it to Cavillino but there is far too much to do with no time available.


Dave

 

Well there are plenty of electrical issues in the 348 that's for sure hot start or not. It is quite possible that I have not been putting these seals in properly causing repeat leaks. I have always done it w/o tools heating the rings in hot water and forcing them over the shaft only to have them stretched out and then slowly some memory in the material brings them back into shape. Those rings are not real seals in my line of thinking but that's all we got to contain the oil. I never liked the design or the material nor have I found a way to get them on wo/ stretching them to some degree.

IMSA car sounds mean! I'd love to be on track with it.

As to Aerodynamics I have answers just empirical ideas w/ no testing. For example my wing is only empircally in clean air being above the roofline. I was amazed by the results so I left it there. I never moved it anywhere else to experiment because it was such a hassle. I am going to smooth the airflow over the rear deck by removing it and changing to lexan held in with dzus fasteners. The back will look more vetteish or F40ish. As a result I can run a truss or tower fabed from aluminum tubing and bolt it right to the bellhouse existing studs. The why of doing this are several like with the wing over the tail I keep hitting my head on it while dinking around the car, the oe decklid weight is very high just try opening the lid without the front helper shocks, I think wings should be on chassis or close to it, too many people on the race track running functional wings mounted in makeshift locations always break up the mounting points over time from the vibration and repeat 200-300lb downforce beating on the mounts. Over time even I have seen cracking in my own attachment aperatus and a closing of the leading edge of my bumper gap to body as the downforce is pushing on the bumpertop despite tight bolts. The OE attchments were never designed for force in my direction and it is catching up with me. The force from a proper wing is not to be discounted.