456 Smoking/Valve Guides Update #2

A bit more info on my 2000 456 (24K miles) which has experienced a rapid-onset case of smoking/burning oil. Search my previous posts for a more detailed description. Diagnosis: leaking valve guides, which were of original bronze and the same problem the 355 crowd is well acquainted with.

1) Thanks to Brian, I had the shop at Ferrari of Denver fabricate a special plate to run a leak-down test on the individual cylinders/rings. Very good news here. All results showed tight rings, leakdown no worse than 3% on any cylinder. No explanation why the prior leakdown with heads attached showed some ring leakage; perhaps the tester wasn't as familiar with this engine and how to read various sounds and other clues. This is very good news indeed, no need to go into the bottom half of the engine. FYI, the heads have been removed with the engine in the car.

2) The parts are in and FoD have begun work on replacing the leaking valve seals. See my prior posts for pictures of the exhaust valves.

3) Pictures of the piston heads (for the 2 worst-leaking cylinders) as well as the intake valves are shown below (per request of Brian and others). At this point, looks like a standard valve guide problem and I should be good-to-go.

4) Forgot to mention this previously, but the engine mounts were also shot on my car (another well-known defect on 456/550s). Easy fix at this point, given the other work we're doing.

I'll update as more info becomes available.
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Definite proof that Mr. Brian is an exceptionally valuable resource!

 

Hello Diablo 456,
Good news indeed for you, however, forgive me for insisting, but you should have FoD investigate why only two units out of 12 developed this problem.
The excessive wear of the valve guides, in my modest opinion, may just be the effect, not the cause of the problem and as such, it may come up again in the future, if it is not corrected.
Saluti,

 

That is a pretty standard failure mode. I have 3 355's in the shop now for valve guides. On 2 of them only one cylinder show a problem. I have had cars with 2 exhausts and 1 intake guide absolutely devestated and the other 37 guides just fine.

 

Any clou why the pistons have different patterns on the top ?

 

reflections

 

They don't. Look closely, the first photo has the piston near the bottom of its stroke. You're seeing reflections against the (thankfully, pristine) cylinder wall.

 

You are quite right. At a second glance it becomes obvious.

 

So is this a freak thing, or can we conclude that all or some model year 456 engines have the same valve guide issues as the '95-'99 355 engines and this is possibly a widespread issue? Brian, have you seen this on a 456 before?

Birdman

 

I have a client that is losing compression on one cylinder. It has not gotten bad enough to tear down. I have heard of a very small number of problems but not only is the fleet of 456 and 550's smaller but the motors are not as highly stressed.

This one is just like the 355's though, when it starts going bad it happens fast. I have a 355 here now for a valve job. At an easy 9800 miles I did a comp and leak down test. It had 7 or so percent leakage and 190 lbs in 1 cyl. 2500 easy miles later it has 46%. That is the reason so many are now refusing to do PPI'S. Customers will not believe we did our home work and blame the trouble on us. The car I have here now I warned the owner that 7% was not a good sign and he took the chance. If I went on here and said 7% was heading for trouble I would be excoriated by 355 owners, many of which are still in denial

 

It seems as if the 355 have a issue here as noted. What are the statistics on the 456/550/575?

I had mine pulled out on my 30K mile 550 and they were perfect.

Brian--any thoughts?

 

I'm not sure I understand. Pulled what out?

 

Sorry--I have my valves pulled out to look at a few of them as one was bent by the mechanic. They were in perfect condition. My question is in your experience have you seen many problems with them? This is really the 1st I am hearing of a 550/575 with valve guide issues.

 

Now I understand.

Just so you know, for starters in the dealers we usually see enough things even early on in small percentages to give us a pretty good idea what is down the road. Also then and now out of the dealer there are a couple of guys around the country that keep in touch to keep our collective ears to the ground with what we consider good sources of information. Then consider the cars have been around almost ten years now.

Now balance that against the fact that the fleet of 550's and 456's is small as opposed to the 355 so we have a pretty small data base. The 550/456 tends not to be driven as hard as a 355, the 12 cyl motor is torquey so is rarely revved hard. It is a very understressed motor against a 355.

I say all that just to set the stage for the comments that we knew the 355 motors were headed for trouble long before the cars were out of their 5 year production run. We fixed lots of them and replaced quite a few under warranty. Not the 12. Not counting the engine replacements that happened because the oil pressure sender was broken off I have heard of very few that have even had their heads off for reasons that can be confirmed as real.

Different cars get different reputations inside the car business, the 550 has had a great and deserved reputation. The 456 less so but not for reasons having to do with the motor.

I have a client with a 456 that is losing compression on one cylinder. It has not gotten to the point we feel it needs to come off yet. I have heard of a few others but certainly not enough to raise any doubts about the cars. I have been wrong before, time will tell.

 

Brian,

I do not understand. Why do you see this on just one cylinder and not wear over the entire head? What is the pathogenesis of this problem?

 

Brian,

Thank you for the insight, it makes very good sense.

 

I think it is as simple as garbage guides and maybe blend in some amount of bad workmanship.


Back when the 80-82 oil burning 308's were being addressed we were being sent valve guides for those motors that did not in about 50% of the guides meet specs for concentricity. Ferrari's response was to change the tolerance for concentricity. They had been building motors for who knows how long with those junk guides and did no know they did not meet spec. Still when faced with reality they did not fix it. The guides are still junk. One of the problems and one of the big things that runs the cost up in doing a really good valve job on these motors is repalcing a guide that is that crooked. My machine shop buys guides that are undersized and puts the head in a fixture, dial indicates the existing valve seat and bores the new guide to the seat location, then finishes up the seat. The alternative is to grind the seat into never never land on the holes that had very crooked guides. That takes a lot of time but is the difference between the valve jobs that cost a few hundred as opposed to a couple of thousand but the difference is worth every penny. That is also one of those areas that cause many to suggest we are gouging because of the name of the car.

The parts being made in house are for the most part very good in quality but the vast majority of problems with these cars is the really low quality of some of the parts that are being supplied by contractors that in many cases I have no doubt are somebody's cousin. If Ferrari would hold their contractors feet to the fire and insist they meet specs I would bet 75% of the problems would vanish.

 

Agreed! I also think and it is rumored that Ferrari likes the low bidder. I once offended a Bosch tech rep suggesting that Bosch sells Ferrari their "seconds" because there is no way a bosch connector in a Ferrari with less than 10k miles should blow apart vs my BMW with 100k miles on the same bosch connector. Every supplier has parts that don't meet spec and I think Ferrari buys all they can get. I am sure you know the 348 has a combo of Ford, Bosch, AMP, and Delphi connectors. Now that is superior engineering! Thanks for your info and insights as always.

 

Brtian, when I rebuilt my 308 motor a few years back, I had the heads re-worked by a reputable race motor builder (Sgheiza's machine shop http://www.brodix.com/dealersearch/dealersearch.html). I bought new SS valves and new guides from SSI. But the mechanic decided to sleeve the guides with bronze sleeves rather than replacing all the guides. He only replaces 3 of the original guides. I told him to do what he thought was the best way to go (price not being an issue). He said it was better to sleeve them. So far so good.

Thoughts on this?

 

Not a bad idea esp when you consider the concentricity problem I mentioned. Often just putting in a new guide the old fashioned way winds up moving the head of the valve so far you grind away half the seat making a new home for it. My guy sometimes orders valves from Ferrea with a thou or 2 larger stem and just bores out the existing guide. We do that all the time with wrist pin bushings.

 

Low bidder? No question about it. But as far as buying up second inventory I would dissagree. I can see companies dumping reject inventory on them though because they know it would not be caught, at least not for a long time. As far as connectors they sub out the harnesses and until mid 90's they were made buy an Italian Co. With the exception of the 348/Mond t era they were really pretty good. They are now getting them from Delphi and I am not impressed. Fewer problems but when there is one is is ugly.

 

At 17,000 miles my 2000 550 is running just fine but should it start to smoke and be diagnosed as valve quides on just a few cyclinders should I have all guides changed while the heads are off or only those showing signs of being or becoming bad.

If the guides are still not made to an acceptable spec. I'd would worry about replacing bad with bad! But to back up a little...just why do these few valve guides wear so badly...if it's material quality that's a second concern along side of sloppy specifications/tolerances.

Replacing bad material with like will just lead to more problems but replacing good material qualty guides as described by Rifledriver sounds like it should work fine.

Leaving the question of poor material quality...is it really a potential problem?

Hotrod

 

I would do them all. The new guides are a different material and seem to be of much better quality.

 

Regardless of what make or model you run adding an upper cylinder lube to your fuel at every fill will undeniably contribute to the longevity of your guides and rings.

 

Any comment on this Rifledriver?