Would you buy a 355 with bronze valve guides?

Popcorn

 

Nothing wrong with good bronze valve guides. It is the occasional brass ones that cause problems.

 

What he said.

The truth is, you really can't know what is in there unless you personally bought and installed them. There's no problem until there is.

The workmanship is at least as important as the materials.

These parts were a do-over for a client that had new guides put in at a dealer.
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Asking because I don't know; what other components within the motor are bronze? An oil analysis can tell...

So, monitoring the engine oil at specific intervals can provide trend analysis e.g. increasing content levels of various metals as they wear. Too bad that we don't have the baseline and operational/performance data.

 

The assembly number is what we need. But, given a 96, it's likely the guide are bronze unless replaced.

Also, not all bronze is bad - manganese bronze is excellent but that's not what the factory used.

Do a compression test. If the compression is good, don't worry about it. Drive and enjoy.

 

my 355 had guides replaced with a bronze alloy ..... so far so good ....

 

Lol, you beat me to it

 

This is a very complex and highly debated topic. See this thread and watch the video.

http://www.ferrarichat.com/forum/348-355-sponsored-bradan/519350-poor-compression-high-leak-rate-%3D-bad-valve-guides.html

In summary, if the car has good compression and the price is right along with it being a good car in other ways, buy it.

If compression is low, add some BG44K, drive the snot out of it for a 100 miles or so and do the compression test again. If the compression improves, it's not bad guides as they don't correct themselves but carbon build up can with an additive and hard running.

 

Surely whether the valve guide is worn or not, it is the function of the valve stem oil seal sat above it, to stop engine oil getting into the combustion chamber.

Never any mention on these valve guide threads about simply replacing worn, 20 year old hardened rubber stem seals with nice fresh pliable ones, especially in a 5 valve head.

 

Yes, but not without a PPI including compression and leak down numbers. And that is good advice for any of them, but in particular in ruling out this costly issue that could be there on earlier 355s.

 

I, like yourself was concerned about this when I bought my 96 spyder with 24,000km. I had a very reputable Ferrari specialist do a compression test and inspection before purchase...I was very concerned about having to rebuild the heads. After 11,000km, I started burning a lot of oil and then had the infamous header problems. Weird thing is, I dropped the car off at the dealer and it actually "passed" a leak down test.....wasn't good enough for me...I had the heads removed and sent to a rebuilder in California who does a lot of Ferrari work. He was kind enough to send a video of him literally being able to move the valves back and forth in the guides...horrible. Something to keep in mind is that your cats will disguise the problem for quite a while and then they give up....mega$$. I took the plunge and went with the full fabspeed system from the headers all the way through cat deletes right to their sport exhaust. I will give an honest review of this as soon as the car is back together mid August. Having said all this, I did my homework and it's still a lottery when you purchase these cars....and I wouldn't change a thing.....the car has appreciated enough to justify all the work and honestly, these cars cars have a personality....when they are happy, you will be ecstatic....these aren't emotionless daily drivers

 

If you just replace the stem seals, it might slow oil use, but won't fix the compression issue.

 

John, the need for a leak down is a bit of a myth. If the compression is good, no need at all for a LD. If poor, the LD can help determine if the leak is in the heads or the block.

 

True. If it compression came back bad on a potential purchase, I would walk.

 

Perhaps but many factors would be reviewed.

 

Leak down is an essential diagnostic tool for evaluating engine condition. Compression alone, particularly just looking at the final value tells little. A perfect example of why leak is critical is an engine I'm currently rebuilding. Compression is nearly identical across the board, but pumps up to the final value slowly. Based on the compression alone logic, the engine is fine. A road test reveals lower that expected power. The slow to pump up, but even compression numbers is very telling...A leak down test revealed 20% leakage across the board. A teardown revealed excessive ring gaps, along other things.

 

You are right.

This is something that is poorly understood but for which there is no shortage of internet "experts". Most of what I read in this thread (and others) is baloney.

 

I bought an early 95 with stock guides and no ppi. Best purchase I have made

 

Interesting how you did not mention the compression values. I'm sure that would tell more of the story.

And, Tim - I'm a mechanical engineer and a guy who gets his hands dirty. Many of us "internet experts" have credentials.

 

But you are just an "internet expert" Jim

 

Since we are on this topic, what guides would you recommend installing on these motors Tim?

A while back Dave Helms was using the sintered steel guides, if I remember correctly.

How do the sintered steel and the manganese bronze guides compare?

 

My car is an early 95 as well with the OEM guides I believe. I went with what the general consensus on the forum recommended before purchasing and did have a compression test and leakdown test done. I know that is not a guarantee for future problems but does give some information on the current state of the motor. I also had it done by a reputable shop that knows these cars well.