355 bypass valve

Interesting failure. I have not seen that one. The quick test shown to me by fellow chatter "jh355" was to open the valve (on the whole assembly) and stick your finger over the vacuum fitting and see if you can hold vacuum and keep the valve open. If it released, bad bellows.

 

John,
Since this part is used on other cars (BMW M3) you might be able to source a new one through a BMW dealer or independant parts house for much less than through a used Ferrari parts dealer. In the alternative, I noticed Capristo sells the entire assembly (including the valve) for less than $1000, which is considerably less than the official Ferrari part, and likely better constructed as well.

Nicks' Forza Ferrari is a Capristo dealer.

 

I saw another 355 owner post about the valve and said his M3 had a similar set up. The concern is the spring tension and range of movement is the same or not. They might be application specific. And BMW may require you to buy the entire thing as well...

Nick posted about the Capristo replacement valve. I think it was actually $900 list price. And it had a neat feature that allowed you to adjust the opening rpm of the valve. So you could have it open slightly sooner or later if you wished.

 

You might check eBay for used 355 exhaust from which you can salvage the bypass assembly.

 

Yeah, specialized recycling has them occasionally for crazy prices, but might be worth trying to low ball them on an offer.

 

Yes, according to Nick the Capristo valve was a direct replacement. Contact him for details.

 

I have a used bypass valve with only a 1000 klm's of use (it still looks new) but have not decided to sell it yet. I know they go for $2200 new plus taxes but what are they worth second hand?

 

ok........ I remember that happening to mine a while back...... I asked around looking for a used one to no avail . So I made a billet alluminum housing that screws together which gives me the ability to 'replace' the membrane should it go south again .

But the easiest and cheapest way to fix this...... is to find 360 muffler tips on ebay or someplace and remove one of its diaphram cansiters. They are identical to the 355s and they have two!!!

 

Glad I could help....... here is a used 360 exhaust on ebay for you....... . Maybe you can get him to ship only the tips to save on shipping....

http://cgi.ebay.com/ebaymotors/FERRARI-360-MODENA-MUFFLER-AND-TAIL-PIPES_W0QQcmdZViewItemQQcategoryZ33636QQihZ009QQitemZ190218102291QQrdZ1QQsspagenameZWDVW

 

FYI. www.allferrariparts.com sells the bypass valve for $1,245. part number is 155006. I believe.

 

The problem with the OEM valve is that it defaults into closed position if there is a vacuum problem, when the valve fails many owners are UN aware that the valve has failed, during this time it is causing excessive heat as the exhaust gasses cannot flow at high RPM.

The Capristo version includes an electrovalve that operates in a way that the default failure setting is open rather than closed. The price is $ 995.00 USD with free worldwide shipping. It is also an upgraded valve with ceramic bearings, far superior to any other valve on the market.

 

I guess I'm not that bright but the purpose of that valve is to change the exhaust restriction to help flow at mid range throttle response then open for free flow at high rpm like what corvette is doing to get another 6hp from its LS3 motors with their bypass exhaust system???? These valves when malfunctioning at hi rpm are helping to????? eat some valve guides?? increase reversion???? If there is even a chance of this why not use an non-valved exhaust system tuned for what you really want wide open throttle? Doesn't the 355C use a valve replacement that basically defaults for hi RPM for racing? Do these 355C cars also see the same rate of valve guide damage as non-challenge cars? I don't seem to hear problems like this with challenge cars. Vern....do you have any comment on the bypass valve?

 

When bought my 355CH a few years back the check engine lights would come on at idle and then go off at around 3000 rpm. It took me a month or so to figure out why this was happening. At idle I noticed that I was actually getting suction on the outer exhaust tip/pipe, the inner exhaust tip/pipe was flowing in the right direction. The challenge exhaust exit tips/pipes flow in the fashion that the outer one connects to lower/cat exhaust only and the inner is the exit for the bypass/upper exhaust only and there is no bypass valve to stop the flow from going to upper exhaust at low rpm. The upper exhaust flows so well as compared to the lower that air is actually sucked the reverse direction thru the cat side and over the 02 sensor to give a incorrect reading and causing the CELs to come on. If you look at the flow of the pipes from the inside you can actually see why the exhaust wants to go to the upper flow pattern (path of least resistance). When the engine reaches around 3000 rpm there is enough flow thru the headers to push the flow out the upper and lower sides(the right direction of course). I removed the cats(installed pipes with 02s plumbed in) and inserted header baffles in the upper system to create just enough back pressure at low rpm to force some flow thru the lower system to keep the flow going out instead of in and keep the CELs off at idle.
I don't think the 5 valve head is the problem I think it is the exhaust set up. the upper exhaust causes the suction not the 5 valve setup(MVHO). If you put a set of 360 headers on a 355 the reversion dilemma would go away, again my MVHO. I also think that Ferrari designed this system in conjunction with the intake system, remember the 360's intake design is different than the 355. So my above comment about the 360 headers may cause some power loss.
FBB I only have about 15,000 street miles on a new valve job that was done on my car after it was raced for 6000 miles. So who knows why my valves were done ie; race miles or just bad guides??? So far so good on the valves, remember as I have said before my engine has no heat traps; no shielding,(ceramic coating instead), no cats, no muffler other than those header baffles and no air pump.