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355 Teves hydraulic brake delay valve leak

Discussion in '348/355' started by MAD828, Sep 8, 2020.

  1. MAD828

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    Had the undertray off to rebuild the shift linkage and replace the bushings. Noticed a pool of brake fluid on the middle undertray.


    It’s leaking from the brake delay valve. This being a Teves system it shares common parts with the likes of Jaguar. The part is discontinued and seems a common problem on the Jaguars as well. Has anyone else encountered this and what would the suggested fix be?


    Can a generic delay valve be installed?


    The part number for the Jaguar item is CBC4223 and it too is discontinued.

    Hasn’t shown any noticeable brake deterioration but it definitely wouldn’t be helping things with the leak.

    Pictures for reference.





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  3. GTO Joe

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    • That thing is basically a proportioning valve. Does anyone know the ratio? I know there are a number of racing valves that can be adjusted that would do the equivalent if we knew what to dial in. One other thing. In your picture it looks like your leak is coming from what looks like an o-ring on the left fitting. Anyone ever have one of these disassembled?
     
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  4. asgor

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    What's the Ferrari part #? I can probably help you if you provide that.
     
  5. MAD828

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    The part number is: 134597 labeled as delay valve.
     
  6. MAD828

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    Yes it does look like it’s leaking from the o-ring. Haven’t tested the torque of the fitting yet.

    There seem to be some off the shelf items that look close to identical in terms of fitment but I’m not sure on the pressure the valve is set to.

    Here is a picture of the part new:


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  8. asgor

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    Aside from trying the usual suspects (T. Rutlands, Eurospares, etc.), the cheapest available - though used - seems to be here. It does appear to be in excellent conditions.

    Sorry, couldn't find any silver bullets with this part (i.e. cross-reference beyond Jaguar).
     
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  9. m.stojanovic

    m.stojanovic Formula 3
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    According to the Jaguar manual, this valve limits the fluid pressure on the rear brakes. This is necessary because the rear brakes are operated directly by the fluid pressure coming from the ABS pump, via the modulating valve inside the MC, and not by the MC piston. If it is bypassed, there is a risk of rear brakes locking. I am sure that the Jag and the Ferrari valves, although look identical, are set at different pressures (different rear brake pistons, pads and rotors, different weight distribution etc.).

    I have tried to separate an old valve from a Jag at where the O-ring sits but it is not possible. The Jag forums also confirm that it is not separable. Some say that on a Jag, the BMW valve (Ate) can be used, p/n 34-33-1-152-494, but I doubt its pressure setting is suitable for 348/355.

    https://www.fcpeuro.com/products/bmw-abs-pressure-regulator-34331152494

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  10. Qavion

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    Looking at the Jag forums, the o-ring just covers some weep holes.

    If you try to disassemble the valve, the Jaguar forums pointed to this generic valve video (including some warnings on where to apply pressure). Skip the first 5~6 minutes.



    There are some real horror stories if these valves break (not just from the perspective of brake lockup).
     
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  11. MAD828

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    Thanks Miro that’s helpful information.

    I would say that on heavy braking the car does seem to go light at the rear which might indicate weak rear brakes as the front nose dives.

    I wonder if the marking number is an indication of pressure? The OEM part is marked with it, I will check what is marked on my one currently fitted.

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  13. m.stojanovic

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    If you don't want to spend big money on a genuine Ferrari one, you can try (as suggested) using an adjustable brake proportioning valve. Here's a very compact one but with 1/8 NPT threads (you can get adapters to convert to metric):

    https://www.ebay.com/itm/Speedway-Compact-Adjustable-Brake-Proportioning-Valve-/133374154828

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    You can then try different setting until you are happy with the braking behaviour. If you get the ABS kick-in when not really expected, it would mean too much pressure on the rears and just back the regulator off a bit.
     
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  14. MAD828

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    Thanks Miro, it would be hard to find the Ferrari part even if I wanted it new.

    I will look into getting a similar adjustable type so the bias is suitable to the car. Will report back once I get some progress. I wonder if anyone else has had this issue.
     
  15. Ferrarium

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  16. Qavion

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  17. MAD828

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    Just an update I took the chance on a used Jaguar delay valve CBC4223.

    According to workshop manual the delay valve adjusts output pressure equal to input pressure minus 8.5 bar. The Jaguar item is identical in this regard. Both the original Ferrari delay valve and the Jaguar item are marked 8.5 and have the same direction of flow.

    I have removed the leaking valve it’s badly corroded and replaced with the newly sourced part. Now to bleed the rear brakes and road test. Hopefully will notice some more stopping power.

    The Jaguar valve is easily found online and a fraction of the price asked from Ferrari wreckers for one that’s come off a binned F355. I paid about $70 pounds for this one. Both items are NLA from factory new so it’s not an option to buy new unless there is some old stock lying around but be prepared to pay the 2500 USD as above. Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
     
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  18. Ferrarium

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    It makes sense given that the Jags and 348/early355 used the same abs pump as well. Let us know I bet it works great.
     
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  19. m.stojanovic

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    There are two devices here, called in the Ferrari catalogue "Delay Valve" and "Valve Corrector" (Pressure Regulator?):

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    I have a Jaguar delay valve which also has "8.5" stamped on it. I don't think it is related to pressure as this thing is called "Delay Valve" or "Pressure Delay Valve". The thing on the right should control the pressure. Identical looking unit is used on certain BMW E30-s and it is called "Pressure Regulator" or "Pressure Reducing Valve":
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    This BMW pressure regulator has "5(arrow)25" stamped on it and the Ferrari unit has "5(arrow)20" so it appears that they a set at different pressures.

    On the other hand, a document that I have on the Jaguar Teves ABS system states that the "Pressure Reducing Valve" maintains pressure differential of 6 bar [87 psi] between the front and rear circuits but, in the parts diagrams, the Jaguar unit is shown as a Pressure Delay Valve, same looking as the Ferrari "Delay Valve" and Jaguars do not seem the have a Pressure Regulator like the BMW one.

    So, it is a bit unclear which unit on the Ferrari does exactly what. Following the description, I would understand that the "Delay Valve" just delays somewhat the application of pressure to the rear brakes as it is applied the moment it is applied to the front brakes master piston. Some delay is needed to the rear brakes to give time to the front brakes master piston to move and start applying pressure to the front brakes. And the "Valve Corrector" should actually be a pressure regulator (limiter) to prevent too much braking force on the rear brakes that are operated directly by the hydraulic pressure of the system.
     
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  20. Ferrarium

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    I found a nice clean one from a jag, when I get it I'll run it in ultrasonic cleaner and low pressure air then throw it in my parts box. When I put a BBK on next spring with SS lines I will probably put it on and take the old one out, clean it and store it. I have seen 2 of these have issues past few months out here and they are NLA.

    Btw I read on Jag forums that a the bmw one was used a few times even though the spec is not the same its close. The Jas had the same pressure as the Ferrari so if it worked on the Jag it may work on these cars. The rear brakes may either bite sooner or later however depending on how the pressure works.
     
  21. m.stojanovic

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    I don't think there is any problem using a Jag Delay Valve. This thing seems to be part of the Teves braking system, related to how the MC operates, and, I believe, it is there to equalise the start of pressure application between the front and rear brakes and not to bias front-rear. Since the MC-s and the working pressures are the same Ferrari-Jag, this device should be the same on both (and both, Ferrari and Jag, delay valves have the number 8.5 stamped on them). On the Jags, the delay valve is placed next to the ABS block in the line that goes to the rear brakes.

    I have seen the Jag post about replacing the delay valve with the BMW valve but I don't think it is a good alternative as the BMW valve is a proportioning valve, not a delay valve.

    I think it is the second thing on the Ferraris, the round thing connected to the delay valve, what does the proportioning. The number stamped on it is 5(arrow)20. I have read about Lotus proportioning valve which is marked 3/15. According to the Lotus forums, these numbers mean that up to 15 Bar, there is no proportioning. Once the pressure exceeds 15 Bar, the proportioning starts and pressure on the rear brakes is being kept at 30% (number 3 in the valve marking) of the front brakes pressure.

    Following the Lotus valve marking, the meaning of the 5(arrow)20 on the Ferrari valve may mean no proportioning up to 20 Bar and thereafter the rear brakes pressure is kept at 50% of the front pressure.

    Similar looking valves for BMW have numbers 5(arrow)25 and for Porsche 944 5(arrow)18.

    BMW:
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    As to the delay valve, Mopar (~USD 35) has similar looking valve as the ATE one, used in Chrysler Cirrus, Dodge Stratus, Plymouth Breeze 1997-2000.

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  22. Ferrarium

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    I assume you meant to
    I assume you mean to type CBC4233 and not CBC4223.
     
  23. MAD828

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    Correct - miss typed. Bleed the brake and clutch lines and the pedal feel is a lot better. Will road test in the coming days.
     
  24. m.stojanovic

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    I "tested" my Jag delay valve by blowing through it - in the direction of he arrow, there is a fare bit of restriction to the blow and, in the opposite, quite free. The only thing I could see inside the valve is a tiny steel ball. This is probably the check valve that allows free flow in the opposite direction (brake pressure release).

    When you get your Jag valve, can you do a similar blow test and let us know. I would like to compare my test with another valve to know whether my valve is good or not.
     
  25. Ferrarium

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    I believe there is a spring and some xrings in there that pushes and seals against the arrow direction, I have seen rebuild kits for American models and those had those parts at lease not sure about the jag but there has to be a spring and I suspect they disintegrate over time. But yes definitely plan to make sure the mechanism is free. Will let you know.
     
  26. MAD828

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    Reporting back that the leak is now resolved and my brakes are not only functioning normally but the pedal is noticeably firmer now too, much improved pedal feel.
     
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  27. m.stojanovic

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  28. Ferrarium

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    I got my new delay valve and I have a new pressure regulator coming from England.
    The delay valve, I can insert a thin hex key shank down the fluid port and push. On both ends I do this ad there is a spring loaded valve on both ends when you push against it. It appears to be a 2 way check valve of sorts.

    I tried separating the 2 halves but it was stuck and at the risk not not being able to tighten it back up and having a leak, I left it.
    I can actually blow air through both ends as well one end is easier.
    I will be filling it with brake cleaner (depress ball and fill) and running it in an ultrasonic cleaner and blowing it out with compressed and repeat in many cycles air for 8 hours or so. I will do the same for the regulator when I get it. When I do brakes and lines in the spring I will replace those 2 and clean the old ones and store them for future.
     

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