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308 timing gear cover removal

Discussion in 'Technical Q&A' started by ham308, Apr 1, 2004.

  1. ham308

    ham308 Formula Junior

    Nov 3, 2003
    358
    NE Switzerland
    Full Name:
    Richard Ham
    I hope I'm half way through replacing the inner and outer bearings on the cam driveshafts with the engine in the car. I've got the dreaded oil pick up tube off and it's 3 studs, (thanks to Robert Garvin and Verell's posting on the old site). Removed all the nuts and vertical studs on the timing cover and now the timing cover should slip off horizontally.

    It moves freely about half an inch and then bang, it comes up against something metallic that stops it dead. Anybody got any ideas what it could be?

    It doesn't look like it's colliding with the water pump. I can get a hacksaw blade all around the edge of the cover.

    When it's gone it's half an inch the shafts can wobble, so they are most likely already free of the inner bearings.

    Am I missing something?

    I guess I'll remove all the horizontal studs tomorrow to give a bit more freedom to move the cover.

    Grateful for any suggestions.....
     
  2. robertgarven

    robertgarven F1 Veteran
    Rossa Subscribed Owner

    Feb 24, 2002
    5,082
    Ventura, California
    Full Name:
    Robert Garven
    ham,

    Before you go any farther get a marker and mark all the aligments, as when you to put it back together everything will be much simpler. The timing gears are pressed into the gears in the block so what I did was get some wooden shims and start gently tapping them around the edges and it will slowly come off. You will then need a inside bearing puller to get the inner bearings out. the t gears have a helical cut gears so when you put it back together it has to be exact and as you tighten up the nuts the t gear shaft is pressed into in inside gears you dont want to make a mistake.
     
  3. 4re gt4

    4re gt4 Formula 3

    Apr 23, 2002
    2,279
    Roseburg, OR
    Full Name:
    Hans E. Hansen
    Is it just me, or does that look like some kind of cartoon face?
     
  4. Dale

    Dale F1 Veteran

    Oct 7, 2003
    5,211
    uk
    Full Name:
    Dale Juan
    LOL,Looking at it yes it does,

    cheers
    Dale.
     
  5. ham308

    ham308 Formula Junior

    Nov 3, 2003
    358
    NE Switzerland
    Full Name:
    Richard Ham
    Cartoon face indeed. I thought this was a highly technical site :)

    Anyway, I'm as chuffed as nuts now, since the cover is off.

    It turned out to be the oil pump housing was sticking down about 2 mm and stopping the timing cover sliding out, (photo).

    The solution was first to remove as many of the studs as possible, which wasn't very many even with loctiting the double nuts. Then once I could see what the problem was, a bit of judicial levering of the oil sump casting downwards, (surprisingly flexible really), allowed the cover to slide off.

    I'm also relieved to see that the front inner bearing looks knackered. So all this effort may even be worthwhile. Phew!

    Richard
     
  6. carguy

    carguy F1 Rookie

    Oct 30, 2002
    3,313
    Alabama (was Mich.)
    Full Name:
    Jeff
    Pardon my possible stupidity here...but wouldn't if have been simpler if the cam belts were driven directly off the crankshaft like on my TR? Was there some sort of clearance issue that caused Ferrari to use offset gears? No offense intended, just want to improve my fcar knowledge. Thank You.
     
  7. ham308

    ham308 Formula Junior

    Nov 3, 2003
    358
    NE Switzerland
    Full Name:
    Richard Ham
    Could you drive 4 camshafts off the crankshaft directly? Wouldn't it be one hell of a belt, flapping about....

    Sure would make things easier though.
     
  8. carguy

    carguy F1 Rookie

    Oct 30, 2002
    3,313
    Alabama (was Mich.)
    Full Name:
    Jeff
    The TR crankshaft snout sticks out far enough for two drive sprockets, and two cam belts, one for each head. The drive sprockets are back to back, with the one closest to the engine block driving the cams on the left side, and the one farther out driving the right side cams. I'll try and post a pic...and also my apologies for hijacking this thread a bit.
     
  9. Verell

    Verell F1 Veteran
    Consultant Owner

    May 5, 2001
    6,992
    Groton, MA
    Full Name:
    Verell Boaen
    There are a lot of things about 308s that could have been simpler. A single belt system like the 348 & most DOHC V6s now use for example is certainly a lot simpler.

    We actually have essentially no direct info into the 308 design team's decision making process. So here's my $0.02 on this question for whatever it's worth:

    A dual belt system driven directly off of the crank would have made the overall engine (ie: the crankshaft, & one bank of cams) about 50-60 mm longer. It would have also required offsetting the alternator,water pump, & A/C mounts a similar distance to the right end of the engine to allow their drive belts to clear. Thus the frame and possibly the entire rear body would have had to be wider to allow clearance & service access.

    Ham,
    The oil pump housing hangup is a problem that hasn't been reported before!

    BTW, one of the sump-timing cover studs goes all the way into a pressurised oil passageway in the timing cover. There's a tapered o-ring groove milled around the hole.

    It's very hard to get the o-ring to stay in place throughout the re-assembly process, particularly while re-installing the stud. If, after reassembly & starting the engine, oil starts oozing out around the stud, remove the stud, degrease the hole & stud w/brake cleaner, then liberally coat the stud's threads with RTV & screw the stud back into place. The RTV will be forced into the o-ring groove by & around the stud by the threads in the timing cover. This usually takes care of the leak.
     

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