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Engine Rattle On Cold Start Up

Discussion in 'TD5' started by Fresh Cod, Jan 4, 2012.

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  1. Fresh Cod

    Fresh Cod New Member

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    Hi Guys,

    I have noticed there is a rattle from the front of my Defender '99 TD5 engine on cold start, it sounds like it’s the timing chain, as if it does not have enough tension, after a few seconds it runs fine. It’s a metallic rattling sound coming from the top front of the engine. When it starts from warm it is fine.

    I will check for oil in the ECU tonight but I doubt that is the issue. Do the timing chains ever need to have work done on them or could it be something else? One other thing is, I don't have the engine cover on so there is a slim possibility the engine does this anyway and I haven't heard it before, although it does not sound healthy.

    Any help at all is appreciated, great site with lots of great help, keep up the good work lads!
     
  2. sierrafery

    sierrafery Well-Known Member

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    It might be a play in one of the pulleys/tensioner which centers itself while engine is running... it's not very common but after 200.000. even the timing chain could worn out ...depends on how the car was maintained and driven...the A/C clutch used to makes tricks too. Take off the auxiliary belt and start it so... if the sound will be there aswell then its something within the engine
     
  3. Fresh Cod

    Fresh Cod New Member

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    Thanks for the reply. I will give that a try over the weekend. Is there any way of working on the timing chain without taking the head off? I have been looking around the internet for similar problems but can't seem to find anything. Anybody know of a link?

    Cheers,

    Cod.
     
  4. CharlesY

    CharlesY Well-Known Member

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    Very possibly it's a noisy hydraulic cam follower aka tappet.

    Get a probe stethoscope and listen at the engine lid.

    If the engine runs quietly after a little while it will be fine.

    For Heaven's sake don't dive into the guts of the engine till you are pretty sure you KNOW what's up!
     
    Last edited: Jan 9, 2012
  5. CharlesY

    CharlesY Well-Known Member

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    Remember, the TD5 engines have 5 cylinders but only 4 glow plugs.
    Don't even THINK about asking why!

    When the engine is started from cold, the FOUR glow plugs heat up, and the front FOUR injectors are triggered to fire in fuel. The number 5 injector doesn't become operative until the engine speed is high enough to make sure it fires number 5 even without a glow plug.

    I think this is to avoid sending unburned fuel vapour down the exhaust and into a catalytic converter.

    Anyway, while it is on 4 cylinders it might sound a bit rough.

    I still think a cam follower would be my number one suspect.
     
  6. Fresh Cod

    Fresh Cod New Member

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    Thanks for your reply CharlesY. It lasts about 30 seconds to a minute but it sounds like something is slapping off something else. If it is a tappet will it be fine to leave it alone?

    I have noticed there is a hissing noise coming from the fuel pressure regulator when the fuel pump is priming on start up, but no leaks I can see. So I purged the system of air (key in second position and press accelerator 5 times) and the noise in the engine didn’t happen, started it again the next day from cold without the purge, FPR hissed and the engine made the rattle, so the following day I purged it again before starting from cold, FPR hissed and engine didn’t make the noise.

    Just coincidence?

    I'm going to order new O-rings and gasket anyway and put them into the FPR.

    Thanks for the help, much appreciated!
     
  7. sierrafery

    sierrafery Well-Known Member

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    The FPR if there is any problem with it will leak fuel... dont disturb a dry FPR ... 90% of cases the o-ring kit is not a cure anyway.
     
  8. CharlesY

    CharlesY Well-Known Member

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    Right .... the tappets are filled with oil, and they are designed to "leak down" very slowly. They should fill back up very quickly, possibly before the driver hears the rattle. They may fill up while the starter motor is churning away. There is effectively ZERO valve clearance when all is well, so quiet running.

    Now then, when an inlet or exhaust valve is SHUT there is no pressure from the CAM trying to squash the follower. The system for that one valve is relaxed, and the follower is fully extended, and held that way by a little spring inside it.

    But, when a valve is OPEN, the valve spring is pressing hard on the cam follower trying to close it in.
    So the oil gets slowly squished out. Now the follower is SHORTER, and there is a hefty amount of "valve clearance" and that is what causes the slapping noise when you start the engine up

    So . . . it depends on where in rotation the engine STOPS, which valves will be "ON CAM" and being held open.

    A 4 cylinder engine always stops in one of TWO positions 180° apart. That is why starter ring gears got such a hammering in the days of inertia starters.
    In those, it is sometimes possible to guess which follower needs to be replaced.

    But a FIVE cylinder engine can stop just about anywhere, 5 places only 72½° spaced. This means that just about any valve might be "on cam" when the engine stops - it's a random chance, and it WILL be several valves.

    That may be why you hear it sometimes, and not others.


    I agree with the suggestion from Sierrafery it is probably not a fuel pressure regulator issue. Take care, and as long as the engine runs quietly after a few seconds, I feel confident there isn't an immediate problem.

    There may be a follower on the way out,
    so keep that idea in mind.

    When that happpens the rattle won't stop.


    OK?

    (sorry about bold - it made the reply clearer)
     
    Last edited: Jan 10, 2012
  9. Fresh Cod

    Fresh Cod New Member

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    Thanks Sierrafery and a big thanks to you CharlesY for taking the time to write a great reply, I would happily buy you a pint or two if you lived nearby!

    So basically don't worry about it, its normal for the oil to drain from the tappets when parked and cause it to make a rattle sound for a few seconds on start up. (Have you guessed it’s my first Defender yet:)

    I replaced the engine a few weeks ago, among other things, and I'm probably getting a bit excited over every single noise :doh:

    I'm planning on giving her a full service top to bottom in a few weeks, would it be wise to take the rocker cover off and see if the locknuts are tight and the tappets correctly gapped?

    Thanks again, great forum!
     
  10. sierrafery

    sierrafery Well-Known Member

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    That wont hurt...and as u are already there u could insure yourself for the next few years and put a new injector loom
     
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