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Thread: Piston glazing and your "modern" diesel

  1. #1
    JamesH Guest

    Piston glazing and your "modern" diesel

    Hi All

    I have a 300tdi and have heard in past years it is bad to let diesels idle, the pistons glaze. Yet Ive also heard that modern diesels and modern fuel makes this pretty much a problem of the past.

    Can you let a 300tdi idle for say 20mins at a camp site to give the battery a charge or something?

    How long would be too long (healthy cooling system assumed)?

    thanks in advance

  2. #2
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    It is actually the bore (cylinder walls) that "Glaze up", in most cases it is caused by the piston rings not making firm enough contact with the bore. Compressed air and fuel go down the piston to the rings and in behind the rings and force them against the bore. So when an engine is idling and not much pressure being produced the rings are not being pushed into the bores as hard and this causes the bore to glaze up. When you run an engine "in" you are told not to hold constant speeds for long periods, as this same effect happens, you should work your engine to get the rings to conform to bore shape and bed in. Also Synthetic oils can cause glazing when running in a new engine, Mineral oil is the go for the first few oil changes. My BA GT ran Synthetic oil from new and was using more oil than it should, FPV engineers recommended Mineral oil and drive it like I'd stolen it, after another 5K it was run in. I have had diesel trucks and I only ever let them idle long enough to cool down and the turbo to spool down and cool, Regards Frank.

  3. #3
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    300tdi's need to be worked on a regular basis

    if you cant haul a heavy trailer every now and then, then use some C.E.M. occasionally...

    works wonders in my experience....
    2007 Discovery 3 SE7 TDV6 2.7
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  4. #4
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    Manufacturers reccommend as little idling as possible.

    It takes 30 secs - 1 min on startup to get full oil pressure to the entire engine. That is the longest you should let it idle when cold.

    Hot idle is best avoided as much as possible. You can "deglaze" an engine by driving it hard, but it is best not to glaze it in the first place.

    If you need to charge a battery - it is better for the engine to go for a short drive - the battery will charge faster too!

  5. #5
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    When I bought my tdi in 98 cylinder glazing was the most complained about problem with them,the reason was that the synthetic oil that was standard back then wouldn't let the rings bed in.My engine was still using oil at 40k so I changed to penrite and haven't looked back.As posted above,wait a minute at start-up but from then on drive or stop.It is a very common problem on engines that are run without load. Pat

  6. #6
    d@rk51d3 Guest
    Yep, give the engine load, not free revving. This helps bed in the rings, and prevent glazing.

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