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Thread: Tdi 300 rough when cold but seems to improve after running for a while?

  1. 16th January 2021, 03:26 PM #1
    zwitter
    zwitter is offline Master Subscriber
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    Tdi 300 rough when cold but seems to improve after running for a while?

    Howdy learned partners.

    Well I have a 1996 Defender 130 with the 300Tdi lump. Done 330,000km odd. It gets regular oil and filter changes etc but not much more except when things break.

    Anyway for quite some time it has seemed to be running a little rough when cold but it seems to improve when hot. It always starts first go, even if I don't wait for the glow plugs. It blows the smoke when starting like most do.

    So my concern is is this potentially going to get worse!

    My thoughts are tapet/ rocker gap out of spec? Or an injector not firing right? or worse a burnt valve?
    I plan to check the rockers, maybe even tomorrow.
    I have in the past cracked the pipe to each injector and listen for te drop in revs and they all seem to have same impact.
    I have been told to fiddle with the injector pipes so one injector is pointing skywards and then crank engine and see what the pattern looks like? But that sounds very messy and probably not really going to tell me much?

    So any ideas? I do not have oodles of spare cash, having been unemployed through most of the covid period. But I am an engineer and do have good resources to a point.

    Any ideas gentlemen?

    The engine seems to pull ok, should I just turn up the stereo and ignore it?
    thanks
    z
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  2. 17th January 2021, 04:41 AM #2
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    rick130
    rick130 is offline Moderator Gold Subscriber
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    Rocker clearance is critical on a Tdi, blown out clearance usually shows as performance down across the rev rang though.
    Valve lash caps have a habit of brinelling/cracking/disintegrating.
    Aftermarket Chev 8mm ones are the go, genuine prematurely fail. I think I used Manley lash caps the last time I replaced a set on a new head about six years ago?
    Start there, rocker clearance should be checked at almost every oil change, it is that critical.

    I'd be thinking the rough running is more an injector or compression issue.
    Possibly a dirty/fouled injector with a poor spray pattern.
    The initial crack pressure can be tested on your existing ones, or if original just get a new set of injectors after checking compression and leak down.
    Actually, you could try a fuel cleaner.
    BP's DieselGo is effective but hard on the oil, I'd do an oil change after running a dose through the tank.
    Redline RL2 used to be my go to, it was the kindest on oil, lubricated the pump and injectors and very effective at keeping things clean but not sure on availability these days
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  3. 17th January 2021, 05:47 PM #3
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    roverrescue
    roverrescue is offline YarnMaster Supporter
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    Lumpy when cold idle
    Is there a tinkle (not lumpy) when hot

    My gut says lash caps / clearances


    A good mechanic like JC can measure the lash clearances BY EAR at idle from about 100m away on a tdi

    It is that obvious

    Heck post a video on here and see what we come up with

    My other go too would be slightly retarded timing from belt stretch (when was last t-belt change) or poor fitment

    Always time a tdi via plunger lift at the back of the pump as opposed to poking a drill bit into the front of the pump 🤦*♂️

    I ran tdi for I think about 750kkm
    I had injectors cleaned once and put brand newbies in also - they don’t seem to be like a tojo which Shag out tips and “new injectors” fixes a number of woes

    Get the mechanicals running in spec before changing parts

    Steve
    '95 130 dual cab fender (gone to a better universe)
    '10 130 dual cab fender (getting to know it's neurons)
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