1600 rebuild.

Discussion in 'Mech Tech' started by ginger ninja, Jul 4, 2019.

  1. Just took this one apart on a friend's t2. It had overheated and we found out why this cylinder was low on compression! Is it ok to just change the culprit piston and barrel plus the head on this side? Or do u have to change all for balance, even power or what have u. Hoping it's the former due to cost! Also where is a reputable but value for money place to get the parts from? Also is there a special tool to get the circlip out on the piston? Over heating was probably thermostat/thermostat flaps but well look at that later. Cheers in advance folks. [​IMG][​IMG][​IMG][​IMG][​IMG][​IMG]

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  2. It’s going to need a full rebuild I’m afraid
    All those little bits of metal will have traveled round the engine with the oil and damaged the bearings etc.
    ginger ninja likes this.
  3. Looking at the head you'd be as well to strip the bottom end as there's been loose metal action ...
    Personally I'd check the valves / seats and reuse the head if the budgets' tight ??

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  4. As said above...I would be stripping that down because the piston has been dragging bits of the piston and barrel into the case and oil.
    A bet would be if you could just get 1 piston and barrel (they are sold in sets) it wouldn't be long before it fails again due to debris in the oil knackering the bottom end bearings.
    Strip it, clean it and check everything. New bearings and piston if your lucky
    Sorry to burst your bubble....
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  5. Thanks everyone. No bubble burst. Was half expecting this tbh. It does look as though the piston disintegrated and hit the head. And I’m asking this as a novice not to be difficult but the barrel and piston look a very tight fit for obvious reasons. So how would any metal debris get past and into the crank case? It does look as though the damage was in the head and valve area, wouldn’t it be restricted to this area?


  6. Yes you have damage to the head...bits of metal smacked between piston and head.
    You also have damage to the piston wall, scuffing the barrel and the oil control ring has plenty of bits in it..... the bottom one.
    This will of been dragging bits into the oil in the crankcase.
    ginger ninja and Lasty like this.
  7. The filings work past the piston on the up stroke and as the oil splashes the barrel it'll collect the debris on the way down .
    It would run with just a single barrel / piston replaced and the head sorted but probably not for long .
    Doesn't take much to wreck the main bearings ...

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  8. Thanks chaps. You lot are amazing. I better tell him the not so good news. Is a new engine using this one as an exchange the most cost effective route now do you think? Is it worth stripping and inspecting first? If new engine route where from do you reckon?

  9. You're getting quite in to this spanning lark :thumbsup: 20190428_123135.jpg
    ginger ninja likes this.
  10. It’s all a facade Iain!
    Thanks for the pickiest mate. I’d do anything rather than mark my books!

    Iain McAvoy likes this.
  11. That's the $100 question.....
    It depends on how much work you want to do and money you want to spend doing it for yourselves or money you want to spend buying a longblock engine and fitting the bits off your old engine onto it.
    If time is not important I would do it myself,,,but that's me
  12. There is less metal in the space above the piston than is missing from the piston. Some will have been spat out the exhaust.
    But the piston partly melted so the metal will have cooled off on the cylinder wall where it was sprayed from under the piston rings then scraped by the oil control ring ( the crud on the oil rings will be aluminium and carbon) and then washed into the engine as a fine metallic sheen in the oil.

    Meanwhile, oil found its way the other way.

    This crud will need to be flushed out , ideally one would unplug and clean out the oilways and then refit new tapped plugs to the oilways.
    However , my previous engine lasted 28988 miles after only spending a couple of hours back flushing the oil ways on a commercial parts washer with a nozzle attachment.

    It really is the fact that the engine was so abused to reach that condition that there will likely be heat related damage in the bearings too.

    The cylinder heads are probably OK.
    It will be easier to source and replace the whole set of pistons and cylinders.

    You are at a point where you might as well pause and make the engine as good as possible, check all the bearings and dowel pins while you have it apart and decide if it looks like it needs line boring and new bearings etc.

    And dont forget to find the fault that caused the piston to melt in the first place - ignition timing, points gap closing up, air leak or blocked carburettor jet, or a heavy boot on the pedal...
    Lasty and ginger ninja like this.
  13. Depends how much you want to get into it.

    You could just change the piston/barrel and flush the oil out and it might go on for years or it will give up in a few trips.

    My mate has a engine with over 2mm end float and he has been driving it like this for years no problem. He’s taking the view it’s knackered so might as well drive it until it gives up.
  14. Thanks very much. Very useful indeed.
    I’ll let you know how it progresses.


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