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Compression testing questions....


Outrage

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Hey all,

Glutton for punishment, I've purchassed another Land Rover, SIII 2.25D (to supplement my offroad craving whilst i finish my LTWT). Problem is that its failed on its emmissions and smokes like a gud un(Only paid £30 so not surprised). Been told that the best way forwards is:

Compression test

Change the fuel

Overhaul the injectors

recondition injector pump.

Where's the best place to get a compression test gauge? Once I've got one how do I use it and how do I interpret the results?

Ideally i'd just take it to Surestart and have them do the lot but with no tax, test and MOT I can't get it there, plus the clutch is also on it's way out but I don't want to change that till I know if the engine is repairable.

Any help would be appreciated!

Cheers,

Lee

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You can drive it to a place for pre-arranged repairs.

If you get a compression tester make sure it is suitable for diesels, they operate at a higher pressure than petrol engines.

The procedure I use (for my petrol engine) is

1) run engine upto operating temp

2) remove all plugs

3) insert gauge in cyl No1

4) crank engine on starter until max pressure indicated

5) write down max pressure

6) repeat for all cylinders

7) repeat again, this time with a bit of redex in each cylinder.

All readings should all be fairly close, if one cylinder is down it could be head gasket, rings or valves, but if it is up with the Redex in it will be valves.

If the pressure is down with and without Redex it is gasket, valves or a holed piston.

If the two middle pistons are down it will be the gasket between the two pots.

If the readings in each set are consistent abut differ between Redex and no Redex this indicates general engine wear.

Sprinkle the above with a liberal dose of "could be", "possibly" and "most likely"

Don't know if it would be OK to do this modern engines with a catalyst though.

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You can drive it to a place for pre-arranged repairs.

If you get a compression tester make sure it is suitable for diesels, they operate at a higher pressure than petrol engines.

The procedure I use (for my petrol engine) is

1) run engine upto operating temp

2) remove all plugs

3) insert gauge in cyl No1

4) crank engine on starter until max pressure indicated

5) write down max pressure

6) repeat for all cylinders

7) repeat again, this time with a bit of redex in each cylinder.

All readings should all be fairly close, if one cylinder is down it could be head gasket, rings or valves, but if it is up with the Redex in it will be valves.

If the pressure is down with and without Redex it is gasket, valves or a holed piston.

If the two middle pistons are down it will be the gasket between the two pots.

If the readings in each set are consistent abut differ between Redex and no Redex this indicates general engine wear.

Sprinkle the above with a liberal dose of "could be", "possibly" and "most likely"

Don't know if it would be OK to do this modern engines with a catalyst though.

Hi Roger,

Thanks for the reply it all sounds 'fairly' straight forward.

I didn't know you could drive with no tax or MOT for general repairs, assumed it was only if you are heading for an MOT?

Cheers,

Lee

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To quote my brand new failure notice :(

....comitting an offence ......except when

* Taking to a test station.....test booked in advance

* Bringing it away.....to a place of repair

* Taking it to or bringing it away from a place where by PREVIOUS ARRANGEMENT repairs are to be, or have been, made to remedy the defects for which the vehicle was failed.

It doesn't say how many times you can make the trip, if you have a mate who does repairs and you do your own repairs I suppose you could drive it between the two ad-infinitum.

You must have insurance though.

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Don't try the Redex or oil trick with a tdi. The fluid will just fill the combustion chamber in the top of the piston and you may hydraulic the engine and bend the con-rods. This is easy to do with these engines. At least it doesn't break the crankshaft.

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