300tdi misfire and smoke

[ScottW]

My father's disco (which he only got on wednesday) started playing up this morning. He'd been out for a drive and just went to leave again only to find the engine was running on 3 cylinders. Accompanied by lots of smoke (white blueish I think). The car had a new head put on it a few weeks ago.

What would be the plan of attack for diagnosis? Petrol engines we understand, but we are still learning with the diesels.

[roverrescue]

To run a mechanically injected dieso (300tdi) needs clear air to the manifold and clear fuel to the injectors.

-check air filter plus that there is no obstruction, delaminated, damaged inlet tract pipes and hoses.
-check fuel filter +/- replace - and check getting clear fuel to the pump and then injectors.
-if the above checks out and the head was done recently, they may also have done the timing belt at the same time, if the belt was poorly adjusted and slipped its timing a 300tdi will run like a rough dog when only a little out SOOOO check the injection pump timing at TDC.

My gut feeling with only limited info is number 1 - its not breathing - but either way it shouldnt be too hard to trouble shoot if it was running but now isnt.

Steve

[ScottW]

The hose between the airfilter and turbo had come off, but that shouldn't affect anything. We put that back on, and checked the pipe coming out of the turbo. It was clean enough (no oil) so no problems there. We just fired it up and it idles a bit rough, and is still on 3 cylinders. The smoke coming out is a grey brown colour. Not blue or white. I was hoping it wasn't the head or gasket.

He did fill it up from a freedom servo yesterday, which according to a web search use imported fuel with up to 20% bio-diesel, which apparently will 'clean' the fuel system. Would the 40km trip home, sitting overnight, along with a short drive this morning have possibly dislodged enough crap in the system to block stuff?

[davrac]

If you have an engine miss on a diesel you need to figure out what cylinder is missing. Easiest was to determine this is to have the engine running and crack off each injector line one at a time.

This will allow you to identify which cylinder os missing as well as check that each injector is getting an injection pulse from the injection pump.

Has the coolant level changed? (after the head gasket was done)

Does the engine have a loud ticking? could it be a loose rocker arm not opening a valve if it is ticking?

Whitish blueish smoke would indicate unburnt diesel or burning oil. Probably unburnt diesel if has a miss as lack of compression on one cylinder will not be igniting the diesel fully thus the whitish blueish smoke.

First thing is to establish which cylinder is missing as I said at the beginning.

And yes it might be worth checking the pump timing and other basics as well. But it it very easy to just crack the injectors to see if the miss is specifically on one particular cylinder

Hope this helps:)

Dave

[ScottW]

We have established the problem. The third rocker from the front doesn't move when you kick the engine over. (Fuel off of course) We pulled the rocker gear and the pushrod is straight. Is it possible for a lifter to collapse? We put the rocker geat back on and it seemed to be where it should, but after kicking the engine over a little, it's back to where it was. No.3 rocker clearance is 15mm :(

Removing the rocker gear again and re-fitting the pushrod, everything seems to be working. We will adjust the rocker clearance before we fire the engine up so that it doesn't have the chance to pop out again.

We live on a big hill and dad was towing a small trailer this morning, so it may have popped the pushrod just before he got home.

edit:
Looking at this page :
300tdi cam assembly (http://forums.lr4x4.com/index.php'showtopic=24695)

we can't see how the end could pop out of place and slip down the side of the lifter.