Engine rebuild help!

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DISCO2OWNER

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Good Morning Landy Owners!

I have recently rebuilt my TD5 engine by installing a new short block and refurbishing the head, all ancillarys had to be swapped from the old block to the new one and the head was skimmed which I also put new valves put in. Now its all back together but it is experiencing a loud knocking noise which sounds like its coming from the cam cover but you probably know it isn’t easy to determine a noise from an engine especially a TD5. Any ideas of why it is doing this???
The block was brand new by a very reputable company and has a warranty so i believe that could be ruled out but why is it doing this??

To give you my background I work on classic cars for a living so I have a broad background of knowledge (i have also done engine rebuilds before) but this is my first major job on my Land Rover, I take care of all my maintenance and repairs on my disco (all the common problems too hit everyone of them!) and have never had any problems although I knew this would not be easy!

Any ideas or anything I can look at???

Regards

Thomas
 
I worry about him saying the head was skimmed ..... which is a dodgy thing to do in a TD5 because of interference problems between valves and pistons.

It might just be the compression ratio is too high now.

But it sounds more like pistons and valves connecting, OR one or more injectors bottoming-out.

CharlesY
 
Have all the injectors gone back into the original cylinders they came out from ? Each injector is coded to its specific cylinder & can only be changed with diagnostic equipment .
 
Fitting the injectors in different holes wont cause mechanical knocking.

Skimming the head also wont affect compression ratio as the TD5 head is flat bottomed without chambers. If the head was skimmed and the valve seats recut it should be OK.

If the valve seats were not done then there could be valve/piston interference.

If it was valve interference caused by setting the timing chain wrongly the engine would not run or it would have destroyed the new head in short order. Only way to tell is to take the head off again and have a look.

If the engine runs my guess is that the injectors are not adjusted properly and are bottoming out.
 
Fitting the injectors in different holes wont cause mechanical knocking.


IT MIGHT !!!!

Skimming the head also wont affect compression ratio as the TD5 head is flat bottomed without chambers. If the head was skimmed and the valve seats recut it should be OK.

If the valve seats were not done then there could be valve/piston interference.

If it was valve interference caused by setting the timing chain wrongly the engine would not run or it would have destroyed the new head in short order. Only way to tell is to take the head off again and have a look.

If the engine runs my guess is that the injectors are not adjusted properly and are bottoming out.


Depending how long the engine has been running since the rebuild, could it be a hydraulic cam-follower not filled up yet? These "MUST" be stored the right way up when they are out of the engine to help ensure this problem doesn't happen.
 
Depending how long the engine has been running since the rebuild, could it be a hydraulic cam-follower not filled up yet? These "MUST" be stored the right way up when they are out of the engine to help ensure this problem doesn't happen.
Could be but they should fill up very quickly as they run at full oil pump pressure. I would have expected them to stop tapping within a few seconds of start up unless they are damaged of full of dirt.
 
Could be but they should fill up very quickly as they run at full oil pump pressure. I would have expected them to stop tapping within a few seconds of start up unless they are damaged of full of dirt.





It could take up to TWENTY MINUTES to fill some hydraulic cam followers.

Five MINUTES would not be unusual.

In some designs, if a follower was stored incorrectly and became drained, it may be DESTROYED on start-up due to a lack of oil inside to "cushion" the blow from the cam.

But you will know best I expect.

The fact is that it is making a bad noise and you don't know why.

CharlesY
 
Got out of bed the wrong side CharlesY? The real fact is I know as much about why his engine taps as you do without seeing it up close.

OK so what happens when you fit new ones? They dont come pre-filled or the right way up in the box. When they dont have any oil in there is no "impact" as they effectively dont open the valve fully or in some cases at all. The oil is not to cushion anything - it dont compress and it would play havoc with the valve timing. It would be like using rubber shims in an engine without hydraulic followers. When they run properly there is absolutely no play between the cam lobe and the valve as the aduster takes out any play. How can I put this?

HYDRAULIC LASH ADJUSTERS DONT RUN WITH CLEARANCE !
 
If hydraulic followers/lifters stuck, then should easily be able to hear a regular missing/popping noise quite clearly at end of exhaust pipe.


I didn't say STUCK, I said NOT FILLED WITH OIL which is quite a different thing.

I am not sure if you understand how a hydraulic cam-follower works, but I am sure you will tell me you do.
 
Got out of bed the wrong side CharlesY?

Not me. I am the epitome of patience ...



How can I put this?

HYDRAULIC LASH ADJUSTERS DONT RUN WITH CLEARANCE !


Oh yes they do. If there was no clearance the cam would be running steel to steel on the follower, and neither would last five minutes like that.

They are designed to fill with oil and take up the slack gently, but not so hard as to force away the oil film between the rubbing parts.

The clearance isn't much, but it is always there, and every time the cam hits the follower it re-sets itself just that tiny bit if all goes well.

But FIRST, the follower must fill with engine oil.

If it does not fill, or if its inner valves fail and leak, there will be a HUGE gap between cam and follower and a VERY nasty ticking noise, which is what is being complained about.

I may not be right in this case, but what is written is what can happen.
 
they are only a simple piston with small filler hole if empty of oil you will get tapping but shouldnt hurt them ,oil pressure trys to overfill them but spring pressure with engine speed forces stops them overfilling and opening valve ,this keeps valve clearance to zero without the need of a gap of convention set up were gap is needed to make sure valve is never partially held open
 
they are only a simple piston with small filler hole if empty of oil you will get tapping but shouldnt hurt them ,oil pressure trys to overfill them but spring pressure with engine speed forces stops them overfilling and opening valve ,this keeps valve clearance to zero without the need of a gap of convention set up were gap is needed to make sure valve is never partially held open

Oh Dear JamesMartin .... you just don't see how complex a hydraulic cam follower is, nor do you see WHY they have to be like that.

Let's leave it now. There is no point in going on.
 
I didn't say STUCK, I said NOT FILLED WITH OIL which is quite a different thing.

I am not sure if you understand how a hydraulic cam-follower works, but I am sure you will tell me you do.

Charlesy, go blow it out you arse, last time I give you as much as the time of day you arrogant prick, don't mean you gotta take it out on those willing to offer assistance. go ---- yourself.:mad:
 
Oh yes they do. If there was no clearance the cam would be running steel to steel on the follower, and neither would last five minutes like that.

/
Thats why most followers have hardened rollers or balls as the cam lobe bearing/wearing surface. From memory the TD5 uses ball ended followers. I'll have a poke through my spares and see if I can confirm that.

I'll concede that there is normally a minute film of oil between the two which varies in thickness as the oil gets hotter (or your oil gets tired cos its not been changed for 20k miles) and can be displaced quicker. As already said a knackered follower would make a ticking sound.

An old bush remedy for curing a sticking follower was to drain the engine oil, fill with ATF, then run the engine at idle for a few minutes. Drain again and refill with engine oil and if you were lucky it would have flushed the problem follower clear. DONT GO FOR A THRASH DOWN THE MOTORWAY WITH ATF IN YOUR ENGINE though! Just let it idle for a few minutes. As with all things you do this at your risk but it has worked for me several times. Never tried it on a TD5 though.
 
Oh Dear JamesMartin .... you just don't see how complex a hydraulic cam follower is, nor do you see WHY they have to be like that.

Let's leave it now. There is no point in going on.
i think i do ive built enough lr engines i think you dont its not complex at all and thats why they are used as they maintain freeplay free valve opening system ,all metal to metal parts have film of oil thats what pumps does
 
i dont understand the need for clearance for lube film how would this work when opening the valve when follower is forced up , it has no clearance but still has oil film
 
There is no clearance that you can easily measure but the microscopic oil film does not have enough time to completely collapse due to the viscosity of the oil and the duration of the valve opening. The TD5 cam lobes also dip into their own little oil puddles everytime they rotate (you can see the puddles full of oil in the top of the head if you take the cam cover off) which helps lubricate any load bearing surfaces. Oil is also pumped up and through the followers which does the same.

The followers can not adjust to a specific gap as they have no way to measure it. They pump up until they cant any more which takes out any wear on the cam lobes and/or valve stem ends. If you get grit in the followers from dirty oil they can jam in the wrong position in which case you get a tapping sound or excessive wear on the cam lobe and follower bearing surface which are both hardened. The followers are designed to flow a certain amount of oil by way of restrictors which keep them properly adjusted against the cam lobe for each revolution.

The reason you need gaps (adjusted when cold) for shims or tappets is because as the engine warms up any gaps close up and if you did not allow for this you could have valves not fully seating when closed or valves trying to open further than they mechanically can.

Of course after all this balanced and well considered discussion :p we are still no nearer to discovering why the OPs engine is tapping.
 
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