[me_sid]

Diagnosis over, issue is with the engine and that too mechanical. I just came back from the A.S.S. Will update with pics, once I complete some official calls. Please bear with me.

[idea]

Engine Mechanical Failure @11000 Km. Disheartening. Awaiting further details for complete understanding.

[hajaar]

Let's not be too hard on M&M. My ford fiesta (Jan 2006 model) had its engine replaced within 10 days, had its serpentine belt cut within the first 30 days of purchase. The A/c stopped working within 6 months and the dashboard electronics failed after 3 years of driving.

[shivshanker]

Originally Posted by me_sid

Diagnosis over, issue is with the engine and that too mechanical. I just came back from the A.S.S. Will update with pics, once I complete some official calls. Please bear with me.

I remember reading something similar on TBHP wherein the pistons were melted, think it was a Scorpio or a Bolero not sure.

Question for the learned, would an unintentional petrol mix cause this kind of a problem.?

The reason I ask this is I too have the Baleno which is petrol and my Navara which is a diesel truck, there have been plenty of instances wherein I have lifted the wrong handle at the petrol pump only to realize my mistake in time.

Regards,

Shenoy

[roy_libran]

Originally Posted by me_sid

discussion with Dr. S. Sengupta ( SS Traveler). And till now his logic sounds good, according to him this can happen most probably due to sump pump failure.

Conjecture - Bad metallurgy and/or misalignment during assembly?

[debuda]

Originally Posted by me_sid

Ok coming back, the fault has been diagnosed. The hydraulic clamps that pushes down the valves when the grooves of the crank rotates, has broken. For 8 valves there are 16 of these clamps, out of which 3 has broken. And because of this there's abrasion on the grooves.

To the best of my knowledge, the XUV engine has 16 valves, i.e., 4 valves per cylinder. These 16 valves are actuated by two overhead camshafts. These two camshafts are driven by the crankshaft through a chain drive.

I'm not able to understand what you meant by 'hydraulic clamps'. AFAIK, no hydraulics are involved in the valve actuation. The cams force the valves open or shut purely mechanically.

Every valve is spring-loaded and the natural position of each valve is closed. Only when the valve stem is pushed down against the spring force, it opens. The spring is attached to every valve stem with the help of a retaining collar and this collar is locked in place by a pair of collets or locks.



Is it the case that some of these collets have given way? If that happens, then the affected valve will lose its spring force and will fall into the cylinder by gravity. It is then likely to foul with the piston and get damaged.

[me_sid]

I guess this is the collet. And then if you can see the grooves debuda, in the picture you can find, the abrasion on them caused by the rotating crank shaft. I am sure that's the terminology they have used "Hydraulic Clamps".

[me_sid]

Now that the total engine has been dismantled, what Shamindra da (SS Traveler) has said is becoming a reality. The oil pump seems to be faulty, I will update with details in the evening once I return from the A.S.S.

[SS-Traveller]

Originally Posted by debuda

To the best of my knowledge, the XUV engine has 16 valves, i.e., 4 valves per cylinder. These 16 valves are actuated by two overhead camshafts. These two camshafts are driven by the crankshaft through a chain drive.

True. One cam operates the inlet valves, the other operates the exhaust valves.

Originally Posted by debuda

I'm not able to understand what you meant by 'hydraulic clamps'. AFAIK, no hydraulics are involved in the valve actuation. The cams force the valves open or shut purely mechanically.
Is it the case that some of these collets have given way? If that happens, then the affected valve will lose its spring force and will fall into the cylinder by gravity. It is then likely to foul with the piston and get damaged.

Here goes a zoomed-in view of me_sid's XUV cylinder head, and a quick lesson

The yellow rectangles demarcate the 'slots' where the camshafts fit in, and are held in place with a clamp over the camshaft, running on journal bearings - which look something like this...

Look at how the 'slots' on the left have been severely damaged.

Now notice the little holes circled in red, inside the slots - these supply oil to lubricate the rotating camshafts and their bearings, maintaining a thin film of oil between the moving parts. That's why they are called 'hydraulic clamps' by M&M. At some point, the oil did not come through those holes and the surfaces ran dry, causing that kind of damage.

The circles in green are the ends of the valve stems, against which a metallic finger pushes - in an arrangement that is similar to this diagram below...

The circles in blue in the first pic are where the other ends of the fingers fit in, and there is a pressurized oil supply coming up through the little hole inside - this eliminates the requirement of clearance adjustments and 'tappet noise', since these are hydraulically self-adjusting fingers.

Originally Posted by me_sid

The oil pump seems to be faulty...

Once the oil pump fails (even partially) and cannot generate adequate pressure to lift oil to the top of the head, this is what is expected to happen. Presumably, oil pump failure will also mean damage to other parts of the engine, including pistons, cylinders, crankshaft, turbo and myriad other components that need oil to work fine.

It would therefore make a whole lot of sense for M&M to replace the complete engine for me_sid.

Hope this explains things in a simple manner.

[smarth.katyal]

Originally Posted by SS-Traveller

Once the oil pump fails (even partially) and cannot generate adequate pressure to lift oil to the top of the head, this is what is expected to happen. Presumably, oil pump failure will also mean damage to other parts of the engine, including pistons, cylinders, crankshaft, turbo and myriad other components that need oil to work fine.

It would therefore make a whole lot of sense for M&M to replace the complete engine for me_sid.

Hope this explains things in a simple manner.

Another explanation that came to my mind when you said the pump could not pump enough oil to circulate through the entire engine is clearances. I have seen this on some video on youtube where the pump and oil level and everything was proper but clearances were out. What i mean is, even if one of the hole gets bigger in dimension(radius increases), more oil will come out through it, and thus pressure through other holes will drop. This phenomenon is quite popular in old cars that have done quite a lot of mile munching,upwards to the tone of 200k. But it may also point out to machining problems in the engine casing itself. What i mean to say is, if this is the case, even replacing the oil pump wont help. One would have to inspect which of the hole is out of spec and then adjust accordingly. Just my two cents.

[dean5545]

Originally Posted by smarth.katyal

Another explanation that came to my mind when you said the pump could not pump enough oil to circulate through the entire engine is clearances. I have seen this on some video on Youtube where the pump and oil level and everything was proper but clearances were out. What i mean is, even if one of the hole gets bigger in dimension(radius increases), more oil will come out through it, and thus pressure through other holes will drop. This phenomenon is quite popular in old cars that have done quite a lot of mile munching,upwards to the tone of 200k. But it may also point out to machining problems in the engine casing itself. What i mean to say is, if this is the case, even replacing the oil pump wont help. One would have to inspect which of the hole is out of spec and then adjust accordingly. Just my two cents.

They are trying to get the entire engine replaced so it eleminates this problem.

[scopriobharath]

Has Mahindra offered to replace the engine?

if the head has been opened at 11,000 kms, it is definetly not a good sign. Dust is known to get in even in Engine workshops in countries like UK.

Here, i notice engine is being worked upon in the open.

Get additional 1 year warranty from Mahindra or an engine replacement.

[abirnale]

While we already have found answers for why, what and how, the question remaining is when?
And I hope you aren't going to pay anything out of your pocket for this open heart surgery?
Has M&M offered you a replacement vehicle meanwhile?
Is the issue being managed only at dealer service level by regional engineers or any top-ups are involved?
So far looking at your responses and experience, it seems like M&M has handled the whole episode very well. The real testimony to the manufacturer and dealer is when they deliver on your expectations and create the wow experience!

[debuda]

Originally Posted by SS-Traveller

The circles in blue in the first pic are where the other ends of the fingers fit in, and there is a pressurized oil supply coming up through the little hole inside - this eliminates the requirement of clearance adjustments and 'tappet noise', since these are hydraulically self-adjusting fingers.

Once the oil pump fails (even partially) and cannot generate adequate pressure to lift oil to the top of the head, this is what is expected to happen. Presumably, oil pump failure will also mean damage to other parts of the engine, including pistons, cylinders, crankshaft, turbo and myriad other components that need oil to work fine.

SS-Traveller – thanks for the information regarding hydraulic tappets. It’s good to know that the XUV engine uses hydraulic tappets (also known as lash adjusters or hydraulic valve lifters) which help to maintain almost zero tappet clearance (making the engine more quiet) regardless of engine temperature and wear. Also, it obviates the need for periodic tappet clearance adjustments.

Anyway, as far as me_sid’s XUV is concerned, the main suspect seems to be lubrication failure. If that is indeed the case, the following tell-tale signs should have been expected :

1. Low oil pressure warning lamp should have come on.
2. In all probability, there should be a DTC code for low oil pressure. If so, the ECU should have registered that DTC code. I’d advise me_sid to check from the A.S.S. whether they found any such DTC code after connecting the OBD / laptop (usually, the OBD is capable of showing not only the current DTC codes but also historic ones).

Engine lubrication failures are usually quite catastrophic in that widespread damage takes place if the engine is operated for some time after oil failure. It appears that in this case the first failures took place in the valve actuating mechanism leading to some valves getting stuck in the open position. That, in turn, led to loss of compression in two cylinders and the engine stopped (and could not be restarted) preventing further damage.

I find it rather ironic that me_sid has been changing his engine oil at a much higher (5 times!) frequency than recommended by the manufacturer and still his engine fails due to (apparently) an oil related issue.

Lastly, if there is no recorded DTC regarding low oil pressure and all other parts of the engine are found to be in pristine condition, it may be concluded that total lubrication failure is not the culprit. In that case, either a localized lubrication failure or material failure due to faulty assembly or defective parts could be suspected.

This is the first reported (at least on TBHP) incident of engine failure in a XUV, that too in a relatively new and sparingly used car, and needs to be followed up to its logical conclusion. In any case, complete replacement of the entire engine assembly under warranty should be insisted upon.

[interc00led]

To me it looks like this is not an oil pump related failure but something else.

The damage is visible only on the intake side.
Intake HLA and intake cam bearing surface is damaged.

Check the intake side oil gallery for any kind of blockage. Break open the casing of oil filter and look for any metal debris in there, it can tell a lot of things.

If any metal particles are found in the filter then remove the oil pump and check for any damage caused by foreign particles.
Same with the crank journal bearings.

IMHO, it is better to replace the entire engine rather than repairing it.