[vikram_d]

Hey folks

I have a Dzire diesel which has run around 55,000 kms in about 2 - 2.5 years and is under extended warranty. This car is primarily used by our driver for all the household chores like picking & dropping kids, taking madam shopping etc.

The story so far. A few days back my driver got the car home and parked it. When he tried to start the car after about half an hour it just would not start. No warning lights, no nothing. All seemed fine but it wouldn't start.

So called up the MASS folks and they came over and to cut a long story short, the car was towed to their service center. They did all their normal diagnostics and everything came up fine. But the car would still not start.

Then the decision was taken to open up the engine because we had exhausted all other options and also after having a discussion with Maruti engineers. The car has had all its scheduled servicing done at the same MASS where it is now. So service history is not in doubt.

Now my question what can cause such a drastic compression loss on all four cylinders of a completely stock car? The MASS folks have come up with varying theories and I have some of my own

Theories about what might have happened

1. Timing chain could have snapped - a highly unlikely theory keeping in mind it has a timing chain and not a belt. Moreover a timing chain snapping would have led to disastrous sounds in the engine which I am sure my driver would have paid attention to. Moreover, when we opened the engine we found that the timing chain was fine.
2. Magic disappearing pistons - This is one of my silly theories, which again is highly unlikely. . Again all the pistons were found to be perfectly intact and all cylinders were in expected conditions. no scratches no marks, no piston slap, no nothing.
3. Overheating engine - Again unlikely as the ECU would have made the car go into Limp Mode and would have been recorded as a DTC in the ECU.
4. Stuck valves - Again this would not result in a compression reading of zero.
5. Bent valves - This would have also caused a huge racket in the engine. On checking all the valves were perfectly fine.
6. Stuck valve lifters - This one was a theory till we opened the engine and found it to be the culprit. The MJD engine has hydraulic lifters and we found all the 8 exhaust side valves in open position.

Now, my question, what can cause all valves to be stuck open like this? I have never seen nor heard of all valves being stuck open before. We did a complete check of all hydraulic port and lines and found no blockages anywhere. What could have caused all 8 exhaust valves to become stuck like this?

Update: I had forgotten to ask the service engineer if there were any DTC's recorded in the ECU. He has now informed me that there was camshaft position sensor DTC recorded. So they replaced the sensor and even then the engine would not tick over.

[Rudra Sen]

Mods note: Thread moved from Assembly Line to Technical Stuff.

[Rehaan]

Something here doesn't make much sense.

You're telling me they removed the head and ALL 8 exhaust valves were stuck open??

cya
R

[autocrat]

All 8 valves can not remain in open position, either valves or the camshafts must be damaged. Engine was running when your driver parked the car, so obviously it was fine till then, could there be a damage during the first cranking?

[mayankk]

could it be that the timing has gone awry, and the valve open position has become the default, instead of shut?

EDIT:and similar offset for intake and exhaust too as well.

[vikram_d]

Originally Posted by Rehaan

Something here doesn't make much sense.

You're telling me they removed the head and ALL 8 exhaust valves were stuck open??

cya
R

I was not present when they opened the head, but that is what the mechanic told me, also confirmed by the service engineer. But for some reason I find myself doubting this story.

Originally Posted by autocrat

All 8 valves can not remain in open position, either valves or the camshafts must be damaged. Engine was running when your driver parked the car, so obviously it was fine till then, could there be a damage during the first cranking?

All valves and both the camshafts are perfectly fine. I just saw them this morning. Driver says car was perfect till he parked it and being a very old driver I have no reason to doubt him.

Originally Posted by mayankk

could it be that the timing has gone awry, and the valve open position has become the default, instead of shut?

EDIT:and similar offset for intake and exhaust too as well.

There was a camshaft position sensor DTC in the ECU. They replaced the sensor with a sensor from their test drive car and still the car would not start. I will discuss the cam position point with the Maruti engineer. Waiting for them to visit the MASS and give their feedback.

Another theory - What if the pistons rings have gone bad? I know they can't all call it quits at the same time. But assuming the worst case scenario that they did, can the compression on all cylinders drop to zero?

[autocrat]

Originally Posted by vikram_d

All valves and both the camshafts are perfectly fine. I just saw them this morning. Driver says car was perfect till he parked it and being a very old driver I have no reason to doubt him.

In a 4 cylinder 4 stroke engine, there is one cylinder firing every 180 degree rotation of crank. The firing order may be something like 1-3-4-2.

Ideally, the valves must completely close just before the piston reaches the top dead centre in the cylinder, and then the diesel:air mixture will ignite, the piston is pushed down to BDC, and on return of the piston, the exhaust side valves start opening and by the time the piston reaches TDC again, the valves must be completely open until the piston reaches TDC, and exhaust valves close and inlet valves open up to provide the cylinder with a fresh charge.

When the first cylinders piston touches the TDC position, the pistons in the other 3 cylinders are in a different position, and therefore the corresponding valves will be in a different positions.

Its quite strange for all 4 sets of valves to be open, but its necessary to look at the cam profile design and the timing diagram, and then check if the cams are behaving as designed on the head.

Did your driver fill up diesel on the same day? did u check if the diesel filters water separator? Its a good idea to drain the diesel in the tank, check fuel filter, feed pump, fuel lines and then fill in fresh diesel, prime the lines, crank the engine and check if it fires to life.

IMHO, opening the engine is the last thing to be done. I don't know why ASC people are so eager to open engine / clutch / gearbox

I hope the MJD roars back to life soon!

[Aroy]

The only way all the valves can be jammed open is if hydraulic pressure jammed them there, which seems doubtful, as the cam lobe will push it back. It can only happen if each cam is actuated individually (but that is in future), but normally the cams are machined from a single piece and cannot move with respect to each other. In variable cam timing the whole cam is rotated with respect to a central position, but no way can all the cam open all the valves at the same time.

It highly possible that while opening up the head, MASS messed up so that the valves are all open. They must have removed the cam shaft and then observed - highly possible in this condition, but impossible with cam shaft in place.

Apart from timing, there should be sufficient compression for diesel to ignite. So before opening the engine up, they should have checked the cylinder pressure then the cam sensor then timing.

[humyum]

Does the Swift not have hydraulic valve lifters ? Check if the Hydraulic fluid from the lifters has leaked out by any chance and hence the issue.

[theMAG]

Piston rings/pistons/leaking head gasket/bust valve/cracked block ?

[Catalyst_delhi]

Sound to me like a warped block due to heat or camshaft failure.. Though it is highly unlikely at 50k. Very strange

[vikram_d]

Originally Posted by autocrat

Did your driver fill up diesel on the same day? did u check if the diesel filters water separator? Its a good idea to drain the diesel in the tank, check fuel filter, feed pump, fuel lines and then fill in fresh diesel, prime the lines, crank the engine and check if it fires to life.

IMHO, opening the engine is the last thing to be done. I don't know why ASC people are so eager to open engine / clutch / gearbox

I hope the MJD roars back to life soon!

No the driver did not fill fuel on that day. We opened the engine as a last resort and after consultation with Maruti engineers.

Originally Posted by Aroy

Apart from timing, there should be sufficient compression for diesel to ignite. So before opening the engine up, they should have checked the cylinder pressure then the cam sensor then timing.

They said that they did both dry and wet compression tests and in both of them all cylinder pressure readings were supposedly zero. I was not there at that point of time so I cannot be 100% sure as to what the readings were.

Originally Posted by humyum

Does the Swift not have hydraulic valve lifters ? Check if the Hydraulic fluid from the lifters has leaked out by any chance and hence the issue.

We are investigating hydraulic issues also like line blockages and other stuff.

Originally Posted by theMAG

Piston rings/pistons/leaking head gasket/bust valve/cracked block ?

Pistons are ok, the block is being diagnosed to check for any cracks and so is the head for any heat related warpage.

Originally Posted by Catalyst_delhi

Sound to me like a warped block due to heat or camshaft failure.. Though it is highly unlikely at 50k. Very strange

They mentioned a DTC in the ECU showing camshaft position sensor error. So before opening up the engine they put in a different sensor from there test drive vehicle and even with that the engine would not start.

The thing that I cannot get my head around is how can all cylinders have zero compression as claimed by them. I really have doubts on this story and sadly i wasnt around at that point of time to verify their claims.

[mayankk]

What was the diagnosis on timing belt and its associates?

[vikram_d]

Originally Posted by mayankk

What was the diagnosis on timing belt and its associates?

Timing belt/chain was fine. No problems with it.

[VeyronSuperSprt]

Originally Posted by vikram_d

.

The thing that I cannot get my head around is how can all cylinders have zero compression as claimed by them.

There are certain situations that will lead to there being no compression on all your cylinders. They are:
1. If you have a cracked head,
2. If you have a blown head gasket,
3. You have a warped head,
4. You have a cracked block between each cylinder.

However, there would have been symptoms such as uneven idling, missing on occasion etc which may not have been noticed by the driver. My driver has the same problem, he does not notice things going wrong, he only points out after they have gone wrong.