Puma running on 3 cylinders?

[zedder]

Got my 1998 Puma MOT´d today without problems, but joy was very short-lived: after a short motorway trip It feels now like my Puma´s engine is running on 3 cylinders. On idle engine vibrates and kind of shakes and from exhaust pipe comes sound in a rhythm which is not very healthy sounding for a 4 cylinder in-line engine. Car is still barely drivable because on higher revs it accelerates well enough and problem´s severity changes a bit giving a hint that there is something happening on all cylinders on higher revs.

I guess there are few possibilities: faulty spark plug, ignition lead or coil pack. I had a Nissan Cherry once which had a broken valve (can´t remember inlet or exhaust) but it was much worse then and it was not driveable. Is it common that Puma´s got cylinder valve damages?

Anyway, tomorrow I´m gonna check plugs and whatever I can with my limited tool assortment and if cannot find obvious reason for engines behavior I have to limb my Puma to a garage.

Could somebody give a short list what to check and in which order?

 

[Ginger Tom]

Personally I'd go with
Plugs
Leads
Coil pack

Hope you get it sorted mate

 

[zedder]

Cylinder compression test and few other things told that a exhaust valve is most likely damaged.What are my reasonable options?

Cylinder head must be removed and after that the garage which did the test can tell if valve is indeed broken, but is it likely that cylinder or piston has been damaged also?

Is it a good idea to get all valves replaced while cylinder head is removed or is it enough to get just one new valve and get other ones cleaned?

I´m not gonna do anything myself because there is the VCT thing. I have removed cylinder head from two other cars few years ago and replaced a valve or two, but this time professionals have to do it.

 

[DOH]

Hi
I note you are in Finland, Do they have an emission test as part of a Finnish MOT, if they do and you had the valve problem , it should have shown up as a high Hydrocarbon reading (HC).
Before going to the expense of stripping your engine which will result in £100's +++ or Euro's to you! There are a number of things to try first before stripping the engine.
If the garage is competent, he should be able to identify from the readings if the valve is damaged or not, before stripping.
Any idea what the 4 cylinders readings were?
Also, since this problem has occurred, has the engine become tappety i.e on 1 cylinder in particular?

From the answers to my questions, I will be able to advise you on your next course of action

 

[zedder]

Hi
I note you are in Finland, Do they have an emission test as part of a Finnish MOT, if they do and you had the valve problem , it should have shown up as a high Hydrocarbon reading (HC).
Before going to the expense of stripping your engine which will result in £100's +++ or Euro's to you! There are a number of things to try first before stripping the engine.
If the garage is competent, he should be able to identify from the readings if the valve is damaged or not, before stripping.
Any idea what the 4 cylinders readings were?
Also, since this problem has occurred, has the engine become tappety i.e on 1 cylinder in particular?

From the answers to my questions, I will be able to advise you on your next course of action

Emission test is part of Finnish MOT, but it was done few weeks before MOT and I only gave a certificate to an inspector yesterday. HC readings were 12 ppm both on idle and higher revs.

If I understood correctly what mechanic told me other cylinder´s pressure readings were ok. Mechanic told also that it clearly looks like engine is sucking air from exhaust pipe.

So it clearly seems that an exhaust valve is broken. Only other explanation for this problem is that valve spring is broken? That would be revealed before cylinder head removal anyway.

I´m prepared to pay partial cylinder head reconditioning, but if there is something wrong with cylinder itself, then the game is over I guess. My Puma is not one of the finest ones but I really would like to keep it. I have no time to go looking for another Puma (it would be difficult to find a decent one here in Finland and I have no time right now to go to Germany to find one).

 

[DOH]

if the valve spring was broken the valve would be hitting the piston as it wouln't be able to close properly. You would have heard that .
Exhaust valves can break , but if it did, you will have punched a hole in the top of the piston. the engine could still run on 3 cylinders but would emit loads of smoke out the exhaust.

Are all the other compression test readings approx 170psi and the faulty cylinder 50psi?
(This information is relevant for me to diagnose your problem properly)

 

[zedder]

I saw myself that gauge showed practically zero on faulty cylinder. I have not readings with me. There cannot be any serious problems with other cylinders because It can´t be possible to drive a Puma with less than 3 properly working cylinders.

I don´t think a valve is broken into small pieces but only a part of it´s edge is missing and this part has burned in cylinder and flew away from exhaust. Is it likely that this kind of thing damages piston or cylinder badly?

 

[DOH]

if you remove the spark plug shine a torch light down the affected cylinder , you will be able to see if there is any damage.
the piston needs to be down a bit from the top of its travel(tdc). Otherwise you won't be able to see most of the top of the piston.

Now I know it is zero, the next test is to inject some oil down that plug hole and see if the reading momentarily increases. If it does, you have either a piston or piston ring problem. Zetec piston rings can get stuck and they can also break.

A useful method to test whether a valve is leaking without the expense of specialised diagnostic equiptment . Is to destroy/ remove the internals from an old long reach Zetec plug 14mm. Weld on to the remaining threaded part, a pcl (quick release airline fitting).

The following procedure is to be carried out whilst the engine is not running:

Now with the rocker cover removed, ensure the exhaust valve is closed, (the cam lobe will be pointing upwards)

Now thread newly made adaptor, down the plug hole. attach to compressed air at 60-80psi. Now listen for the sound of air escaping inside exhaust manifold.
If that's OK, turn engine until inlet is closed. and listen for air escaping in inlet manifold.

Incidentally, there is a position where both inlet and exhaust valves are closed, the cams will be rocking.
(I unfortunately don't have a camera to send you a photo, but the cams lobes will be pointing towards each other.)

You will now have identified which valve is faulty.

Before stripping the engine, check that the offending valves clearance isn't too small.
It might be possible to restore compression simply by using a thinner shim to allow the valve to close properly.
Yes it is possible that you have simply a burnt valve.

The HC readings at the time of the test were ok.

It is possible to free off stuck piston rings without stripping the engine, If you identify that you have a piston ring problem, let me know and I will tell you what to try next.