Technical 1.2 8v Rough idle, oil cap/dipstick smoking

[Cichaczech]

Hi,

untill now I always found answer to my Punto problems in other threads and thank you for sharing your exeriences, becouse every time it was easy fix

I own Punto 2002 1.2 8V Petrol/LPG with 170 000 miles. 1500 miles ago head was removed, thanks to blown gasket. Valves and seats was checked, but was OK (replaced in 112 000 miles), with repaired valve clearences, new timing belt, waterpump.... was put together and ran like new engine, with little smoking from exhaust.
Last week I was driving on highway for about 2 hours and when I came home engine idle was rough like it was running on 3 cyl.
Next day - morning start problem and 3 cyl. simulation, gets little better when engine is in work temp.

What I have done ->
- new HG leads
- checked coils OK - swapping them and disconnecting HG leads, engine will run on 1st and 4th cyl, but stall or wont start on 2 and 3.
- mechanic checked compression and sayed it is fine from 13 to 11 bar.

Problem is in 2nd or 3rd cyl.
No error codes.
Now no smoke from exhaust like before but lot of smoke from oil cap, oil dipstick tube and PCV.
Rough idle on Petrol and LPG.

Do you have any idea whai it could be?
Thank you.

 

[judderbar]

I am guessing but if 2 and 3 are not firing well and have got oily then the compressions will look better because of the oil.

Still guessing and with almost no clue what i am talking about my guess is 2 and 3 are connected via a failed head gasket.

 

[portland_bill]

If I understand the history from the first post.
1. At 112000 miles, head removed and valves and guides replaced.
2. At 155000 miles, head gasket replaced.
3. now, 170000 miles, poor running and smoking from oil cap.

1. Why? What was the problem being addressed at that time. What was found, what was replaced. Was the cause diagnosed, or just the failure.

2. Again, why? Failed gasket is easy to see, but after only 33000 miles, what was the cause of its failure?

3. Combustion pressure is getting into the crankcase. This is usually past the piston rings, but can also get there past valve stems (rare and unlikely to be noticeable), and can go via a failed gasket if it leaks into the oil drain channels. Failure between cylinders usually just shows as poor compression, and most common failure is into coolant.
Piston ring failure can be old age, but tends to arrive slowly over many miles/years. Sudden or quick failure usually points at overheating issues. Overheating may not be a catastrophic boil, just running too hot for prolonged periods will still do the damage.

Cylinder head will have to come off again, but time is needed to inspect and analyse to find the cause, not just point at the effect.

The new gasket (at least for Panda 1.2), comes in a sealed bag. The gasket is coated with a sealant that cures when exposed, so gasket must not be unwrapped until immediately before fitment, then fitted and head popped on immediately. If unwrapped and left exposed, the sealant will start to cure before fitment, and it will not seal properly. Could this be the reason? If so, is easy to fix.

 

[Cichaczech]

At 112 000 miles head overhaul was made because of exhaust valve failure due to driving on LPG.

At 168 500 miles new head gasket because of cooling water loss and exhaust fumes in water.

Now 170 000 miles - rough idle and smoke.

Our trusty mechanic was doing the last repair, but even he can made mistake or I can be unlucky and the new gasket failed after 1 500 miles (if it is blown between 2 - 3 cylinder).

 

[varesecrazy]

At 112 000 miles head overhaul was made because of exhaust valve failure due to driving on LPG.

At 168 500 miles new head gasket because of cooling water loss and exhaust fumes in water.

Now 170 000 miles - rough idle and smoke.

Our trusty mechanic was doing the last repair, but even he can made mistake or I can be unlucky and the new gasket failed after 1 500 miles (if it is blown between 2 - 3 cylinder).

Why not remove all 4 spark plugs.. line them up in order

You will soon see which cylinders are ok..and which are not

How often were you checking the coolant level..? A leaky radiator could be a 'silent killer' of head gaskets

I lost HG's 6 weeks apart through a similar leak
Heater Matrix : wet carpets

 

[portland_bill]

When the head gasket was last changed, due to coolant loss, was the head gasket assumed to be the cause, or was another cause found and fixed? Head gasket is likely to be the victim, and if the cause of the coolant loss has not been identified, that could be the reason for this failure too.

As Varesecrazy says, heater matrix can cause slow loss, and will be difficult to diagnose, as it will only leak when hot, so the coolant evaporates. Water pumps also only leak when running, so coolant evaporates, leaving no obvious evidence.