International Lancia Forums

Dear Friends,

After so many years of plesant driving and 166.000 Kms trouble free, I just experienced a major problem with my much loved Thema turbo 16v S3.
The cam belt just broke leaving me with some bent valvles.
My mechanic is watching the extension of the problems but, at least one cylinder is dead!!
I had the distribution done 66.000 kms ago (2001), and I'm a bit surprised.
For now, we think that it broke because of the plastic cover that covers the chains, since no bearing is damaged or even the tension adjuster.
The plastic cover is a bit bent over the inside, just on top of the upper engine support.
With the years, a lot of small plastic and rubber (from the belt) particules fell inside the distribution pulleys, bearings and belts making the belt to miss one or two teeth and finally breaking it.
It all happened to quickly, without a notice, and the only good thing is that the car was beeing driven at a very low speed, around 55kph to 65kph.
Is there anyone out there, that can send me the procedure to rebuild the valvle head with torque values and sequence of tighten.
Any other major advice is most welcome.

All the best,

Miguel Cabral

Portugal

Hi Miguel,
Have just rebuilt an S2 turbo engine but am waiting for a power supply unit for my scanner. Before you go any further it is important to check the height of the cam lobes as they wear. If there is wear on the lobes it progresses rapidly and the performance will drop off rapidly after over haul. In addition the metal swarf can contaminate the engine and turbo. With wear on any lobe the camshaft must be replaced.
You will also need to replace the rubber valve seals and camshaft seals.
Come back to me if you have not got the data you want by next week
Paddy

Paddy,

Since you're clued up on camshafts, do you know if there are any markings on the cams to denote which is the inlet or exhaust cam?

I suspect that mine may have been accidentally swapped when the oil feeds were replaced during a top end overhaul. Since the new head was fitted the engine has been very jerky when driven on a trailing throttle at revs less than 1,500 rpm.

It feels like the fuel pressure is surging or a cylinder is missing, but the pressure regulator was swapped over for the original with no noticeable change in the engine characteristics and the engine drives fine under all other conditions.

I've also swapped throttle potentiometers and ECUs, but without improvement.

Cold starting first thing in the morning is immediate as is hot starting 5-10mins after switch off, but starting under any other conditions requires several turns. Maybe a temp sensor, but that was swapped as well so the odds are against that unless I'm really unlucky with my stock of spares!

Cheers
Mike

Hi Mike,
Took a look at an old pair out of a series 2 engine and could not see any obvious distinguishing marks. Even the stamped part numbers seem the same but they are not easy to read. I will ask some techies in Fiat here as they must have some method of telling them apart. When I ordered a new pair of camshafts some years ago they came in sealed plastic bags with inlet and exhaust clearly labelled on the paper part number..... If all else fails try a TDI gague and check opening and closing angles of the #1 inlet and exhaust valves.
Data for 92 16v ie camshafts:
Inlet opens at 0 btdc closes 43 abdc
Exhaust opens 43 bbdc closes 0 atdc.
However the cam lift values are different: inlet 8.22mm and exhaust 7.07mm. Hope that helps.

The problem is either mechanical, electrical, fuel or very occasionally a combination and I would suggest you eliminate them in that order. Had a problem with my old car that took ages to sort until I sat down and made a logical list of possibilities and eliminated them one by one.

Start with the cam shafts and eliminate them as a problem.

Then check ignition timing with a strobe.
Try it on each plug and see if there is any electrical problem - I have had plug electric leads give a similar rough running problem. Ensure the TDC sensor has the correct clearance. You could have a weak ignition coil or power module which will affect firing

I would suggest giving the car a burn and then idle it for about 5 minutes. Then check plugs with a strobe for spark condition, then take them out and check for under/over carbonation. A "Colour tune" kit is handy if you can get your hands on one at your local car parts dealer as it allows you to see the flame colour and condition of the spark (It screws in as a replacement for a spark plug and has a glass centre section).
It may be something as simple as an air leak in the induction, a cracked pipe, incorrect assembly of the auxiliary air valve system, faulty coolant temperature sensor or even a problem with your air flowmeter.
But most likely it is as a result of reassembly.

If you need values for any of the above contact me directly by email.

Paddy

Gurus in Fiat say that the camshafts are stamped:
Inlet with an "A"
Exhaust with "S"
Paddy