My 1990 F348 had a serious engine failure last week... A few minutes after cruising in town, and following a 1st to 2sd shift change, it started running in just one bank... I had the car trailed to the mechanic (the car had the belt changed and a tubi installed 2 months ago, the belt was new and the car was running very well until then). After checking everything from CPUs to the power module/ ignition coil, we found that the coolant temperature sensor had failed, causing the inlet camshaft drive gear for cylinders 1-4 to move from the right position due to possible high fuel pressure inside the combustion chamber... The belt seems to be OK and with the right tension... Everything else is in place. The mechanic will get the motor out tomorrow to check if there is any damage to the valves... Did anyone ever had such a problem? I have already read previous threads on 348s running in just one bank, but have never heard of coolant temperature sensor failures and engine break downs... THANKS
I don't have a 348, but it seems impossible that a temp sensor or fuel pressure would cause a camshaft to move in any direction. It sounds to me that a belt tesioner may not have been tightened correctly and moved just enough for your belt/cam gear to "jump a tooth".
I must agree with you... But that was what they told me... I am not a mechanic or engineer... I can only say that the belt seems to be OK and that no other camshaft moved/ jumped a tooth (shouldn´t that happen if the belt was loose?) After the belt change, the car made +/- 200kms with no problem whatsoever, everything worked nicely, the engine seemed a swiss clock and the tubi was really amazing
Your camshaft jumped a tooth on the belt because a water temperature sensor caused high fuel pressure inside the combustion chamber??? I don't think so. That sounds ridiculous.
BS! The only way a cam belt can jump teeth, is if belt tensioner was not properly tensioned OR........cam gear is worn out, which is very rare to see in any car.
Thanks guys! I agree with you all... Just hope that the damage isn´t much (apart from the valves...). Can this be easily fixed? Should I expect more damages?
You may be lucky and only have bent valves. Heads have to be removed for inspection. Only hope that they did not crack the tops of the pistons, then its a major engine overhaul. Not good. Hopefully it is just a bent valve or two. I wonder if your mechanic should cop this bill or part of it.............
It's impossible to tell just from your description how bad the damage could be. If the valves hit the pistons, then you at least have some bent valves to deal with. You MAY have damaged pistons, or damaged valve guides or seats. It's going to be VERY expensive to fix. Another way that the belt could have jumped is if the water pump seized.
True, but Ferrari has a nice design feature on the 348 in that the smooth, untoothed backside of our timing belt drives the water pump, whereas the front/inner toothed side of the belt drives the cam shafts. This safety feature prevents most water pump failures from causing belt/engine interference problems.
A one-tooth jump would not cause valve interference. The likelihood of overheating causing a cam to sieze just enough to jump a tooth is somewhere between slim and none. Take the car to another mechanic and do not tell him what the first one said. Another geographic area would be good.
