Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Engine Knocking 1.6 Sigma

A bit before it's first service (10K miles?) I found the oil only just up to the bottom of the dip stick but no sign of the oil light!!. I would also suggest that a firms car doing 28K a year is going to be worked a tad harder than the same engine in a 4/4. To be fair the oil consumption did improve with use.

As Rich says the oil light only comes on when the engine is about to go bang.

On piston engine light aircraft a new, rebuilt or re-manufactured engine is run in flat out but with careful attention to oil temperature. When oil consumption has stabilised to minimal level it's deemed run in, usually after 10 -15 hours from memory. Those that have endured continued operation at low power levels can allow bore glazing and consequent high oil consumption. The glaze can be bust by operating at high power levels, again to reduce then stabilise oil consumption. This trick is often used by ferry pilots prior to a long sea crossing across continents.

On Classic Mogs being discussed here the oil light is driven by pressure so only comes on before engine start or for a second or two after oil change until filter is filled (always partially fill mine first). On the CX cars though there is no dipstick but a selectable readout on the display. An owner recently suffered the oil warning light coming on but solved by adding oil until display read 5/4. No I don't understand either but it worked in extinguishing warning.

I had the same experience this spring. The engine ran like it was about to die on me. I replaced the MAF sensor, coil pack, and ignition wires to name a few suspects. I also had an injector problem in the past. But none of that really helped. In the end, it was the spark plugs. One was absolutely dead. I would start by changing the spark plugs. 2014 4/4 Sigma engine.

A faulty spark plug can breakdown under pressure, had this problem years ago. I change my plugs every service.

Thank you all for your input.

Oil level is fine and I've given the MAF sensor a cleaning.

I went for a short drive and aside from the initial concern when I originally posted, it's not happened again. I'm off on a longer drive this coming Monday so let's see.

In my case, the MAF sensor was already a culprit twice. Unfortunately, cleaning did not bring a lasting improvement. If the MAF sensor is the real cause, then I would buy a new one. It doesn't have to be a Fomoco for way too much money. I would recommend buying a MAF sensor from Hella, for example, which have lasted a long time for me.

If you ever suspect the MAF sensor then with the engine running just disconnect the electrics and see what happens. The ECU will let the engine run in default mode and although it will only have basic adjustment it should run smooth.

If you have an OBD2 reader plug in and look for fault codes. Cam and crankshaft sensors can cause all sorts of running issues and will flag up as a fault with a code. If your cam belt or chain has skipped a tooth, yes it is possible! you may get a cam shaft positioning code and investigation will show that the cams if there are two, will be out of sink with each other, ie. one has skipped a tooth or two and you will be surprised at what running issues you can get. No, it's unlikely that you will get interference between valves and pistons but you will get out of cinque compression/exhaust opening times on one bank of valves and some knocking! If suspected invest in an aftermarket set of cam and crank locks and check alignment. Chain tensioners usually have hydraulic/mechanical tensioners, the mechanical applies a certain level of tension but only enough to keep things in place when not running, rather it relies on the oil fed pressure to do the real job and they are notorious at wearing out and letting oil leak out!. First symptom is chain noise on start up for 5-10 seconds. Act on this before the chain fails!

Thanks for that Sewin.

It's not happened again and it was just that one time. It is now getting close to where the timing chain should be changed so you now have me wondering. I am taking it tomorrow for a service so will be sure to bring this up. I will also give it a quick scan first thing in the AM before I set off.