I'm hoping you can help me diagnose a problem with the 300TDi engine in my Defender 90 losing power. I have found I've needed to change down a gear when going up hills that it normally has no trouble with. But more significantly, I'm struggling to get it above 55mph in 5th gear. The engine runs as smoothly as normal at lower speeds but the power starts to drop off when I get above 50. (I can feel it sporadically backing off and then pulling forward again - if it were a petrol engine, I would describe it feeling as though the engine were misfiring.)
Interestingly, the problem occurs at the same speed even if I'm going downhill, which suggests to me that it is RPM rather than power related. The weather has been cold here over the last few weeks, but not so cold that I can blame it on fuel waxing (the problem happened last night at about -1degC). I have had no problems starting the engine, and it idles smoothly (or, at least, as smoothly as a 30TDi ever idles). I was wondering whether the RPM governor in the injector pump ever gives problems (I have a lifetime's experience with petrol engines but very little with diesels).
I am going to replace the fuel filter because that's a cheap and simple step to take, but I am not entirely convinced that this will fix it. Have any of you come across this type of symptom before? Any ideas what might be the problem?
Many thanks in advance for your advice!
Roger
Interestingly, the problem occurs at the same speed even if I'm going downhill, which suggests to me that it is RPM rather than power related. The weather has been cold here over the last few weeks, but not so cold that I can blame it on fuel waxing (the problem happened last night at about -1degC). I have had no problems starting the engine, and it idles smoothly (or, at least, as smoothly as a 30TDi ever idles). I was wondering whether the RPM governor in the injector pump ever gives problems (I have a lifetime's experience with petrol engines but very little with diesels).
I am going to replace the fuel filter because that's a cheap and simple step to take, but I am not entirely convinced that this will fix it. Have any of you come across this type of symptom before? Any ideas what might be the problem?
Many thanks in advance for your advice!
Roger