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How easily do P38 diesels start?


geoffbeaumont
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Had a look at a P38 last night - diesel manual, and come back with one or two questions :)

The seller told me to give it a bit of accelerator as I started it - I deliberately didn't and it turned over happily enough but didn't start. As soon as I depressed the pedal it started. Is this normal for these engines or a sign of excessive wear/head gasket issues/glow plugs? It did have 130k on the clock. I didn't think it was idling particularly smoothly either.

Other than that it seemed okay, the important bits were all in working order but the interior was a bit tired and the exterior plastics faded - neither of which would bother me if the price was right, but I don't think it was. We'll see when I've had a look at some more vehicles, maybe I'm just being unrealistic about what I can get!

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Diesel P38 Range Rover starting difficulty – some diesels do have a problem with firing up they do eventually start but need a bit of winding up.

I have seen someone selling on ebay claiming to cure the problem. My friend had one and I never got to the bottom of it.

If you don’t mind winding it up it dose not mean that there is other problems with the motor. (He had his chipped by the way which is worth doing but did not cure the problem)

Not sure if this is the same problem you describe as you say it started with a bit of gas, never made any difference to my friend’s one

Hope it helps

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The seller told me to give it a bit of accelerator as I started it - I deliberately didn't and it turned over happily enough but didn't start. As soon as I depressed the pedal it started. Is this normal for these engines or a sign of excessive wear/head gasket issues/glow plugs? It did have 130k on the clock. I didn't think it was idling particularly smoothly either.

I don't think it is normal for these engines - I don't see the query regularly described on forums.

From other experiences with this engine I'd say it indicates wear in the high pressure injection pump.

As a straight six it should idle smoothly, the six cylinders self dampen the vibrations inherent in having pistons shooting up and down the bores. Note this is a characteristic of the configuration, and as such applies to a lot of straight 6 engines.

Taking both the issues together (not starting without throttle and un-smooth idling) I suggest the idle speed is too low.

The normal way of adjusting this is via a diagnostic electronic tool talking to the BMW engine electronics.

The abnormal way is by wrecking the security screw on the pump and mechanically moving the top box on the pump. I found this 'facility' while curing another problem, and I don't recommend this method as it's a long way from being exact; there is no adjusting screw, the result depends entirely where the box sits as you tighten the 4 screws that secure the box.

I suppose the throttle pot or it's adjusting linkage could be worn, giving an incorrect pot value to the ECU, but I don't place much value on this possibility.

Poor warm / hot starting IS often described on forums, and I think that is what Scube is referring to. As he says, it isn't always cured.

Poor idling on its own could be injectors requiring a service / replacement. 5 of the 6 can be overhauled, but number 5, with the start of injection sensor, can only be replaced.

I have no experience of head gasket failure with this engine, so I would be looking for other signs, like excessive steam from the exhaust, or mayonnaise in the cam cover.

HTH

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I don't think it is normal for these engines - I don't see the query regularly described on forums.

From other experiences with this engine I'd say it indicates wear in the high pressure injection pump.

As a straight six it should idle smoothly, the six cylinders self dampen the vibrations inherent in having pistons shooting up and down the bores. Note this is a characteristic of the configuration, and as such applies to a lot of straight 6 engines.

Hmm, that was pretty much my thoughts - it's been a while since I drove a P38, but I remember Ben's being significantly smoother than a Tdi (or, for that matter, the 3.9V8 classic I had at the time, at least to drive) and pretty much instantly starting on the key despite being quite worn and smokey.

If I already had the vehicle it would be worth looking into the other possibilities, but as I'm buying it's walk away time.

I have no experience of head gasket failure with this engine, so I would be looking for other signs, like excessive steam from the exhaust, or mayonnaise in the cam cover.

I didn't get as far as even opening the bonnet - the car wasn't as tidy as it had been described on the phone, and it was almost impossible to look it over properly with the owner talking at me constantly. I'm not sure if he was deliberately distracting me or just the sort of person who never stops for breath, but it concerned me enough along with everything else to make me decide I wasn't interested.

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I'd have to buck the trend of what's been said here and say I seen plenty of P38A diesels at work with this exact problem. I don't know exactly what causes it because as you've said they will start with a bit of right foot and some cranking, most people don't bother getting it sorted. I would imagine its a fuel drain back / air leak issue. I will see if I can find a definate an answer for you tomorrow.

Mark.

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I have one with the starting problem and occasional rough idle, I have also had the dreaded head gasket problem.

Check the expansion tank for signs of oil or exesive heat, smell the water and check the colour and smell of the engine oil.

Check for diesel in the sump.

Check hot start, (will it start well and clean)

Check cold start does it require extra heat.

Drive it, does it die around 2-2500rmp

If it dont feel right for C&rist sake run away quickly, dont walk, run !!

You could contact me as I will sell you one with all these problems NOW !

Having said all that, Range Rovers are addictive, when it does run well it's superb and any problem you find might just be the spill/return pipes.

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Unless of course your findings produce a significant price reduction.

Right now, I don't need to be taking on a car that needs work, so not even if the price is right! If it was just the consmetic stuff I'd have tried to knock the owner down, but I'm walking away from anything that looks like it'll cause me trouble (so why am I after a Range Rover :lol::o ).

Anyone, looked at a much nicer one today for only slightly more, and I'm buying that. Doesn't have air con or cruise control, both of which I'd have like (wonder how hard they are to retrofit... :unsure: cruise seems like it ought to be easy enough...) but it's in very good condition and has been really well looked after. Also done 20k less than the other one. And it's blue, so the wife like it :rolleyes:

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I will see if I can find a definate an answer for you tomorrow.

Asked the question and:-

If the issue is only from cold - usually glow plug issue.

If the issue is when hot or cold - usually either fuel drain back, put non return valve in system; or low voltage causing low cranking speed meaning that the crank position sensor can not generate a decent reading.

Mark.

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It is not direct injection and will allways need heat to start it at 130k.When cold is often no problem but when warm the temp sensor that controls the glow plug relay will switch the relay off or cut the time down too much. We used to make a modification which cured this. Some did have a drain back problem but very rare and a blocked with leaves pick up filter caused starting problems with one mainlywhen the fuel level was low in the tank.

The timing chain will be wearing at this mileage, the cam timing will be retarded and performance will be down a small percentage as no doubt will the compressions, both related to oil quality over it's life . The pump drive will be retarded too but the pump will compensate via it's sensors.

This won't affect tickover unless as already posted it is too slow, 10 rpm can make a surprising difference.

Of course there are other factors re roughness, needs a diagnostic to analyse it at same time as sorting tickover.

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