Ask The Guide

It’s a bit hard to imagine how removing and replacing a transmission could make an engine misfire or backfire. Unless, that is, you’ve managed to bump part of the engine’s electronic controllers, wiring, sensors or even something as simple as pinched or displaced a vacuum line somewhere in the engine bay. Incorrect ignition timing can make an engine do this, but, again, that’s nothing to do with the transmission.

It could even be a complete coincidence. But did the vehicle sit for any length of time while the transmission was being fixed? You might find the battery has discharged over time. Modern, electronically-controlled engines do not like low battery voltage and can run poorly as a result.

If the engine power has returned since this episode, I’d be willing to suggest that what happened is that the vehicle had gone into limp-home mode. This happens when something like the transmission or engine becomes hot enough that to continue at normal pace might cause damage to the vehicle. It’s the car’s way of saving its own life, if you like. When it does, you can expect a warning light and a reduction in power, just as you experienced.

Towing a caravan up hills is a great way to get a transmission really hot, or even a turbocharged engine such as the one in your LandCruiser. If the vehicle returned to normal once it had cooled down, then you shouldn’t have any ongoing problems, but another oil change and perhaps transmission service might be a good idea as these fluids can lose their mojo once they’ve been really hot even once.

There are plenty of reasons why a diesel won’t start in the morning. This can often be traced back to a problem with the fuel system or the glow-plugs which are needed to warm the combustion chambers before the diesel will ignite.

As for the noise, it pays to remember that diesel engines are inherently noisy, but if you’ve owned the car for a while and are familiar with its normal level of racket, then any new or louder noises signal a problem. If, indeed, the new noises are connected to the engine’s refusal to start easily, you might be looking at an engine with worn out internals. At that point, it’s time to recondition or replace the original engine.

But before you do any of that, have a diesel specialist look at and listen to your engine running, and you might find the problem is a simple one after all.

It’s quite common for an oil pressure sensor to develop a fault where it sends the incorrect information to the car’s computer which then lights up the low oil pressure warning. But since you’ve already replaced this sensor, maybe that’s not the case here.

The big clue is that fresh oil and filters improved things a little, which makes me think it’s a genuine oil pressure problem. I also reckon you might be bang on the target by suggesting that it’s an oil pick-up problem. The oil pick-up lives in the sump of these engines and if the pick up inlet is blocked or partially blocked by sludge from the engine, it can fail to suck up enough oil to maintain the correct oil pressure. The higher the revs, the bigger the pressure shortfall. Failing that, sludge can block the various oilways around the engine that allow the oil to get to where it needs to be. Either way, you wind up with insufficient oil pressure and flow and risk destroying the engine.

I wouldn’t have thought 136,000km on an engine would have it showing signs of oil sludging, but that’s based on proper maintenance (not to mention that even modern diesels are filthy things inside). Have you owned the vehicle from new? Has it always been serviced correctly and promptly? If it’s been neglected (even one skipped oil change) it can develop the deadly sludge and it can be all downhill from there.

Possibly the best course of action would be to remove the sump and check the oil pick-up strainer for signs of gunk and build up. If that’s okay, then two or three quick oil changes (say, every 1000km) with an engine oil designed for trucks (which has lots of detergent as an additive) might clean things up internally enough to keep the oil pressure light at bay.

The other thing to try would be a new oil pump. Like any engine component, these can wear out over time and kilometres but, again, I wouldn’t expect to see significant wear on one that’s just 136,000km old. Other causes to consider would be excessive bearing clearance in the engine (due to wear or damage). In that case, a tear down and rebuild is the best option, because worn engine parts don’t repair themselves.

This is a relatively simple diesel engine you’re dealing with here, so the first thing to check is the fuel supply. A dud or worn out fuel pump can mean the engine isn’t getting any fuel to the injectors, at which point it will never fire up. Even if you had a single injector playing up, you’d expect at least the odd cough from the engine as it tried to start on three cylinders, but from your description, there’s nothing going on under that bonnet.

The other common thing that stops a diesel starting is non-functioning glow plugs. These are designed to pre-heat the combustion chamber so that the fuel burns when it’s compressed by the pistons (a diesel has no spark plugs, remember). Without this pre-heating process, the fuel may refuse to ignite and the engine won’t fire. But don’t rule out the simple stuff like a blocked fuel filter that is preventing the fuel flowing from the tank to the injectors. A split or damaged fuel pick-up inside the tank can also lead to a lack of fuel at the engine, as can an air leak anywhere along the fuel line.

I take it the smoke is coming out the tailpipe when you crank the engine, even though the engine is not starting or, at least, not running to the point where the car can be driven. It sounds like you might have 'cooked' the engine as old school mechanics would put it. When the radiator started leaking, allowing the coolant to escape, the engine overheated and 'cooked'. Which means the severe heat inside the engine damaged something sufficiently that the engine now won’t run.

You could be dealing with a blown head gasket or a warped cylinder head, or even damage to the pistons. The smoke you’re seeing when you crank the engine could be oil smoke that’s a result of fired piston rings due to the overheating episode. The first thing to do is let a mechanic run a few tests on the engine to determine whether it’s retrievable or junk. From there, you can make an informed decision on whether to fix the car or cut your losses and simply walk away. If the engine is damaged beyond help, a second-hand engine from a wrecked Tiida might be an option if you decide you want to keep the car.

For a start, it’s never a good idea to drag a car anywhere with the wheels, hand-brake and steering locked. You can damage anything from the transmission, steering column, driveline and even ruin (flat-spot) the tyres.

If the clicking noise when you drive it wasn’t there before, then a mechanic would suspect that there’s been damage done to the front driveshafts. This would be consistent with the car being forcibly dragged along the ground. If you’re worried, have a mechanic check the car over and send the repair bill to your (now possibly ex-) housemate.

From memory, the centre orange light on this vehicle indicates whether the locking centre differential is engaged or not. When the light is on, the diff in engaged. When it’s flashing, it’s in the process of engaging electronically. For this process to occur, the main transmission needs to be in neutral, so trying to get the vehicle to move and change gears while the diff is somewhere between engaged or disengaged, might be the problem.

I’ve also heard of problems with the sensor that detects whether the centre diff is engaged or not on this make and model. Sometimes the sensor can die, other times it’s just a wire that has fallen off, but it could mean that the vehicle is confused about what to do and the transmission is stranded in neutral as result.

Try rolling the car forward a few metres (if possible and safe) to see if that small amount of movement allows the diff to engage and normal operation to be restored.

It’s possible that all these faults happened at the same time from different causes. But you’d have to agree, it’s much more likely that there’s a single cause for all this stuff happening at once. In which case, suspicions are always drawn to the car’s body computer. This controls a huge range of functions including the lights, climate control, dashboard, entertainment, central locking and much more.

Like any computer, they can be faulty from new or sometimes just need a reboot to put them right. I’d start by disconnecting the battery overnight to see if the car comes good after you’ve reconnected it. But even if it does, a trip to the dealer is in order, to log the problem for future warranty claims.

Peugeots of this era were not known for the high standard of their electrical systems. Even when new, they gave trouble, in fact. But to find your problem, here’s my first question: Have you altered or added anything to the car that runs on electricity? This could be a new stereo head unit, amplifier, extra gauges to monitor the engine, auxiliary lights or even a sat-nav or dash-cam system. Any of these additions could be somehow remaining powered-up when you lock and leave the car each day, flattening the battery overnight.

Does the car have an alarm system? These are notorious for draining batteries and older ones especially so. Have you checked things like the light in the boot? If this stays on due to a faulty micro-switch, you could easily have a flat battery next morning. Find a dark place to park the car and then have a good look around it for any signs of a light stuck on somewhere.

In some cases, you might find the cause of the problem is the body computer which is randomly switching on various systems (including even the headlights) when you’re not looking. By the time you go to the car next morning, the lights are off because the battery is completely flat.