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4.2 Turbo problems? Please help


Well-Known Member
Apr 6, 2010

I went up to Dudley today... booted it most of the way (80 -90) - shortly after turning onto the M5 I noticed that I was loosing power :sick: I managed to limp home 50 - 60 (if I pushed any harder if felt like it was about to die, same when going up steep hills).

Got home and changed the fuel filter, when I pulled off the fuel pipes neither of them appeared to have any fuel in (although the filter had a bit) and the filter was very gungy. On fitting the new filter, the priming button didn't seem to pull any fuel through. So I took the filter off, filled it with fuel, refitted and tried to start - surprisingly it did, but on a test drive it felt the same, lacking power as if it was on limp home mode, not sure if I can hear the turbo either.

Question is how do I know if I have a turbo problem or fuel starvation from some component between the tank and filter. For example is there a tank lift pump? the manual mentions a fuel solenoid, where is this located? Oh and sometimes there is blue smoke when I try to rev hard, most of the time the exhaust is realy clean.
Hi Paul

I originally removed the filler cap when trying to prime the filter. I tried taking it for a run again with the cap off and no difference. Btw I think I might be able to hear the turbo (faintly), not too sure though.
Another thing to try (only for a short run) is to remove the air pipe from the turbo. The turbo does not make a lot of nosie anyway, well mine does not.

I'll give it a go tomorrow... what will this tell me! If there is no difference would this suggest a turbo problem?
hi mate first thing i would do is take the rear seats out and pull the carpet back. Under there is a inspection plate with three screws. Take that off and your to the fuel tank. Take the fuel sender unit out the top of the tank and on the pick up up pipe there is a filter. I take mine completly off and chuck them as you have the main 5 micron fuel filter anyway. 9 times out of ten that is the problem.
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If it doesn't have a pickup fuel pump, then you can install one of those inline Pierburg fuelpumps just in front of your fuelfilter.

Great when you install a new fuel filter, pumps it up automatically. And you pressurise the feed and return lines just enough to hear any problem long before they hit you in a bad way.

I've had clogged vents, critters chewing on fuel lines just enough to cause airbubbles, clogged return lines and fuel pickup filters, clogged venting tube inside the tank. A pierburg gives you a little more peace of mind. And an easy fuelfilter change :thumbup:
Hi Karl

Took the filter off the fuel pick up on the sender unit - it was covered in crud - so I spent half hour washing it... thought I had it licked, took the car out, but it was the same. To add to the symptoms, when the car changes up at 45mph, driving with a feather on the gas, the car shudders when in top gear until it reaches about 55mph - any ideas :?

I'm sure that I could hear the turbo kicking in at times. But now I'm thinking about taking the turbo pipe off to see if the performance is the same and looking at the EGR system... Get the feeling that I'm just about to learn a whole lot more about my LC :roll:

Probably also take off fuel and return pipe at the filter and sender end and blow down it to ensure that it's clear.

The Pierburg fuelpump sounds like a good idea, where to I get such a thing?
Yes, looks like an idea. What capacity and pressure should the pump have?
It's been a while since I fitted mine. About 5 years ago I think.
You can get them at a decent car parts store.

I'll look up the specs and take a pic of it.
Quite a simple installation, just make sure you've got a fuel return line so excess pressure can be relieved into your tank. Otherwise the pierburg will run in it's own juice all the time and eventually wear out the impellar.

If I'm correct the HDJ80 has a fuel shut-off valve somewhere. Nevertheless I rigged the pierburg so that it would run with the ignition key on ACC.
Pop the hood, disconnect the feed line and you've got instant access to 80 liters of non-explosive fire starting fluid.
Use to go camping/fishing in damp conditions quite a lot :thumbup:
Sounds like you already got good advice, I ran into a similar thing on a friends car--just had it serviced and running poorly. truned out the filter was sucking air and just needed tightening up a little.

My experience with fuel solenoids has been they are either on or off---I look there if it does not start at all, but that was heavy equip mainly

last but not least fuel contamination with water
Paul, Karl, Chris, mssrs Smith,

I've managed to sort it :dance: Just I was loosing faith in the old truck, it turned out to be a simple service item (I think!)

Blew the fuel lines through (not too much muck), then primed up and took the air filter out... took it for a run and guess what! Car runs great! So I'm assuming that it was the air filter all along.

Got the following jobs lined up for the weekend:

1. Syphon fuel out of tank (sender end) clean out any crud I can find and refil with clean fuel
2. Follow maintainance steps for EGR valve ( ... t/vent.htm)
3. Fit an inline Pierburg fuel pump (recommended by Chris)

Once again thanks to all!
I’m guessing it was the fuel pick up in the tank, not the air filter.

I’ve had it before with an 80 series in the middle of nowhere; the truck lost power and would hardly get up the hills. I stopped checked the fuel filter - which was fine, took the fuel filler cap off to see if there was a vacuum - again ok. So I removed the suction pipe from the tank and blow down it, refitted the pipe and would you believe it back full power. I had to repeat the process a couple of times on the trip.
The long term fix was to remove the tank and clean it out; I’ve not had a problem since.

Here's a pic, there is an error in my previous post. I wired it up to the ON on the key switch. You've got a power out box somewhere in the engine bay.

Spoke too soon :oops: Did about 20 miles and the car went back to how it was. So I've spent the day stripping out the EGR system and Inlet manifold, both where full of black gunge about 5mm thick. Cleaned it all out including the ports in the cylinder head. Should start to reassemble tomorrow.

Given the amount of yuk I guess the cat is probably also full of the stuff. Any ideas how to clean the Cat without destroying it? Btw fuel seems to be getting through ok now, but I will fit an inline pump as soon as I can source one! :(
The Walbro FRB-5 fuel pump is usually recommended for 80 series and I'd imagine it's just the job for a 100 series as well. I've bought 2 from in the past and had good service.

You might have some crud floating about in the tank and that's why it comes and goes?
Had to remove this gunk on my diesel commuter fitted with EGR a small bmw diesel.

It is created due to the exhaust gasses mixing with some oil fog from the turbo.

Cleaned the inlet manifold and the egr valve with some simple gasoline. Tried degreaser, wasn't effective. Gasoline desolved it more easily.

Remove the cat and give it a gasoline bath perhaps?
Didn't remove the cat on my diesel commuter, but then I didn't have any ill effects. Just noticed all the gunk when changing out glowplugs.
I did wash the pick up filter on the sender unit (which was really full of cr*p) Sunday evening & replaced the fuel filter, on the subsequent test drive there was no improvement, I then removed the air filter this morning (started the car it ran ok, refitted the air filter), blew out the fuel line and filled the fuel filter with new diesel again, before priming it and the car continued to run ok for a while. After it began to act up again I emptied the tank, refilled with clean diesel - no improvement.

It was at this point that decided to look at the EGR and Inlet manifold, cleaning with detergents at first and then petrol followed by a good old jet wash.

It would be good to know what ill effects are caused by the gunk in these parts?? Would it effect air flow for example? Also I'm relatively new to diesels - would my '01 truck have a cat? On petrol catalysts neat petrol would cause damage, are diesel cats different? If so any ideas how they work? Also looking at the gunk on the inlet ports of the cylinder head, this stuff must have got into the engine, would it have caused any damage? I've not noticed the car smoking either cold start or underload before yesterday??
I don't pay as much attention to the diesel threads as I used to but wasn't there a recent case of power loss because a butterfly or flap on the inlet somewhere was failing to open properly?

EDIT: Nope, don't suppose it's related: viewtopic.php?f=13&t=8353

Weren't you having spill valve problems Nathan, I take it you've ruled that out?