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VW LT 28 campervan

Fulltimedad

Fulltimedad

Extreme Landy Fan
Site Donor
An annoying problem with the campervan that’s been around for a while but on my list to try and sort out .

It’s a straight 6 2.4 diesel DW variant engine , similar to that used in older Volvo cars I am told.

Starts well and chugs along at 55 - 60 on the motorway but after a long fast run when you slow down say at the slip road and then pull away again it’s very sluggish then will clear after a while . Free wheels ok and wheels aren’t hot so it’s not brakes ( which I wondered so stripped and cleaned them )

No electronics at all apart from a fuel cut off solonoid on the diesel pump . I’m assuming this is just on / off ?

Can’t think what else would allow the van to be fine at speed , never going to be fast as she’s heavy, but then whatever happens and loss of power . If I drive the engine hard it will eventually get back up to speed and be fine slowing down and speeding up again until I slow right down . Annoyingly it doesn’t always happen .

Any thoughts gratefully received . Doesn’t make the van unusable but is frustrating.
 
Check the air filter and any associated pipework in case its collapsing internally. (thinking warm... Softer?) Might also be worth checking the tank for any crud that might be in the bottom... Plastic tank on these iirc, so it shouldn't be rust.

Failing that, it sounds like a fuel pump problem. I can't remember if it's an electric pump on these?
 
Big Sandy said:
Check the air filter and any associated pipework in case its collapsing internally. (thinking warm... Softer?) Might also be worth checking the tank for any crud that might be in the bottom... Plastic tank on these iirc, so it shouldn't be rust.

Failing that, it sounds like a fuel pump problem. I can't remember if it's an electric pump on these?
Click to expand...
Thanks @Big Sandy . Hadn’t checked air side apart from changing the filter - I’ll have a look around that side. It’s a funny set up , behind drivers seat with a huge air box and air pipe similar to the landys .

Pump is mechanical. Changed drive belt a couple of years ago but timing wasn’t disturbed .
 
Any smoke when it happens? I would have thought that if it was air restriction then you would see diesel smoke..?
If no smoke then I would be thinking low fuel pressure (due to restriction?).
If this was a landy then my first suspect would be lift pump... Haver you an easy(ish) way to add a pressure gauge into the supply to the pump? from the top of the filter housing? and see if the supply pressure drops..?
 
Oil pressure ?...thinking, when you're running at higher revs you're getting plenty of lubrication, but when you come off the oil pressure drops enough for the combined frictions to make it feel a bit sluggish and heavy ?... Does it get hot at all ?
Fuel pressure ? Not enough pressure to the injectors making it feel a bit lean....not even sure if that's possible, I'm still learning diesel stuff so tend toward similar ideas to a petrol ;)
 
Only other thing I can think of is to check the throttle control isn't sticking? What @mikeau says about smoke is a good point, if its not smoking then that could suggest a fuel control rather than a fuel/air supply issue.

If it had been a later model with a turbo you'd have said air mass meter, but no electronics, yaay! Kind of narrows it down. A bit... And, yes, fuel shut off solenoid is exactly that, on, or off. It either runs, or it don't.
 
Thanks @Big Sandy @mikeau and @freqmikey . Took the boy out for a run and of course it didn’t do it 🤣🤣 but will check for smoke next time it does it , no smoke then it’s fuelling I guess .

Interesting about throttle cable as they are routed in a convoluted way and pedal is a strange constraption as well .
Never gets hot in fact runs colder than it should but these engines are known to overheat so I’ve not fiddled with that . New water pump when timing belt done earlier this year .

Oil pressure 😳 hoping not .

I’m running some liqui moly through it at the moment then I’ll change the fuel filter so be interesting to see what the filter is like .

I need to do some reading as I don’t know if it has a fuel lift pump 🤔frustratingly there is no Haynes for the diesel version but will be something on google or the members forum .

Thanks for your ideas and suggestions . 👍
 
I'm thinking injector or injector pump or fuel pump. Anything affected by hotter thinner fuel. Is the bleed off looped into the feed or filter?
 
Thanks @Big Sandy . Advisory was wishbone upper bushes and they’re spot welded on 😱 so that’ll be fun . Fuelling resolved with 2 tins of liquimoly and blasts on the motorway and it’s cleared and can cruise at 60 now rather than 50 ish and not sluggish when coming off A road . So I think I had ?sticky? Injectors if there is such a thing
 
Aye, nice one. Probably just gummed up nozzles, or a bit of carbon. Good result.

I use Diesel Rhino (cheaper to buy on amazon than on the manufacturers site!) at every top up, when they did the sniff test on the T4 the readings were well below the limit. I've used that stuff for years, 1mk/litre of fuel. It's a cetane improver too, so more bang for your buck. It's a 3 tonne vehicle, 2.3d, and I average 33mpg. It was in the mid 20's when we got it. So, its not cheap initially, but pays for itself over a couple of tankfuls.
 
Ive been using this for a while;
www.hydra-fueladditives.com

Hydra Diesel Power Blast Injector Cleaner Fuel Additive

Hydra Diesel Power Blast Injector Cleaner Fuel Additive | Fuel Types | Diesel | ISO Certified, Same Day Dispatch
www.hydra-fueladditives.com

HYDRA Diesel Power Blast Treats UpTo 375 litres + Diesel Injector Cleaner 250ml: Amazon.co.uk: Car & Motorbike

HYDRA Diesel Power Blast Treats UpTo 375 litres + Diesel Injector Cleaner 250ml: Amazon.co.uk: Car & Motorbike
amzn.to

Seems to feel better but I have no comparison to other diesel additives (the only thing I compared was the price and the Amazon reviews).
 
Quite impressed with that liquimoly - more expensive than some but does the job

Diesel Rhino - I’ll have a look for that 👍 I tried Millers in the landy but didn’t notice any difference really .

Yep I weld (badly) 🤣🤣 . New foray into suspension as never touched it before but interesting to learn 👍
 
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