low top speed

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yudansha

New Member
Posts
38
Location
liverpool
Hello all
bit of a weird one this, my 300tdi r reg is having trouble getting past 65 on a flat road will sometimes get to 70 but wont hold it for long, seems speedy enough, for a disco that is, around the earlier speeds up to 50 so is brilliant for driving around the city streets and the turbo seems to belt in at 2000 revs so that seems to be behaving. I have even had it decatted to see if that gave the old darlin a bit mpore oomph.
getting decent mileage out of what i put in but just no welly.
 
there is a chance that the viscus cooling fan is nacked and is perminantly in the locked up posision, i removed the fan on my 98 tdi auto all together as it gives a little bit more mpg and power and will easily get up to 80-90 mph no probs :)
 
Is it standard other than the decat? Bigger tyres, suspension lifts and bolt on extras can all affect the top end, mine goes a max 75-80 now and thats with tuning it up due to the big tyres and extra weight...
 
Yup its standard. Was hoping to start adding and amending when the money gets a bit better... lift, bigger wheels some other bits...
I love my landy and use it every day for work and its reliable as anything and as i said up to 60 its fine.
I have had faster out of it but as i only use it round town with a little off road never got around this speed for a long time but on the motorway the other day just couldnt get anything out of it.
very stupid question but why would the fan affect the top speed???
 
Have you serviced it?

The way diesels work is if its not going well, then its either not getting the fuel in, air in or air out! You've covered the air out with the decat, what about air in? Intercooler and air filter should cover that. Next its fuel in, is the pump getting enough fuel into the engine? Is the fuel filter clogged? Have you drained the sedementer recently?
 
yudansha said:
Yup its standard. Was hoping to start adding and amending when the money gets a bit better... lift, bigger wheels some other bits...
I love my landy and use it every day for work and its reliable as anything and as i said up to 60 its fine.
I have had faster out of it but as i only use it round town with a little off road never got around this speed for a long time but on the motorway the other day just couldnt get anything out of it.
very stupid question but why would the fan affect the top speed???
Click to expand...

Hi yudansha

the idea of a viscus fan is that it more or less freewheels till the engine starts to get hotter than normal like heavy towing up a steep hill then the fan locks up to spin at the same speed as the engine is rotating to keep the engine cool then once to temp drops the fan unlock and freewheels again, the viscuse fan is prone to this problem and the best way to test it is with the engine switched ( OFF ) try and spin the fan with your fingers if its tight its stuck in the locked up position and will put more drag on the engine at low speeds and if it spins ok then the prob isn't the fan.

the reason peeps remove the fan is because the fan ( working correctly ) tends to over cool the engine anyway but still with a bit of drag so with the fan removed but kept in the back of the car with the right spanner looses that bit of drag and runs at normal temp just as it would with the fan fitted, infact with the fan off i find the engine runs cooler on the gauge than it does with the fan fitted meaning with the fan fitted the gauge reads just under normal and with the fan removed the gauge reads a little bit more under still :)
 
done the service...no joy..
the lever on the fuel lift pump is very slack ...I have ordered a new one,
unfortunately not a delphi one but will let you know how that goes when fitted.
 
I would give it a dam good service then clean sediment bowl, intercooler, inlet manifold turbo pipes and run the fuel tank down clean out fuel lines and run some injector cleaner first before getting any bits to bolt on.

Posabley after that remove the EGR valve and replace the lift pump
 
yudansha said:
done the service...no joy..
the lever on the fuel lift pump is very slack ...I have ordered a new one,
unfortunately not a delphi one but will let you know how that goes when fitted.
Click to expand...

I would get a Delphi as a spare-my last Britpart lift pump just made 2 weeks,before it ruptured round the back and pumped biodiesel into the camshaft area-so complete oil change as well :)
 
Lovely and not scaring me at all :D
did a service on it the other day so know all the filters and everything are fine. I am going to check all hosing for splits as well

egr has been removed and it has been decatted.... only noticed a little bit different on lower end pulling away but this is probably my extremely over active imagination
 
fuel lift pump changed and tried on the motorway... got to 50 in third and managed to get to 70 (the giddy heights) but struggled after that... hmm. I also checked for smoke at the back and its clearer than a nuns conscience.
 
Last edited:
yudansha said:
fuel lift pump changed and tried on the motorway... got to 50 in third and managed to get to 70 (the giddy heights) but struggled after that... hmm. I also checked for smoke at the back and its clearer than a nuns conscience.
Click to expand...

This is sounding more like a breathing issue to me?

I can't be arsed reading back through but have you removed the intercooler and given it a really good clean out? New air filter? This isn't a HUGE one now, but it is a problem. A restriction in the pipework?
 
put a new air filter in will get the intercooler checked out when i get a bit of time... as i said up to 50mph its quite nippy as a landy goes and still really fun to drive..
 
also as mentioned its had the egr blanked out... mind you saying that the drop in performance was before this so the gunk could have been in there before..

another dozy question... would this have also affacted my mpg numbers
 
Have you cleaned out the fuel sedimenter. It's the thing on the chassis rail near the rear offside wheel, on the inside of the rail. Looks like a fuel filter housing.


These never get serviced so end up getting full of a jelly-like substance that reduces/stops fuel flow to the engine.

DO NOT TRY AND REMOVE THE WHITE PLASTIC TAP ON THE BOTTOM, IT WILL BREAK!!!!

You need an 11mm ring spanner to undo the retaining bolt which is accessible at the top of the housing. Undo this, then carefully remove the bowl. Marvell at the pond-life within !!! Clean and replace .
 
I cleaned out the intercooler and was about to start on the inlet manifold when I noticed a huge split at the bottom of the elbow I have missed first time, thankfully I manage to procure 1 from the land rover supermarket for the princely sum of 4 pounds. Because I have no patience I changed it in the car park and drove home the difference is unbelievable it's a different car.
I feel an idiot for missing this first time round but realistically it has made me do some much needed maintenance.
Many thanks for all of the wonderful assistance
 
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