2003 VW LT35 - Turbo Whistles & Loss of power

[robertwo]

Hi (sorry for the essay below)

As the title suggests I have a 53 Plate VW LT35 109 bhp that has done about 69,000 miles.

The problem I am having is that the Turbo seems to be getting louder, by this I mean I keep hearing whistling, usually when I let off the accelerator as it is hard to hear over the engine noise otherwise.

The other problem is that randomly the van loses power momentarily, usually in 4th or 5th gear. The loss of power is hard to describe, but it feels like for instance a release of pressure has happened - it happens so quick it is hard to judge a speed that it happens at, type of road conditions etc....

I changed the oil a few days back and this problem has become less noticable. I was traveling before the oil change on a journey of about 50 miles and this was happening every few miles. I did the same journey yesterday and this problem only occured a couple of times. I'm not sure on the specifics, but I think it happens when accelerating in 4th or 5th when around 45-55mph.

A little history on the van - I only purchasd it back last november and I didn't notice this problem until I sent it to VW to have it checked over as I was going to be out of the country for over a year with the van. They found that there was a problem with some pipes from/to the Turbo and that there was a leak on the intercooler (sorry not sure if thats correct - I mean the shinny silver radiator in the front fo the van where these pipes go to). Anyway, VW replaced these and serviced the van at great expense to me and the van has run good ever since, except now and again this loss of power happens, but it was so infrequent that I didn't worry about it until now.

Things I have checked - Air filter is clean; tightened all the clips on the large rubber hoses from the turbo; changed oil (not filter); added some redex to a tank of diesel to see if it helped any (it might have a bit or it could have been the oil change as both done at the same time). The oil was replaced with a Elf (I think) 10W40 oil that meets the VW 505.000 specs.

BTW, the vans accelerates fine, starts perfectly (actually starts better cold than hot), drives fine, no smoke ect

I'd be grateful to hear from anyone with any ideas as I will not be back int he UK with the van for a few months so would like to try and solve this if possible.

Thanks

Rob.

[GeorgeOK]

Hi Rob, sounds like you need a new fuel filter.

[rayl]

Hi Robertwo, the milage is nice and low for the year, take it its not had a hard life ? when you say vw did a service do you know which service they did as georgeok said the fuel filter may need a change if never been done before or a long time ago, ref the turbo whistle mine has done that since new (53plate 400,000plus miles) had a new turbo when van was young 1yr ish but not changed due to whistle, but new turbo whistled and still does to this day on slow down not had any probs from it though, a couple of others on here may give there opinion on the whistle as to if its a problem or not, you seem to have checked the obvious items, if it has not been done already may i sugest that the cam belt get changed sooner than later if its the original belt, this one little item seems to be the devil that kills most good lt engine's off when they snap, a bit £££££ when done by vw but certainly cheaper than a new engine.

[anilkumar]

hi threre my dad has a lt 35 2.5 tdi 05 with 137 k on it. is it normal to have a quite a bit of lag in 1st and 2 gear but when in 3rd it fliles owner before me used to change oil every 5 k due doing lots of motorway miles timing belt being done and a new turbo a few thosuand miles ago

[rayl]

Hi, never had a noticable lag in first and second gear power has been there through all the gears with mine, check pipes going to and from turbo, seating, condition, clips etc, although when i think back to when van was brand new in 2004 on first pull away from cols she used to chuck black smoke out and cough stutter then was alright for rest of day, was called back if memory serves right for a new ecu as some had faults in them, but been fine since...ray

[milljoo]

hi,you have probably sorted your loss of power problem by now. i thought i would say about my van, LT35 158BHP, also loosing power. i could hear a hissing noise, which i thought was the rubber hose from the turbo to the intercooler. spent days checking, they were all o.k. then i found a split in the plastic end cap of the intercooler!! so for £85 (G.S.F) fitted a new intercooler, sorted.

[boisty]

Take a look at the following link: LT35 Losing Power (http://www.vwaudiforum.co.uk/forum/showthread.php?84993-LT35-Losing-Power)

7 pages of threads regarding a similar condition which may help.