Club 80-90 Forums

I've got a 1989 tdi vw afn 1.9 conversion on my bus and i pretty sure the turbo has just give up .I've seem to have lost a lot of power ,its running ok but with no power . i can not here any turbo whistle when i rev it as well .just wanted to know is changing the turbo an easy job any tips etc .can anybody recommend a good turbo surpplier

More information on your conversion is required before any real diagnosis can be made-however Normal turbo is a VNT15 which relies on vacuum to alter the nozzle geometry within the turbo. If the diaphragm canister on the turbo is defective then no amount of vacuum will operate the VNT arm to give you turbo boost-the engine will run but will not develop any significant power. This is where i would start.
Get asistant to start the engine whilst viewing the operating arm of the diaphragm-this should move round 10-12mm if it dosent move and you can still manualy move the arm(against cannister return spring) then canister or vacuum piping from the N75 solenoid valve is likely to be at fault.You really need to check all small bore pipework for cracks/perishing as any leak will affect the performnce.I do not have to hand a diagram of the vacuum control circuit but I'm sure a google search will point you in the correct direction.
Are you also sure that a turbo pipe has not come off/is leaking so engine is behaving like a normally aspirated one?
Check and check again- a blown turbo will normally indicate its demise by a smoky exhaust at least.
Something to be getting on with before thinking about parting with hard earned cash !!

Obviously if its a afn transplant without electronics(ecu etc) disregard above.
Good luck.

Thanks for the reply it is a full afn conversion with ecu etc i will check everything you have told me to check .Is the vnt15 a standard turbo that would be fitted to a vw passat or audi a4 so if it is the turbo i can buy one .

yes the VNT15 is the standard turbo fitted to the a4 and passat up to around 2000/2001.Somebody like Midland Turbos should be able to supply a new turbo(which i believe will be a 'refurbished one') but you could always send your unit in for cartridge replacement and maybe save a few bob.
Do you know whether the turbo has been indexed to put the oil drain at the optimum position and does the return go to sump or the block ?
I'm assuming the engine is still at 50 degrees . There are many different vag components used in these conversions such as intake/exhaust manifolds hence my ??. I run the turbo on the old JX manifold which although not ideal gives me a better oil return IMO than say a sharan engine donor using that particular inlet-plus i keep the original exhaust(using a turbo adaptor).

panic over i found the 6mm rubber 90 degrees elbow on top of the actuator had split into two, so i put a temporary bit of 6mm rubber pipe on and the turbo is working again. cheap fix