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Discussion Starter · #1 ·
Hi all, 1st post and all that so a quick intro:

I have a not very exciting tdi 90 Bora and a Fiat Coupe 20V Turbo. My mate is a mechanic and has been looking for something a bit more fun that the Bora but still a bit practical. He has found a W plate Golf GT Tdi, i think its the 130 and it's deffo a PD engine. The story is that the turbo blew and filled the exhaust with oil. The owner had a new turbo and exhaust fitted but the garage couldn't get the car to boost. It drives fine, just no boost pressure.

While the car was at the garage someone nicked the alloys, the garage went to VW and bought a brand new set, must have cost a fortune!!

We popped over for a look and its started perfectly, idles nicely and when you rev it you can hear the turbo spool. No MIL on the dash, just no boost. I dont know what work the garage that changed the turbo carried out, whether or not they checked the intercooler etc for oil.

Anyone care to hazard a guess or suggest any things that could be at fault? I'm reasonably mechanically proficient ( i own a fiat coupe after all!) and obviously my mate will help me. It's just a bit of a risk buying a faulty car. It's in good nick otherwise and done 147k, what sort of cash is it worth?

Cheers, Paul
 

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Sounds daft but is there no boost or just very very little? When I take out my MAF sensor this is what I get, feels like limp mode.

Unplug the MAF sensor and see if it makes a difference (Plugs in just behind the air filter)

Best of luck.
 

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It must be 115bhp.
Is there any smoke when driving?
If it's in constant limp mode I would be looking for incorrect vac pipes or incorrectly adjusted turbo actuator.
Put it on any fault code reader and check engine faults (after reseting them) if there is a boost deviation one it could be used as a guide. Negative deviation points towards vacuum/contol problems and high deviation points towards turbo vanes being wedged open.
The cat loves to block when the turbo fails but that's normally indicated by massive smoke.
 

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Finding someone with vcds might help. Component like the turbo actor can be checked using engine output testing, live data can see if the maf is gone etc.
 

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Discussion Starter · #8 ·
"Unplug the MAF sensor and see if it makes a difference (Plugs in just behind the air filter)"

I'll try that, thanks :)

I would say it felt like limp mode, was pretty dark so i couldn't see if there was much smoke but it felt lifeless like my ibiza tdi did when the turbo vanes clogged up and it overboosted and went into limp mode. AFAIK it has a new cat on it too. My mate reckons its maf related, it would certainly explain things. I wont get another chance to look at it till ive actually bought it. Anyone hazard a guess at a guide price?
 

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Ah yea W plate, like Aham said it will be a PD115 as the 130/150 weren't made until 02, though the replacement turbo 'could' have been for a 130, you'd have to find out about that though.

And as the turbo had just been replaced i'd say Aham is spot on in what is causing the problem, i skim read posts to much... :D

Depends what condition it's in, but considering you can get relatively good condition ones for £2k i'd say about £1200-1600?
 

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Discussion Starter · #10 ·
Right, further news is that it has been hooked up to the fault code reader in my mates garage. It came up saying there was an error with the boost pressure controller. Would i be right in thinking this is the n75 solenoid? Can i test it without using vcds? ie, blow through it then connect 12v to it, then blow through it again and see if its opened or closed?

Thanks for the advice so far :)
 

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Discussion Starter · #12 ·
I dont know if it said a number, he didnt mention that. I think the scanner they have is bosch so i dont know if it displays the code number.

Could i swap over the N75 from my TDi90 Bora or does it have a different system of boost control, being a non variable vane turbo?
 

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Discussion Starter · #14 ·
Ok, got the car home and had a good look at it, pretty chuffed so far [Y]

I took the N75 valve off and checked it over, it was giving me a resistance of 10 ohms across the terminals. When i connected a small 12v battery across the terminals there was no clicking of the valve opening and when i blew through the hose and put the battery on it i still couldnt blow through it. Then i noticed a large crack on the bottom of the valve where the coil is, I tink the coil has burned out and split the plastic of the valve body.

I take it this is highly likely to be the problem? Any ideas what the VW part number might be?



 

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Discussion Starter · #17 ·
Well, i got a new valve from VW for £43 and fitted it. It made no difference but can't do any harm as the old one was clearly knacked!

I unplugged the MAF and the car felt exactly the same. I checked the MAF on my Bora and it had the same part number so i swapped them over and it feels like a different car, boost is back in a big way!

Comparing it to the non-PD engine in my Bora is it same to say they drive differently? The bora seems to have more torque lower down the rpm range and doesn't feel like a turbo car ie, less noticeable "kick" when the turbo comes in. The PD seems to be fairly flat for a few hundred rpm and then the boost comes in and it takes off.

One last problem with it is there is a drip of oil onto the undertray and it seems to be from the very top of the engine and there was oil sitting in the rubber cup round the filler neck. Is it possible for them to leak/blow oil out here or is it someone clumsy spilling oil when they filled it?

Car has just had new OE turbo & full exhaust due to old turbo blowing its oil seals and filling the exhaust etc with oil.
 

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So it was the MAF sensor tha was away?

Are you sure it's an oil leak or is it maybe just some drips from spilt oil from before?
 

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Discussion Starter · #19 ·
Yep, the MAF was dead and the N75 was faulty too.

It's definately an oil leak, i've removed the undertray and wiped up any oil that i could see. Then run the engine with a white board under the car and there is spots of oil on it after a couple of minuutes. I think i have traced the leak to the turbo oil feed pipe where it goes into the turbo. It appears to be tight but should it have an o-ring or any type of seal on it? Any ideas why it would be leaking?
 

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Discussion Starter · #20 ·
Found the oil leak. The turbo oil feed pipe screws onto an adapter that screws into the turbo itself. The oil feed was tight but the adapter was slack and also had a washer missing between it and the turbo housing.

Car is all cleaned up and goes well but i have a couple of further questions:

The rear brake pipes on the rear beam are corroded. They go from the flexi that goes into the caliper back to a union just in front of the beam, they run along the rear beam and are held down by wee clips. Are these a VW only part as the flexi is crimped onto the steel pipe thats corroded.

What oil should i use? PD oil seems to be a minefield!

My headlamps seem to have a projector lamp in the light cluster that doesnt light up when all the lights and main beam is switched on, i dont have a fog light switch on the dash as far as i can see. What are they for?

They are directly under the indicator lamp in this pic:

Posted Image
 
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