Safe to drive MK4 with failed turbo?

Buying a 2002 TDI Jetta for cheap. My friend says he has driven this car since the turbo is not working. Drives slow, he says....oh yah! I intend to look it over before deciding if I myself want to drive it home or call AAA to haul it.

I understand that if the turbo blows apart, it will waste the engine...having replaced turbos and heads on Cummins engines before.

What if the turbo is simply seized. This creates a restriction, so power is far less, but may allow me to putt the car home.

Never owned a TDI (had BMW 2.4, Benz SD), so can I take the intake off and look at the hot side of the turbo to determine anything?

Why would I want to drive it home? To check out all other systems...brakes...steering, etc for eval. Is it a restorable driver or partscar?

First of all you need to check oil level, and if there's blueish smoke at exhaust you cannot use the car, because it'll burn all the engine oil.

I suggest to check the turbo visually before using the car, it'll be much safer

I definitely wouldn't risk it, just because it doesn't show signs presently, who knows what might happen 5 minutes down the road.
You risk engine runaway blowing the engine and/or burning the engine oil completely causing the engine to seize the rod bearings and worse!

Definite risk, but....
I would ask why he thinks the turbo is shot. If it's just low power, good chance it's something else. You''ll want to do your own evaluation, we try our best to help, we can only interweb guess. Question owner about symptoms, smoke, noise, leaks, whatever you can think of.

find a vagcom and scan it....

borntofli said:

find a vagcom and scan it....

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got a vag-com.
1. most concerned with a turbo that spins and destructs.
2. not so much worried about a turbo that's seized and is obstructing flow/power.
3. concerned about a blown seal that dumps oil into the engine.
i'll inquire of how he determined turbo bad. He says he's got all the maintenance records since day 1, so I assume he brought it to his mechanic and got the bad news.... whatever that was...needs a new turbo or maybe some extensive shop work...diagnosing, trying fixes, r&r parts, etc.
He gave this car to his growing kids, and now they're out of the nest.
How about an OBD scan as a rough first Dx effort? My vag-com is on my laptop and just isn't convenient to operate in the field.

I would use vag-com, laptop is just what it is.
Obd won't pull everything available, just generic codes. May be that there's a key clue and you won't be able to catch it with generic obd reader.

Just a guess if visually the turbo looks OK and there is no signs of leaking oil, then it just may be in LIMP mode causing the low power, if it is that case then you may be able to drive it home provided that its not a long drive. but to be safe I would most likely get it towed.

Buyer says it's in limp mode, keeps dropping the turbo mode when hard acceleration/high speed. i'm going to put-put it home.

Maybe just a dirty/malfunctioning MAP sensor? The one behind the passenger headlight.

ccaissie said:

Buyer says it's in limp mode, keeps dropping the turbo mode when hard acceleration/high speed. i'm going to put-put it home.

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Does not necessarily mean the turbo itself is shot, but something needs to be corrected. Scans, engine codes etc, go from that info. I dealt with limp mode on my older tdi for years.. just gotta cycle key to get functionality back

^ditto^

As already suggested...

Scan it! Inspect it! Check the oil! Does it smoke idling? Does the engine start-up okay? Coolant level up? How much oil has the owner had to put in it?, etc, etc.,

There's nothing here but, He said, she said! Where's the proof besides low power?

Limp mode can be a result of several things and not always the Turbo itself.

Gave it a good once-over. All levels good, no smoke, started nicely runs very well. Kept it under 60mph, sweet car.

I'll do a scan and review all the maintenance receipts...everything saved since day ONE.

Good rubber, 50K left on timing belt. very happy. will research the turbo diagnostics and take care of the simple stuff to eliminate those. It was just getting too expensive to maintain....Since I've worked on diesel equipment , I'm not scared of the mechanical side of it. The electronics however scares the **** out of me

Sounds like your VNT Actuator could be stuck.

Check if your actuator moves on start up, if not it could be sticky vanes. Very simple fix. I bought a sub 500 dollar car with the same issues. 40 bucks later turbo is perfect, I also put a new intercooler in, and ALL brand new vaccum lines.

What about plugged intake, you know EGR buildup over the years? Many things cause limp mode and no boost conditions. Check turbo, intake, vacuum hoses and vacuum pump. Please let us know how it goes.

Did the receipt for the timing belt indicate all the rollers and water pump were changed?
If the water pump bearings or roller bearings go it could cause the belt to slip.

Drove it today. It actually has good boost 3rd gear full throttle until about 60, then it cuts out and will not accelerate any further, and behaves sluggishly. Then CEL comes on.

I hadn't really done a hard repeated test to get this kind of reading...Reset with key is effective.

So, turbo actually works, but goes into limp mode. I'll follow up on all the help offered on the limp issue. Now I get it.

ccaissie said:

Drove it today. It actually has good boost 3rd gear full throttle until about 60, then it cuts out and will not accelerate any further, and behaves sluggishly. Then CEL comes on.

Click to expand...

Next, use vag-com to get the code -before- shutting the engine off. Will probably be for over boost.

Log the run again in vag-com logging MAF, Boost, and N75 percentage.

You can upload the log to: https://malonetuning.com/news/14
It will create a bar graph that the wizards here can look at and give you an idea what it could be.

The following thread (which is also linked in 'BobnOH' signature) is a good guide for what steps to check to proceed in a good order rather than throwing money at rare causes prematurely. Best bet is to follow the steps in order listed until you find the one, or several, causes of your issue.


http://forums.tdiclub.com/showthread.php?t=179589


Side note #1: If the turbo is frequently in limp mode or a permanent low power condition, then excess oil can sometimes accumulate in the intercooler (from normal crankcase vent vapors) so it's a good idea to drain that before fixing the problem. That eliminates the possibility that your first full dose of boost pressure might force some accumulated oil into intake.


Side note #2: Once you figure out the (likely) simple, fix it's probably best not to mention it to your friend.