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Cooling the turbo


vegaluca
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Hi ya,

I just picked up my MK iv GTI 1.8t last week and am stoked with it, 3 door beefy zippy mechine.

The question I have is ... do you need to let the car stand idle with the engine running for a few minutes after a spin, to let the turbo cool down ?

A friend of mine told me that you have to do this and another said that the GTI is a hard engine and you don't have to, whereaz with a scooby the engine is reportedly "softer" and needs to stand running idle for a few minutes. I have been letting it sit idle for about two minutes after each run and to be honest ... it sucks monkey balls !

BTW ... I carried out a search first but couldn't seem to find anything about this, mayby I was doing it wrong UHOH7.GIF

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No idea what your mate means by "hard" and "soft" engines. My own experience is with Subarus, but I'd apply it to any car with a turbo...

If you stop immediately after a hard run, then it is advisable to let the engine idle for 1 or 2 minutes (no need for any longer). In most circumstances, you'll have been pottering along some side streets or in traffic before you stop, so the turbo will already have cooled. i.e. you only really need to let it idle if you've pulled in after a proper B road blast, or into motorway services, or maybe into the pits at a trackday - that kinda thing. 169144-ok.gif

I'm no mechanic, so hopefully someone else can clarify: the reason for doing this is to allow the turbo components to cool while the engine is running and oil & coolant are circulating. Turning off straight from a fast run will leave the turbo components extremely hot and prone to cracking.

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Wasn't it said that there is a mechinism to cool it down after you have left the car. I honestly can't remember and I am no mechanic either but something like it pumped oil round to cool it down.

Or is this in place but its still advisable to do this anyway.

It doesn't state anything in the manual about care for the turbo and as this time the manual is quite comprehensive I would of expected it to be in their

Edit: My mistake just seen it says MKiV GTI, please just ingore me NONO3.GIF

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Yes, the GTI comes with certain automatic systems....If you listen hard you can actually hear some of them. The simple physical fact is though that it's very bad to thrash any engine while still cold. With performance comes a certain amount of extra care. A friend of mine had an old Ferrari and used to sit in it for at least 5 minutes before a wheel was turned. I know that technology has advanced but the same basic principles remain.

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I've got a few mechanic friends and they reckon that the best way to warm your engine/turbo up is to drive it. They say to keep the revs down for the first few miles, generally until the temperature needle starts to move, then gradually build the revs up until the needle is vertical, then you can go for it wink.gif Only takes 5 minutes and avoids that costly turbo rebuil frown.gif

On the cooling down side; I have a brilliant b-road leading to my village and I go for it over there, but as soon as I'm into the village I select a high gear and cruise under the turbo cut in until I get home. This gives a few minutes for the turbo to start cooling whilst the oil is still circulating.

You can get, as mentioned, delays that will keep the engine running, however I do believe that it is illegal to do this, at least on a public street. I have no idea why and I'd have to contact a copper mate to ask for sure, but be careful smile.gif

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I do the same as you, Stevie and would much rather continue such habits than fit an aftermarket device. The old Ferrari I mentioned wasn't turbocharged.

I think the principle of the law is that you shouldn't leave a car unattended if you are no longer in control by leaving the scene.

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[ QUOTE ]

One of my mates also mentioned that some guys fit a delay cut off, so you can park up, lock up, walk away from your car knowing that the engine will shut down after two minutes.

[/ QUOTE ]

Yep thats called a turbo timer. A friend of mine has one and you can set the amount of time the engine is left running after the keys are taken out of the ignition.

You can pick them up on Ebay for about £50 I think?

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I've always been told not to thrash until the oil temp has reached optimum...as the GTI hasn't got an oil temp gauge......but on other cars I've had that do have an oil temp gauge, these are normally only just starting show an increase in oil temp when the Water temp gauge indicates it has reached optimum.

I'm giving mine another 5 mins of max 3K revs after Water temp has hit vertical, especially on these cold mornings.

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According to a PDF I have on the GTI engine it says.

[ QUOTE ]

To prevent carbon build-up on the turbine

shaft in the turbocharger, an auxiliary

coolant pump provides additional coolant

circulation for a certain time after the

engine is shut off hot. The pump forces

the lower temperature coolant against the

normal direction of flow. The coolant flows

from the radiator through the turbocharger

to the engine block and back to the cooler.

[/ QUOTE ]

So it looks like it is already built in smile.gif

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Hey Mike do you happen to know if thats just in the MK V or would it apply to the MK IV too ?

Thanks a mill for the replys guys I really didn't know about driving it on when the car was cold, I see that ye guys refer to yer temp guages when they reach vertical ... mine just goes to ten o clock when she's warmed up.

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IIRC, the main reason why keeping the engine running for a minute or so after a blast is a good idea is to let the turbo vanes slow down from the very high roational speeds they get up to when the turbo is boosting.

Switching the engine off while the vanes are still whizzing at max speed is akin to switching the engine off while the car's doing 80 - you'll kill the internal bearings. The turbo oil feed is pumping only while the engine's running, so switching off stops the cooling lubrication getting to the bearings.

At least, that was the story when I flew Spitfires over Dresden during the war...

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It never ceases to amaze me how many sports/high performance cars don't come fitted with an oil temp gauge.

In cars I've had with one fitted it takes several more miles for the oil to get upto temp after the water has. In manual cars often the tell tale sign is when the gearshift becomes less stiff.

Regarding cooling the turbo, if I've been driving quickly I just try and take it steady for the last couple of miles before I know I'm going to stop.

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My high-end Pioneer SatNav&Audio head unit has an additional option, sold separately, of monitoring all sorts of tech info about the car's systems which probably include oil temp but it's a very expensive option. I'm now curious and will check it.

Otherwise I wonder if anyone produces an aftermarket oil temp guage. Twinned with a turbo boost guage would be very cooool!

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[ QUOTE ]

My high-end Pioneer SatNav&Audio head unit has an additional option, sold separately, of monitoring all sorts of tech info about the car's systems which probably include oil temp but it's a very expensive option. I'm now curious and will check it.

Otherwise I wonder if anyone produces an aftermarket oil temp guage. Twinned with a turbo boost guage would be very cooool!

[/ QUOTE ]

Sorry to high jack this thread but I'm also very interested in fitting the Pioneer or Alpine sat nav. Red do you have any pics of what it looks like with the screen open, how easy was it to fit and whats the quality of the sat nav like? Also is the audio quality better than the standard fit VW system?

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[ QUOTE ]

[ QUOTE ]

My high-end Pioneer SatNav&Audio head unit has an additional option, sold separately, of monitoring all sorts of tech info about the car's systems which probably include oil temp but it's a very expensive option. I'm now curious and will check it.

Otherwise I wonder if anyone produces an aftermarket oil temp guage. Twinned with a turbo boost guage would be very cooool!

[/ QUOTE ]

Sorry to high jack this thread but I'm also very interested in fitting the Pioneer or Alpine sat nav. Red do you have any pics of what it looks like with the screen open, how easy was it to fit and whats the quality of the sat nav like? Also is the audio quality better than the standard fit VW system?

[/ QUOTE ]

Red posted a thread about it some time back, I'll have a quick look for you and post it if Red doesn't get back first.

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[ QUOTE ]

Sorry to high jack this thread but I'm also very interested in fitting the Pioneer or Alpine sat nav. Red do you have any pics of what it looks like with the screen open, how easy was it to fit and whats the quality of the sat nav like? Also is the audio quality better than the standard fit VW system?

[/ QUOTE ]

check out the pictures of Red's installation in the link below.

http://www.tyresmoke.net/ubbthreads/showflat.php/Cat/0/Number/565317/page/0/fpart/3/vc/1

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[ QUOTE ]

[ QUOTE ]

mine just goes to ten o clock when she's warmed up.

[/ QUOTE ]

It should go to the 12 o'clock (vertical) position, and shouldn't change either no matter how you drive it. Might be worth getting this looked at.

HTH 169144-ok.gif

[/ QUOTE ]

maybe he's a couple of hours behind grin.gif

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[ QUOTE ]

check out the pictures of Red's installation in the link below.

http://www.tyresmoke.net/ubbthreads/showflat.php/Cat/0/Number/565317/page/0/fpart/3/vc/1

[/ QUOTE ]

Many thanks for this link, I've just printed it of to read it and keep it for reference.

I'm very seriously tempted by this Pioneer Avic system. I'll have to go and demo one. I'm mainly interested in sat nav, tv, cd/radio and the car management.

Red, now you have been using yours for a while, whats the verdict? Would you still buy it again?

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