Turbo Diesel vs EO(ff)C

[Arragonis]

Hi,

I've tried EOC a couple of times to get used to the idea. Inflating tyres to the sidewall limit makes the steering usable so thats fine.

One question which struck me though is turbo temps. One thing advised to Turbo drivers including diesel, is to let the engine idle when stopping from high speeds - for example taking a break on the motorway. This was to allow cooller oil to circulate through the turbo and prevent heat soak doing nasty things to the seals.

My question is would EOC do the same thing, leave the hot oil sitting in the turbo ? There is airflow of course but the turbo is buried behind the engine, under a cover and just above the exhaust. Also with a grill block it isn't going to get much flow.

I had some suspected turbo issues recently and new ones are very spendy - luckily I just had a leaky boost pipe fixed with some gaffer tape for now.

Thanks.

A.

[Daox]

I wouldn't recommend a lot of EOC to turboed engine users for that reason. That, or you have an electric oil pump that continues to run after the engine has been shut down.

You might be able to get away with it more if you used synthetic oil, but I'd gather more info on it before trying it out.

[tasdrouille]

I don't agree with letting your turbo cool down by idling with a diesel when getting off the highway. Up to 70 mph my turbo is not even pushing 5 psi. Just the time you spend getting off the highway till you can actually park is plenty of time for the turbo to cool down.

That being said, I would not pulse and glide with EOC in my TDI on a regular basis. I don't like the fact of requesting max boost for ~10 secs and then immediately have the oil sit in the turbo. I do however EOC if I've been driving lightly in the previous minute or so.

[Arragonis]

If EOC is any top tips then it may be worth adding this caveat.

[vtec-e]

Originally Posted by Arragonis

If EOC is any top tips then it may be worth adding this caveat.

+1

I have to let my yaris idle for about 4 to 5 seconds before moving off due to some weird lack of power after i start it. It's a bit of a pain when i get caught short at a light that unexpectedly goes green. Perhaps my oil pump is getting tired and takes a little longer to get up to pressure......oh dear....spendy, as they say!

ollie

[ShadeTreeMech]

Does the Yaris have a turbo? your description would fit a turbo that hasn't spooled up yet, which would be cured with a bit of revving in neutral.

[dremd]

As some one who has coked up turbos in the past I may have some insight.

Below are my ***understandings***

1) PSI is not what is going to cause failures (preventable with a turbo timer), center housing temps are (which are largely dependent on EGT's. ("we" are cooking the oil in the turbo after shutdown, which leads to coking, which leads to poor lubrication then failure)

2) Synthetic oils ability to withstand much much higher temps is a huge asset here.

3) If we are running our center housings (turbo oil temperatures) up near/ above coking point, then we will have very quick oil breakdown (another god point for doing Used Oil analysis).

4) if the center housing is not at/ near the varnish/ slugging/ coking point then the heat soak from exaust should not push the center housing up too much farther.

5) even the worst oil available today is better than almost any oil available 20 years ago.

Anybody interested should go hang out on Bobistheoilguy, not so much for opinions, as for information.

If any of my understandings are wrong, please correct me.

[Arragonis]

If the Yaris has VVT then it may be an oil pressure issue, I think (maybe wrongly) the VVT system uses oil pressure to make its adjustments. Maybe a non-return filter may help.

dremd - you may be right. A lot of VRS owners have put down turbo failure to not allowing the turbo to cool - kind of you hammer down the motorway at 70-90, stop for a pee and shut the engine off in the rest area / services straight away. Do it enough times and the oil in the turbo stays there happily cooking.

Not sure about coking, the issue reported is that the seals start to fail rather allowing oil into the turbo and lots of blue smoke, rather than the bearings failing which would be poor oil supply due to it coking.

Of course I could be wrong too. I feed mine the VW spec 505.x (I think thats the spec) synthetic oil and at the moment it uses non between changes which is why my I looked elsewhere for my recent turbo smoke than worn parts. Luckily my gaffer tape / turbo boost pipe fix seems to have cured it.

[dremd]

Originally Posted by Arragonis

If the Yaris has VVT then it may be an oil pressure issue, I think (maybe wrongly) the VVT system uses oil pressure to make its adjustments. Maybe a non-return filter may help.

You are correct about oil pressure, I've had a few Toyota VVTI motors apart before.

Originally Posted by Arragonis

dremd - you may be right. A lot of VRS owners have put down turbo failure to not allowing the turbo to cool - kind of you hammer down the motorway at 70-90, stop for a pee and shut the engine off in the rest area / services straight away. Do it enough times and the oil in the turbo stays there happily cooking.

Not sure about coking, the issue reported is that the seals start to fail rather allowing oil into the turbo and lots of blue smoke, rather than the bearings failing which would be poor oil supply due to it coking.

Of course I could be wrong too. I feed mine the VW spec 505.x (I think thats the spec) synthetic oil and at the moment it uses non between changes which is why my I looked elsewhere for my recent turbo smoke than worn parts. Luckily my gaffer tape / turbo boost pipe fix seems to have cured it.

To be honest, I forgot about turbo seals

Is your VRX a PD? I'm not up to date with Euro TDi years/ motors.

MY ALH TDI used just over 1 cup in the last 60,000 miles (last drain), I thought I was burning a little bit, but an astute friend noted that that is about the amount that I have sent off for sampling.

[ShadeTreeMech]

Originally Posted by Arragonis

I feed mine the VW spec 505.x (I think thats the spec) synthetic oil and at the moment it uses non between changes which is why my I looked elsewhere for my recent turbo smoke than worn parts. Luckily my gaffer tape / turbo boost pipe fix seems to have cured it.

I suspect the smoke you were seeing was as result of lost boost pressure--the boost pipe you fixed was on the pressurized side, correct? Assuming that, the smoke was likely unspent fuel the engine injected while expecting full boost pressure. Hence the reason naturally aspirated diesels tend to be a bit smoky; the extra air helps to burn all the fuel.