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The mkiv Supra Owners Club

An awful end to a great night!


JackyBoi

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You might have fried your piston rings causing excessive crank case pressure which, in turn, blew your oil cap off.

 

I hope not, but if so then hey ho it's a rebuild over winter, not ideal obviously but if it's gotta be done its gotta be done!

 

Ouch expensive mistake!

 

Well a turbo rebuild should be cheaper than an engine so fingers crossed thats all it is

 

Fingers crossed indeed [emoji108]

 

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If you had a lack of oil to the turbo you would have had a lack of oil to the engine.hope it is just the turbo.

 

Yup oil level was halfway when it all happened, didn't cause any warning lights or a loss of oil pressure (supposedly) but there's a lot of potential factors involved i.e did the cap wiggle off by itself, did fried piston rings & high crank case pressure cause it to come off, was the turbo seal already on its way out, or am I just very unlucky as my thread has already proven :p

 

I'll be letting everyone know exactly what went wrong once it's all been stripped down :thumbs:

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Guest Budz86

I'd say the blown oil seals are more to do with you using anti lag, seen it happen more than once. Syvecs wouldn't have caught that as it won't be much oil being lost but will create loads of smoke.

 

As for filler cap being left loose, it won't cause a noticeable pressure change in the system but it will make a hell of a mess!

 

 

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Might be worth taking the logs from the Syvecs and getting Ryan to.look at it :)

 

Good idea, I think I'll do that since I can now actually access my ECU lol :)

 

Loss of oil pressure is never going to make the cap come off, you must have left lose.

 

I couldn't have left the oil cap loose, last time I touched it (prior to this breakdown) was when I changed the oil on 14/05/16 - if it was left loose then it's been loose since then and I see no reason why it wouldn't have come off much sooner!

 

Pmsl :D

 

Jacky, you might want to check your floor pans are still intact.

 

To be honest I thought I felt a draft coming from below [emoji848] phahaha

 

I'd say the blown oil seals are more to do with you using anti lag, seen it happen more than once. Syvecs wouldn't have caught that as it won't be much oil being lost but will create loads of smoke.

 

As for filler cap being left loose, it won't cause a noticeable pressure change in the system but it will make a hell of a mess!

 

/QUOTE]

 

You could be right, although my thinking is that the thing that initially caused all of this was the oil cap coming off, which lead to oil loss, which led to a failing oil seal which lead to even more oil loss... My mechanic will be able to tell me soon enough - she's being recovered today.

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I think it's more likely that the crank case pressurised, blowing the cap off. Could be a turbo issue i guess, but I'd be more inclined to believe it is cylinder (piston ring?) related. A compression test should reveal all.

 

Even if the turbo is kaput, I would personally still do a compression test for what little it will cost. And *if* the cause is some weld slag, I would strip the head off to make sure none of it has found its way into the cylinders (unlikely, but certainly not impossible, and not worth the gamble)

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Whether the cap is on or off is irrelevant to oil pressure. So long as the level in the sump stayed high enough to not cause oil starvation the engine and turbo should not have suffered. if you are REALLY lucky I could JUST see that if enough oil was sprayed around it could get sucked through a none stock air filter and be in the inlet tracts. What happens if you run the engine on a fast tick over for a good few minutes, does the smoke clear? Or have you already done that? There's a slight danger that if the turbo seal has blown you could blow a LOT of oil down the exhaust, so be sure to check dipstick level before and after a few minutes, and watch the oil pressure. a badly blown turbo seal may not show as a drop in oli pressure, but worth seeing if you perceive any difference, hot.....

 

This where a Garrett turbo is a Godsend as it can go to any UK Garrett agent and be rebuilt. these US things are a PITA as sending it to the States with associated carriage two ways and a hefty manufacturers repair bill makes them uneconomic to fix.

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Oh, and anyone running anti lag on a road car engine / turbo is just asking to have a rebuild on their hands, it's strictly WRC rally car territory, and they have special manifolds, "proper" anti lag maps, and trick turbos that cost well over 5K a pop. Plus their budgets exceed the GNP of Bangladesh....

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You could be right, although my thinking is that the thing that initially caused all of this was the oil cap coming off, which lead to oil loss, which led to a failing oil seal which lead to even more oil loss... My mechanic will be able to tell me soon enough - she's being recovered today.

 

Oil Cap coming off is going to make a mess, but won't cause oil seal to fail as it has nothing to do with oil pressure.

 

The only times I've seen oil caps/breather systems etc come off is on turbo engines with excessive crank case pressure (RB25 chucking it's oil on full boost straight out rocker covers from excessive bottom end wear and large turbo) Let's hope you didn't screw it on properly rather than having cc pressure issues.

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RB engines have poor drain back routes from the head, and tend to have a rather excessive amount of cam oil supply in any case, so are rather different to the 2JZ's which have admirable oil drain paths from above the head. An excess of blow by is checkable in seconds, with no tools. A leak down test will allow leakage to actually be quantified. I would say looking at the video, if it's not oil already in the inatke from being sucked through the filter, and which will disperse after a few minutes, it's the turbo seal that's gone. That is far too much smoke for bad rings at those RPM levels.

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I think it's more likely that the crank case pressurised, blowing the cap off. Could be a turbo issue i guess, but I'd be more inclined to believe it is cylinder (piston ring?) related. A compression test should reveal all.

 

Even if the turbo is kaput, I would personally still do a compression test for what little it will cost. And *if* the cause is some weld slag, I would strip the head off to make sure none of it has found its way into the cylinders (unlikely, but certainly not impossible, and not worth the gamble)

 

I would have thought that any pressure caused by the crank case would much rather escape through my vent-to-atmosphere breather setup than a solid oil cap

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