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The mkiv Supra Owners Club

Exhaust fume questions..


Andrew

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If an exhaust had an hole in it would smoke/fumes bellow out the car on occasion? Or would it just make a loud noise?

 

From memory I remember an old car I had when the exhaust fell off (literally), it sounded like a tractor, but I didn't recall smoke.

Others have told me, yes if a hole appeared you would on occasion get puffs of exhaust gas fumes coming out.

 

Could a hole cause a build up of fumes where they are not able to leave the pipe correctly?

 

Still trying to get to the bottom of my smokey exhaust. Obviously a new exhaust is in order.

 

Cheers,

Andrew

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When driving or stationary a plume of greyish smoke emits indiscriminately or mainly after driving for sometime. For instance my journey to work takes 40mins - 1 hour over 15miles and it only happens once or twice.

I posted awhile back about this but thought it was only when I came to a stop that the smoke came out, but on closer observation, I noticed it happens under many different circumstances. People replied and said it could be thin oil seeping through, turbo seals, etc.

Thing is I didn't for one minute think it would be attributed to a corroded exhaust pipe.

 

On the join between the back box and the pipe connecting to the mid pipe, there is a series of holes. Started off small but are now starting to join together to create one big hole about 2 inches long.

The smoke appeared to get worse, so I got some of that exhaust repair cement and it appears to have gone away, trouble is because it was/is indiscriminate I have know way of knowing until it happens again.

 

As I say some people are putting it down to the pipe, but like you I wouldn't have thought an exhaust pipe should emit any kind of smoke unless problems in the engine, others are saying different though :blink:

 

My only theory is that because the exhaust has the hole the fumes are not leaving the tail pipe properly and building up.

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Classic early turbo seal failure. The reason the smoke seems to have got more noticeable with the appearance of the hols is the holes are relieveing back pressure and a lack of back pressure makes the seal problem worse. Some back pressure post the turbo(s) helps seal a turbo in the early stages of failure. That's why in the first stages you only get smoke at idle or during gear changes.

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Somthing I didn't want to hear, but thanks Chris all makes sense now.

In my previous post people suggested turbo seals being the problem, I was just hoping it was something else.

 

So much for running 1.1 bar, obviously the turbos aren't up to it. Shame really as I have only run 1.1 bar on a few occasions, and have the boost gauge set to warn me at stock FC so I lay off the pedal.

 

More investigation needed I guess, slim chance it could be something else.

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Usual cause is crap oil, or infrequent oil changes, seeing more of this recently. If the underside of the oil cap, and the area within the cam box you can see with cap removed is crusty or heavily deposited expect that crap oil has choked the oil feed and bearing housing of a turbo or turbos.

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Thanks Chris I'll check that out.

 

Not sure of the cars previous history (has full Toyota history), but I change the oil and filter every 4000-5000 miles.

People may remember a post I did a while back about the dodgey Toyota dealer I believed didn't change my oil on a service, since that day I do it myself.

 

Annoying thing is I baby this bloody car :mad:

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