Deposits inside Exhaust Tips

[wwr]

Suddenly I'ved noticed WHITE deposits inside my exhaust tips. I thought they were just water spots but they are hard and I can't get rid of them. 13,000 miles on the car. I use Chevron 93 about 98% of the time. Any help? Car has a slight miniscule blip at idle. I've never seen this on any car I've had before.

Thanks,

wwr

 

[Steve Calvin]

I'm not a mechanic but doesn't white residue indicate running lean? Have you had it checked to see if it's throwing any codes? That'd probably be my first step.

 

[wwr]

Thanks Steve

It goes on the machine next week. I thought it might be calcium deposits from our water when rinsing it when washing it. Sometimes water sorta "puddles" in there.

Thanks,

wwr

 

[jrose7004]

Back in the day, on a road trip white inside the exhaust tips was good!

 

[XLR8]

Back in the day, on a road trip white inside the exhaust tips was good!

May sound like a dumb question but... what is the cause of black residue inside tailpipes? And why was white residue considered good?

JAG

 

[Dons97]

May sound like a dumb question but... what is the cause of black residue inside tailpipes? And why was white residue considered good?

JAG

Black meant incomplete detonation and that deposits were being exhausted. I thought white meant you forgot to rinse off all the soap and it got caked on.

 

[XLR8]

Black meant incomplete detonation and that deposits were being exhausted. I thought white meant you forgot to rinse off all the soap and it got caked on.

So how does one remedy incomplete detonation? And you're talking to a combustion engine novice here - what deposits do you mean?

 

[Dons97]

So how does one remedy incomplete detonation? And you're talking to a combustion engine novice here - what deposits do you mean?

Many, many causes and possibilities. Bad gas and bad timing from the old days. When gas/air mixture detonate and not all the gas burns, you get leftover stuff coming out the pipes. Burning oil is another cause of deposits on the pipes.

 

[XLR8]

Many, many causes and possibilities. Bad gas and bad timing from the old days. When gas/air mixture detonate and not all the gas burns, you get leftover stuff coming out the pipes. Burning oil is another cause of deposits on the pipes.

Ok... I have used Chevron premium gas with Techron which C4C5 recommends since I bought the car last year @25k miles. If I'm not seeing a loss of oil, would this then point to timing?

 

[Dons97]

Ok... I have used Chevron premium gas with Techron which C4C5 recommends since I bought the car last year @25k miles. If I'm not seeing a loss of oil, would this then point to timing?

Not necessarily at all. I believe there will always be "incomplete" detonation. That's why car makers are always looking for ways to better burn gas. Hemi's for example used a hemispherical shape to provide better burn more power. More valves per cylinder to provide better mixture/exhaust. Better gasolines with better additives...

Believe me I'm no expert by any means, and there are about 50,000 people at the CAC could answer better/smarter than me (but I'm the only one up now!).

I think if ever there's a car with complete detonation, it would be super efficient and therefore would be unwelcome by the oil companys.

 

[XLR8]

Believe me I'm no expert by any means, and there are about 50,000 people at the CAC could answer better/smarter than me (but I'm the only one up now!).

:L Ah - but you know more than I do. Forgive me if this is another dumb question, but... how many valves per cylinder do our Vettes have?

 

[DRTH VTR]

Black meant incomplete detonation and that deposits were being exhausted. I thought white meant you forgot to rinse off all the soap and it got caked on.

I think "detonation" is not the best word to use here. Perhaps incomplete combustion would be better. "Detonation" generally implies an incorrect condition within the combustion chamber, where fuel/air mixture ignites from a source other than the spark plug. Detonation is a harmful, generally abnormal condition. I say this just so we are all talking the same language. Thanks for listening.

 

[XLR8]

I think "detonation" is not the best word to use here. Perhaps incomplete combustion would be better. "Detonation" generally implies an incorrect condition within the combustion chamber, where fuel/air mixture ignites from a source other than the spark plug. Detonation is a harmful, generally abnormal condition. I say this just so we are all talking the same language. Thanks for listening.

Thanks for the clarification, Jim. As you can tell from my posts, I'm truly a novice as to the inner workings of the internal combustion engine. I do want to understand better but I know so little that sometimes I fear my questions are more of a bother than an invitation to share knowledge.

Thanks again...
- Jane Ann

 

[DRTH VTR]

:L Ah - but you know more than I do. Forgive me if this is another dumb question, but... how many valves per cylinder do our Vettes have?

Two. One intake, and one exhaust. The valves are opened and closed based on how the camshaft is shaped. On many engines, there are multiple camshafts over the top of the valves (overhead cam). These engines are often capable of higher RPM limits, and can more easily take advantage of variable cam timing. The cams are driven off the crankshaft using a belt. The Corvette uses a single cam in the block (overhead valve). The cam is driven off the crankshaft using a chain. The valves are activated by pushrods and rocker arms. It is simpler and less expensive than than overhead cams. I believe that the only overhead cam engine put in production Corvette was the LT5 in the ZR1. It had 4 valves per cylinder, 2 intake, and 2 exhaust. I believe that all other 'Vette ingines used 2 valves per cylinder.

 

[DRTH VTR]

While I am on my soap box:

There is very little unburned fuel coming out of a modern engine. What does come out is combusted in the catalytic converter. The inefficiency in an engine has to do with how much of the potential energy in the fuel is converted to motion, and how much is converted to heat. The great majority of the energy that is released in burning fuel is in the form of heat. If that could be converted to motion, instead, we could get more miles out of the fuel.

The big limitation to engine power is how much air you can get in and out. It is easy to squirt lots of fuel into the combustion chamber. The amount of oxygen will be the limiting factor. That is why 4 valves are generally better than 2 valves. They open more of the top of the cylinder and allow the gases in and out better. Air can be forced into the cylinders using a supercharger (driven off the crankshaft) or a turbocharger (driven by exhaust gases).

As far as oil burning in C5 Corvettes go, it is generally related to how the car is driven. Light load, high RPM conditions favor oil burning. If you have an automatic, and you leave it in "drive", you will not see those conditions. If you have a stick and drive around town at 4000RPM, you are more likely to burn oil.

Enough out of me. I hope this provides some insight.
Jim

 

[XLR8]

Jim, Thank you for taking the time to share the information with me that you have. It has provided some insight and makes a few things I've read or heard a little bit clearer.

I was pleased to find a link to the website "how things work" in another thread and I'll do some reading there too.

Thanks again!
Jane Ann

 

[rwpeders]

:L Ah - but you know more than I do. Forgive me if this is another dumb question, but... how many valves per cylinder do our Vettes have?

There is an in and an out valve in each cylinder.

 

[rwpeders]

Jim, Thank you for taking the time to share the information with me that you have. It has provided some insight and makes a few things I've read or heard a little bit clearer.

I was pleased to find a link to the website "how things work" in another thread and I'll do some reading there too.

Thanks again!
Jane Ann

You may not know a lot about how your car works, but Jane Ann, you have a great taste in automobiles. And since you are hanging around the Mississippi Gulf Coast, I hope all these huricanes have not been a problem for you or that great ride of yours.