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14 votes
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What is this yellow powder on my exhaust manifold?

IMHO that powder is either: Dust, that got "burned" by the hot exhaust manifold and transformed into some yellow-looking substance. Sulfur, as the color has a striking resemblance to sulfur. The ...
Martin's user avatar
  • 8,458
12 votes

What is this yellow powder on my exhaust manifold?

If your engine was running / exhaust manifold hot; the yellow is then zinc oxide. It would result from a galvanized steel manifold which has naturally oxidized. At room temperature the ZnO is white , ...
blacksmith37's user avatar
  • 3,688
9 votes

How to retighten exhaust manifold nuts?

Firstly.. If there is a gasket it should be replaced. If the studs etc are in very good condition then you could try undoing & re-torquing them. However due to the materials and heat cycles ...
Orb's user avatar
  • 5,067
8 votes
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How to test for a leak in the exhaust manifold gasket?

Seeing as how your car has a turbo, the only place it would be leaking and you'd hear a ticking noise is pre-turbo, so the exhaust manifold at the head (header) and the down pipe on the hot side to ...
Pᴀᴜʟsᴛᴇʀ2's user avatar
6 votes
Accepted

What socket fits the Catalytic-converter-to-Exhaust-manifold stud?

It's called a double D or shock absorber socket
user9181's user avatar
  • 1,392
5 votes
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Broken Exhaust Manifold Stud - How to remove?

You should definitely try to extract it. Preparation: Heat the manifold with a blowtorch Jolt the bolt with a pin punch Soak the bolt with bp-blaster or another penetrating oil Removal If the bolt ...
Martin's user avatar
  • 8,458
5 votes

Can I cut these two bolts to remove the exhaust manifold on a 99 Ranger

Try torching them again. The only bolts that I couldn't get off with a torch are the ones that snapped. If the bolt didn't turn an orange glow, you're not getting it hot enough. Cutting them off, as ...
tlhIngan's user avatar
  • 12.2k
4 votes
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Could this be the source of an exhaust leak

That appears to be the gasket. Take a look at the rockauto parts selector, it has a tab like that.
Attila Hooper's user avatar
4 votes
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Fixing an exhaust leak at the O2 threads

A copper washer could be a better bet - your anti-seize is designed to stop threads seizing so as it is not primarily designed to seal them it may not, however you could be lucky and it will.
Solar Mike's user avatar
  • 34.6k
3 votes

Stripped header bolt hole. Can I repair w/o taking out the engine?

Yes, you can do it, if you have sufficient access to the hole. A tap with handle is going to be around 2"-4" long. Do you have enough clearance to get it in place, perpendicular to the surface of the ...
3Dave's user avatar
  • 3,159
3 votes
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How to clean exhaust manifold mating surface

If the manifold studs come out easily enough that would make the gasket cleaning job easier, however they're usually a bit stubborn to remove so working around them is better than risking damaging the ...
Orb's user avatar
  • 5,067
3 votes
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Is it ok to use a used manifold and downpipe?

There's nothing inherent to say that using a used part won't work. Most likely your mechanic was advising against it as it can prove to be a false economy because of the amount of labor involved in ...
motosubatsu's user avatar
  • 10.2k
3 votes
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What options do I have for installing an O2 sensor in a cast iron exhaust manifold?

You can drill and tap a cast iron, yes, only difference - it is more fragile than steel, but it should not slow you down. Other option is to weld it in lower part, where the steel pipe starts. It ...
Arturs Bolsunovskis's user avatar
3 votes

Can I cut these two bolts to remove the exhaust manifold on a 99 Ranger

You COULD drill the head enough or grind them just enough to get the rest out. Slip it off and see if you can get a pair of locking pliers on it after you get it off. If you don't regularly use tap ...
cloudnyn3's user avatar
  • 3,343
3 votes

How long can I drive with exhaust manifold leak?

Depends.. how far is it to drive it to a place of repair? Because driving it around any further than that isn't safe, in fact it isn't really safe to do that particularly if you're already smelling ...
motosubatsu's user avatar
  • 10.2k
3 votes

Removing upside down flange nut in a deep hole

Here is my suggestion: Find another flange nut which is the same type, a flange nut with the "grippers" (don't know what else to call them) on it. Drill out the threads just enough so it ...
Pᴀᴜʟsᴛᴇʀ2's user avatar
2 votes

What sort of temperatures do exhaust manifolds on large engines reach after normal operation?

It depends on many factors like operating revolutions, engine performance, manifold location (cooling), etc. If you are concerned about overheat - don't worry, hot manifold is okay. Some high ...
Arturs Bolsunovskis's user avatar
2 votes
Accepted

Can I cut these two bolts to remove the exhaust manifold on a 99 Ranger

I would do as you suggest and cut them. Once you have got the manifold off the engine, you could drill the old bolts out and then just use a normal pair of nuts and bolts to fasten the exhaust to the ...
HandyHowie's user avatar
  • 25.4k
2 votes

How to test for a leak in the exhaust manifold gasket?

Use a shop vac. Attach the hose to the side that blows with tape. Then tape the other end to the tail pipe. Now turn on the vac. its time to use the soap with water in spray bottle spray everything to ...
Jamie Corbin's user avatar
2 votes
Accepted

On a 2004 Mitsubishi Lancer, Can a separated catalytic converter be re-attached to the exhaust manifold?

Yes, it can be repaired with an aftermarket unit. The manifold has visible welds on it already, so it can be welded to. Almost any aftermarket catalytic converter should be weldable. To perform this ...
Eric Urban's user avatar
  • 1,286
2 votes

Broken Exhaust Manifold Stud - How to remove?

After a lot of research, I decided to start by trying a pair of vice-grips on what was left of the stud. I cranked them down real tight, and it came right out. If that didn't work I'd have been ...
Dylan Cross's user avatar
2 votes

How to test for a leak in the exhaust manifold gasket?

I'd say hyd lifter failure is pretty unlikely unless you ran your engine to extremely high RPM's right before this started. A leaking exhaust manifold can produce a sharp and short puff of exhaust ...
JMR's user avatar
  • 69
2 votes

Coolant flows straighr from rad to muffler?

Usually that indicates there is an issue with either a head gasket problem or a cracked block. In either case, it's not good and is going to be major surgery or engine replacement. From your ...
Pᴀᴜʟsᴛᴇʀ2's user avatar
2 votes

Removing upside down flange nut in a deep hole

I had an idea of using a 12pt socket that is a tiny bit smaller than the flange, put on extension, hammer on, then unbolt. I did not have a flange nut to test, so tried with a nut and washer which is ...
Chris's user avatar
  • 915
2 votes
Accepted

Air filter turned black due to exhaust manifold leakage

Yes, you should replace it. The black color shows that the filter has trapped the particulates that tried to enter the engine. At this point the filter is effectively clogged.
jwh20's user avatar
  • 12.1k
1 vote
Accepted

What is the best TurboCharger dump Pipe Length for a turbodiesel engine?

I don't think you mean dump pipe (wastegate), where the length is meaningless unless it was a major restriction. I think you meant down pipe, which is after the outlet of the turbine. The best ...
SteveRacer's user avatar
  • 12.4k
1 vote

What is the best TurboCharger dump Pipe Length for a turbodiesel engine?

Most aftermarket street performance systems dump to atmosphere. If your system dumps to the inlet in order to avoid incorrect MAF readings and rich transient throttle conditions then I'd go with the ...
Steve Matthews's user avatar
1 vote

Diagnosing a p0420 code for 2005 nissan x-trail 2.5L

Hi I would the sensor after cat converter, the voltage should be 0.000>0.570 once in a while going to 0.750. If that’ok then I would check cat converter being blocked needs cleaned if possible or ...
Dick Mcmullen's user avatar
1 vote

Loud engine-related noises after impact to exhaust system: any recommendations to pursue?

If there is a tennis ball sized dent in the exhaust system then there are two possibilities. It may be that the dent is causing a restriction in the system which is causing pressure to build upstream ...
Steve Matthews's user avatar
1 vote

What is this yellow powder on my exhaust manifold?

The answer by @Robert is correct. This yellow powder is Hexavalent Chromium CR(VI), the most toxic form of chromium. It is found on exhaust manifolds as a result of heating stainless steel to 600°C. ...
Jon Jaroker's user avatar

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