White Deposits In The Exhuast Ports/Back Of Exhaust Valves

[philbey]

Yo diggity...

 

I pulled the headers off my porsche motor and noticed white deposits in most of the exhuast ports. There was also some buildup on the back of the valves. Take a look at the pics.

 

Anyone have any idea what this might be? I've never seen it before, but i assume it's something to do with lean burning, similar to tuning by sparkplug colour.

 

Just to add to this, Porsches were fitted with smog pumps that pumped fresh air into the exhaust ports for emissions. Burns off any unburnt mixture. If you look you can see a shiny new hex head plug where I've blocked off these ports. I've only just fitted these plugs, prior to that, the actual brass piping was still connected but the pump was missing, and only just capped off.

 

I wonder whether this may have something to do with it?

 

Let me know your thoughts.

 

TP

Edited September 21, 2010 by philbey

[Trev]

Looks like calcium build up from poor fuel.

[maxyboy55]

looks a bit like oil deposits, do they have valve stem oil seals?

how tight are the valves in the guides?

 

the lack of an air pump shouldn't effect it too much

 

but generally it looks like it might have been burning a bit of oil

 

max

[Evan G]

+1 for fuel

[altezzaclub]

Scrape some off and have it analysed at a chemical lab somewhere.

 

Does it look like the corrosion salts that appear in the exhaust sometimes? They grow on a spot where corrosion is eating into aluminium. Although that doesn't coat a valve like you have there!

[Evan G]

you didn't put NOS energy drink in the fuel did yah? :P

[philbey]

Looks like calcium build up from poor fuel.

 

Hmm good point. Don't know much about it myself, any insight trev? potential for damage etc?

 

looks a bit like oil deposits, do they have valve stem oil seals?

how tight are the valves in the guides?

 

the lack of an air pump shouldn't effect it too much

 

but generally it looks like it might have been burning a bit of oil

 

Yeh they have stem seals and I suspect they're on the way out, when I park on a really cambered road it tends to puff a bit of smoke on startup, I suspect because the oil is high enough to weep past the seal. Very occasionally. Maxy you're saying that burning oil could cause this white buildup then?

 

also, don't be fooled by the oily crap all around the cylinder sleeve, I just fixed some a significant oil leak on the motor.

 

Scrape some off and have it analysed at a chemical lab somewhere.

 

Does it look like the corrosion salts that appear in the exhaust sometimes? They grow on a spot where corrosion is eating into aluminium. Although that doesn't coat a valve like you have there!

 

Pretty certain it's not corrosion. As for fuel, I only run her on 98 octane, the previous owner was probably a tight arse though and ran it on decaf.

[philbey]

Ah evan, that's where I went wrong LOL.

 

BUT - that does prompt an interesting memory recall: I do run that valve saver stuff in it?!!? could that possibly be the problem?

Edited September 21, 2010 by philbey

[ke70dave]

hmm white to me sounds like an oxide of some kind, which is to be expected since combustion burns with oxygen

 

combustion produces NOx and SOx right, both of which are oxides...what does NOx and SOx look like? can they be a crystal form like that? (though they are produced in gas form as far as i am aware...)

 

maybe that air pump was keeping these by products under control (unsure how....) and with it removed it allows one of them to be produced in a higher doseage enough to form that powdery substance?

 

i may in fact be taling rubbish, and can thus be ignored!

 

i like the idea of mr altezza about getting a small amount analysed by a chemical mob...

Edited September 21, 2010 by ke70dave

[Twinky]

I second the oxodising of an abnormal chemical in the system. I usually see this stuff build up on aluminium when left in the weather (same stuff, white powdery substance).

I would suspect the protagonist here is a chemical that you are adding, especially saying that it is a valve saver. If you can, find the packet of the stuff and read the contents.

Post the chemical make up here if you can. I would say that is %100 the extra chemicals fault. At this point i would steer clear of the valve saver.

 

A chemical test done for a private customer might get a little pricey.

 

If your spark plugs are not built up with the same white powdery substance then it is the extra substance.

[philbey]

It's a common mod to remove the air pumps with no problems. I thought I'd test the knowledgebase here on the RC to see, before I hit up the Pelican parts Porsche forum. That joint's got 15 times more members than the RC but there's about 50 times more bullshit responses LOL.

 

I'm suspecting the valve saver, but I'll redo the valve stem seals too.

[Trev]

Hmm good point. Don't know much about it myself, any insight trev? potential for damage etc?

 

Any on the plugs too?

 

Normally just change the plugs and be done with it.

 

Oh and for you 'engineers' calcium build up is an oxidisation.

[altezzaclub]

I'm suspecting the valve saver, but I'll redo the valve stem seals too.

 

I'd go for that too- contact the manufacturer and send them the photos. It might contain metal salts like potassium that will crystallise out after combustion.

[Trev]

Since this is the most common valve saver used I will post the MSDS.

 

http://www.flashlube.com/images/stories/pdfs/valvesaverfluid-safety-data-sheet.pdf