Picture of my Burnt Valve

[byeboy]

Well, it seems ant-climatic to go through such a journey of discomfort and discovery...only to find a tiny piece of exhaust valve #2 burnt off..but its enough to make my 850 idle poorly, but still run smooth and powerful at speed (although I know it'll do better after surgery)...



The other valves all looked good, and I didn't bother seeing if they held gasoline without leaking, because the head is going into the Machine Shop in the morning. I tried to show the condition of the valve guides, shooting in the exhaust ports, but my flas just bounces back, showing a Black Hole....but every valve stem has carbon on it, two of the guides show leakage down the stems, so its time for its 175,000 mile freshening.

The pistons all have carbon, like the head... (the #2 is wet because I sprayed a short burst of Sea Foam Deep Creep on it to see if it would dissolve any carbon..it did not)



I was all set to bring each up to the top, the hit them with my Scotchbrite discs..but decided to read some opinions on Google (I know the expert respondents may be some 11 year olds who never held a sparkplug in their hand), and the consensus was to leave them alone...that mechanical cleaning, no matter how carefully done, releases some very tiny bits of carbon to lodge between the cylinder walls and rings, as well as the ring grooves themselves. Clean the pistons off all nice and shiny, and the engine will be toast shortly thereafter...so I'm leaving well enough alone, and just spraying some oil on the walls to keep any rust from forming.

[rspi]

Thanks for the pic. That seems like a lot of carbon.

[Rocky]

Thanks for the pic. That seems like a lot of carbon.

yikes. That is the "dirtiest" engine I've seen in a long time.
The question is why do much carbon?

[byeboy]

I agree, folks! I was not pleased when I flipped that head over!...but its always had premium gas, Mobil one oil with 4,000 mile changes, and almost exclusively highway miles...at least for the last 75,000 miles. 175,000 miles total, car was running smooth and powerful until valve. 24-24 MPG, with mild driving habits. Valve stems look cruddy, too! I did have a bad running 'episode' when turbo inlet hose went south, almost stranding me, but I limped it (running horribly bad, and barely able to maintain 20MPH) for about seven miles until I got to a place I could fix it (hose clamp at Intercooler had popped off the new hose I had put in 100 miles earlier). I put can of Sea Foam in crankcase, drove 20 miles more, then changed oil, filter, and ran a can of Sea Foam in the gas tank right after that.

Did the Sea Foam in any way contribute to this carbon mess? Could my Cat be plugging up?

What's to blame?

[rspi]

Ouch!!! I was hoping Mobile 1 and 91+ octane would keep the motor clean but I see I am wrong. I'm about to pull a head off of our S70 GLT that has had 91+ and Castrol for the past 50k. It has a bad head gasket so we'll see tomorrow. I did the PCV on the car about 2 years ago and the intake was very clean. I did the PCV on my R and the intake was as bad as the bottom of your head. As anyone would, I hope I never have to pull the head off the R.

Maybe, just maybe the PO wasn't doing the same.

[MoVolvos]

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Was your engine using oil? Piston ring blow-by and rich fuel are usually the causes of Black Piston Tops.

Excerpt from Post Below: In the late fifties, we used to get rid of carbon my pouring water down the carburator. It would work OK by pouring it down an intake stack at a time. We used to pour it in with a bottle until the motor almost stalled & would stop in time for it to recover. Be careful doing it in your garage or some other sensitive place, because a HUGE, GRAY BLACK cloud of smoke comes out of the exhaust. Nowadays there will be somebody around to say something negative about that.

http://forums.pelicanparts.com/porsche- ... avoid.html

In the early 80's my old timer Mechanic did this on a friend's big V8 that was knocking pretty bad. Thought it was a rod and after poring water from a Anti-Freeze container it solved the problem.

This is what I use currently
http://www.pelicanparts.com/catalog/sho ... co_pg9.htm

I continue to use and had used this on a New Complete Rebuilt engine Mitsu 3.0. (Valve Clacking from day one and so much for trying to support the local builder) The Head Gasket gave out after 50k. When the head was pulled the Hash Marks from the rebuild was still there and everything was clean as a whistle. A two generation shop owner I used for the Head Gasket told me he has never seen such as clean engine.
http://www.pelicanparts.com/catalog/sho ... co_pg8.htm

Blessings,
BKM
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[byeboy]

The water approach still has a lot of advocates. One has to be careful to not introduce it too rapidly, or Hydrolock could occur, bending a rod, so it is to administered to a fast idling (3,00 RPM+). Water Injection systems used to be relatively common in the 50's and 60's, which sucked water through the intake vacuum tube. I had friends that swore by those systems, and seem to recall that it was claimed that the Luftwaffe used them on their fighter planes in WWII.

It was marketed as an Anti-pinging, Anti-knocking device by J.C. Whitney I recall, so probably is still being sold on ebay !

[MoVolvos]

The water approach still has a lot of advocates. One has to be careful to not introduce it too rapidly, or Hydrolock could occur, bending a rod, so it is to administered to a fast idling (3,00 RPM+). Water Injection systems used to be relatively common in the 50's and 60's, which sucked water through the intake vacuum tube. I had friends that swore by those systems, and seem to recall that it was claimed that the Luftwaffe used them on their fighter planes in WWII.

Ah, The Germans!

"The truth is that synthetic oil was developed by the Germans during World War II so that their tanks could operate in the cold temperatures of their widely scattered battlefields."
http://www.swepcousa.com/lubesite/tt899.htm


Blessings,
BKM
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[jblackburn]

This is where name-brand gas with detergents and cleaners makes all the difference.

I might do 1/2 a can of Seafoam treatment on it once you get it back together, then rev the snot out of it on the highway. Blow that crud out of there!

[erikv11]

You can dissolve the majority of that carbon by just soaking a folded-in-quarters paper towel with generic carb cleaner, then raise up the piston and lay the soaked towel on the carbon. Here's the key: lay something (very) flat and with even a little weight, on top of the towel. I used a scrap piece of glass i had in the garage. It keeps the carb cleaner from evaporating, basically an open casket, cold Seafoam treament. Use Seafoam if you want but it is pricey. I like B-12 chemtool. After 15-20 minutes, lift it up and easily wipe away a LOT of the carbon. Repeat if you feel like it, then move on to the next one.