I bought an Si head with bent valves, and in in the chamber where the valves are bent it's all brownish and the exhaust valves are a tan color instead of black with carbon like all the other valves. What causes this to happen?

 

so its just the one cylinder? i wonder if it hydro locked? is it baked on or just on the surface could be like a rust residue if the engine sat upside down or something with water in the one cylinder..

 

If it is baked on, I would say there was something in that cylinder that had EXTREME heat. I mean something detonated. It just seems apparent to me that something like that could cause the tan look.

 

What do you mean by 'baked on'? I just went and tried rubbing some off onto my finger and it looks like that brown color is on there pretty good because it wasn't really rubbing off. I'm thinking that maybe, he left it running after bending the valves (would it even run w/that bad of bent valves though?) and then exhaust kept backing up into the combustion chamber without the normal flow of that intake valve.

As far as I know, the engine wasn't hydrolocked. I bougth it from a kid who supposedly overreved and bent the valves (He also sold me a GSR tranny that he said worked perfectly but that actually had a messed up 3rd and 4th gear and bad mainshaft bearing, so you can't really trust what he says). I'm pretty sure that's not rust though because it doesn't rub off and those valves definitely are not the color of rust, more like a sand color, and it's caked on there pretty good. It's like the carbon caked on, but it's tan instead of black, and maybe not as grimy.

 

did the motor blow a HG? thats what it looks like to me ..seen valves that color from blown HG take the head off and there is mixture sitting in the cylinder

 

tan exhaust valves are totally normal


Modified by dbiker207 at 6:36 PM 12/17/2006

 

http://www.putfile.com/dbiker207

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Throwdown &raquo;</TD></TR><TR><TD CLASS="quote">did the motor blow a HG? thats what it looks like to me ..seen valves that color from blown HG take the head off and there is mixture sitting in the cylinder</TD></TR></TABLE>

I didn't ever see the motor when it was running or in a car, so I don't know. There isn't any way to really tell now that the head is off, is there?

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dbiker207 &raquo;</TD></TR><TR><TD CLASS="quote">tan exhaust valves are totally normal</TD></TR></TABLE>

Why would only those two be tan, vs. every single other valve black?

 

the other ones being black is not normal. the exhaust valves get tan from the super hot exhaust gasses traveling past them when the valves open, the intake valves have cool intake air and fuel flowing ove them when they open (effectively cooling them). the exhaust valves should be the same color as the spark plug.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dbiker207 &raquo;</TD></TR><TR><TD CLASS="quote">the other ones being black is not normal. the exhaust valves get tan from the super hot exhaust gasses traveling past them when the valves open, the intake valves have cool intake air and fuel flowing ove them when they open (effectively cooling them). the exhaust valves should be the same color as the spark plug.</TD></TR></TABLE>

So oil was either getting past the rings, or the headgasket was bad? It does kind of look like there is a lot of grime in the ciombustion chambers on the head that shouldn't be there. The spark plugs also look kind of the same black color as the black valves.

 

sounds like the person that had the head before you ran the engine really rich, that black buildup is carbon. the carbon could also be from running really high compression, the higher the compression the more carbon buildup there is gonna be.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dbiker207 &raquo;</TD></TR><TR><TD CLASS="quote">sounds like the person that had the head before you ran the engine really rich, that black buildup is carbon. the carbon could also be from running really high compression, the higher the compression the more carbon buildup there is gonna be.</TD></TR></TABLE>

Stock block, stock head basically, so no high compression.

 

someone needs to rename this thread 'misinformation'

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by full Circling &raquo;</TD></TR><TR><TD CLASS="quote">someone needs to rename this thread 'misinformation'</TD></TR></TABLE> meaning???? why dont u explain any info i got wrong instead of being a dick. i am just telling my opinion

 

um no. i'm not going to try and explain something i don't know. i'm just gonna state that's theres misinformation in the thread, and wait for some truth to show up.

 

the other thing that i forgot to mention is that cylinder was cleaner because the unburnt gas probally cleaned the carbon off alittle

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by full Circling &raquo;</TD></TR><TR><TD CLASS="quote">um no. i'm not going to try and explain something i don't know. i'm just gonna state that's theres misinformation in the thread, and wait for some truth to show up. </TD></TR></TABLE>
no your just an idiot who doesnt know what he is talking about. i actually do i have gone to school for this ****. if you dont believe exhaust valves are supposed to have a tan color then search combustion chamber on yahoo images and look at the pics of used cylinder heads with valves. and if you knew anything or had actually ever had a motor part then your opinion might matter.

 

It is a combustion engine that requires Fuel, air, and spark not a motor that require electricity. However I agree exhaust valves show be a reddish brown. Clean valve or valves that look as if some material has been removed implies water or coolant being that neither combust and neither compress at the ratio air and gas do in the cylinder. The result is extreme pressure that essentially pressure washes the cylinder. Black is a rich condition and grainy is from blow by. Oil has a ash content and some oils have more than other. The result of pressure sneaking passed the rings causes Positive case ventilation in Naturally aspirated engines and escapes from PCV bales back into the engine. The partially burnt oil returns through the intake valve and collects there and the remaining unburnt oil, after the power stroke is then pushed out the exhaust valve which is extremely hot and it burns off on contact, Leaving hard granular residue on the valve face. The thing to be consider or be paying attention to is the valve head and contact ring. It the head a perfect circle, if the ring even and on the same potion of the face all the way around, is it pitted. Does it move smoothly through the guide, does it have carbon deposit on the stem that could prevent it from closing all the way. Is the stem straight. Does the retainer groove have any damage that will prevent the retainer’s from locking into the stem. Are the valve spring covered in burn material and do they all require the same amount of pressure to compress.