BIZARRE Spark Plug Color?

[savatreatabvr]

Changed the plugs in my 1973 Chevy C20 454 and found a interesting color on one plug! You can see from the pics below that one plug is yellow, and it's actually a brighter yellow than the pic shows. All the other plugs were normal, I even metered them all and they had proper resistance so what would cause only one plug to have such a crazy color?

[85chevy86]

would antifreeze happen to be leaking in that cylinder?

[savatreatabvr]

Originally Posted by 85chevy86

would antifreeze happen to be leaking in that cylinder?

Not likely because there is not antifreeze in the 454, just water. Could plain water cause it to turn yellow?

[Just call me Sean]

Antifreeze would be my guess too. Plain water would wash it clean.

[MountainGoat1966]

Maybe he has the same space aliens messing with him that are always goofing around with me.
Or something causing that cylinder to run extremely lean .......

[KQQL IT]

Used to drive a c-60 with a 366 that was always overweight. It would make orange hue on the plugs. But not that

[willett]

http://www.circletrack.com/techartic...?__federated=1

According to this the cylinder is getting too hot. Which cylinder did it come out of?

[savatreatabvr]

Originally Posted by willett

http://www.circletrack.com/techartic...?__federated=1

According to this the cylinder is getting too hot. Which cylinder did it come out of?

Number 8 cylinder. I don't have a thermostat in it but the 454 never get hot even here in Phoenix.

[Nin92]

Looks like high speed glazing. Happens when cylinder temperature increases rapidly under heavy acceleration. Causes the deposits to melt and form a hard coating. What heat range are your current plugs?

[savatreatabvr]

Originally Posted by Nin92

Looks like high speed glazing. Happens when cylinder temperature increases rapidly under heavy acceleration. Causes the deposits to melt and form a hard coating. What heat range are your current plugs?

Not sure, they are just basic cheap plugs from Autozone.

[Ozzy2013]

Not good looks like that cyl is running lean.

[beamn7]

I know you said it doesn't get hot but I would certainly put a t-stat in it and 50/50 coolant mix. The main function of the t-stat is to slow the coolant flow down enough to allow the proper amount of heat transfer from the block to the coolant as well as keep it at the calibrated temp. Straight water has a lower boiling point than 50/50 mix. Straight coolant or straight water can cause overheating.

As for the plug, I would say that cylinder is running hot/lean just as others have mentioned.

[savatreatabvr]

Originally Posted by beamn7

I know you said it doesn't get hot but I would certainly put a t-stat in it and 50/50 coolant mix. The main function of the t-stat is to slow the coolant flow down enough to allow the proper amount of heat transfer from the block to the coolant as well as keep it at the calibrated temp. Straight water has a lower boiling point than 50/50 mix. Straight coolant or straight water can cause overheating.

As for the plug, I would say that cylinder is running hot/lean just as others have mentioned.

I put a T-stat in it but it reached operating temp way fast and was slowly getting hotter so I pulled it out. I'll pick up another one maybe it was bad. I'm confused, how can one cylinder run leaner than the other 7 when it has a carburetor (Edelbrock 1407)?

[rs72z]

Intake gasket leak.

[savatreatabvr]

Originally Posted by rs72z

Intake gasket leak.

No joke, I've been thinking about putting a aluminum intake on it, now just may be the time to do it!

[beamn7]

Originally Posted by savatreatabvr

No joke, I've been thinking about putting a aluminum intake on it, now just may be the time to do it!

I'd second that. Spray a little brake clean or carb clean around that intake runner while she's running. Any change in the idle will tell you there is a leak....

[kalbert]

Originally Posted by savatreatabvr

I put a T-stat in it but it reached operating temp way fast and was slowly getting hotter so I pulled it out. I'll pick up another one maybe it was bad. I'm confused, how can one cylinder run leaner than the other 7 when it has a carburetor (Edelbrock 1407)?

That is bad. You have a problem here and the thermostat is not causing it.

You must run coolant/water mix. Coolant has anti corrosion components, wetting agents, lubricating qualities, and changes the boiling point of water.

A common misconception about the thermostat is that it controls how *hot* the engine gets. This is not true. The thermostat controls how *cool* the motor *could* be in ideal operating conditions. Mechanical problems will make it run hotter than the thermostat can control. Specifically a bad head or gasket will create an air pocket behind the thermostat that will not transfer heat from the coolant to the pellet so it opens to allow coolant to flow.

I would suggest a leakdown test on the cylinder in question. My expectation is you will see/hear air leaking into the cooling system. Bad head or gasket. This would explain the overtemp problem and the plug condition.

An interesting note is that not running a coolant/water mix can cause corrosion and fluctuating temps (excessive expansion and contraction) that can cause heads and gaskets to fail (among other things, burned valves). Not running a thermostat can also cause wild fluctuating temps resulting in the same. So which came first, the chicken or the egg?

[savatreatabvr]

Originally Posted by kalbert

That is bad. You have a problem here and the thermostat is not causing it.

You must run coolant/water mix. Coolant has anti corrosion components, wetting agents, lubricating qualities, and changes the boiling point of water.

A common misconception about the thermostat is that it controls how *hot* the engine gets. This is not true. The thermostat controls how *cool* the motor *could* be in ideal operating conditions. Mechanical problems will make it run hotter than the thermostat can control. Specifically a bad head or gasket will create an air pocket behind the thermostat that will not transfer heat from the coolant to the pellet so it opens to allow coolant to flow.

I would suggest a leakdown test on the cylinder in question. My expectation is you will see/hear air leaking into the cooling system. Bad head or gasket. This would explain the overtemp problem and the plug condition.

An interesting note is that not running a coolant/water mix can cause corrosion and fluctuating temps (excessive expansion and contraction) that can cause heads and gaskets to fail (among other things, burned valves). Not running a thermostat can also cause wild fluctuating temps resulting in the same. So which came first, the chicken or the egg?

How do I perform a leak down test on a budget?

[Ozzy2013]

Originally Posted by savatreatabvr

How do I perform a leak down test on a budget?

You can buy a leak down tester cheap or rent one at autozone i think i would just buy one .Put the cyl you want to test on top dead center screw the fitting in the plug hole leaving all other spark plugs in the motor and hook up you air hose and pressurise the cyl and see if your valves are leaking or if you have a cracked head or bad head gasket etc.If you have never done it Google it or go to youtube .Good luck.

[kalbert]

Originally Posted by savatreatabvr

How do I perform a leak down test on a budget?

You can get a simple leak test kit for ~$50. You also need an air compressor, they range from about $100 for not a very good one up to as much as you care to spend. You can also probably rent one for $50/day. Its possible your auto parts store can rent you the leak down tester for free.

[Ozzy2013]

Originally Posted by kalbert

That is bad. You have a problem here and the thermostat is not causing it.

You must run coolant/water mix. Coolant has anti corrosion components, wetting agents, lubricating qualities, and changes the boiling point of water.

A common misconception about the thermostat is that it controls how *hot* the engine gets. This is not true. The thermostat controls how *cool* the motor *could* be in ideal operating conditions. Mechanical problems will make it run hotter than the thermostat can control. Specifically a bad head or gasket will create an air pocket behind the thermostat that will not transfer heat from the coolant to the pellet so it opens to allow coolant to flow.

I would suggest a leakdown test on the cylinder in question. My expectation is you will see/hear air leaking into the cooling system. Bad head or gasket. This would explain the overtemp problem and the plug condition.

An interesting note is that not running a coolant/water mix can cause corrosion and fluctuating temps (excessive expansion and contraction) that can cause heads and gaskets to fail (among other things, burned valves). Not running a thermostat can also cause wild fluctuating temps resulting in the same. So which came first, the chicken or the egg?

Yea i suggested a leak down and comp test a few posts back sounds like he doesn't have the equipment .

[savatreatabvr]

Originally Posted by Ozzy2013

Yea i suggested a leak down and comp test a few posts back sounds like he doesn't have the equipment .

Yes I posted my compression test results and no I don't have a "Leak Down Tester"! Why you ask? Because I'm on a tight budget! That's also why I drive a 1973 Chevy truck!

[lha1992]

Well if you put that new intake on put a timing light on it an make sure she's time to 12deg or so. Timing could be off but you never know? Even if it is on one cylinder its doing this on.

[Ozzy2013]

Do your self a HUGE favor and do a compression test and a leak down test if you have low compression .It is an awesome test that should be done but seldom is!It tells you so much about the condition of your motor.

[savatreatabvr]

Originally Posted by Ozzy2013

Do your self a HUGE favor and do a compression test and a leak down test if you have low compression .It is an awesome test that should be done but seldom is!It tells you so much about the condition of your motor.

I've done a compression test and all 8 are around 110psi + / - 5psi, That sounds a little low to me but what is a stock mid 70's 454 compression supposed to be, 100psi, 120psi, 140psi, 160psi? I've looked online and get various numbers.