Pulled heads...so how does this happen?

[mgreen1872]

SORRY FOR BAD/BLURRY PICS!

Background info:

Before I start, I give many apologies and many thanks to the guys who offered to help me out with a DIS but I had the car towed on home anyways. DIS tested bad before this little incident and I replaced it a couple days prior.

Car ran perfect, 94 ATX bone stock. Driving down interstate at 70mph, engine lurches, slight power loss, once I get off the interstate I have a steady miss. Got it home finally and check compression. Front Bank: 190-190-188 Rear bank: 192-0-190-- Check bad cylinder again w/ oil same result, so today I pulled the head(s) off. Attached is a pic of what I found on the bad cylinder, now I have seen burnt valves, cracked seats, lightly cracked valves around edges but never an ENTIRE CHUNK missing... amazing enough the cylinder was not damaged, bore still has cross-hatching so I am sure that this chunk of metal is just lying in wait in the exhaust so I will be sure to blow out the cats and such... but how does this happen??

 

[jimtash]

Running lean and detonation. Or the valve spring broke.

 

[mgreen1872]

strange... the car ran with a stuck thermostat for a couple of months before I bought it (changed it and blew out converters as soon as I got it) thought it would have been running rich -- also had absolutely no codes prior to this either...the PO also used quaker state and there is about a 1/2 inch of sludge and gum all over the heads....

 

[kevinspann]

1/2 inch of sludge? I'd find another motor before doing anything with that one. It seems poorly taken care of.

 

[mgreen1872]

starting to think the same... funny thing is the PO had every receipt for every oil change... LOL-- he thought that was something great, I just sent him pics of the heads and gunk --

 

[jimtash]

Sludge won't cause that unless the valve was glued to the seat by it. Nor will it affect compression ratios but carbon will. It appears to have an A/F ratio problem causing that cylinder to run too hot. Look at the valve where it's white. Probably heated it up way beyond tolerance around the edges and cause it to cracked.

Lean fuel ratios cause high exhaust temps and if his thermostat was stuck open, he was running with too much gas in the system. The cats took a dump because of it and so did this exhaust valve.

For the record, running lean means less air for the given amount of fuel. There's unburnt fuel leftover from the combustion process and it ends up burning in the exhaust.

Wikipedia definition:

Lean mixtures improve the fuel economy but also cause sharp rises in the amount of nitrogen oxides (NOX). If the mixture becomes too lean, the engine may fail to ignite, causing misfire and a large increase in unburned hydrocarbon (HC) emissions. Lean mixtures burn hotter and may cause rough idle, hard starting and stalling, and can even damage the catalytic converter, or burn valves in the engine. The risk of spark knock/engine knocking (detonation) is also increased when the engine is under load.

 

[220ksho]

For the record, running lean means less air for the given amount of fuel. There's unburnt fuel leftover from the combustion process and it ends up burning in the exhaust.

Running lean means less FUEL for the given amount of AIR.

 

[jedhead]

Ran too rich for too long, the cats overheated, crumbled parts of the cats sucked back into the engine on a downshift. IMHO.

Bob

 

[mgreen1872]

well pulled the oil pan off and suprisingly the bottom end was clean and did not look to bad.

Looking for some opinions here:

Engine has decent compression so I know rings are good - Bottom end looks fairly clean and solid - Car ran great until this, no noise, codes or issues -

but also, the top end is gummy - looking at the multitude of oil change receipts I see that the car has been using standard quaker state 5-30 for the last 3 years- the thermostat was stuck open for a few months

Should I just do rod bearings, have heads rebuilt, clean out cats and keep current engine or would you start looking for another one to start with?? Either way "FULL" history of my current engine or another used one will be unknown and a full machine shop/rebuild bill is out of the question at the moment....Thanks

 

[NotSoSlowSHO]

If the bottom end looks decent Id just do rod bearings, and have the heads refreshed.

No need to find another motor.

 

[SHOtimer]

Ran too rich for too long, the cats overheated, crumbled parts of the cats sucked back into the engine on a downshift. IMHO.

This.

If the bottom end looks decent Id just do rod bearings, and have the heads refreshed

This...or buy a used head. Might be cheaper. There are several in the classifieds....for example:
http://www.shoforum.com/showthread.php?t=112253

Doug

 

[rubydist]

yeah, I'd be really tempted to buy a set of heads and refresh those rather than trying to salvage ones that are all full of 'gunk'.

 

[sperold]

I never had any luck with Quaker State oil.
I have been told that the gunk is parafin that is created in the engine and is encouraged by the chemical makeup of the crude oil.
All of the oils back in the day looked like what you are describing. Tear apart any old 390 or 289 (that has been dormant for 30 years) and you will see a gunky mess.
Reuse whatever you want from the motor, but by the time you put in new seats and maybe guides and whatever else, you might do better with different heads, but check them out first.

 

[wjayg]

DIS Module

I guess you wont want the 2 used DIS Modules for $30 to your door including freight? I know they sat wrapped up in a usps priority box for 4 days in my work van because you said, "but I will WITHOUT A DOUBT take them from you"
So I gather from your post you wont be needing them?

 

[JRA2000TL]

Most folks on here swap motors when they have any kind of semi-serious issue that could come back to bite you in the ass. 3.0 motors cost peanuts, or you can do the 3.2 swap. Looks kinda nasty in there. I see you're from GA. If you're near the Atlanta metro area, chances are you can find a good SHO motor cheap. If you're in BFE, maybe not so much.

If you can't source a good, used, low mileage or well taken care of motor from someone, you may have to just fix what you have. Used motors can be a gamble too. If I were in your shoes, I would get a new set of loaded heads at the minimum if I didn't swap the motor. Good luck.

 

[itwonder]

It is possible the valve stuck and the piston lightly tapped it - enough to break off a chunk.

 

[SHOtimer]

Before I start apologies and many thanks to the guys who offered to help me out with a DIS but I had the car towed on home anyways.

...i'm haven't read an apology yet. Seems like someone would like one.

I guess you wont want the 2 used DIS Modules for $30 to your door including freight? I know they sat wrapped up in a usps priority box for 4 days in my work van because you said, "but I will WITHOUT A DOUBT take them from you"
So I gather from your post you wont be needing them?

 

[mgreen1872]

I guess you wont want the 2 used DIS Modules for $30 to your door including freight? I know they sat wrapped up in a usps priority box for 4 days in my work van because you said, "but I will WITHOUT A DOUBT take them from you"
So I gather from your post you wont be needing them?

yes and I sincerely apologize... when I needed the DIS I was a long way from home and stranded and very seriously assumed I would take them from you. Again, very sorry but thanks for the offers to help! Let me know if you want me to reimburse you for the troubles......


Yes, I assume the rebuild cost on the heads will be extensive, not sure what or how much to expect exactly but I will weigh my options. I have decided to keep my current engine but the head issue is still up in the air....

 

[wjayg]

Reimburse

Dont need you money, was just trying to help, you & I both know someone else bought them but it would of been nice if this wasn't the last thing I heard from you!

ok, thanks for the call earlier, however, I will not be able to send any money till thursday

 

[pjtoledo]

I never had any luck with Quaker State oil.
I have been told that the gunk is parafin that is created in the engine and is encouraged by the chemical makeup of the crude oil.
All of the oils back in the day looked like what you are describing. Tear apart any old 390 or 289 (that has been dormant for 30 years) and you will see a gunky mess.
Reuse whatever you want from the motor, but by the time you put in new seats and maybe guides and whatever else, you might do better with different heads, but check them out first.

the lead in those older fuels also had a lot to do with gunk buildup.


Perry