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Discussion Starter #1
I just got the heads off my engine and found the obvious culprit. Cylinder #4 is nice a clean while the others have major carbon buildup. Now again I am not an expert but I would think that if the cylinders were firing and running properly that they would be nice and clean, no carbon. You can see in the pics the nice clean piston and the others as well as the valves on the head. So why the hell do I have so much carbon buildup? Obviously I had a head gasket failure on #4 and it is clean because the water/coolant kept it that way. Please help me as I am naturally concerned about the carbon buildup.
Thanks


 

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looks more like you were burning valves or #4 wasnt fireing at all and jsut getting a nice cleaning from gas, and i woul dremove that antifreeze from you rcylinder before it leaks down,
 

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Discussion Starter #3
stangmata50l said:
Doesn't look that bad to me at all. how many miles on it?
It only has around 20K on the rebuilt motor.

colinlesser said:
looks more like you were burning valves or #4 wasnt fireing at all and jsut getting a nice cleaning from gas, and i woul dremove that antifreeze from you rcylinder before it leaks down,
Maybe it was not firing because so much coolant was getting in there. Thanks for the heads up on the coolant. I'll get it out right now.
 

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Discussion Starter #4
stangmata50l said:
Even at 20k, IMHO, that carbon buildup is nothing to write home to mom about.
OK. Thanks. Thats what I have been hearing.
I am also wondering what I can use for a straight edge to check for warpage. I have a feeler guage that goes down to .0015". Can I just go buy a nice metal ruler or do I have to get something guaranteed machined straight? After that anyone see why I shoul not be able to start putting it back together? Oh. And should I take the other side/head off or leave it?
 

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Discussion Starter #6
Gacknar said:
Remember to get new head bolts.
I got new ARP bolts when I rebuilt the engine. The guys at Summit Racing said they were good for 3-4 more times. One more thing. I am going to clean my intakes real good at one of those do it yourself car washes with engine cleaner and then the power washer. Can I do the same for the heads or should I not get water on them? Thanks again for everyones help.
 

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he doesnt need to replace the bolts unless they are TTY bolts, also i would get the head off and do that gasket anyway since your there. Another thing though, somthing is not right there on the valves because my engine before i rebuilt it had arround 80k on it and didnt have anywhere near that kind of carbon build up, and he only has 20k? somthing isnt right with that. and that uneven bruning on the heads is a indication thats somthing isnt goin right cause what he said is #4 looks too clean to be working right, or #4 is working right and the others are getting cooktified

EDIT: now that i think about it, put it all back together with the new gasket and put a couple hundred miles on it gentely then break it down again to see if it happens again, if it does somthign is seriously wrong, and why is your piston white?
 

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That piston is "white" because that one is at the top and the sun is shining on it. Why the hell would he want to put it all back together and tear it back apart in a few hundred more miles? :twak If you don't have a straight edge and all you want a shop to do is check and make sure it's still flat, I can't see any shop charging you to lay a straight edge across your head surface.
 

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Discussion Starter #9
RLKBOB said:
That piston is "white" because that one is at the top and the sun is shining on it. Why the hell would he want to put it all back together and tear it back apart in a few hundred more miles? :twak If you don't have a straight edge and all you want a shop to do is check and make sure it's still flat, I can't see any shop charging you to lay a straight edge across your head surface.
Yes that piston is in the sunlight. It is actually metal colored just as a new piston would be. I am taking the heads to a machine shop on Monday and they are going to surface them for $125. I really do not want to build it back up and take it apart again. However I do think i have a problem. Number 8 has some pitting and what looks to be detonation. It looks like the area around the valve in the head is melting. It has a rough bubbly look/feel to it. The piston looks ok but again I think there is alot of buildup on all of them. What could be causing this possible detonation?


 

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It might just be the way the carbon is built up. See what it looks like after it's cleaned off. If it is from detonation then maybe your timing is advanced too far or you're running too low octane gas for the compression ratio you have. Don't jump to too many conclusions, have the shop let you know if there's a problem.
 

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Looks like your plug has quite a bit of build up as well. When was the last time you changed or checked your plugs? A fouled plug would likely contribute to that carbon build up.
 

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RLKBOB said:
It might just be the way the carbon is built up. See what it looks like after it's cleaned off. If it is from detonation then maybe your timing is advanced too far or you're running too low octane gas for the compression ratio you have. Don't jump to too many conclusions, have the shop let you know if there's a problem.
I think he is safe on that aspect. Look at that huge dish in each piston. He must be around 8 1/2 to 1 compression. So with such a low compression, I wouldn't be worried about pre-ignition problems, it just can't happen.

 

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Discussion Starter #14
The plugs were new at rebuild 20k miles ago. I really don't think it is just carbon buildup but I will see what the machine shop has to say. If the timing was to advanced wouldn't all the combustion chambers have detonation? All the plugs and chambers have the same buildiup just not that crazy detonation/melting looking crap like in those pics.
 

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I don't think you should loose any sleep over that carbon build up. My last 302 spun several bearings (this will happen when your truck is running for too long while laying on it's side). I had about 4000 miles on it at the time, just broke it in. Anyways, when I took the heads off, I was surprised at just how much build up there was. Wasn't as much as yours, but based on what was there, mine would have looked like yours at the same mialage, so don't sweat it.
 

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Discussion Starter #16
waltman said:
I don't think you should loose any sleep over that carbon build up. My last 302 spun several bearings (this will happen when your truck is running for too long while laying on it's side). I had about 4000 miles on it at the time, just broke it in. Anyways, when I took the heads off, I was surprised at just how much build up there was. Wasn't as much as yours, but based on what was there, mine would have looked like yours at the same mialage, so don't sweat it.
I agree but I am concerned about that buildup/detonation on #8. That is not normal.
 

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Have you moved the pcv hose out of the #8 cylinder.I know on the 5.8 there was a big issue with the way the pcv was only run into the #8 cylinder causing premature failure of that cylinder.Just a thought.
 

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Discussion Starter #18
Jayrus said:
Have you moved the pcv hose out of the #8 cylinder.I know on the 5.8 there was a big issue with the way the pcv was only run into the #8 cylinder causing premature failure of that cylinder.Just a thought.
I don't think that is much of an issue anymore. I now have Edelbrock upper and lower intakes. The upper allows for better flow of the gasses. Also my PVC valve is over #4. And I am actually going to plug that and have my PVC coming out of the back of the lower intake. It is for a Mustang so there is a port on the back (PITA to get to) for a PVC valve.

stangmata50l said:
I'm curious to know what your timing was set at.
I had originally had it around 11 but I had it to the shop recently to check it and I don't know what it was set at. I'll find out Monday.
 

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Discussion Starter #19
Some interesting info. I just noticed that the intake gaskets I just got from Summit were wrong. So I ordered the correct ones. Edelbrock instead of Fel-Pro. Then I noticed that on my invoice from when I bought all my parts for the rebuild that the head gasket PN was different than that of the head gaskets I just got. So it turns out that I had the wrong head gaskets to begin with. I had Fel-Pro 1011-1 gaskets. Apparently those are for up to 1989. I now have Fel-Pro 1011-2 gaskets. I should have noticed this back when I did the rebuild as the Edelbrock Head instructions said to use the 1011-2. Anyway. The heads are going to the shop on Monday and I hope to have the parts and everything ready to go back together by the end of the week. Now to figure what is going on with the detonation.
 

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How was your spark plug wires routed? Crossfiring or (induction firing) could have caused that if that plug wire was running too close to another one. As far as the rest of the cylinders they look pretty good. Oh another thing I noticed on the cylinder your worried about was by looking at the valve I'd say that cylinder was running hot. (Exhaust valve is extremely white)this could have been caused by the wrong head gaskets(check coolant holes against new ones) I wonder if before cyl. #4 got steamed cleaned if it wasn't the same way and excess pressure is what blew the gasket?!? Just a thought. Keep us informed about how this goes. Glad it wasn't something serious.
 
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