Type 4 Head Leak After 300 Miles?

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chitwnvw
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Type 4 Head Leak After 300 Miles?

Post by chitwnvw » Wed Feb 07, 2007 7:57 pm

Have the engine out to put in new transmission.

Was chasing down some oil dribbles and had a decent amount of stuff off, so I decided to take off the head so that I could put a groove next to the plug hole for the CHT wire.

Here's what I found at approx. 300 miles...

Heads cylinder 4 and 3. A small spot of blow out at top of pic (actually bottom of engine) Very black and sooty. Do a lot of city driving. Hopefully in normal range during ring break in...
[albumimg]448[/albumimg]


Cylinder #3. Note spot of oil dribbling at bottom.
[albumimg]451[/albumimg]

Cylinder #4.
[albumimg]450[/albumimg]

#4's cylinder wall.
[albumimg]452[/albumimg]

Any suggestions, concerns, advice? :-)

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Amskeptic
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Post by Amskeptic » Wed Feb 07, 2007 9:55 pm

Hello Cold Chicago Denizen,
You should not have any evidence of combustion leaving the chamber. Something is not straight here. Did you use cylinder sealing rings? I would get a very light touch-o-flycut to make extra-damn-doubly sure that the cylinders have a flat and exactly parallel surface to seat upon that head. You need to torque the heads correctly in three stages to 22 ft/lbs, wait 20 minutes, and add 1 ft/lb as you go through the sequence again. Make sure your threads are clean and lightly oiled. Each head nut should spin on with your fingers.
Colin

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Post by Gypsie » Wed Feb 07, 2007 10:17 pm

not to hijack your thread shytownveedublyew(am I pronouncing that right?)
but since the subject of rings has come up I am wondering how critical the with or without rings is. I have, within the past two years, changed the heads on both sides. The 1-2 was rebuilt with a blown (previously welded) valve seat. When I bought the new head I got the head and all the fixins. Gaskets and seals for everything that came apart. The part store sold me rings for the head (there were rings with the old head) I put it all back together and drove it for the next year and a half. Recently the 3-4 side blew a plug insert (that made my bowels loosen after it blew as we were going onto the freeway and I drove it the next 1/2 mile to get back off again.)
New head, new gaskets, seals, rings. Same store, same box as before only this time I didn't just throw away the "inspected by #14732" papers inside the head box. One of the sheets said- This new head is manufactured so that you will not need to use rings" or something like that. I installed the head without the rings (I took them back and bought some other stuff). No probs except the little picker in the back of my head saying 'what if the 1-2 side was the same 'no-ring' type of head?"

Any thoughts- compression probs? imbalance?
Since I will have the engine out soon perhaps I should break open that side and look closer. I don't want to have to as I usually don't fix what aint broke. How broke would it be if there were rings on a no-ring head?
So it all started when I wanted to get better gas mileage....

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Post by vdubyah73 » Thu Feb 08, 2007 6:11 am

Doesn't anybody lap the barrels to the heads anymore? You use valve lapping compound on the sealing surface and spin the barrel back and forth till they are nicely mated for life. Remember which cylinder was lapped to which barrel and keep them together upon assembly.

Bill
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Post by vdubyah73 » Thu Feb 08, 2007 6:16 am

Gypsie wrote:not to hijack your thread shytownveedublyew(am I pronouncing that right?)
but since the subject of rings has come up I am wondering how critical the with or without rings is. I have, within the past two years, changed the heads on both sides. The 1-2 was rebuilt with a blown (previously welded) valve seat. When I bought the new head I got the head and all the fixins. Gaskets and seals for everything that came apart. The part store sold me rings for the head (there were rings with the old head) I put it all back together and drove it for the next year and a half. Recently the 3-4 side blew a plug insert (that made my bowels loosen after it blew as we were going onto the freeway and I drove it the next 1/2 mile to get back off again.)
New head, new gaskets, seals, rings. Same store, same box as before only this time I didn't just throw away the "inspected by #14732" papers inside the head box. One of the sheets said- This new head is manufactured so that you will not need to use rings" or something like that. I installed the head without the rings (I took them back and bought some other stuff). No probs except the little picker in the back of my head saying 'what if the 1-2 side was the same 'no-ring' type of head?"

Any thoughts- compression probs? imbalance?
Since I will have the engine out soon perhaps I should break open that side and look closer. I don't want to have to as I usually don't fix what aint broke. How broke would it be if there were rings on a no-ring head?
Gypsie, do a hot compression test. If your readings are within specs run it.

Bill
1/20/2013 end of an error
never owned a gun. have fired a few.

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Post by chitwnvw » Thu Feb 08, 2007 6:43 am

vdubyah73 wrote:Doesn't anybody lap the barrels to the heads anymore? You use valve lapping compound on the sealing surface and spin the barrel back and forth till they are nicely mated for life. Remember which cylinder was lapped to which barrel and keep them together upon assembly.

Bill
They were lapped and followed the torquing sequence in the Wilson book.

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Post by chitwnvw » Thu Feb 08, 2007 7:45 am

I took a couple close ups. I don't know if they help much.
[albumimg]455[/albumimg]
[albumimg]454[/albumimg]

When I touched the streaks to see if they had harmed the head, they felt oily and wiped away easily. The metal underneath looked unharmed. I'd be tempted to think it had just leaked out when I was taking it apart if it wasn't for the obvious blow out markings on the upper flat area.

When I was assembling the engine, I turned over the engine by hand and heard a metal twang, and took the heads and cylinders off to check everything out. I ended up thinking it was a pushrod seating.

Anyway, when I retorqued the heads there was some sealant on the throughbolt threads. Maybe this messed me up.

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Post by Westy78 » Thu Feb 08, 2007 6:37 pm

Take a read here. Might want to try the Permatex Copper Coat that Charles mentions.

http://forums.aircooledtechnology.com/s ... d.php?t=41
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Post by chitwnvw » Thu Feb 08, 2007 8:39 pm

Westy78 wrote:Take a read here. Might want to try the Permatex Copper Coat that Charles mentions.

http://forums.aircooledtechnology.com/s ... d.php?t=41
It's interesting what he had to say about building up a carbon seal. I remember an argument 'tween skeptic and ratwell a while back about whether this was possible.

I noticed today that the area on the bottom of the head chamber and the piston, the area that was getting more of a wash in gas and oil, in that area the carbon build up was peeling up and washing away. In other areas a little ridge had formed between the head and the inner wall of the cylinder.
[albumimg]486[/albumimg]
A little hard to see but there's a ridge where the black ends and the cylinder seats.

I got a little paranoid and took off the other head.

Looks pretty good.

#1
[albumimg]487[/albumimg]
[albumimg]489[/albumimg]

#2
[albumimg]488[/albumimg]
[albumimg]490[/albumimg]

No obvious evidence of leaking. There was a teaspoon full or two of gas in #1. Some in the intake also. Hopefully, just a by product of removing the carb.

Now if I lap or do a little flycut on one side of the engine, does that need to be mirrored on the other side?

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Post by bottomend » Fri Feb 09, 2007 12:04 am

Maybe it's just the photo but the cylinders look waaaaay too shiny to me. How is the cross hatch pattern? This could be the primary reson you're getting oil/gas/leakage.

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Post by Sluggo » Fri Feb 09, 2007 11:29 am

chitwnvw wrote:
Sluggo wrote:Your heads are sealed better than mine!
I was going to pm you, but since you've chimed in, did you do anything to improve your seal 'tween the heads and cylinders when last you had it all apart?
I checked em and couldn't see any reason why they weren't sealing. I just cleaned em up and torqued em down. The leak went away but came back. Just not as bad. I plan on geting new P&C's soon so no big deal.
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Post by chitwnvw » Fri Feb 09, 2007 11:43 am

bottomend wrote:Maybe it's just the photo but the cylinders look waaaaay too shiny to me. How is the cross hatch pattern? This could be the primary reson you're getting oil/gas/leakage.
I'm guessing you're asking about the cylinder walls. They have a crosshatch pattern. I don't have a lot of experience with what's right and what's not so good, so it's tough for me to make a call on that.

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Post by satchmo » Fri Feb 09, 2007 1:55 pm

I don't think you can lap the cylinders on the heads unless you take them off the pistons, right? Then you have the problem of putting the cylinders back on and questionable re-seal of the rings. That is unless you go all the way and take the cylinders and hone them, then perhaps get new rings ... (never ends).

I would just clean the mating surfaces real well, and use plenty of the spray copper form-a-gasket on both before reassembly. Your seal looks pretty good.

BTW, isn't it a good idea to take both heads off rather than just one because of the un-opposed torque from just one head on? Anyone that knows is welcome to chime in.
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Post by Amskeptic » Fri Feb 09, 2007 7:43 pm

That looks like a lot of carbon for only 300 miles. Has the engine only been run in cold conditions for a short period of time?

Is the carbon on your heads and pistons oil soaked or dry?
With the oil shown in your pictures, it looks like the rings are not seated in the offending cylinder(s). But who expects the rings to be seated at only 300 miles? No judgment call possible here.

Spray copper seal may have a purpose in water-cooled engines with water-cooled head gaskets that hold back oil and water as well as combustion gases. I see no place for it in an air-cooled engine. Aluminum serves as a natural gasket device for any surface imperfections. It is soft enough that it will swallow extremely small bits. It cannot, however, and neither can any copper seal-in-a-can, overcome lack of parallel between the cylinders or large scars on either sealing surface, i.e. a scratch in the cast iron barrel or head spigot.

The "carbon seal" argument, Len Hoffman, Jake Raby, the whole gang, I take issue with. I swear sometimes we get lost in intrinsic logic that looks reasonable but collapses under scrutiny. Carbon is porous and will not hold back any gas erosion whatsoever. Carbon build up does not provide a seal. It provides a place for incendiary combustion (pinging) to occur, that's it. If you have an imperfect seal, combustion pressures will find the weak spot. The instant that actual gas flow occurs through a leak, there is no carbon or steel even that can hold it back. There is no carbon in the world that can withstand 2,000* combustion gas leakage. It is ludicrous to claim that a byproduct of incomplete combustion is a desirable state of affairs in a combustion chamber. The only advantage to carbon build-up over time is that it may raise your compression ratio. Anybody want to claim that a carbonized piston will withstand detonation damage along the crown better than a clean piston?
Colin

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Post by satchmo » Sat Feb 10, 2007 11:02 am

Amskeptic wrote:
Spray copper seal may have a purpose in water-cooled engines with water-cooled head gaskets that hold back oil and water as well as combustion gases. I see no place for it in an air-cooled engine. Aluminum serves as a natural gasket device for any surface imperfections. It is soft enough that it will swallow extremely small bits. It cannot, however, and neither can any copper seal-in-a-can, overcome lack of parallel between the cylinders or large scars on either sealing surface, i.e. a scratch in the cast iron barrel or head spigot.

Colin
Well, of course no copper spray-a-goop will fill the gap when you have out-of-parallel surfaces. I don't think that's what we are talking about here, though, Colin.

I think there are a couple of issues, and I will gladly elaborate on them from my vast experience (I have an N=1 so far :joker: ).

The first is the amount of carbon collecting in the combustion chamber. I am concerned that this happens as the result of our desire to have a cool running engine. I tend to keep the timing on the low end of acceptable and the fuel mix on the rich side to avoid overheating. No need to push the envelope, and performance seems good enough. I wonder what would happen if we all had our emissions tested on a regular basis and kept that CO level within spec? We'd probably get less carbon deposits in the chamber. I also have to think that running dual Webers or Dellortos make the problem worse because they seem to have better 'driveability' when they run rich, which is why the mpg is frequently so poor.

Second issue is the head/cylinder seal. When I rebuilt my engine 30,000 miles ago, I used valve grinding compound on the cylinder and lapped them on the flattest surface I could find. Then I lapped each cylinder to the heads. Finally, I used the Copper spray gasket on the mating surface of both the cylinder and the head. No aluminum head gasket. This worked for me and you can see the results below.

Image

When I took the heads off at 30k miles, the copper goop was gone, and I didn't really see any evidence of "carbon seal" either. I think the copper stuff probably disappeared pretty early. But it might have been critical in the initial start up before these parts had a chance to heat up and really settle in. My hunch is that if you get a small leak at the head at first start up, then it will just get worse as time goes on. I want to do everything I can to minimize this possibility. When I put my engine back together, I will probably do it the same way again.

Tim
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First, by reflection, which is noblest;
second, by immitation, which is easiest;
and third, by experience, which is bitterest. -Confucius

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