Why do I keep blowing head gaskets?

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RockinRobin

RockinRobin

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Gen 3 hemi aluminum heads. About once a year I get a water leak and have to replace a head gasket. Motor never runs above 190 water temp. I've been using Fel Pro. I get the heads surfaced every time they come off to make sure they are flat. Compression ratio is 13.5:1. Should I use a thicker gasket than stock since I've had the heads surfaced more than once? Standard thickness is .027 but Cometic has many thicknesses available If you can find them.
 
What are you using for head retention? Bolts or Stud?

If you're having recurring issues my first guess would be loss of clamping force.

Tom
 
O ring either the head or the block and use steel tri-metal gaskets. The o-ring should fit into the compression ring of the gasket.

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Ever surface or check the block decks? Does the leak happen in the same place? Mag for cracks?
 
RockinRobin said:
Gen 3 hemi aluminum heads. About once a year I get a water leak and have to replace a head gasket. Motor never runs above 190 water temp. I've been using Fel Pro. I get the heads surfaced every time they come off to make sure they are flat. Compression ratio is 13.5:1. Should I use a thicker gasket than stock since I've had the heads surfaced more than once? Standard thickness is .027 but Cometic has many thicknesses available If you can find them.
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I don't know if you use copper coat but I would use 10 coats on each side.
I think the bolt spacing has a little to do with it.
I do a lot of cylinder head resurfacing, 3rd gen hemi heads are pretty rare to see..
You could try a thicker gasket if you want, it's not necessary though.
And o-ring the head.
I use copper coat on my head gaskets.
The surfacer at my work had a 24 grit cutter.
It made a little less than desirable ra finish so I felt it would be a good idea. Has not leaked
 
At 13.5:1 have you ever considered that in really good air you might be getting in to detonation causing it to kick the gasket out?
 
PROSTOCKTOM said:
What are you using for head retention? Bolts or Stud?

If you're having recurring issues my first guess would be loss of clamping force.

Tom
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ARP head bolts. Studs weren't available for months when I did the last rebuild. ARP says they don't need to be re torqued. I'm thinking that might be wrong...
 
TT5.9mag said:
At 13.5:1 have you ever considered that in really good air you might be getting in to detonation causing it to kick the gasket out?
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Agreed!! What fuel are you using?
 
I had issues with detonation, never heard it, but the evidence was clear by the material missing, pitting close to the edge of the piston top, opposite the spark plugs. Scrutinize the piston top. My rod bearings also lost "crush".


nother thing detonation can cause is a sandblasted appearance to the top of the piston. The piston near the perimeter will typically have that kind of look if detonation occurs. It is a swiss-cheesy look on a microscopic basis. The detonation, the mechanical pounding, actually mechanically erodes or fatigues material out of the piston. You can typically expect to see that sanded look in the part of the chamber most distant from the spark plug, because if you think about it, you would ignite the flame front at the plug, it would travel across the chamber before it got to the farthest reaches of the chamber where the end gas spontaneously combusted. That's where you will see the effects of the detonation; you might see it at the hottest part of the chamber in some engines, possibly by the exhaust valves. In that case the end gas was heated to detonation by the residual heat in the valve.

Good luck
 
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85glht said:
Agreed!! I had issues with my Omni w/110 octane fuel (25psi and 50 shot of NOS)... started using Maximal or 116 and my head gasket issues went away.
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How long would it take on 110 for your head gaskets to be compromised?
 
RockinRobin said:
Wouldn't detonation show up on the plugs?
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Not necessarily. In my experience the rod bearings ALWAYS show the signs of detonation. The pistons most of the time show signs, depending on material makeup, and the plugs can be hit or miss. I think there are far too many factors to have definitive answers to questions like that. AFR in the chamber, piston design, chamber design, cylinder head material, spark plug location all I think would play a role.
 
The reason I asked the original question is I’ve personally seen gen3 hemis with 10:1 and 20psi on e85 and they’re making 1000 hp plus and not kickin out head gaskets. Just studded decks and MLS gaskets. So something different is happening in your combination IMO.
 
RockinRobin said:
ARP head bolts. Studs weren't available for months when I did the last rebuild. ARP says they don't need to be re torqued. I'm thinking that might be wrong...
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I’d definitely be re torquing the head bolts after a few warm up cycles on a new build.
 
TT5.9mag said:
The reason I asked the original question is I’ve personally seen gen3 hemis with 10:1 and 20psi on e85 and they’re making 1000 hp plus and not kickin out head gaskets. Just studded decks and MLS gaskets. So something different is happening in your combination IMO.
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Alcohol has better resistance to detonation than gasoline too, so that's not an equal comparison. It's very likely that in those instances, alcohol is the determining factor for not blowing gaskets.
 
RustyRatRod said:
Alcohol has better resistance to detonation than gasoline too, so that's not an equal comparison. It's very likely that in those instances, alcohol is the determining factor for not blowing gaskets.
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That just furthers my point. The ethanol has a much higher latent heat of vaporization which does more than just the benefit of the higher octane. The E85 is only like 105ish, but the fact that it pulls so much heat out of the charge when it vaporizes really helps the chamber temps. But (my real point) the gen3 hemis in those circumstances are sealing up the chambers and not kicking out gaskets with very high cylinder pressures, so it’s not a mechanical sealing issue.
 
85glht said:
A day of beating it at the track. Better fuel is more forgiving.
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In my case it takes a year of beating it at the track. An average of 2 races per month and we run 10 months out of the year. If it was detonation I would think it would show up a lot sooner than that.
 
RustyRatRod said:
Really? For 13.5? I'd be runnin 116 or 118.
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At 13.5:1 he doesn't need O rings or that much octane.

If he is going to do O rings you machine a groove in the head and put the wire in the head.

Then you O ring groove the block and that's the receiver groove. And then that requires dead soft copper gasket to work correctly too. And they have their own set of problems.

So I don't suggest that very often.

When you push a head gasket out like that it's usually a tune up issue. You don't have to see detonation on the plugs to get enough detonation to push the gasket out.

At 13.5:1 the fuel I would use is 100 LL Avgas. It will support more compression than what the OP has.

Without knowing his timing curve, plug heat range, cam timing numbers and such it's hard to say exactly what's going on.
 
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