6.9 vs 7.3 Head Gaskets and Boost

[IDIBRONCO]

Those can be used on a 6.9 to block the flow of the outer ports like the later style 7.3. Or they could be modified to allow some amount of coolant to pass, or left out completely as it seems that the 6.9s were built.

Not quite. The 6.9 head gaskets do have a small hole for coolant flow from the factory. In post #9, Wes said that he saw better (I assume this means lower) coolant temps by not enlarging the coolant hole in the 6.9 inserts.

 

[IDIBRONCO]

I’m thinking of just chucking a small deep well socket in the lathe, cutting and sharpening it into a die to precisely cut the coolant ports, I talked to Justin about it and he said he’s run 7.3 gaskets on a 6.9 without issue.

So are you going to offer this as an option on the head gaskets that you sell? It sounds like something I'd be interested in.

 

[Fision]

I’m thinking of just chucking a small deep well socket in the lathe, cutting and sharpening it into a die to precisely cut the coolant ports, I talked to Justin about it and he said he’s run 7.3 gaskets on a 6.9 without issue.

As manufactured the gaskets have a “perimeter” material around all the coolant passages. Will the gasket be ok in direct contact with hot, pressurized coolant or will some type of sealant need to be applied around the cutout?
I have the same feeling as frankenwrench— there’s some obvious answer here that I’m just missing.
And kudos, Wes, for keeping us all posted as to issues that arise as the current limits of these engines get pushed.

 

[Thewespaul]

If there is an interest in the modified gaskets it could certainly be something I could offer ready to go. If you look at a used 7.3 gasket there a number of places sealing coolant ports that have no special sealing parts just the regular gasket material, and as I mentioned above I ran that Q by Justin and he reported running the 7.3 gaskets on 6.9s with no coolant issues to speak of.

 

[Booyah45828]

I wouldn't worry about the sealing of water ports and such. I think you found your issue in the different fire ring thicknesses. Do you by chance know the gasket thickness uncompressed and compressed?

IMO As long as the surface is flat on the head and block, you could spray both sides of the gasket with copper coat and fix the coolant sealing issues.

I see all your examples are from felpro. Have you tried or looked at other brands? I noticed the mahle branded gaskets appear different on summit's website. Might be better?

 

[chillman88]

I noticed the mahle branded gaskets appear different on summit's website. Might be better?

I noticed that myself. The Mahle ones look like there is a rubber ridge around that cooling port on the 6.9 gasket, with a much smaller hole.

 

[IDIBRONCO]

Well I, for one, would sure be interested in the modified head gaskets the next time that I need them. Although there's nothing wrong with them, I just plain didn't like how tightly the 6.9 head gaskets fit over the studs on my 7.3. I was a little bit nervous about possibly doing damage to the gasket. I think it would be easy to do if a person was slightly ham ******.

 

[aggiediesel01]

Not quite. The 6.9 head gaskets do have a small hole for coolant flow from the factory. In post #9, Wes said that he saw better (I assume this means lower) coolant temps by not enlarging the coolant hole in the 6.9 inserts.

Thank you for clearing that up. Makes since now. Lol. And thanks for the non judgemental answer as well. Felt kinda dumb not knowing that

It seems I didn't know it all either. I couldn't see the little holes in the middle in this and the big blue threads. The only other 6.9 gaskets I'd seen were the modified ones in the shop truck idit motor. I looked at the Jerry thread as well and somewhere about post 178 there's a good picture of the hole in the middle of the plug.

Wasn't someone on OB or one of the other sites trying to get MLS gaskets made? Anyone know what became of that? I know they aren't as forgiving when it comes to deck and head surface imperfections but it might be a high boost solution.

 

[Thewespaul]

Copper gaskets were made some years ago, they didn’t work very well. Realistically, the 6.9 head gaskets have proven to be pretty stout just with the recent failure and re-examination/research it seems the 7.3 gaskets are just a more stout piece, and with the clamping we can supply with 1/2” studs they haven’t been a failure point at the current power levels we have these engines at.

 

[IDIBRONCO]

I'm not going to rush out and replace the 6.9 gaskets in my 7.3. I feel that they will be fine since I will be sticking with my Typ4 modded first Gen banks. I don't feel that there will be enough boost to ever cause an issue. Now for the next engine build, in a different truck (someday), that's a different story.

 

[nelstomlinson]

Can't we just take a ball peen and make a little hole where we need it in the 7.3 gaskets? I haven't tried messing with the ones I pulled off, but they don't look too tough to modify.

 

[YJMike92]

I see all your examples are from felpro. Have you tried or looked at other brands? I noticed the mahle branded gaskets appear different on summit's website. Might be better?

I may be wrong, but I have a Mahle head gasket set that came with Felpro head gaskets. I would have to take a look. My engine rebuild is on the back burner due to family issues so I haven't looked at the set in a while.

 

[Derik McClintock]

Some of you who are following along project big blue will already know that we had an odd head gasket failure at around 25 psi. Hg failures above 15 psi on a 7.3 a fairly common, however this engine was recently studded and retorqued to 130 ft lbs at various temperatures to ensure the gaskets were sitting flat and clamped evenly, despite those steps and running nearly double the amount of boost through the same studs and gaskets in the shop truck, this head gasket split at the fire ring and failed in a dramatic way.

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Failures like this are the best opportunity to learn more, and this weird failure at a relatively low boost pressure has been on my mind quite a bit.

For some time many of us have been converting to 6.9 head gaskets to open up more coolant ports in the head and have found a significant drop in coolant temps when running them over the 7.3 head gaskets, now after having this failure I think the 6.9 head gasket conversion actually contributed to the problem. If you look at a 6.9 head gasket like this, you will notice the large pockets in the corner of the gasket where the coolant insert is placed.

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On the 7.3 head gaskets, this area is filled in with gasket material and the coolant passages blocked off.

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Next to each other you can see the differences in gasket material supporting the fire ring on these corners.

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For the longest time I was under the impression that this change in the head gasket was due to increasing pressure from the epa wanting to cut down on cold temperature emissions from unburnt fuel by keeping more heat around the cooler cylinders, which could still be true, but I think international was also concerned about the increased performance of the 7.3s with their increased cylinder pressure and wanted this area of the fire ring better supported, this was also telling by looking at their improvements to clamping force on these gaskets when they went to 1/2” fasteners on the 7.3s, and in the idit head gaskets actually increased the diameter of the fire ring more when they added a turbo to the 7.3 engine.

Moving forward I plan on running 7.3 na head gaskets with modified corners to flow coolant like the 6.9s, just with much more material intact in that area since it won’t be using an insert. If your engine has 6.9 head gaskets I wouldn’t worry about them, I don’t think there is anything wrong with these gaskets and they are likely the best option for na engines or engines with stock turbos that won’t be seeing much boost, I’ve personally taken these gaskets to 50+ psi without any failures in na 7.3s and had them last in studded 6.9s up to 30 psi torqued at 100 ft lbs, so they can certainly handle boost fine, they just seem to be more susceptible to fire ring issues due to the lack of support in the corners of the gaskets.

 

[Goose_ss4]

Anyone look at compressed heights on the mahles?

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[Goose_ss4]

Also anyone have the part number for factory turbo head gaskets?