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1994 K3500 extended cab dually

n8in8or said:
Next one I build, I'd like to use MLS gaskets. That should help.
Click to expand...

Only consider MLS if both surfaces have been machined and leave the cups in the heads so they are flat, MLS doesn't seal well with the cups protruding... the MLS set I have are .038 thick, that's the thinnest they make for our motors...
 
Twisted Steel Performance said:
Only consider MLS if both surfaces have been machined and leave the cups in the heads so they are flat, MLS doesn't seal well with the cups protruding... the MLS set I have are .038 thick, that's the thinnest they make for our motors...
Click to expand...
Yep, that's why I'm not considering it for this engine, but for a future build. Good point on the cups needing to be absolutely flush as well.
 
That's not a blown head gasket.














This is a blown head gasket.






IMG_20150307_110653484.jpg



Its strange how the fire ring on yours stayed in place and the gasket material behind it blew away.

Do those gaskets have the metal reinforced corners at cylinders #7 & #8?
 
Even with studs?! HX55 at 50psi?? :wideyed:
Wow! I mean Ouch!
I destroyed a 6.5 (bent rods) when I had catastrophic head gasket failure, but it didn't do that!
 
Duvall said:
Do those gaskets have the metal reinforced corners at cylinders #7 & #8?
Click to expand...

Yes, they’re reinforced. Top gasket is a used .010 Fel Pro. Bottom is a .010 Mahle that just came off this truck.

3889182D-E22C-4EAA-89B2-85682BC5E678.jpegED146309-22C4-4386-A0A9-D1EBA04F15E3.jpeg

This end wasn’t blown, but it was just starting to tryto push the gasket out.
1BD111D3-58AA-4CD4-A284-0B5DC4D4ED7F.jpeg

Got the heads disassembled and cleaned up for the machine shop. It’s coming back to me now…..this was totally an error by me that could have been avoided, but at the time (summer 2020), I was pushing to get the truck together and running so we could go camping. Alas, I never got it close to that goal and now I’m paying the price for cutting this corner. The deck surface of these heads clearly needed to be resurfaced, but I hoped that with the copper spray on Mahle gasket approach that I could get by. Possibly I could have gotten by if I had stayed with a smaller IP…..possibly. It was a risk, and I knew it at the time, but I still took it. Another “live and learn” moment. Hopefully the machine shop can turn the heads around quickly and I’ll be able to make some noise with it at Dinosaur Camp, complete with the paw-paw cap on it 🥸

8DFF437D-B621-422B-92F8-B6FD47F9D1FD.jpeg
 
Oh and I forgot to mention: last summer I wasn’t even sure if the machine shop was capable of surfacing IDI heads, but I talked to them recently and they said they can, so that’s no longer a worry. Even so, the extra time of having them worked on was a concern of mine, I guess I just traded time last year for time this year. 🙃
 
Looks like you used a scotch type abrasive disk to clean those up? I never use those on heads or deck surfaces because they can take the edge off straight corners so easily and they move a lot of material quickly. I suppose in your case right before a milling it wouldn't make much difference.

I believe I suffered from the same hurry up disease that you did. My heads didn't quite look like yours, but I was always concerned if they were flat and never had them checked.

Paw-paw cap. ;) :dead: :D


MrMarty51 said:
And so, which head gaskets would You think is the better brand ?
Click to expand...


Clean, straight, flat surfaces and Cometic MLS

That is my recipe.
 
MrMarty51 said:
And so, which head gaskets would You think is the better brand ?
Click to expand...

I can't say with 100% certainty which is better, but I can share my experience.

I had +.010 Fel Pros on the Tahoe with this short block and IP for a couple years. Daily driving with ~30psi of boost quite regularly and didn't have a head gasket failure.

This build I used the Mahle +.010 gaskets with multiple coats of copper spray and had this failure not long after I started hitting them with 30psi of boost, but clearly the heads weren't doing them any favors, which makes the results inconclusive.

After I get the heads resurfaced, I'm going to put this back together with Fel Pro +.010 gaskets, partly because I already have them and partly because I know they will work.

Duvall said:
Looks like you used a scotch type abrasive disk to clean those up? I never use those on heads or deck surfaces because they can take the edge off straight corners so easily and they move a lot of material quickly. I suppose in your case right before a milling it wouldn't make much difference.
Click to expand...

That's correct, I used Roloc discs to clean up the deck surfaces on the heads because they're going to get resurfaced anyway. I wouldn't have normally used them for this deck surface. The were just quick and easy to get the old gasket residue off....... I don't want the machinist to be mad at me as soon as I walk in the door, carrying in dirty heads. I also hit them with degreaser and then sprayed a light oil on them. Hopefully it's a quick bath is all they need before they can work on them, and hopefully that helps them to get them processed for me sooner.
 
That’s better.

C3C9FA71-D390-4284-8F82-F02E65F43F3E.jpeg

The guy that did the machining wasn’t there when I picked them up, so I wasn’t able to confirm how much he took off. I was told he took off as little as he felt comfortable, but you can see it was still a fair amount - the square in the precups is gone in most of them. They should definitely seal a lot better now…..hopefully the decks aren’t too flexible as a result. These only have to really get me through a little while though I suppose.
 
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