JD730

Yeah, in my gallery there's a picture of a modified 12 valve gasket for my 24 valve.
From what I understand and read here there is no "marine" gasket, all 12 valve gaskets are the same.

robert chilton

Thera are marine head gaskets for the 12V. Do A search on here and the correct cummins number should pop up. Also there is a thread talking about torqueing the head bolts as the originals are throw away torque to yields. So far my head gasket has held up after I replaced it a couple thousand miles ago. The original was leaing at 220k miles and lasted another 30k modded. I accidentally added to much timing and popped it swapping injector pumps. I did not have the head decked or replace the head bolts. Just cleaned it good and torqued the bolts to the 115-125 ftlbs. My break in was hauling a 14k pound fifth wheel for 300 miles! By the way be glad that the oil didnt mix. I did atleast 5 oil changes in a 100 miles!! Good luck with the head gasket. If you have a cherry picker use it.

1stgenatheart

A little update on my head gasket,,, upon removing the head I discovered that several of my head bolts were NOT torque to Cummins spec... GRRRRRRRR I believe that this has been a problem since day one as I found evidence of minor leakage,,,also and this really disappoints me all my cylinders has virtually no wear,, the factory hone marks are very very clear... awesome! but,,,, #5 has some vertical scaring,,,, what the heck??? I was talking to a local diesel shop and he told me that he has seen this a lot,,, "yep #5 is the one that give problems when you have them" Anyone ever hear of this?? Oh well I must say though I am a little disappointed... I have always loved the Cummins 5.9 and maybe this is my own fault but in my mind they have always been a "bullet proof" engine...... I know that I don't have serious engine problems but still it disappointing...

05CTDN8

I have heard the #5 is always hotter due to design, which is why you want the EGT probe as close to #5 as possible....

wannadiesel

If it's not making bad noises just put it back together.

1stgenatheart

Hi everyone, Well I got the old girl back together And it’s running better than ever. I want to thank all that gave me advice and help. A special thanks to 12flapper By the way here is what I found wrong. On the #2 cylinder the rocker head bolt "the longest ones in the head'" had been threaded wrong from the factory. I would say that only 1/3 of the threads were actually cut into the bolt from day one and it actually loosened up. I guess that one slipped through quality assurance that or the Germans had a few extra beverages at lunch that day any way it held for 17 years. I also ran a tap down each one of the stud holes. Everything looked fine even the hold with the miss-threaded bolt. I did have a valve job done and I resurfaced the head, put new head bolts in and all new gaskets from Cummins. Oh and last thing I herd that there was no need to re torque the head bolts.????? I don't know what the real story is there but I did. I would seriously recommend that anyone removing the head to do the same. Every bolt moved the second time. Well thanks again! This site rocks!

robert chilton

Mine was scored the same way. The rear holes run hotter and the theory is that the rings swell a little more causing the scuff marks. Mine is still working also.

12 flapper

Now its time for more MODS

Dodge359

That was why I broke down and bought the twin ram intake.

1stgenatheart

where did you find the twin ram intakes?

Dodge359

Ibought mine new on ebay ans still paid way to much. I missed a few on the forums that have gone for a s little as $150. They cost $550+ and dont add hp.