The following letter was supplied by Cummins Mid-South-Birmingham. I have typed the main body excepting some of the To: and CC: addresses. Anyone changing a head gasket should keep this info in mind before torqueing the head. The difference is on the front corner of the block, right next to the guide location sleeve. The new gasket on the old block will leave the water port open to the outside.


To: Mark Ketchum/Distributers/Cummins@Cummins

Subject: REF: ISB Head Gasket

Mark, Thanks for your question. We were made aware of this head gasket issue late last week. The original head gasket used on this engine (3942386) superseded to 3945803. A couple of weeks ago we released a new gasket with an added compression limiter to reduce the chance of the head gasket moving around under the cylinder head and causing fretting failures. This new gasket (3957650) superseded 3945803 which was obsoleted. What we are finding out is the new gasket will not work on all engines. There was a block casting change made somewhere along the line and the front edge of the coolant passage at the front corner of the block was moved inward. The new gasket will fit on newer blocks, but will not fit on older blocks with the original passage location since the printed seal pattern has no block deck surface to lay against. The engine you have was built 6/30/98.

We have re-instated the old gasket part number and it no longer supersedes to the new gasket. We are currently working to trace down the block casting change so we can determine ESN first and notify the field of this issue. What you need to do is order and use the old gasket part number (3945803) for this engine. As of this morning, there were 15 old gaskets in stock at MDC. We are also working with Federal Mogul who produces the old gasket to see how soon they can restart production. We could have a serious shortage of the old gasket depending on demand and how soon production can get restarted. So I ask that you only order the number of old gaskets that you currently need. Keep in mind, if you have a newer block the new gasket will work. I wish there was an easy way to determine if you need an old or new gasket without pulling the head, but we are working on that. Until then, you can lay the new gasket up to the block as picture shows below and see if the printed seal will contact the block or “cut thru” the passage. If you have any questions let me know.

Thanks, Tom Rusk

Dated: 2/2/4

 

Hauling,

Good to know information. Thanks.

 

Haulin,

At least now you know it was not something you did. You have had some really bad luck. Hang in there.

copenhagenjunkie

 

I feel for you, Haulin'. First you get a bad thermostat, and now they sold you the wrong head gasket. Didja break a mirror or something? I hope they at least gave you the right gasket for free.

 

Oops, hey guys, I just ran into the info in purchasing the head gasket, that is not what is wrong with mine. The parts man gave me the heads up so that I did not get into it. Mine is a new long block, never touched the head on it, so it is not anything I did, but still is a problem.

I think Cummins should hire me to wring out problems in the engine

 

Yea you and me booth to fix thir problems!!!!!!!!!!!!!!1 I love being thir guiny pig at my expence!!!!!!!!!

 

The head gasket numbers involved are in the original post but there is a further twist. If you purchase a head set which is the usual way, the head set number is the same with either gasket in it. The older head sets have the original gasket in them but the later head sets have the new gasket in it and they both have the same part number. The only way to determine which gasket is in the head set is to open it up and know what the difference is or look at the part number on the head gasket.

In order the get the correct gasket for mine the parts man spent 20 minutes on the computer and found one that was shipped earlier and it had the correct gasket with the same part number.

 

I know its a old post, But cummins told me today that the 3945803 was a 0.50mm thicker gasket, Can you confirm that Haulin?

Thanks for the info, I am going through this right now,,


Merry Christmas.

 

I havent seen Haulin on these forums for years. Not sure if he quit hot shot driving, moved on to newer gen trucks, or got bored of us forum guys.

 

Thanks KATOOM

 

If no one has answered your question yet then I'd try another forum. Dodge Cummins Diesel Forum or Competition Diesel Forums Lots of knowledge at those places.