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Thread: Head Gasket Questions

  1. #1
    Garrett booster
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    Head Gasket Questions

    I'm doing a bunch of research for writing up a FAQ on our head gaskets for the SOHC 2.2 / 2.5 cars. The following is what I have so far. I'm just looking on everyone's opinion and having others fact check me. Here is what I have so far:

    Head Gasket Guide
    There are two basic head gaskets used in the 2.2/2.5L SOHC family of vehicles. Illustrated below is the non cross drilled style of head gasket, Mopar part number 5281064. This is the same style as the former Mopar Performance P4452005 head gasket. This gasket has open steam ports but closed cross drilled ports.



    The other style head gasket is the cross drilled style, Mopar part number 5281065. This gasket is no longer available from Mopar. This is the same style as the former Mopar Performance P4452006 head gasket. Unlike the stock gasket, the Mopar Performance part features double cross drilled ports. Notice in the below illustration how there is only one set of cross drilled holes (highlighted green) between the cylinders. The Mopar Performance gasket will have another set of matching holes towards the front of the block. No production vehicles came equipped with double cross drilled blocks. This style gasket blocks off the steam ports to force coolant through the cross drilled ports to increase head gasket life by lowering head gasket temperature between the cylinder bores. This gasket should not be used with a non cross drilled block because of potential cooling issues.



    The last style of gasket worth mentioning is offered in the aftermarket. It features open steam ports and double cross drilled ports. When used in a cross drilled block, instead of most of the coolant flowing through the warmer cross drilled ports, they are divided among both the steam ports and cross drilled ports. This may cause higher head gasket temperatures in a cross drilled block.



    Below is a list of head gasket part numbers for each year and engine combo. Part numbers highlighted in blue have been superseded to part number 5281064, non cross drilled style. Part numbers highlighted in red have been superseded to part number 5281065, cross drilled style.



    Of interesting note is the application of the non cross drilled head gasket throughout the 1990s. Many online sources indicate cross drilled naturally aspirated blocks existed as early as 1990. The factory parts manual disagree, showing non cross drilled head gaskets were still in use as of the 1993 model year. The factory service manual of the same model year contradicts this by omitting the illustration of the non cross drilled gasket, showing only the cross drilled gasket was available.

    This contradicts the popular notion that "late 1990-1995" naturally aspirated blocks were cross drilled. It seems 1993 may have been the cross over year for naturally aspirated blocks.

    Additionally, the factory parts manual lists the wrong application of the cross drilled head gasket in 1987. The above chart has been corrected to show that 1987 "EDR" code engines use head gasket part number 4387837.

    Opinions / Observations

    The following is a collection of opinions and observations on what is preferred in a head gasket.

    Conjoined Fire Rings


    Many prefer a head gasket where the fire rings are conjoined, such as what is pictured on the right. Many of today's aftermarket head gaskets have fire rings that are not conjoined, pictured left.

    Cross Drilled or Non Cross Drilled

    Dave Zelkowski, a former Chrysler Engineer involved in the development of the 1980s Turbo Dodges, states "The purpose of cross drilling is to reduce the temperature of the head gasket between the cylinder bores." Based on comparing the two styles of factory gaskets, it seems that the non cross drilled style head gasket allows coolant to pass through the steam ports while the cross drilled style head gasket blocks those steam ports to force coolant to pass through the cross drilled ports.

    In the aftermarket, one common feature is for the head gasket to have both cross drilled ports and steam ports open. This gasket is acceptable for use in both cross drilled and non cross drilled blocks. In cross drilled blocks, however, any cooling advantages that the factory intended are lost. This may lead to the unexpected failure of such a gasket in a cross drilled application.



    That is pretty much all I have . Questions, comments, requests for additions?

  2. #2
    turbo addict
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    Re: Head Gasket Questions

    Just stumbled on this. Nice job compiling this!
    Todd

  3. #3
    Rhymes with tortoise. Turbo Mopar Staff cordes's Avatar
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    Re: Head Gasket Questions

    Thanks for finding it Todd, and thanks to the OP for putting it together. That was a great read.

  4. #4
    Garrett booster
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    Re: Head Gasket Questions

    This was the final version:
    http://generalchryslerinfo.blogspot....ket-guide.html

    Slightly tweaked, but mostly the same.

  5. #5
    turbo addict
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    Re: Head Gasket Questions

    Can't believe I missed it the first time around! Nice work!

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