L36 LIM/UIM coolant port bypass 1995-2005
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I've read that the reason for the upper intake failure on the 3800 is the coolant that goes through the plastic intake for the throttle body, so when I did my gaskets and manifold for the second time I figured I would block it off. 1/4 inch NPT plugs and NPT tap from harbor freight pn 91395.
before;
![](https://www.gmforum.com/attachments/gearheads-115/9225-l36-lim-uim-coolant-port-update-tech-info-submission-imag0321.jpg?dateline=1351593567)
I think it was the next drill size up from 7/16 in my drill set.
Iwanted to get the plugs i saw people use on the internet with the allen head but I wasn't able to get them locally so I ground half off the square part. There needed to be less than about 1/8th to fit in the upper intake. I put a bunch of black RTV on it.
Dorman pn 615-180 is the manifold, comes with the gaskets preinstalled, pcv and injector o-rings but not the upper ones so autozone had a oring multipack.
Aluminum intake elbows; another common problem the plastic original ones are like the intake they get hot and brittle and come apart. Dorman pn;47065hp or NAPA bk6601942.
![](https://www.gmforum.com/attachments/gearheads-115/9228-l36-lim-uim-coolant-port-update-tech-info-submission-imag0325.jpg?dateline=1351593567)
before;
![](https://www.gmforum.com/attachments/gearheads-115/9225-l36-lim-uim-coolant-port-update-tech-info-submission-imag0321.jpg?dateline=1351593567)
I think it was the next drill size up from 7/16 in my drill set.
![](https://www.gmforum.com/attachments/gearheads-115/9226-l36-lim-uim-coolant-port-update-tech-info-submission-imag0322.jpg?dateline=1351593567)
Iwanted to get the plugs i saw people use on the internet with the allen head but I wasn't able to get them locally so I ground half off the square part. There needed to be less than about 1/8th to fit in the upper intake. I put a bunch of black RTV on it.
![](https://www.gmforum.com/attachments/gearheads-115/9227-l36-lim-uim-coolant-port-update-tech-info-submission-imag0323.jpg?dateline=1351593567)
Dorman pn 615-180 is the manifold, comes with the gaskets preinstalled, pcv and injector o-rings but not the upper ones so autozone had a oring multipack.
Aluminum intake elbows; another common problem the plastic original ones are like the intake they get hot and brittle and come apart. Dorman pn;47065hp or NAPA bk6601942.
![](https://www.gmforum.com/attachments/gearheads-115/9228-l36-lim-uim-coolant-port-update-tech-info-submission-imag0325.jpg?dateline=1351593567)
![](https://www.gmforum.com/attachments/gearheads-115/9229-l36-lim-uim-coolant-port-update-tech-info-submission-imag0324.jpg?dateline=1351593567)
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