Thread: How to Mod a LIM

Curious why you use pipe sealant instead of some kind of Loctite. Is the pipe sealant better in this application, or does it just not need anything stronger? Any downsides to using Loctite?

I'm doing LIM/UIM mod with L26 UIM. I want to block the coolant ports as I need the ZZP TB adapter plate, which blocks coolant to the TB, so I figure I might as well block it at the LIM and never worry about it again even with though I have the L26 top. However looking at my LIM, the coolant hole closest to thermostat is 5/64-3/32 thick, the other a bit more than 1/8. Relating that to 1/4 npt threads the first hole is a thick as center to center of 3 threads, so at best I may partially catch 2, the other about 3.5 threads C to C so that looks ok. Yours looks alot thicker. My LIM came out of an 03 NA. I'm a bit worried if the first hole will take the plug. Any ideas - thoughts? BillBoost37's pictures looked like his was /14-3/8, I say many threads, anyone else have a thin top like mine?


Also anyone looking for a counter sunk 1/4 npt plug, check your local ACE hardware, just got mine from there, all Ace's I've seen have a section with sliding bin doors filled with all types of npt fittings. I couldn't find these at the auto store and anyplace I did find online would take to long and cost way to much. At 1.99$ each visit your ACE. I am not an ACE employee ! Great place to get metric bolts as well to replace the security torx bolts on TB sensors.


Great tip on your grinding out the U turn coolant ports. I do not understand why those are even divided and require the u-turn fitting. Was this an option for coolant heater or alternate flow path for other engines ? As far as the gasket for this, it is included in the Felpro MS95812 UIM kit. Why it comes in that kit and not the LIM MS 98014T makes me wonder if someone was breathing to much exhaust one day at Felpro.


One more note, someone mentioned what material to use for the coolant plug and another pointed out "An engineer said they are dissimilar metals". Well I'm a nuclear engineer. Yes brass and aluminum are and by being dissimilar, the metal will migrate from one to the other, so it kind of gives it a self welding affect. OF course it more like a self crud like effect, (ever see brass and steel in old water pipes) especially if being thermally cycled, of course that's irrelevant if you are using sealant in there. But that's the basics behind dissimilar metals. No problem using the brass or a steel, it does have anti-corrosive Dex around it.

I would try the 1/8th npt tap, and when you are tapping down on the bigger hole, dont tap down very far. the tap is tapered, so the farther down you go, the deeper the plug will go when it tightens into the hole. I didn't measure the holes on the last one I did, but it was an L36 lower intake manifold. when I installed the plug in the hole, it wouldn't tightened down all the way and fell into the lim, so I used jb weld, and as far as I can tell, it sealed up. the other thing you can do is the dime mod. it's either a dime or a nickel that should fit into the recessed area of the hole, then just use jb weld to glue it in there. a lot of people have done it like that without problem.

I have a question on the porting of the coolant passageway. With basic fluid dynamics and laminar flow in mind is it possible that removing the "restriction" would cause turbulent flow? Effectively not really increasing the cooling systems efficiency.

Maybe my ME mind set is over thinking it but seems like the cover acts as a turn to keep the fluid flowing with laminar flow.

Just a thought, anyone else have any input?

just finished this. taping was a lot of work without a tap handle. I used a 7/16" wrench.

Wondering if anyone had a pic of a slightly better angle of the finished end cap coolant passage? My eyes decieve me and want.to do it right. Thanks in advance