Thread: LIM side coolant port modification / coolant block off

Ive got my new (j.y.) motor on the stand. Gonna regasket the LIM before I put it in the car.

I don't know if I'm going to block off the coolant ports to the blower or not. It seems like a 50/50 mix of folks saying to do it or not. The car is just a driver that will see all seasons.

Regardless of doing the block off, should I enlarge the coolant port on the side? Or should this only be done if the ports are plugged?

Originally Posted by 2004l67

Ive got my new (j.y.) motor on the stand. Gonna regasket the LIM before I put it in the car.

I don't know if I'm going to block off the coolant ports to the blower or not. It seems like a 50/50 mix of folks saying to do it or not. The car is just a driver that will see all seasons.

Regardless of doing the block off, should I enlarge the coolant port on the side? Or should this only be done if the ports are plugged?

I'm doing mine tonight. I would definitely enlarge the side bypass ports. The heads I pulled off, on the rear one.I could see a difference just in the coloring of the metals. The push rods were noticeably darker, as well as inside the head. The whole thing just looked like it ran hotter.perhaps this is normal for the rear head on a fwd v6 to naturally run hotter, or perhaps I'm just over thinking it. Either way I have more peace of mind with more coolant flow to the rear

Originally Posted by BillBoost37

I suggest doing it for better flow. Rear head runs a little cooler when you have better flow.

The side port mod alone, or block the coolant passages to the blower as well?

Originally Posted by BillBoost37

I suggest doing it for better flow. Rear head runs a little cooler when you have better flow.

Bill,

As I was hosing off my LIM, I sprayed water through the holes and got a better understanding of how coolant flows, which raised a question for me.

The two ports on top of the LIM, that route coolant to the TB, that you recommend blocking off, are in parallel with the two on the side of the LIM. That is, the top rear hole and the side rear hole kind of form a "Y" path, and so do the top front hole and side front hole. One "Y" splitting coolant flow and the other rejoining it after the TB.

Is that right? That seems to be how the water flowed.

So, if you block off the top ports, you've reduced flow, and hogging out the side port helps restore it. Correct?

BUT... Does this actually improve overall flow and cooling? Or are you just restoring the flow lost by blocking the top ports?

Given that the TB coolant passage is considered mostly useless, if benign, what do you think about leaving the top ports open, and still hogging out the side port?

There must be a reason they designed the LIM to have that "T end" restriction on the side port. Maybe only to force more coolant through the TB, maybe for something else. Thoughts?

(I guess this is the OP's question, just worded differently)

Originally Posted by wmorrison65

Bill,

There must be a reason they designed the LIM to have that "T end" restriction on the side port. Maybe only to force more coolant through the TB, maybe for something else. Thoughts?

(I guess this is the OP's question, just worded differently)

Exactly what I was thinking. I was thinking of hogging it out, and leaving the top ports functional. Better, more consistent cooling. But also feared that maybe hogging it out and leaving the top open could allow too much flow. I'm over thinking this.

Originally Posted by BillBoost37

I like to block it. There's too many times I've seen a TB gasket blow etc and cause issues. No coolant..no issue.

AHA! Blocking it takes TWO potentially leaking gaskets out of the equation. I knew about the TB gasket but didn't even think about the coolant flowing through it.