Renix manifold heat shield

[hgeranium]

Do y'all keep the manifold heat shield on or does it function fine with the shield off? I notice that the HO and later 4.0's don't have the heat shield above the manifold. The only reason I'm asking is it looks like a PITA to take off and put on to get to things below it (especially because I need to replace my manifold gasket), but I'm also worried about stuff like vapor lock if I keep the shield off once I go through the work of removing it the first time.

[89 MJ]

You'll have heat soak problems without it. Can confirm from experience.

[Eagle_SX4]

I would keep it in place. There is no need to remove it to take off the intake manifold. Remove the air box and you can reach under manifold and get to all the bolts quite easily.

[hgeranium]

2 hours ago, 89 MJ said:

You'll have heat soak problems without it. Can confirm from experience.

Darn, I’m glad I asked. It’s interesting that the newer 4.0s didn’t come with it. Thanks for your insight!

[Eagle_SX4]

8 minutes ago, hgeranium said:

It’s interesting that the newer 4.0s didn’t come with it.

It was a cost cutting measure they cast a poor heat shield into the 91-98 manifolds. The 99+ manifolds also have a similar design.

[Eagle_SX4]

It is my theory that the reason the later 4.0's had worse heat soak issues is because of the fuel rail not a lack of a heat sheild. The later fuel rails went to return less system which lets the fuel sit in the rail longer and is more prone to heat. The Renix fuel rail is the best in my option as the inlet and return lines are on opposite ends. Letting the fuel return to the tank before it has a chance to have heat soak issues.

[hgeranium]

2 hours ago, Eagle_SX4 said:

I would keep it in place. There is no need to remove it to take off the intake manifold. Remove the air box and you can reach under manifold and get to all the bolts quite easily.

That’s great to know. I used your guidance to tighten up those bolts but didn’t know if there was enough clearance with that shield on there to remove the manifold itself. I was not looking forward to having to mess with the fuel rail. 
 

I figure when replacing the gasket itself it’s not too hard to get it set up from below as well?

[hgeranium]

1 minute ago, Eagle_SX4 said:

It is my theory that the reason the later 4.0's had worse heat soak issues is because of the fuel rail not a lack of a heat sheild. The later fuel rails went to return less system which lets the fuel sit in the rail longer and is more prone to heat. The Renix fuel rail is the best in my option as the inlet and return lines are on opposite ends. Letting the fuel return to the tank before it has a chance to have heat soak issues.

Very interesting. Another win for Renix

[Eagle_SX4]

14 minutes ago, hgeranium said:

I figure when replacing the gasket itself it’s not too hard to get it set up from below as well?

The bottom two bolts front and back should be studs and you can place the gasket on those and it stays in place when putting the manifolds back on.

[garyweb3]

I replaced my manifold gasket and while the manifolds were off I stripped and painted the manifolds. I ground off the spot welds on the heat shield and found my exhaust manifold was cracked. Might want to check yours while you have it off