How hot is too hot for a manifold?

[AMC Diplomat]

After not finding any other bad wires, I started investigating the melting temp for battery cable insulation. Most places rate their insulation between 200 and 300 degrees. So I thought ok, maybe there's not enough air flow and the manifolds just get warm and that's what melted the cable. Then I finally dug out the old laser thermometer and I got worried.


This was all after letting it idle from a cold start for about 15-20 mins. 300-400 seems high but not unreasonable. Over 680 on the other side seems like I've gone from "catch the car on fire" to "its getting hot enough somewhere to seize, strand me, and then catch on fire"

I'll be happy to know if I'm overreacting and these mopar manifolds usually get that hot. Better to admit not knowing something than to take a chance.

 

[Mikes5thAve]

If its not glowing don't worry about it.
altho if the passenger one is a lot hotter then drivers you might want to make sure the heat riser valve is moving freely.

 

[AMC Diplomat]

Thanks!

 

[AMC Diplomat]

Just checked the heat riser valve. It's shockingly not seized and moves freely. I wonder if it's just not opening all the way with the spring?

 

[Mikes5thAve]

The spring is thermal and shouldn't cause any restriction when it's warmed up. I think the biggest issue with them is either warm up problems or seizing up.

 

[Yellowdart]

Many years ago, I had a friend, that drove a Toyota. One evening, he openned the hood to show me his engine The manifold was glowing red. Never saw anything like that, before or after. At the time, he told me it always did it, and had no issues with the car. I thought it was crazy, and never forgot it.

 

[Justwondering]

Yellowdart ... which means, you would have burned the biscuits, but could have cooked the bacon.

I've cooked chocoloate chip cookies on a manifold before, but they were just a bit gooey. Eggs always turned okay, but they cooked too quick.

JW

 

[Camtron]

Possible Air/blockage in coolant passages? I know BB Chevys tend to have higher temps on passenger side from coolant routing, could be the same thing.

 

[AMC Diplomat]

Possible Air/blockage in coolant passages? I know BB Chevys tend to have higher temps on passenger side from coolant routing, could be the same thing.

It's consistently hotter on the passenger side since I've started monitoring it. It's probably nothing and I'm just overreacting. It's definitely worse sitting at idle vs coming back from a long drive