Exhaust Manifold Overheating

[Techlight]

Hi All,

Hoping someone can give me some insight here. I did some searches on the forum and google but wanted to get some input from you'all.

My exhaust manifold is running hot: about 550 degrees or a bit more. The cat is at about 450ish, and the pipe before the cat is at about 530ish. The block, radiator, hoses, and intake manifold are all at about 200 give or take some. Right now I'm wishing I would have temp'd the pipe behind the cat.

I just put a new Howell TBI on it and felt like I was getting excessive heat from it. Now I'm in the desert so it's hard to tell what's road heat and what's exhaust heat, but I noticed the wire looms on the new wiring are starting to curl a bit where the sit next to the TBI above the exhaust/intake manifolds. So obviously running way too hot.

I have the timing set at 8* and I'm pretty sure the install went in without a problem but I could be missing something. Is there anything that I could have missed, or not hooked back up that could cause the overheating exhaust manifold? It was running lean before I put the kit on so it may have messed up the cat, but it passed smog well enough. I didn't do anything with the exhaust manifold heater. From what I was reading it seems to be hooked into a relay that is triggered by the oil sending unit (I could be completely wrong here). I doubt that's causing my trouble obviously...but it's worth mentioning.

I"ll probably tear into it this weekend so any tips and suggestions would be helpful.

Thanks in advance...

 

[Posi]

Your temp readings seem fine to me.
exhaust manifolds can run hot, up to 1200*
Your cat is running on the cool side, temps can run from 500* 1500* typically they run around 800*
Your water temp looks fine at 200*
Reposition your wire loom.

 

[Peanut Butter]

You could also use some of this: Exhaust Heat Rape by DEI

 

[Peanut Butter]

Or this: Heat Shield

 

[Torxhead]

One suggestion would be to unplug the intake manifold heater as it might have a bad relay or temp switch and is always on. Although this could be checked with a voltage meter to see if it is always on. You probably do not need it where you live anyway. For test purposes, a mechanical water temp gauge could be put into where the switch that operates that relay also. I am surprised that you did pass Ca. smog if the air fuel mixture is also running hot. Are you still running the oem cat as the newer ones have a straight thru hole and seem to work better.

 

[Techlight]

Thanks for all the replies.

I'll unplug the heater and see if that changes anything. The whole thing just seems really hot to me with the melting and curling of the looms and when I pop the hood after driving there's a ton of heat pouring off it.

Howell doesn't allow much play on the harness so rerouting isn't an option. None of its sitting directly on the manifolds though so that's good. I may grab some of that tape. I'm mostly worried about melting the damn wiring harness.

I probably do have the oem cat since it was hooked up to the pulse air system. I'll look into getting a high flow one or ask my muffler shop.


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[Techlight]

Thought I'd add some pics


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[Torxhead]

FWIW, I was able to get a bit more wiring clearance on my setup and don't seem to have any issue. It was interesting as you stated to remove all those vacuum lines and do all that wiring work. I also got an improvement with the large distributor cap and rotor. All of my smog checks have been at "check only" stations. Do you think you are getting enough coolant thru the intake manifold?

 

[Techlight]

After looking at it a bit more I was able to reroute most of it up higher. Glad I looked at it again.

I took those temps after a 20 min drive home last night. I may drive it some today and retake then since it's about a hundred out right now lol. Although I'm pretty sure 20 minutes is enough to hear my cat up pretty well.




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[Lumpy Grits]

T'light, your temp readings are fine. You need to move the wiring. Or make some type of heat shield up. AMC knew better than to run it that close to the exhaust manifold.
Can you route the wiring to the outside of the TBI?
BTW: Why are you run'n a K&N A/F, with all the silica that's float'n around in our Mojave Desert?
Your gonna have to bring your Jeep by, so I can take a look.
LG

 

[Techlight]

I think I am getting enough coolant through the intake. The motor isn't overheating. The intake isn't that hot on the outer edges away from the exhaust manifold. It's the exhaust that's cranking heat out. But maybe it just feels like a lot of heat to me and not anything the TBI can't handle. But in the center of the exhaust manifold I know it's easily over 600. But as the replies seem to say higher temps I listed are fine so I'm not sure.


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[Lumpy Grits]

Like I said. Re-route the wiring to the outside of the TBI unit and get it away from the main heat source.
LG

 

[Techlight]

They won't go around the TBI unit. I wish they did. Two of them will but I still end up with two on top of the TBI like in my pic.


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[Techlight]

I'm running the kand n because that's what was available. Do you mean I should run a paper filter on it or a different air intake? Eventually I'll put a cold intake in it.

I'll have to swing by at some point for sure.


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[Lumpy Grits]

Make a sheet metal heat shield/deflector to protect the wiring.
OR-Lengthen the wire'n yourownself so it can be routed away from the heat.
This wiring issue is maybe something you should talk to the products tech people about.
LG

 

[Lumpy Grits]

I run either Fram or Wix paper.
You still have my phone number-Just call.
LG

 

[Hedgehog]

Techlight - Lumpy and I agree on many things. On a few things I do not agree with him and K&N air filters is one of them. I've run'em for ????, well a long time. Yes I've read some of the tech. articles Lumpy references. The one I most remember was on K&N efficiency. That one said, although it seems to be non linear thought, the K&N works better when dirty. Makes sense to me, in many applications dirt attracts dirt. I wouldn't panic about using the K&N air filter.

 

[Lumpy Grits]

YUP-This is a point where HH and I agree, to disagree.
LG