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  #1  
Old 04-30-2003, 09:21 PM
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Default red hot exhaust manifold?

Get this....I replaced my head gasket today, and all was well, until the ulitmate highway adventure. I decided to test drive it on the highway to get the bugs out. I pulled over when it started to buck at about 2800 rpms, and the exhaust manifold was RED hot. Any input on this predicament?
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  #2  
Old 04-30-2003, 10:06 PM
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Default Re: red hot exhaust manifold?

High temperatures are usually due to an overly lean mixture or detonation (ping). If you haven't already done so, a complete tune up is a good start. Also check the timing. I have seen the headers on my CJ give off a dull dark red glow at night after a long drive. I've done everything I can to make sure it is tuned right, so I'm just considering this to be normal on my CJ. However, "red" doesn't sound right... How did it run on the highway?
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Old 04-30-2003, 10:39 PM
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Default Re: red hot exhaust manifold?

If it was an all-of-a-sudden problem, my guess would be timing chain. If everything was running fine before, but the chain is worn, it can cause the chain to jump and the engine to run w/ exaust valves partially open causing the heating.
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Old 04-30-2003, 10:52 PM
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Default Re: red hot exhaust manifold?

Why the head gasket change?

Glowing exhaust manifold is not good.
Loss of power is not good.
May indicate worse problems.
When my first jeep blew up the exhaust manifold was glowing red.
That was right before a piston decided to come out of the side of the block. [img]images/graemlins/crybaby.gif[/img]

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Old 05-01-2003, 08:36 AM
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Default Re: red hot exhaust manifold?

Start by having a look at your plugs.
The heat in the manifold is because excess gas is getting burned there instead of in the engine. For some reason all the fuel is not burning in the combustion chamber

I'd bet the plugs are Split Fires, Bosch, Platinums, or some other "one size fits all" Mickey Mouse plugs that the engine wasn't made to run with. What are the chances plugs that fit everything from a Yugo to a tractor that "fit in the hole" are the right ones for your vehicle? Ask your wife how she likes "one size fits all" clothes.

Use the exact same brand and part number the engine was designed around. It's not just a matter of hole size and threads, but heat range (that in itself has many many variables - mixture, compression, gap, R's etc,) indexing, reach, and the ability of the plug to withstand certain other things, like combustion impacts. They are not all the same!

The plugs got too hot, started misfiring, allowing unburned fuel to exit into the manifold and burn there.

After it cooled down it runs again, but may misfire sooner.
Hopefully you didn't melt the tops of the pistons too much, but that's very common when using junk.

If they are the correct plugs in it that the engine designers wanted and it did it, look for retarded or excessivly advanced timing or fuel. Too early a spark, or a too late one will cause chamber temps to skyrocket, frying the plugs and causing the misfire.
Too lean will cause unburned fuel to exit, causing the hot manifold and misfire.
Too rich most likely would get the manifold hot, but not cause the misfire unless it's super super rich.

A timing chain that's slipped will be very hard, if not impossible to start. And you'll hear it crank way too fast.

Let us know what you find.
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Old 05-01-2003, 09:59 AM
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Default Re: red hot exhaust manifold?

do you have a catalytic converter?

it sounds like its clogged up.
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Old 05-01-2003, 12:48 PM
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Default Re: red hot exhaust manifold?

YEah the problem may be my spark plugs, im using split fires. And i asked my wife if she likes the one size fits all clothes, i figure im not gonna get laid for a while... The timing chain is fine, i had checked that for wear before, i had to replace the head gasket because it had blown out the week before. IM gonna replace the plugs and give it a tune up, see how that goes... thanks for all the advice
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Old 05-01-2003, 01:09 PM
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Default Re: red hot exhaust manifold?

Had the exact same problem with mine, it was a clogged cat.
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Old 05-01-2003, 01:42 PM
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Default Re: red hot exhaust manifold?

i just replaced my cat two weeks ago, i dont think that could be the problem. Maybe an exhaust leak?
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Old 05-02-2003, 12:41 AM
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Default Re: red hot exhaust manifold?

I don't know if the '87 258 has a "High Altitude Wire" but you may have mistakenly grounded it while buttoning things up. It's a black wire with a large round lug at the end. On my '81 258 it's located on the main harness near the Dipstick. If it's grounded your engine will run super lean and your exhaust will indeed glow red. Been there, done that, replaced a cracked manifold because of it. It's worth checking. My $0.02 .

Nick
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