Thanks for the input on my last post. Is it normal for the exhuast manifolds to get red hot on a '95 5.8 with a stock exhuast system? I have noticed this before, the pass-side manifold will be cherry red but, the driver side will only be slightly red. It happened again tonight pulling the empty trailer {3500#} and I wasnt pushing it either becuase of the slick roads. If this is normal, then this could be what causes busted manifolds on the 5.8. I have been told it is a common problem on the 5.8, I would have to agree because I had to replace both of mine!
Or is there another problem that causes them to get so hot and the busted manifold is a secondary problem? One shop ruled out the cat converter. Also there is a hissing sound coming from under the hood when I level off at highway speed, goose it or back off and it quits, but comes back when I try to hold at one speed. I was told this was normal " venting" , I call it annoying.
Thanks for any suggestions.
This was my first Ford, it replaced a '83 K-20 4x4 bored and cammed '70 402 big block over 300hp, a pulling machine but, age was taking over and I wasnt impressed with the new style chevy's 4x4 system and knew some guys that had them werent impressed ether. I've had my share of problems with this truck big and small, but 41000 mi {114000 total}, 1 trans ,numerous sensors and valves later it is finally running the way it should. Except that it is now starting to use oil. Oh well.



'95 HD 250 5.8 C-6 4x4

 

I don't think the manifolds should get RED hot. To me, that indicates some kind of restriction in the exhaust system. I know that you said the cat has been checked, but I'd investigate it and the muffler some more.

 

When any part of the exhaust system gets "Cherry Red" , that means something is wrong somewhere. I would start from the manifolds , and work your way back to see if you can figure out the issue. I have heard of cats getting old , and the cermaic inside actually blocking the flow of exhaust thru them , thus causing extreme heat - maybe you should look into that ......

 

I'd try removing the cats and see if it still does it. If it doesn't, replace them.

 

IMHO something is definately wrong.

If it's not exhaust restriction, ie the cat, then the next culprit is either timing (too far retarded) or fuel mixture (too lean). The computer should adjust for both, but if sensors are gone, computer problems, etc... they may all snowball to give you your problem.

Waxy

 

As stated in an above posting, there is a restriction of flow of exhaust. I too have seen cat converters get choked off from their insides collapsing. I have also seen the baffels in mufflers loosen up and restrict exhaust flow over time. The hissing sound that you hear is your exhaust trying to find an alternative exit.

 

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Ditto!

 

sounds to me like yer catalytic convertors are stopped up causin yer sensors to go bad creating a lean situation and turnin yer manifolds cherry red. by the way, if you have to replace manifolds again, go with some headers!

 

I have had this happen with "non computer aided" trucks and the culprit is usually improper timing. Unburned gas gets vented into the headers/manifolds and ignites, heating the metal to red hot.

That's just an idea to look at if you don't find an exhaust problem. As others have said, your computer should be adjusting for this somewhat.

Scott

 

Hey jcoplr-

Is your signature correct? The truck really has a C6 automatic? I thought Ford stopped using that tranny in the '80s. Maybe not on the HD models?

 

I thought it was odd also when I saw it was a 3 speed auto in a '95. Unless, I cant find where they put the overdrive button!

'95 HD 250 C-6 4x4

 

Thanks for your reply, I complianed to my tecnician and he hooked the truck up to his computer and checked the timing ,among other things, and it came back ok. He also said a lean mixture will also do it but it should be missing if something was drasticly wrong. But he couldnt figure out why 1 side would get hotter than the other. I think I am going to look into the exhuast { original w/over 100000 mi} as the previous replys have suggested.

'95 HD 250 5.8 C-6 4x4

 

Dual exhuast should be cheaper than the $500 cat the parts stores have, {$475 at the local Ford Dealer}. Knowing what was involved in replacing the last two manifolds,{many busted studs} I think I will leave them be for now. Do you guys put smaller cats in a dual exhuast or leave them out completely? Thanks