any help with this problem would be much appreciated...

I have a 95 F450 superduty with utility body. Originally used the truck in California, lots of hills/steep grades to climb. I replaced the intake with a K&N whiched helped alot, I started to get cracks in the exhaust manifolds. After replacing 2 right side and 1 left side, I followed a recommendation and installed dual 2.5" exhaust. The manifolds no longer crack, but the exhaust glows red hot under load. I have had to replace / repair the down tubes twice. I am unable to install headers... there is very little room between motor and frame rails on the F450. Nobody makes headers for the truck, and custom would be a nightmare due to space. I have been told that the manifolds are better if heat is a problem, anway.

The motor makes great power, and gets crap mileage... This is understandable and acceptable, but the exhaust problem sucks.

The truck has nearly 200k miles on it. When loaded (which is almost always) it weighs around 10,500 lbs.

Other than the K&N intake and the exhaust, no modifications have been made to the motor.

I am not looking to increase power, just trying to figure out if a tuner would help in controlling fuel mixture to cool exhaust.

Any help would be much appreciated...

-brock

 

Sounds like the K&N intake leaned out the 460 and that is why the exhaust is glowing red. I would deffinetly look at some kind of custom tuning to correct that issue.

 

Headers definatly wouldn't help you those things get crazy hot. Does your truck have factory exhaust? If so you may wanna check your cats and make sure they are not clogged up or something also you may wanna just see about changing your muffler to a more free flowing on to get the exhaust out faster just a thought hope you get it figured out.

 

I agree it sounds like the engine is running lean and that could have caused your cats to fail.

 

I suppose that is the question I should have asked... What to buy to correct lean condition? Not trying to get more power or increase mileage, just trying to stop exhaust from failing.

No cats, 2.5" with huge open Flowmasters.

Thanks again-

brock

 

Also check your 02 sensers, they maybe causing the lean condition.

 

Replaced oxygen sensor, thinking that might do it... didn't help. Can fuel / air ratio be changed with a tuner? I have no experience with program mods, or chip usage. I am almost resigned to replacing the OEM intake system....

-brock

 

Open exhaust and still doing that? I know its a pre OBDII year model truck, but does it have the OBDII system in it? (some cars got it, most didn't)

 

HI!... You need to get someone to do some air/fuel datalogging on the truck. Any chassis dyno's near you? Sounds like you are running REALLY lean. Run it like that for any long periods of time and you will be replacing a engine and CATS.

 

No idea what OBDII is...

 

Everything points to lean condition... It has been like this for a year or so. Got rid of the Cat when I went to dual's. I cut the cat open and it was clean and open.

I was hoping that it wouldn't lead to needing dyno work... finding someone to let me run a 10k lb vehicle on their dyno may be tough.

-brock

 

Just a thought have you checked the timing and seen if the advance is working properly. I might be firing at the wrong time. Just a thought. Any advice is good if it helps HA!!! Good luck you have a tough motor!!!
F96XLT

 

OBDII= On Board Diagnostics version 2
You can read lots more data much easier with OBDII vs the pre 1996 OBDI

 

Late ignition timing will cause hi exhaust temps and poor power.
Check this out.
Late timing causes too much gas still buring when the exhaust valves open.
This becomes worse when the loading is high, engine is reving in lower gears etc.
Good luck.

 

Well, the thing is that it's a 460, and the 460 engines, EFI or carbureted, simply have always tended to crack exhaust manifolds in many of the vehicles they were installed in - ask any owner of an older Lincoln Mark who had the 460 engine how many times they had to replace their cracked exhaust manifolds!

They just don't get enough airflow around them in some models, for example - especially an idling Lincoln in summertime - and the 460 *is* a big motor and puts out a lot of heat. And it is also true that in many of the model years they were made, their emissions setup was such that they didn't; have much timing, and that can indeed cause high EGT's - it's just how they used to do things, both carbureted and the later EFI units.

Now, can that be helped by tuning? Yes, it can - tuning can bring down those combustion chamber, exhaust valve, EGT & exhaust manifold temperatures. It's a good idea to get some A/F's and install an EGT gauge in that truck to see what you are dealing with, and then tune it from there - that would be the easiest thing to do.

We can generally help with that - we do up thru the 1-tons, which is the F-350's, and there are *certain* F-450's that we can tune as well - just give us a call at our number listed below & we can go over this with you in more detail.

In the meantime, just realize that the 460's tend to crack exhaust manifolds from the heat they put pout and in some cases, the lack of air circulation underhood depending on model & especially on how they are operated as well.

I hope that helps a bit,