Hello my fellow Ford Enthusiasts! I have a quick question. I've heard through the grape vines that running straight headers, or an open exhaust will harm your engine and cause exhaust valves to crack, but I 've also heard this is an old wives tale. So I have an 89 Ford F-150 XLT Lariat Longbed Pick-Up truck with the Fuel Injected 5.8 Liter 351 Windsor. I can't afford headers at the moment so I cut off the exhaust right before where the two pipes from each exhaust manifold connected together. There is no muffler, or cat on it. All there is is maybe three foot of piping coming from one exhaust manifold and about a foot and a half from other. My question is will this hurt anything? I drive it daily and I never hear any backfiring, or anything. The only reason I did this is because I love sound of open exhaust. I live in South Carolina where it gets up to 115 degrees in the Summer and down to 18 degrees in the Winter.

 

I've heard that too, and from long time mechanic. After I sort of argued he said it was an issue in cold weather.

 

I mean its not like it's straight exhaust manifolds. There is a decent amount of pipe afterwards. I don't think it will hurt anything I just want a second opinion. Also, my oil pressure gauge fluctuates between the "M" in the NORMAL section to nothing at all and the red "Engine" light comes on. Do you think it's he oil pressure sender/sensor?

 

It will be fine honestly. You got plenty of pipe for it to work fine. I'd only be worried with just the manifolds in negative weather.

 

Well I plan on keeping the pipes connected to the manifolds anyways. I wouldn't run straight manifolds anyways. Is it ok for long trips? Like 200 mile trips? What do you think about the oil pressure? The truck only has 169,400 miles on it. I doubt the oil pump bad ya know.

 

If its fine for warm up and idling around its fine for a long trip like that. At that mileage I recommend having a real oil pressure gauge to get good readings. I seen some engines have great pressure at that mileage and soon that barely hold two psi.

 

I have an aftermarket one that I could hook up to it and I'll be able to tell then.

 

I recommend doing so. you can either rig up a T with some pipe fittings or just run strictly the mechanical gauge and deal with the dash gauge not working. its an idiot light anyways.

 

You might need earplugs on a long trip

 

It's really not as loud as I expected it to be and yea I'll hook all of it up tomorrow so I can actually se what I am working with.

 

The gauge fluctuation is likely a corroded wire connection at the sensor or a bad sensor. Like said, its basically an on/ off switch, if you have the least acceptable oil psi, it will show good, if not, itll show zero, no in between.

Running your exhaust as described wont necessarily hurt anything but without modifying the tune, itll affect low end power, even if its not obvious.

Experienced the differences many times running open exhaust to the muffler shop, to realize it got its ***** back once the exhaust was put on.

 

If the motor had a carb on it then you could expect the motor to run lean and possibly burn valves or melt a piston with the exhaust all chopped off because a carb has no way to adjust itself, but EFI self adjusts constantly so it can work and not result in any engine damage. However it sounds like you cut off the part of the exhaust with the O2 sensor in it and if so that will have a negative effect on fuel consumption and engine life and it would be best for both of you put at least a couple feet of tubing on each side and reinstalled the O2.

 

Actually whenever I bought the truck the exhaust system consisted of a pipe running from each exhaust manifold and them two pipes running into one pipe and connected to a "Thrush" 31-Inch Glasspack. It had no cat, or anything. I only seen one O2 sensor and it was located right where both of the two pipes connected together, so I cut the exhaust off right after that sensor.

 

The truck should only have one O2 sensor but it's not good for it to be right at the end of the exhaust it should have at least a few feet behind it to prevent fresh air back washing the sensor and totally messing up the readings.

 

About 18" is the least I would use to prevent valve damage. Driving with it cut like I'd dangerous. Exhaust fumes can come in the cab if the pipe does go pass the back of the cab.