Just bought a smoke machine.

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ProjectBazza

ProjectBazza

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I've been chasing an exhaust leak in my truck for months now. I can hear it, and I can smell it (when I'm sitting at a stoplight), but I just can't seem to actually see anything, what with all of the hoses and tubes and what-not in the engine compartment. I'm getting an overrich code on my scan tool, and when I pulled my O2 sensor last night it was all sooted-up. Again.

So I replaced it. Again.

Anyway, it should be here on Friday, so we'll see.

Wish me luck!
 
ProjectBazza said:
I've been chasing an exhaust leak in my truck for months now. I can hear it, and I can smell it (when I'm sitting at a stoplight), but I just can't seem to actually see anything, what with all of the hoses and tubes and what-not in the engine compartment. I'm getting an overrich code on my scan tool, and when I pulled my O2 sensor last night it was all sooted-up. Again.

So I replaced it. Again.

Anyway, it should be here on Friday, so we'll see.

Wish me luck!
Click to expand...
What year truck and make
 
ProjectBazza said:
I've been chasing an exhaust leak in my truck for months now. I can hear it, and I can smell it (when I'm sitting at a stoplight), but I just can't seem to actually see anything, what with all of the hoses and tubes and what-not in the engine compartment. I'm getting an overrich code on my scan tool, and when I pulled my O2 sensor last night it was all sooted-up. Again.

So I replaced it. Again.

Anyway, it should be here on Friday, so we'll see.

Wish me luck!
Click to expand...
What did you get?
 
74 360 dart sport said:
What year truck and make
Click to expand...
Ah! You had to ask, huh? :lol:

It's for my '92 F250 I purchased out in Portland, Oregon this past winter. Just a smidge over 100k miles, but the paint is really clean, and it looks dang near brand new underneath.

BJCP5691.JPG


You'd think a full sized truck would have all sorts of room in the engine compartment, but that 460 takes-up a heckuva lot of it, that's for sure.
 
toolmanmike said:
What did you get?
Click to expand...
Since it's not a "critical tool", and I doubt I'll be using it all that much, I tried to find a fog machine at a "party store", but no joy there.

So I went cheap (Chinese?):

Amazon.com

www.amazon.com

Got a 4 day weekend to play with it, and hopefully I can nail down this damn leak.
 
74 360 dart sport said:
Exhaust manifolds leak on the bolts that rust off on the 460 gorilla motors
Click to expand...
You know, being a Ford truck guy (don't tell anyone here I said that!), that's what I thought as well. But the previous owner replaced the exhaust manifold gaskets (or rather, he had them replaced) about 6 months before he sold it, and all of the bolts look good and aren't rusted (this really is a clean truck).

Now I'm thinking I may have a cracked exhaust manifold....

Seeing as how I just installed my third O2 sensor in 6 months, the purchase of/investment in the smoke machine is relatively minor, comparatively speaking.
 
I had a 94 f350 with a 460 and it had no exhaust manifold gaskets from the factory. When it leaked, I put a set of gaskets on it and it quieted right up.
 
TT5.9mag said:
I had a 94 f350 with a 460 and it had no exhaust manifold gaskets from the factory. When it leaked, I put a set of gaskets on it and it quieted right up.
Click to expand...
My God, I hope it's that simple! I had a '92 F150 with a 351, and when I replaced the engine years ago I found the same thing: No factory exhaust manifold gaskets.

I had forgotten all about that....

Thanks!
 
ProjectBazza said:
My God, I hope it's that simple! I had a '92 F150 with a 351, and when I replaced the engine years ago I found the same thing: No factory exhaust manifold gaskets.

I had forgotten all about that....

Thanks!
Click to expand...
I never use gaskets on stock manifolds, unless they are badly pitted. Never had one leak without the gasket, but plenty that did with one.
 
Yeah no gaskets on them. And FYI the EFI 7.5L (460) has different heads than a 86 (I think) and down 7.5L. The ports are different. You can tell the EFI heads by the center bolt down valve covers. The Exhaust ports are raised and smaller than the older stuff so you might look at the manifold castings and see if the part numbers are correct for the year. As I recall the old stuff bolt on but do not line up.
 
dano said:
Yeah no gaskets on them. And FYI the EFI 7.5L (460) has different heads than a 86 (I think) and down 7.5L. The ports are different. You can tell the EFI heads by the center bolt down valve covers. The Exhaust ports are raised and smaller than the older stuff so you might look at the manifold castings and see if the part numbers are correct for the year. As I recall the old stuff bolt on but do not line up.
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I think those years and numbers are about right, as I bought a '95 (?) EFI 460 about a year before I bought the truck (to put it in my '68 F250), and it's sitting on my engine stand:

IMG_4124.JPG


And if it turns out I do have a cracked manifold (in the '92) I'm kinda hoping and praying that I have the part(s) to fix it on-hand.
 
ProjectBazza said:
I think those years and numbers are about right, as I bought a '95 (?) EFI 460 about a year before I bought the truck (to put it in my '68 F250), and it's sitting on my engine stand:

View attachment 1716271257

And if it turns out I do have a cracked manifold (in the '92) I'm kinda hoping and praying that I have the part(s) to fix it on-hand.
Click to expand...
There was an head change in the EFI Motors I think in 94'. The last EFI head casting is the best for performance. Casting number should be F4TE. I parted out a 94' 7.5L and a guy is Michigan and he sent me crates to ship him the heads to him.

There is a guy who sells an adapter to use the bottom of the EFI intake with a carb.

If it has an oil cooler, those are known to leak internally. Just a FYI.
 
I used to work in a Ford dealership and the 7.5 liter and the 7.0 in medium duty trucks had problems with breaking exhaust manifold bolts. I would have a machine shop surface grind the manifolds and use new bolts and torque them correctly. Make sure that the bolt holes all still line up before you spend money on having them trued up. And yes, no gaskets on the EFI version of the Lima motor the older carb versions used a metal shim gasket. You will probably find broken bolts and may break a few removing them. This was the biggest problem with these motors that were otherwise pretty good.
 
dano said:
There was an head change in the EFI Motors I think in 94'. The last EFI head casting is the best for performance. Casting number should be F4TE. I parted out a 94' 7.5L and a guy is Michigan and he sent me crates to ship him the heads to him.

There is a guy who sells an adapter to use the bottom of the EFI intake with a carb.

If it has an oil cooler, those are known to leak internally. Just a FYI.
Click to expand...
The factory did this with propane carbureted versions.
 
I'm not sure if these 460 motors had the AIR pump or not but if it does I would check the tube that bolts to the back of the heads. I have had plenty of 5.0 and 5.8 motors that had either the check valve rot away or the tube itself burn out, causing what sounds exactly like an exhaust leak.
My solution is to remove the pipe and cut the ends off, then crimp them shut and bolt back on as plugs for the holes, remove the AIR pump and related crap, and install an idler pulley. Some also have a small tube running to the catalytic converter, guaranteed to rot off.
 
I have also seen the EGR tube that runs from the top plenum down to the bottom plenum, break causing similar issue. It's a corrugated "flexible" tube. This was on the 302 and 351, not sure if the 460 used the same design.
 
ProjectBazza said:
I've been chasing an exhaust leak in my truck for months now. I can hear it, and I can smell it (when I'm sitting at a stoplight), but I just can't seem to actually see anything, what with all of the hoses and tubes and what-not in the engine compartment. I'm getting an overrich code on my scan tool, and when I pulled my O2 sensor last night it was all sooted-up. Again.

So I replaced it. Again.

Anyway, it should be here on Friday, so we'll see.

Wish me luck!
Click to expand...
Old welder's trick: Squirt some soapy water around. if you have headers, pay attention to the point where the primary tubes enter the collector. Also, stainless headers have been known to crack.
 
bcschief said:
I used to work in a Ford dealership and the 7.5 liter and the 7.0 in medium duty trucks had problems with breaking exhaust manifold bolts. I would have a machine shop surface grind the manifolds and use new bolts and torque them correctly. Make sure that the bolt holes all still line up before you spend money on having them trued up. And yes, no gaskets on the EFI version of the Lima motor the older carb versions used a metal shim gasket. You will probably find broken bolts and may break a few removing them. This was the biggest problem with these motors that were otherwise pretty good.
Click to expand...
Spray the bolts with Maltby penetrating oil first. This stuff is WAY better than anything else I've tried. I'm 76 and been wrenching for a while now. lol If you can't find maltby locally, Google for it in Riverside, California. That is where I found it.
 
Found it! Previous owner had the catalytic converter replaced about a year before he sold the truck, and apparently the exhaust shop didn't bother to tighten the clamps on the silicone AIR hoses....

Complete PITA to get to, and most of the work was done "blind" and one-handed, from underneath, but I got it.....1/6th of a turn at a time.

IMG_6344.JPG


Truck runs pretty decent now, and despite the crappy mileage I get with the 460, I'm going to use it as my "commuter" the next few days (34 miles each way) to really check 'er out.
 
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