So I purchased my 1975 Ford F100 about a little over a month ago and am still getting some things repaired to allow it to pass inspection. Question I have for this post is I am not sure if the engine sounds OK, seems like I hear ticking that speeds up when the engine is reved. But I am not sure, it may be just how it's supposed to sound.

Question 2, Is there any way to reduce exhaust fumes, got the wife complaining about smelling a lot of exhaust every time I run the engine a little bit..... got complaints after I made the attached video. Not sure if this is a muffler issue or does everyone deal with the exhaust smell? I used to have a 57 chevy when I was younger, don't recall the fumes being this strong.

Any thoughts on the sound of the engine engine is appreciated.

VIDEO

 

Another Video of the engine:

 

My first thought was exhaust leak even after you mention your wife's comments about the fumes but after listening to the video I'm not certain, although camera mics pick up that kind of audio poorly so hard (for me) to say. If she is talking about inside the cab, does your exhaust route all the way out from underneath the truck or does it dump before that?

I think I see what appear to be headers. Have you tried checking the bolts? Mine came loose where they went into the mid-pipe and caused a leak. Also I think header bolts are supposed to be re-torqued after some heat cycling. Easy/free stuff to check.

 

If that is a newer engine which was sold with a catalytic converter, especially from the '80s-'90s, then it's going to smell like a pig unless you put cats on it. A '86-'95 5.0 HO with no cats will stink a lot more than say a '68 302.
The reason is, I read on a Mustang site, that catalytic converters allowed the engine engineers to use power-producing cam profiles which were too dirty in the past. So apparently even in the early '60s, the manufacturers had some sort of limits on the stinkiness of engine exhaust, whether self-imposed or not.

 

Hi mate, I'd say its an exhaust leak. When running try and feel for the leak with your hand. First up try around the exhaust manifold flanges - they can blow gaskets if not tightened correctly or retorqued soon enough after running in. Ask me how I know!

Second, try under the truck. You will need to check the collector merges as well as any other join - this includes mufflers and welds.

Going by the smell I would be surprised if you find something further back than the collectors. The smell often comes from the unburnt hydrocarbons being vented into the air rather than progressively burnt as they travel down the hot exhaust and encounter other hot exhaust gases.

Cheers - boingk

PS: The thing about emissions from camshafts isn't really true. More efficient cylinder heads, modern camshafts, tighter tolerances, better materials and manufacturing processes mean a progressively more efficient burn as time has gone on, even with greater performance. This is also true of aftermarket parts. If you have an engine that smells like fuel you either have an exhaust leak, an improperly plumbed crankcase vent (ie no vacuum line from valve cover to carburettor) or a leaking fuel system.

 

I'm puzzled that there's a question about an exhaust leak. Those are ordinarily the easiest things to find when doing even the most rudimentary troubleshooting: they make noise, they emit hot gasses and can be felt, they smell like exhaust. Surely you were able to eliminate exhaust leaks as a possibility before posting here.

If you don't find an exhaust leak, move on to locate other noise sources.

Low oil pressure will cause hydraulic lifters to partially collapse, leading to a noisy valve train. This can result in poor combustion and incomplete scavenging of the cylinders leading to a soot coated exhaust system that then burns off as the system heats up.

Oil pressure should be verified independently of the dash indicator. Plumb in an auxiliary gauge where the oil pressure sending unit or switch is located at the oil filter adapter, then observe the pressure at idle and at higher rpms, both cold and hot.

Determine first if the engine noise is internal or external. You can buy a stethoscope to hear engine noises at Harbor Freight or other vendors, or you can make a stethoscope out of a piece of tree twig... carefully place one end against your ear and the other against different points of the engine. You can locate noises originating under the valve covers (valve train), in the head (valves), in the block (bearings, pistons, rods), pulleys, oil pan and lower block.

After locating any odd internal noises at idle increase the RPMs to listen for changes in the noise with the stethoscope. Using the stethoscope can also to help identify low oil pressure in case you have a sketchy oil pressure sending unit or switch.

 

It's not really inside the cab, as for my exhaust, I have side pipes at the front of the rear tire.
I have not checked the bolts on the headers, will look into that.

I know it's hard to pickup in the video, but there is a "ticking" sound that I am wondering if it's normal. I am not sure if it is lifter noise, as when looking up videos on lifter noise, it's not nearly as loud.
Any thoughts?

 

Stuff rags in the exhaust outlet and run the engine, you'll hear any leaks. Fuel smell is almost always related to poor carb tuning, most people run an unnecessarily rich tune. Unless it's a heavily built motor with poor idle characteristics that NEEDS to be tuned rich, it shouldn't ever smell like fuel. If the ticking isn't exhaust, its probably valve train. Check valve lash, if not that, it's lifter tick.

 

2X on checking valve lash.

That 302 motor you've got needs to have the valvetrain rechecked periodically to ensure that the valve lash is set correctly.

My first guess would be an exhaust leak given the complaint of the smell and the fact that the tick isn't really defined all that well. Usually a lifter or valvetrain tick is extremely noticable...

A comparable sound for a valvetrain tick would be a solid marble hitting a concrete floor. Or a ball bearing hitting a concrete floor. That's not what I hear on the video, so again, it's likely exhaust.

Look for exhaust leaks first. Tighten everything to spec. Recheck, then run it again.

 

Exhaust leaks can under the right circumstances sound like ticking.

 

A blown header gasket can cause a "tick" kind of sound and smell. I would check those bolts for tightness and look around your contact surfaces. With headers a lot of times you can see a "burned" spot where the gasket is broke.

 

Thanks everyone for the suggestions, I am going to first look at the Exhaust leak as that sounds like a likely culprit. You menioned Tightening everything to spec, I assume you are talking about the exhaust manifold bolts? How can I determine what the specs are and would I need a torque wrench to do and verify this? I read elsewhere about there being a proper procedure to tightening up the bolts, this is my first time doing anything like this, anything I need to be aware of before I attempt this, don't want to break any bolts or anything.

Thanks,
James

 

List says 24 foot pounds, but generally you will be able to feel if the bolt becomes too tight - if you are having to strain against the bolt or you feel a sudden increase in tightness then it is more than tight enough.

A torque wrench is an invaluable tool for delicate or precise jobs such as valve train components and bearing caps, but in this case isn't strictly required.

I would remove each bolt one by one, give a quick clean with a wire brush to remove any oxidation, and then give a coat of copper grease or other anti-seize compound to help removal in future... or you could just make sure there are no leaks and tighten them

- boingk

 

2X on the anti-sieze compound. Here's a list of recommendations from Permatex:

From Permatex:

Nickel:
Protects metal parts from seizing and galling at temperatures up to 2400 degree fahrenheit
For use with stainless steel, titanium and nickel alloys
For use under conditions of extreme pressure and temperature
Recommended where copper contamination must be avoided
Suggested Applications: Exhaust manifold bolts, exhaust system bolts, muffler clamps and tailpipe assemblies

Copper:
Prevents seizing, corrosion and galling where high temperature conditions exist
Fortified with high quality rust and corrosion inhibitors
Temperature range: -30F to 1800F
Provides good electrical conductivity
Suggested Applications: Spark plug threads installed in aluminum, exhaust manifold bolts, engine bolts, oxygen sensors, knock sensors, thermostat housing bolts, fuel filter fittings and battery cable connections

Standard:
Highly refined blend of aluminum, copper and graphite lubricants
Salt, corrosion and moisture resistant, this lubricant is ideal for marine use
Prevents galling, corrosion and seizing and to assure easier disassembly
Suggested Applications: For easy removal of spark plugs, cylinder head and exhaust head bolts
Temperature range: -60F to 1600F

There are also non-metallic versions that just use graphite...

 

Another aspect of headers is that the thin metal tubes transmit much more sound than a thick cast-iron manifold does. And the thinner (cheaper) materials are louder than the thicker ones. That's why a selling point in advertising more expensive headers is the thickness of the tubing.
But even a thick tube header is louder than a stock exhaust manifold in most cases.

x10 on checking for leaks though. They are notorious for this.

Headers also lean out the mixture and are often followed up by installing larger main jets in the carb. They may have gone overboard on the jet sizes, or just the opposite.
If you let an engine run too lean, you can get what's called lean-misfire in which the combustion process is not efficient or complete not because there is too much fuel mixed with the oxygen, but because there is too little.
So either too rich OR too lean can make your exhaust smell pretty bad.

In the mid to late-seventies they were just learning about how to reduce emmissions and one popluar way was to run the mixtures very lean. Which is one of the reasons that more and more powerful ignition systems were brought into play.
But since yours is obviously pretty well "de-smogged" and also running headers and an aftermarket carburetor, the tune is up in the air until you start messing with it. No way to tell just by an outward look what jetting or meter sizes the carburetor was outfitted with (most just use them as-is out of the box) or whether it was compatible with the better breathing exhaust, or whether the ignition system is doing it's job.

Hell, it might just need a tune up!

And speaking of de-smogging and stuff, can you see a PCV valve sticking out of the passenger side valve cover? This would be a plastic/metal metering valve with a 3/8 hose running to the base of the carburetor. I see what looks to be the venting cap on the driver's side cover, but can't make out what's there on the back of the passenger side.
If it's just another cap or breather, then you really should install a PCV valve and plumb it correctly (we can walk you through that if it's needed) to keep the engine healthy and running well for the long term.
Like the evaporative emmissions system, it's one of those very beneficial devices to come out of the smog wars. One of the best actually.

Bottom line is that you can actually install a catalytic converter on an old truck (I did) but you need to make sure the engine is tuned very well and stays that way. A poorly tuned truck could wreak havoc on an expensive cat pretty quickly.

Good luck.

Paul