cool! i like it all but the e-pump mod "covers up" the problem.
it pushes fuel rather than relies on suction,thus "eliminates the problem".
ok ok.i'll stop now.

hey check this out!
Vintage Ford Diesel Truck History - By Tom Brewer

you didn't mention the weak blocks yet on the early 6.9's.and not into the block worm problems when SCA's went unmentioned for 7.3l's.
you have a ways to go.its looking good.
im ready to hear about some bored out 420 blocks,and turbo's.

 

haha i knew that Epump part would get ya goin lol. Im only on page 2 of 6-8, but I have every intention of covering the weak blocks and SCAs and turbos. Might even throw in a tidbit about the 1200hp IDI. lol

 

1st paragraph:

I don't know all of the numbers, dates or facts. I'd use the rest of the original 1st paragraph within the descriptive engine, 2nd paragraph.

 

Its that time of year. i had to write a reaserch paper for my MAnufacturing Processes class. wrote it on diesel engines. then i had to give a presentation in my Public speeking class, so i tought the class how to change oil in a 7.3L IDI.

 

"Of course, just like any other engine, the 6.9 had a few common problems. The most common being the return lines giving up the ghost and leaking air leading to hard start situations."


Return lines for what, extra 12 volt electricity and it goes to the battery to keep it charged......right?

 

yep, 13yrs. old 8th grade

 

Thanks for all the replies guys, I really appreciate the input. Keep em comin

 

Well here she is in all her glory.

International Harvester/Ford 6.9 and 7.3 IDI Diesels
John Boggs
Baker College of Owosso

In 1978, International Harvester and Ford Motor Company reached an

agreement for the research, design and manufacture of a powerhouse diesel engine

which would ultimately launch a never-ending revolution. After countless hours of

excruciating testing, the 6.9L Indirect Injected (IDI), naturally aspirated (NA), V8 diesel,

inhabited the engine bay of the Ford ¾-ton and 1-ton heavy-duty trucks. The 6.9L IDI

produced 170 horsepower and 310 foot pounds of torque. In 1988, the 6.9L IDI was

replaced with the 7.3L IDI. The 7.3L IDI produced 185 horsepower and 360 foot pounds

of torque. Both engines pale in comparison to present day diesels, but started a lifelong

heavy-duty truck feud between Dodge Chrysler, General Motors Company, and Ford

Motor Company. The 6.9/7.3L IDI diesels were proven to be reliable, solid engines and

were used in a wide range of applications, but as a good as a setup as they were, they

weren’t without a few common problems which of course meant they went through a

few changes during their production run.

The 6.9s were blessed with a cast iron block and four bolt main bearings. This

made for a solid bottom end and base to build off of. It also got a forged steel

crankshaft, plenty heavy enough to handle the forces developed in such an engine. To

aid in cold starting, International Harvester Company designed the engine to include

glow plugs. Glow plugs are a threaded plug that screw into the cylinder head of an

engine and use electricity to create heat in the pre-combustion chamber to help raise

the temperatures inside the cylinders to the 500 degrees Fahrenheit necessary for diesel

fuel to auto ignite. The glow plugs used were Motorcraft/Beru ZD1As. These are non

temperature limiting single coil glow plugs designed to run off 6 volts. The way that IH

designed the glow plug relay, the 12 volts that started at the battery was stepped

down enough that by the time the juice made it to the glow plugs it didn’t burn them

up. Between the 20.7:1 (1983) 21.5:1 (1984+) compression of the 6.9, and the glow

plug system, they are fairly easy to start in the cold when the starting system is in good

shape. For those extremely cold nights, a block heater was also included.

Of course, just like any other engine, the 6.9 had a few common problems.

The most common being the return lines giving up the ghost and leaking air leading to

hard start situations. International Harvester Company designed the return line system

with plastic caps on top of each injector with O-rings sealing the cap to the top of the

injector, and rubber lines running from each of the caps. After several heating/cooling

cycles, the O rings would become hard, and if disturbed would leak air into the return

line system. The reason that this leads to a hard start is because the 6.9 depends on

vacuum to hold prime. The 6.9 has a mechanical fuel pump that is operated off of a

lobe on the camshaft, so of course fuel is only pumped when the engine is turning.

Owners would crank on the starter longer than normal without doing anything accept

pumping fuel. Once the air was finally purged from the system, the engine would fire

right up no problems. The problem is, after a while, all that cranking takes its toll on the

starting system. A worn out starter won’t spin the engine fast enough to create the

heat necessary to ignite the fuel, leading to a hard start. If the first problem is not

corrected in a timely fashion, it creates other problems as well and leads to quite an

upset owner. A common modification is to add an electric fuel pump, which doesn’t fix

the problems, it just covers them up. It also, if not properly done, creates the risk of

rupturing the diaphragm in the mechanical pump and filling the crankcase with diesel

fuel.

Another common problem that affected both engines was the Crankcase

Depression Regulator getting plugged up and causing excessive oil usage. At high rpms,

a valve in the CDR is supposed to close to keep the engine from burning its own oil, but

when the CDR isn’t cleaned regularly, it won’t close and the engine ends up burning oil.

The CDR also is supposed to redirect vapors from in the crankcase into the engine to be

burned. Some people abandon the CDR altogether and install a road draft tube instead,

similar to what is found on most semis. The road draft tube works just fine, but some

don’t like it because it tends to make the underside of the vehicle oily.

The early 6.9s blocks were weak in the area around the block heater and

prone to cracking. If the block heater wasn’t used, this was not much of an issue, but

if it was used, you ran the risk of the block cracking and possibly being out an engine.

If the block cracked, your options were to try to have it welded, or scrap the thing and

get another engine. The issue was quickly corrected by Ford.

The 7.3 had an issue that mainly affected it, but on occasion could affect the

6.9 or for that matter any high compression engine. When they decided to bore out the

6.9 to 7.3 liters, it made the cylinder walls dangerously thin. This made the 7.3s much

more susceptible to cavitation. Cavitation happens when bubbles form on the cylinder

walls and eat away at the metal that forms the cylinder. If this is allowed to go on long

enough, the bubbles will finally eat a hole right through the cylinder wall. Then your

options are to scrap the engine, or try to sleeve the offending hole. The unfortunate

thing is that due to the already thin cylinder walls, your rebuild options are limited.

Once cavitation happens, there’s nothing that can be done to reverse the affects,

however cavitation can be stopped and prevented. The use of supplemental coolant

additives or SCA’s is necessary to prevent cavitation. What the SCA’s do is line the

outside of the cylinder wall and form a sacrificial protective layer that the bubbles eat at

instead of the cylinder walls. It’s recommended that you check the SCA levels in your

coolant every six months to ensure maximum protection from cavitation.

The 6.9s fuel system is a relatively simple one, and is stone age compared to

the diesels of today. A Standadyne DB2 rotary injection pump is the heart of the

system. This pump only develops injection pressures of about 3200 psi, nothing

compared to the newer engines. The injection pump is quite a complicated piece of

engineering, and a whole essay in itself could be written on it. Basically, pressure is

built up inside the pump, and as it turns, ports are uncovered which the pressurized fuel

is pushed through and is fired through the injector. The pump controls, injection

pressure, timing of the injection event, metering of the fuel injected, and firing the

injectors in the correct order. Inside the pump, there is an Allen head screw that

adjusts the amount of fuel that is delivered to the engine. This screw is useful for fine

tuning the engine, and helping to adjust the boost if turbocharged. The pumps timing

also plays a key part in tuning the engine for power and fuel economy. Underneath the

timing cover there is a mess of gears with timing marks. Once all the timing marks are

aligned, the pump can be adjusted finer by turning the pump to the drivers or

passengers side. The factory provided two timing marks on the pump housing to get the

timing within a ballpark range. It makes it so the engine can be run and driven enough

to get the dynamic timing set.

The engine was used in many different applications. It powered Ford pickups from 1983

up till 1994.5. It was also used in medium duty trucks and busses. The IDI was great

engine for lots of different things do to the versatility of it, and the reliability of it. The

engine only requires one wire to run, and has a reversible oil pan which allows it to

adapt to different configurations. The lack of computers, and a very basic fuel system

will allow it to run on an array of fuels. It can run on standard number two diesel fuel,

biodiesel, automatic transmission fluid, vegetable oil, engine oil, and gear oil among other

things.

In 1994 Ford decided to turbo charge their 7.3 engines. These engines stayed

the same as their naturally aspirated brethren, with a few exceptions. The turbo

engines had bigger wristpins, and had the return lines re-routed away from the turbo.

Also the glow plug controller was relocated to the passenger side valve cover instead of

the back of the engine where it used to live. Ford decided to go with an ATS turbo that

added only about 5 horsepower. Many believe that the engines output figures were

fudged so as not to better the new Powerstroke that came out the following year.

Obviously no one would want to buy the newer engine if the old engine was more

powerful. The smashed downpipe and 2.25 inch outlet flange of the turbo helped to limit

its output. Almost immediately after ford started selling the new turbocharged IDIs, ATS

came out with an upgraded downpipe and outlet flange that greatly reduced exhaust

restriction and boosted power quite a bit. Since 1983 aftermarket turbos had been

available for the IDI from banks, hypermax, ATS, and the little known ray-jay. 7.3s are

only good for about 15 psi of boost in stock form, 6.9s not much more than 10. If the

boost is allowed to go any higher, the chances of a blow head gasket increase

exponentially. Most people overcome this issue by installing head studs instead of the

stock head bolts. After that, holding intake gaskets becomes a problem.

Aside from turbo charging, there are many other modifications that IDI owners

have come up with to get the most power out of their engines. One would be the soup

bowl mod. Underneath the air cleaner, there’s a big bowl shaped thing that is believed

to hinder air flow into the intake. Cut that bowl off and you have the soup bowl mod.

In addition to the soup bowl mod, a lot of people build homemade ram air intakes. There

are also performance injectors and injection pumps available from DPS, and Moose

products. Moose products builds the moose fuel systems that deliver unbelievable

amounts of power and have a great spray pattern. Moose fuel systems are generally

only recommended for use with turbo charged engines, but they do make a nice rebuilt

pump for the person that chooses to remain naturally aspirated. They are a favorite

among people building their IDIs for performance, and for your average Joe looking for

quality fuel system parts. There’s also an online source that will regrind your camshaft

for you that’s supposed to increase torque and horsepower.

All in all, the 6.9L and 7.3L IDI’s were reliable power plants that put out a

respectable amount of power and were good for many years of service. They were used

in many different applications, and only had a few common problems all of which were

cheap to fix. Today the old IDI’s are almost forgotten, except for the few owners and

enthusiasts that still keep them alive. Just remember, every time you see a commercial

on the television for the new Powerstroke, or Cummins, or Duramax you can thank the

old IDIs for starting the wars between the big three companies that allow the consumers

to reap the rewards that take the form of the high horsepower diesels of today.









References
7.3L IDI Diesel Pre-Powerstroke Ford Diesel Power.(n.d.) Retrieved from
7.3L IDI Diesel

How the Stanadyne DB2 Fuel Injection Pump Works. (n.d.) Retrieved from
Oliver Diesel - Engines & Outdoors

Bomacz, R.T. (2007, March). International 6.9L Engine - Diesel Tech

The IDI Father Of The Power Stroke. Diesel Power

Bennet, S. (2011) Heavy duty truck systems (5th ed.) Delmar, Cengage Learning

 

First year for the 6.9 - 1983
Last year for the 6.9 - 1987
By 1988 all production 7.3
through early 1994
1993 and early 1994 had turbos but were not powerstrokes

6.9 - Max H.P. 175 Torque 318 ft. lb.
7.3 - Max H.P. 185 Torque 338 ft. lb.
7.3 turbo Max HP 190 Torque 388 ft. lb.

6.9 max torque at 1800 RPM
7.3 max torque at 1600 RPM
7.3 turbo max torque at 1400 RPM

Both max HP at 3300 RPM.

83 6.9 compression ratio 20.7 to 1
84 thru 87 6.9 compression ratio 22.5 to1
88 thru 94 7.3 compression ratio 21.5 to 1

7.3 external identification variance from 6.9 - New fuel filter/fuel heater/water sparator, larger/taller cylinder head bolt bosses with ribs. Dual mass flywheel on 5spd.

Crankcase differences
Cylinder bore - 6.9 = 4.00"
Cylinder bore - 7.3 = 4.11"
Stroke for both - 4.18"
Top deck thickness - 6.9 = .500"
Top deck thickness - 7.3 = .560"
Oil drain Back holes - 6.9 = 3/8"
Oil drain Back holes - 7.3 = 7/16"

Cylinder head changes
Cylinder head bolts - 6.9 = 7/16"-14 UNC 5.25" long
Cylinder head bolts - 7.3 = 1/2" - 13 UNC 6" long
Cylinder head bolt washer 6.9 = .105" thick
Cylinder head bolt washer 7.3 = .134" thick

Head bolt torque -
6.9 with new bolts = 75ft. lbs.
6.9 with used bolts = 85ft. lbs.
7.3 new or used = 100ft. lbs.

Cylinder head gasket changes -
Fire ring I.D. 6.9 = 4.14"
Fire ring I.D. 7.3 = 4.22"
Gasket cutouts elimitated between cylinders on the 7.3 to eliminate cosmetic corrosion phenomenon.
Viton oil drain back sealing rings added to the 7.3 (also used in later versions of the 6.9 head gasket, then eliminated again).

Head design changes -
6.9 features "centered" glow plugs, while 7.3 are "off-center"
Injection nozzles have been retracted on the 7.3 .060" to facilitate Federal and state emission certs.

Precombustion chamber volume -
6.9 = 18.34 cm3
7.3 = 20.42 cm3 (increased only for emissions certs)

Precombusion chamber inserts are physically interchangable, however the throat has been redesigned to distinguish them apart, and the 7.3 prechamber cub has an embossed "88" on it.

Valve Stem -
The 7.3 valve stem oil sheild is larger to reduce hydrocarbon emissions. Intake and Exhaust sheilds have been color coded, even though they are identical and interchangeable.

Coolant passages -
The lower corner coolant passages on the cylinder head on the 7.3 have been plugged. This change is introduced to eliminate lower corner gasket coolant seepage during cold start engine warm-up. Mating passages in the block are also plugged. (could be why we hear more 7.3 overheating issues).

Exhaust valves - The 7.3 exhaust valve has had its alloy composition changed, with more nickel, chrome, and silver content, and decreased manganese content. The 7.3 valves may be used in the 6.9, but not the other way around.

Piston and ring sizes increased in accordance with bore changes. The 7.3 utilizes select fit pistons at the manufacturer. The engine is produced with A,B,C and D size pistons and cylinder bores. When re-using pistons, "A" pistons should go in "A" cylinders, and "B" pistons in "B" cylinders and so on. These letters are stamped on the pistons and the cylinder bores at the bottom of the bore when viewed from the crankshaft side. Service part pistons can be utilized in any bore, and are identified with an "S".

Flywheel -
IMPORTANT. DO NOT USE 6.9 flywheel or vibration damper on 7.3 or vice versa. If components are intermixed, engine vibration and premature component wear may be encountered. For identification, compare these part numbers.
Vibration damper 6.9 1805414C1
Vibration damper 7.3 1809117C1
Flywheel Auto 6.9 1803219C1
Flywheel Auto 7.3 1809212C1
Flywheel manual 6.9 E7TA-6477-AB
Flywheel manual 7.3 E8TA-6477-AA

Injection Pump - Changes have been made to increase fuel flow and change ignition timing on the 7.3. Low and High altitute calibrations are available for both.
6.9 High - 1807568C91
6.9 Std. - 1807560C91
7.3 High - 1809045C91
7.3 Std. - 1809121C91

Injection lines - Due to the .060" retraction of the injector nozzle on the 7.3, all 7.3 injector lines have been shortened by .060" However, all lines with the exception of #1 on F series, and #4 on E series, are interchangeable between 6.9 and 7.3.

Cylinder wall honing -
Plateau cylinder wall honing has been implimented on the 7.3 to promote ring seating and engine break-in.

Front cover -
The 7.3 features an embossed front cover to improve sealing and eliminate water pump replacement due to gasket seepage.

Firing order is 1,2,7,3,4,5,6,8.

All this stuff came out of the 1987 7.3L diesel engine technician's update, which was used to quickly bring up to speed a 6.9 diesel mechanic.

 

holy moly, wish I coulda had all that info at my disposal sooner. Already have the essay turned in....

 

john your essay was really good... way to go!

and then dave comes along and whips one up (pry right off the top of his head) lol

 

woah.idi info overload.i love it guys!



lets go pats!

 

Pretty good. Since you are writing a report for school lets be technically correct. These engines don't have "pre combustion" chambers they have "turbulence" chambers and they don't have "injectors" they have "nozzles". there are big differences between each of the terms.

 

This is borderline sticky material lol. At any rate will have to remember this thread for reference purposes. Almost too much info for one thread lol

 

Care to elaborate on this? Either I'm mis-educated as well as the manufacturers, or I really don't understand what you mean.

I think I get what you mean about the "pre combustion chamber inserts", I recall them being called something fancier like swirl chambers in a VW publication on IDI diesels.

But as far as I know, our engines have "injectors". The "nozzle" is a specific part of the "injector" assembly. So please explain what you mean here? Because I really don't know where to by "nozzles" for my engine, but have seen "injectors" listed all over the place.