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Discussion Starter #1 (Edited)
Want to start off saying I'm new to the Diesel World and Stop. So hello everyone....

I have a few questions related to how do I identify 6.9's and 7.3's apart??

Reason I'm asking is I bought a truck load of parts to sell and along with this load of misc. parts was 5 complete Motors laying on skids. All I was told is they are 6.9 and 7.3's. I'm wanting to sell them as cores to someone, but before I can I want to know what I have. Been asked if they are small cam big cam and etc. Me being a newbie I'm lost ...


They are complete from intake to oil pan. Along with some injection pumps...They are all none turbo motors.


Are the blocks or heads worth anything as far as cores?? Any Inst on this would be very helpful.


Thanks ahead of time guys.!!



Zach
 

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If the tag on the side of the motor is still there it should tell you which motor it is.

I know that the 7.3's ran off a serpentine belt and the 6.9 runs off of V-belts.

The only problem with that though is I'm not sure if the early 7.3 had v-belts or not.

The fuel filter block I know is different too. The only thing I can tell you about that is the 6.9 has a shrader valve on the side of it.

I'm interested in one of the cores if the price is right.
 

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The early 7.3s did have V belts. They switched to serpentine in 91 or 92 I think it was.
 

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Discussion Starter #4
Thanks for the info so far.

Is there a number stamped on the block to tell what year they are?? Like they do on Ford gas motors??

What about the heads....Any way to ID those also?? I have another skid with heads on them. And about 6 pumps laying there.
 

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All you wanted to know........ thanks to Mel

The recent thread on which is better (6.9 or 7.3) got me to reading this book I borrowed from Bob at the IDI Weekend, and it turns out there are a lot of subtle differences between the two beasts. I figured there needs to be a deffinitive list, so here it is.

First year for the 6.9 - 1983
Last year for the 6.9 - 1987
By 1988 all production 7.3

6.9 - Max H.P. 175 Torque 318 ft. lb.
7.3 - Max H.P. 185 Torque 338 ft. lb.

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

Both max HP at 3300 RPM.

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 cup 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.

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. Also inside, was a chart which I found interesting. It shows the amount of HP required for a given frontal area at a given speed. I don't want to type up the whole chart, but I'll give you one column, for 55 MPH

Area in Sq. Ft. - HP required
50 - 56
60 - 66
70 - 78
80 - 89
90 - 99


That should be of interest to those of you with campers. - Mel
 

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The engine serial number will tell you. The number is stamped on the block inbetween the drivers side head and the injection pump. I have a pic of this in my members gallery here. The first digits will either be 6.9D or 7.3D. You.ll probably have to scrape some crud and/or sealer to see the full number.

Also 6.9 headbolts have a 7/16 head while a 7.3 will have 1/2.
 

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About the pallet of heads. Are they new or used or rebuilt. As posted above, the stamped numbers on top of the block will tell you lots about the motors. In late 93 year these 7.3 idi motors were turbo equiped and the rods had bigger piston pins. Also the exhaust valves were changed to an inconel material because of the higher heat issues with the addition of the turbo. The oil cooler bundle had more fins per inch in the turbo coolers too. Thats the only oil cooler bundle we can buy these days. Even if the numbers stamped into the block state that its a turbo motor you will really only know when you remove the pistons and check the rods or the cast in serial numbers if its really a turbo motor. Some say that all motors built in late 93 are turbo setups.
 

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Discussion Starter #8
Selling 6.9 / 7.3 Cores!!

I have a few rebuilt heads along with used heads. I'd like to sell everything soon. I'm willing to part everything out also....Everything is none info cores. I have complete Long blocks 6.9 and a non turbo 7.3,heads and pumps. I'm located in Evansville,IN

Make offers.
 

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Just remember if you remove the heads ..... use the reverse direction of tightening the head bolts (ie #17 down to #1) several rotation times in small increments is required to loosen without cracking the heads.
 

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The easiest way for you to quickly tell the difference is the head bolt size. They are both 12 point, but the 6.9 has the smaller 7/16 head while the 7.3 used 1/2 inch.

Heath
 
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