Hello to all! I am new to the world of diesel, and I have a couple of questions. I have an '87 F250 extended cab, 4 speed, 4WD with the 6.9 in it. I wanted to know about horsepower and torque ratings for the engine, and any problems that are inherent to this engine.

Thanks.

 

kf4hog,
Welcome to FTE and the IDI diesel forum.

Horsepower 185
Torque is about 330 Ft. Lbs.

How many miles on the engine?

Change the oil every 3000 miles.
Service the CDR at every oil change.
Change the air and fuel filter at 9000 miles or less.
Service the glow plugs every 6 months or so to make sure they are all working.
Batteries must be at least 850 CCA rated or better.
SCA levels in the cooling system must be watched.
Find a good fuel supplier and get your fuel there, a couple of cents saved per gallon is not worth the headache that bad fuel can cause.
The 87 was the last year for the 6.9, that is the best of the bunch.

I know you have lots of questions about the answers I have given. Bed time for me now though, there will be more people in that can explain the terms that you do not understand. You have found the best source of information about your truck that you will ever find. There are a lot of very experienced diesel owners here about every day.

Please come back often.

 

My chart says the 6.9 is 175 HP - Torque 318 ft. lb
7.3 185 HP - Torque 338 ft. lb.

The values are at flywheel not the rear wheels.

No major problems with the engine, It is a real tuff engine that will last a long time if you just take care of it.

 

Below is a comparison of the differences between our beloved IDI's. All this Information 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 at a Ford dealership. Note that some of the torque specs changed for head bolts later when turbochargers were added to the 7.3, and the 6.9 by third parties. These torque specs are generally 10 lbs over base figures. Also note that the comments regarding flywheel mixing are contradictory with Ford part numbers for the 1987 version of the 6.9 which uses a 7.3 flywheel from the factory.

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 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.
__________________

 

WOW!! I think I've learned more about this truck in the past day than I could have in a month! Thanks much!!

THe truck has 208,000 miles on it. The last guy who owned it only drive it 6 times, and I'm not really sure how long he had it, but I get the idea he had it at least a year. When I bought it, there was just a very black drop of oil on the dipstick. I added a gallon of Rotella oil, and that brought it into the operating zone on the dipstick.

What is the CDR?

How do I service the glow plugs?

What are SCA levels?

I do greatly appreciate you guys teching me a thing or two about my "new" truck.

 

SCA= Supplemental Coolent additive. It can be tested I think but it is just as well to change the coolent that has sca already in it or purchase sca from the ford dealer or a truck stop.

 

Ask the previous owner about the coolant - have they been adding FW16 or DCA4 to keep a proper SCA level? It is very important for stopping cavitation. You can get test strips to check the SCA level from NAPA, International, or Ford. the SCA level should be between 1.5 and 3.0. The 6.9 has thicker cylinder walls so it is not as important as on the 7.3 but it is still a good idea to keep the sca up to proper levels.

 

Thanks Guantman. This SCA....is it similar to Red Line's Water Wetter? The previous owner seemed to not know anything about fluid levels and such, as he never even had the oil changed while he owned it and did not even know the condition of it.

 

Sorry kf but I am not familiar with Red Line's Water Wetter.

 

Here's an article about removing glow plugs (actually, its an article about how to remove them the best way as to not lose the tips in the cylinder)
http://www.members.shaw.ca/k2pilot/