Engine good? How do you know?
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Joined: Aug 2010
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Engine good? How do you know?
I just got a 94 IDI 7.3 turbo'd F250 4x4 with 120k miles on it. It needs more suspension work than I thought so just debating selling it vs. fixing it all up. Body is good, drivetrain seems good. But I wanted to know if there are any low cost ways to make sure that I have a good engine before I spend a ton of money on everything else.
One thing that worries me is that she seems to take longer to start then she did a month ago when I bought her even though Ive only driven a few miles. Sometimes three or four attempts. Runs rough for a few seconds and then dies. About the fourth attempt she smooths right out. Smokes blue and black for the first five to ten seconds then runs clear. When she's warm she purrs like a kitty and although I dont know anything about diesels, she sounds good and smooth to me. No unusual noises or clatter.
I understand a compression test is pretty pricey. Is there any other way to tell if Ive got a good engine?
One thing that worries me is that she seems to take longer to start then she did a month ago when I bought her even though Ive only driven a few miles. Sometimes three or four attempts. Runs rough for a few seconds and then dies. About the fourth attempt she smooths right out. Smokes blue and black for the first five to ten seconds then runs clear. When she's warm she purrs like a kitty and although I dont know anything about diesels, she sounds good and smooth to me. No unusual noises or clatter.
I understand a compression test is pretty pricey. Is there any other way to tell if Ive got a good engine?
Cargo Master
Joined: Mar 2010
Posts: 2,230
Likes: 149
From: Higginsville, MO
like joe said your probably getting air in the return lines.... very common happened to me and had the same problems your having..... also check the GP's if you got some that aint working then you'll have similar symptoms take a test light and hook to positive battery unhook GP wire and touch the tip of the plug that the wire goes on should light up if not plugs probably bad
if bad replace with MOTORCRAFT plugs only
ive done a suspension overhaul on my truck it can be done cheap or it can be done right.... id do it right.... ive probably spent 1000-1500 dollars on the suspension but hey.... its solid..... and im happy with it
if bad replace with MOTORCRAFT plugs only
ive done a suspension overhaul on my truck it can be done cheap or it can be done right.... id do it right.... ive probably spent 1000-1500 dollars on the suspension but hey.... its solid..... and im happy with it
Methanoholic
Joined: Mar 2009
Posts: 6,442
Likes: 8
From: Maine (NorCal Native)
Compression test is as inexpensive as you can buy a tester for ... Maybe $40!
Your starting and rough running problem is from air in the system most likely from leaking return lines, simple fix. Remember just because they are not leaking fuel does not mean they are not leaking air, air molecules are smaller then Diesel molecules.
To correct the Air Intrusion Install a Injector Installation Kit
Many prefer to toss the o-rings in the kit (I highly suggest you do) and use these Viton Return O-Rings - McMaster-Carr Item 9464K24, Viton is impervious to Diesel.
For the Injector Installation Kit installation You can follow Starmilts Humorous Fuel Return Replacement Procedure, I like to cut the 6 pieces between the Injectors to 4-1/16", Use a sharp razor blade to cut the hose and Vaseline to lubricate the o-rings, you do NOT need to pull the Injectors to replace the copper seals unless they are leaking compression, spray a little soapy water around the Injector base to test for compression leaks.
For proper fuel system bleeding you can use steps 1 through 4 and 13 through 15 of the Fuel Filter Replacement.
You may also want to test the glow plugs...
*** Glow Plug Test. ***
Test light test of the glow plugs:
Only use Motorcraft/Beru Glow Plugs
-Enjoy
fh : )_~
Your starting and rough running problem is from air in the system most likely from leaking return lines, simple fix. Remember just because they are not leaking fuel does not mean they are not leaking air, air molecules are smaller then Diesel molecules.
To correct the Air Intrusion Install a Injector Installation Kit
Many prefer to toss the o-rings in the kit (I highly suggest you do) and use these Viton Return O-Rings - McMaster-Carr Item 9464K24, Viton is impervious to Diesel.
For the Injector Installation Kit installation You can follow Starmilts Humorous Fuel Return Replacement Procedure, I like to cut the 6 pieces between the Injectors to 4-1/16", Use a sharp razor blade to cut the hose and Vaseline to lubricate the o-rings, you do NOT need to pull the Injectors to replace the copper seals unless they are leaking compression, spray a little soapy water around the Injector base to test for compression leaks.
For proper fuel system bleeding you can use steps 1 through 4 and 13 through 15 of the Fuel Filter Replacement.
You may also want to test the glow plugs...
*** Glow Plug Test. ***
Test light test of the glow plugs:
- Unplug the Glow Plugs.
- Attach one end of a test light to 12v+ battery.
- Touch the other end to the terminal on the end of the Glow Plug (where you unplugged the harness)
Does it light up?- Yes, Chances are it's good.
- No, Replace with Motorcraft/Beru ZD1A for 83-86, ZD9 for 87-94.5.
To do a positive test use a volt/ohm meter and test the ohms between the terminal and base. Should be .5 to 1 ohm resistance.
Only use Motorcraft/Beru Glow Plugs
-Enjoy
fh : )_~
Senior User
Joined: Feb 2007
Posts: 119
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thanks for posting a link to that injector kit procedure. i found the kit at napa for $37.99. i may attempt that this weekend. my 93 7.3idi is taking just a hair longer to start. normally i bump the key and the engine fires right up but now-a-days i have to crank for 3 or 4 seconds before it will start.
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New User
Joined: Aug 2010
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Diagrams
Is there a good site that shows the basics of how a 7.3 works and labels parts? Im a total newbie, and I really dont know how a diesel works. Pretty familiar with gas engines but this is my first diesel.
(Not sure if Id recognize the return lines if they slapped me in the face
(Not sure if Id recognize the return lines if they slapped me in the face
Methanoholic
Joined: Mar 2009
Posts: 6,442
Likes: 8
From: Maine (NorCal Native)
The return lines are the 3/16" or 1/4" hoses that run between the Injectors.
Being you have a 94 Turbo, they run a little different because of the Turbo location.
The ultimate return setup would be ...
The return line from the IP goes to the first Injector on the left bank through all the Injectors to a return tee at the back of the motor ... This allows air to bleed from the IP as well as coolant for the left bank of Injectors!
The return line from the filter head goes to the first Injector on the right bank and through all the Injectors to the return tee at the back of the motor ... This allows air to bleed from the filter as well as coolant to the right bank of Injectors!
As for learning about how the 6.9/7.3 works ... Ask questions here, they will get answered!
tpolley,
As soon as it starts how does it run ... If you need to do returns, it will die (or try to) right after starting.
You can also pull the fuel filter after it has set over night, if it's not completely full you have air Intrusion and likely need to do returns.
Hard starting could just be glow plugs. Use Motorcraft/Beru glow plugs ONLY!!!
-Enjoy
fh : )_~
Being you have a 94 Turbo, they run a little different because of the Turbo location.
The ultimate return setup would be ...
The return line from the IP goes to the first Injector on the left bank through all the Injectors to a return tee at the back of the motor ... This allows air to bleed from the IP as well as coolant for the left bank of Injectors!
The return line from the filter head goes to the first Injector on the right bank and through all the Injectors to the return tee at the back of the motor ... This allows air to bleed from the filter as well as coolant to the right bank of Injectors!
As for learning about how the 6.9/7.3 works ... Ask questions here, they will get answered!
tpolley,
As soon as it starts how does it run ... If you need to do returns, it will die (or try to) right after starting.
You can also pull the fuel filter after it has set over night, if it's not completely full you have air Intrusion and likely need to do returns.
Hard starting could just be glow plugs. Use Motorcraft/Beru glow plugs ONLY!!!
-Enjoy
fh : )_~
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Senior User
Joined: Feb 2007
Posts: 119
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if you go to youtube and search redbeard0183, i think its the 3rd video you'll see a startup of my truck after it had been sitting for a week.
for what its worth, that is.
i did the video because i was going to sell the truck and i had a link to that video on the craigslist add because some people were asking if the truck was hard to start.
i decided to keep the truck.
for what its worth, that is.
i did the video because i was going to sell the truck and i had a link to that video on the craigslist add because some people were asking if the truck was hard to start.
i decided to keep the truck.
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Post Fiend
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From: concord ca
Senior User
Joined: Feb 2007
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that's 90% of your problem. 3 seconds indicates that you have probably 2 burnd out glow plugs. if you loose any more than 2 maybe 3 glow plugs the system will not work at all.
mine comes on for 8 to 14 seconds.
