Notices
1999 - 2003 7.3L Power Stroke Diesel  
Sponsored by:
Sponsored by: DP Tuner

Failed Compression 99 7.3L

Thread Tools
 
Search this Thread
 
Old Jul 9, 2020 | 07:44 PM
  #1  
BeerThirty's Avatar
BeerThirty
Thread Starter
|
New User
Joined: Jul 2020
Posts: 12
Likes: 0
Failed Compression 99 7.3L

Hey everyone,

Got a 99 F350 with 76832 miles on it. Was a barn find, put new battery in it, drained fluids ran separate fuel line with new fuel etc to get it started, it ended up starting,, but had excessive blowby. Had a mechanic friend run a compression test and #5 & #7 are failing. Tried swapping injectors etc issue still same.

So my question is, with such low miles I'm assuming pulling it is probably a better option then getting another engine. With a failed compression test on 2 cyclinders, whats the odds of the block being smoked? Im assuming i won't know till i pull it out of the truck etc.
mechanic won't do a rebuild so I'll be doing that myself.

Thanks
 
Reply
Old Jul 9, 2020 | 09:22 PM
  #2  
Walleye Hunter's Avatar
Walleye Hunter
Hotshot
10 Year Member
Liked
Loved
Community Favorite
Joined: Mar 2014
Posts: 10,750
Likes: 1,065
From: Douglassville, PA
Ya can never tell. I think I'd pull that head and look inside before I pulled it out
 
Reply
Old Jul 10, 2020 | 05:55 AM
  #3  
SkySkiJason's Avatar
SkySkiJason
Hotshot
Joined: Jul 2008
Posts: 12,782
Likes: 2,142
From: N.GA Mountains
Club FTE Gold Member
Did he do a physical COMPRESSION TEST or digital CYLINDER CONTRIBUTION TEST?

Is there blowby (pressure and puff puff puff) at the oil filler cap?
 
Reply
Old Jul 10, 2020 | 09:57 AM
  #4  
BeerThirty's Avatar
BeerThirty
Thread Starter
|
New User
Joined: Jul 2020
Posts: 12
Likes: 0
Originally Posted by SkySkiJason
Did he do a physical COMPRESSION TEST or digital CYLINDER CONTRIBUTION TEST?

Is there blowby (pressure and puff puff puff) at the oil filler cap?
physical and yes a insane amount of blowby
 
Reply
Old Jul 10, 2020 | 12:45 PM
  #5  
SkySkiJason's Avatar
SkySkiJason
Hotshot
Joined: Jul 2008
Posts: 12,782
Likes: 2,142
From: N.GA Mountains
Club FTE Gold Member
Originally Posted by BeerThirty
physical and yes a insane amount of blowby
Probably gonna need an engine.

Customer I’m working for right now explained he went all winter giving his 7.3 ‘a little ether’ to get it started because GP’s were bad.

It only takes ‘a little’ to break a ring or worse....
 
Reply
Old Jul 10, 2020 | 12:50 PM
  #6  
SkySkiJason's Avatar
SkySkiJason
Hotshot
Joined: Jul 2008
Posts: 12,782
Likes: 2,142
From: N.GA Mountains
Club FTE Gold Member
These blocks are tough.

Depending on the amount of cylinder wall damage, you can get away with just a bore and new pistons or possibly just sleeves and stock size pistons if the other cylinders measure good.
 
Reply
Old Jul 10, 2020 | 12:52 PM
  #7  
BeerThirty's Avatar
BeerThirty
Thread Starter
|
New User
Joined: Jul 2020
Posts: 12
Likes: 0
Originally Posted by SkySkiJason
Probably gonna need an engine.

Customer I’m working for right now explained he went all winter giving his 7.3 ‘a little ether’ to get it started because GP’s were bad.

It only takes ‘a little’ to break a ring or worse....

I jasked to pull the head they quoted 12 hrs so ust told them this morning to pull the engine considering itll have to come out anyway. hopefully next week ill be able to get a better idea. It was $850 to do the engine R & I. I doubt it was ethereal. I'm going to assume clogged air filter that let dust around it or running with a bad injector as the ones we pulled out were in pretty bad shape and it wasn't like sitting for a long time bad shape either.
 
Reply
Old Jul 10, 2020 | 01:39 PM
  #8  
SkySkiJason's Avatar
SkySkiJason
Hotshot
Joined: Jul 2008
Posts: 12,782
Likes: 2,142
From: N.GA Mountains
Club FTE Gold Member
I’ve got a good running complete engine here I was going to use for a friend’s project, but plans have changed. I also have a couple longblock cores left. PM me if you’re interested. I’m on the GA/NC border.

Fair price, but ask the shop to leave your AC and PS systems intact!!! No need to spend money on those parts if they’re not broken.



 
Reply
FTE Stories

Ford Trucks for Ford Truck Enthusiasts

story-0

Top 10 Ford Truck Tragedies

 Joe Kucinski
story-1

AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make

 Brett Foote
story-2

Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!

 Michael S. Palmer
story-3

Ford's 2001 Explorer Sportsman Concept Looks For a New Home

 Verdad Gallardo
story-4

10 Best Ford Truck Engines We Miss the Most!

 Joe Kucinski
story-5

2026 Shelby F-150 Off-Road: Better Than a Raptor R?

 Brett Foote
story-6

2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!

 Michael S. Palmer
story-7

10 Most Surprising 2026 Ford Truck Features!

 Joe Kucinski
story-8

Top 10 Ford Trucks Coming to Mecum Indy 2026

 Brett Foote
story-9

5 Best / 5 Worst Ford Truck Wheels of All Time

 Joe Kucinski
Old Jul 10, 2020 | 03:51 PM
  #9  
BeerThirty's Avatar
BeerThirty
Thread Starter
|
New User
Joined: Jul 2020
Posts: 12
Likes: 0
Originally Posted by SkySkiJason
I’ve got a good running complete engine here I was going to use for a friend’s project, but plans have changed. I also have a couple longblock cores left. PM me if you’re interested. I’m on the GA/NC border.

Fair price, but ask the shop to leave your AC and PS systems intact!!! No need to spend money on those parts if they’re not broken.


I'm up in iowa, but I'll keep it in mind. Engines getting pulled Wednesday so hopefully by Friday I'll know if the block/cyclinders are worth it or not
 
Reply
Old Jul 11, 2020 | 02:52 PM
  #10  
Bonanza35's Avatar
Bonanza35
Lead Driver
20 Year Member
Liked
Loved
Community Favorite
Joined: Sep 2005
Posts: 9,399
Likes: 188
From: Norco,CA
Club FTE Silver Member

Let us know what you find! I know a guy who just put in one piston, still running today. I wouldn't do that but it worked for him.
 
Reply
Old Jul 11, 2020 | 09:09 PM
  #11  
RA101725's Avatar
RA101725
Banned
Joined: Dec 2018
Posts: 3,541
Likes: 458
That's a surprisingly low mileage for dead cylinders or bad injectors. Does it have the stock airbox? Signs it's been hot rodded?
 
Reply
Old Jul 12, 2020 | 11:56 PM
  #12  
BeerThirty's Avatar
BeerThirty
Thread Starter
|
New User
Joined: Jul 2020
Posts: 12
Likes: 0
Originally Posted by Brandonpdx
That's a surprisingly low mileage for dead cylinders or bad injectors. Does it have the stock airbox? Signs it's been hot rodded?
Everything is OEM. Never tuned etc. Original airbox. The filter i pulled out was insanely dusty. But it also sat for a long time.. wasn't moved after the widows husband passed other than to get it in the machine shop
 
Reply
Old Jul 13, 2020 | 04:32 AM
  #13  
MoBill122's Avatar
MoBill122
Papa Smurf
15 Year Member
Liked
Loved
Community Favorite
Joined: Nov 2009
Posts: 1,079
Likes: 204
From: Woodstock, GA
Club FTE Gold Member
I'd pull the valve cover and watch it running.... and run a scope into those cylinders...
 
Reply
Old Jul 13, 2020 | 10:19 AM
  #14  
7.3 Powerstroke Guy's Avatar
7.3 Powerstroke Guy
Mountain Pass
Joined: Dec 2014
Posts: 219
Likes: 7
From: Pennsylvania
Originally Posted by Brandonpdx
That's a surprisingly low mileage for dead cylinders or bad injectors. Does it have the stock airbox? Signs it's been hot rodded?
Sounds like it may be an early 99 with the stock airbox that doesn't seal well. I've noticed this as a trend on some e99 trucks, especially those used in a dirty environment.
 
Reply
Old Jul 13, 2020 | 10:53 AM
  #15  
BeerThirty's Avatar
BeerThirty
Thread Starter
|
New User
Joined: Jul 2020
Posts: 12
Likes: 0
Engines getting pulled today. Going to check cyclinders thurs if not to bad itll get overhauled. probably going to do the Motorcraft oem with arp studs etc unless there's a better one to do. Any recommendations on air filter box.. also any other recommendations on parts I should swap out or add? such as gauges etc.. Thanks
 
Reply



All times are GMT -5. The time now is 04:10 AM.

story-0
Top 10 Ford Truck Tragedies

Slideshow: Top 10 Ford truck tragedies.

By Joe Kucinski | 2026-05-18 19:34:33


VIEW MORE
story-1
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make

And it might be even better than that.

By Brett Foote | 2026-05-18 19:26:42


VIEW MORE
story-2
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!

Slideshow: Does lowering an F-150 Lobo RUIN the ride quality?

By Michael S. Palmer | 2026-05-18 19:20:37


VIEW MORE
story-3
Ford's 2001 Explorer Sportsman Concept Looks For a New Home

Slideshow: Ford's bizarre fishing-themed Explorer concept has resurfaced after spending decades largely forgotten.

By Verdad Gallardo | 2026-05-12 18:07:46


VIEW MORE
story-4
10 Best Ford Truck Engines We Miss the Most!

Slideshow: The 10 best Ford truck engines we miss the most.

By Joe Kucinski | 2026-05-12 13:09:47


VIEW MORE
story-5
2026 Shelby F-150 Off-Road: Better Than a Raptor R?

Slideshow: first look at the 810 hp 2026 Shelby F-150 Off-Road!

By Brett Foote | 2026-05-12 12:50:07


VIEW MORE
story-6
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!

Slideshow: Everything You Need to Know about the 2027 Super Duty Carhartt Package!

By Michael S. Palmer | 2026-05-07 17:51:06


VIEW MORE
story-7
10 Most Surprising 2026 Ford Truck Features!

Slideshow: 10 most surprising Ford truck options/features in 2026.

By Joe Kucinski | 2026-05-05 11:17:22


VIEW MORE
story-8
Top 10 Ford Trucks Coming to Mecum Indy 2026

Slideshow: Here are the top 10 Fords coming to Mecum Indy 2026.

By Brett Foote | 2026-05-04 13:49:49


VIEW MORE
story-9
5 Best / 5 Worst Ford Truck Wheels of All Time

Slideshow: The 5 best and 5 worst Ford truck wheels of all time

By Joe Kucinski | 2026-04-29 16:49:01


VIEW MORE