1992 5.0 piston question
Thread Starter
|
Cross-Country
Joined: Jan 2006
Posts: 85
Likes: 0
From: Talking Rock
1992 5.0 piston question
I have a 1992 F-150 5.0 that may need a new piston. Does anyone know what kind I will need (cast, forged, or hypereutectic)? I'm trying to be prepared for whatever when I get the #8 piston out (low compression) so I dont have to wait on parts or go on parts runs.
Last edited by MattV; Nov 29, 2007 at 10:10 AM.
FTE Legend
Joined: Jun 2006
Posts: 31,930
Likes: 1,499
From: Ottawa, Ontario
The truck motor has either cast or hyper pistons.. depends upon the year. But as Hemi says.. don't put the cart before the horse, find out what the problem is before ordering parts. As an example low compression is just as easily caused by a valve problem as it is by a piston problem.
More Turbo
Joined: May 2003
Posts: 524
Likes: 72
Well if the cyl's are worn, a std size piston will not work. If the cyl's are great, why over bore and use oversize.... Lots of reasons to wait. Add to that the fact that you have to disasemble the motor to get the pistons out, you will probably want to do bearings, and other things. Maybe the crank is worn, maybe not... Its your time, and money, but probably not the first thing you want to buy. Also you state "piston" not pistons. You plan to just replace one? The chance of getting one the same weight as the others is very slim.
As for your Q.. The stock ones should be cast. IMHO if you are replacing them all[and you should] I would not run a cast piston in a truck. I would run hypers at least.
As for your Q.. The stock ones should be cast. IMHO if you are replacing them all[and you should] I would not run a cast piston in a truck. I would run hypers at least.
Postmaster
Joined: Jun 2005
Posts: 2,656
Likes: 1
Originally Posted by MattV
The valves arent the problem. That has already been checked many times. What does it hurt to buy a piston? If I dont use it, I can return it.
but how were the valves checked?
I'm just trying to save you some money and time........when you get it apart you can tell what kind of piston it is by looking inside it....
if the piston has come apart there is a good chance you will need to over bore it.....due to cylinder damage..... so why buy a std. piston when you might need 8 .030 over size.
Have you have the heads off?
Thread Starter
|
Cross-Country
Joined: Jan 2006
Posts: 85
Likes: 0
From: Talking Rock
Yeah, the heads are off and have been checked out at the machine shop. The valves were all good and neither head was warped. So they got vatted and new guides, ready to bolt on. The top of the #8 piston looks good and the walls of the cylinder still have crosshatch, so I'm left to think that the ring(s) on #8 have gone south. Since the whole top of the motor is off, I am going to do a shortcut and raise the motor up, drop the pan, and take the #8 piston out to see if the rings really are the problem. I should have mentioned all this before so that you guys didn't get only part of the story. I am open to suggestions. Oh, and the head gasket wasn't blown either. Clear as mud? 
Trending Topics
Postmaster
Joined: Jun 2005
Posts: 2,656
Likes: 1
Did you do a wet compression test?
What was the test results? just wondering........
also i think the 92 might have forged pistons...I know I am running 9? pistons in my truck and they are forged.....
one way to tell if they are forged is to put a straight edge across the deck and measure how far down the piston it when it's at TDC, The forged pistons had a taller compression heigth putting the top of the piston at close to 0 deck. if the piston is like .015 to .020 down the hole @ TDC good chance they are cast....
What was the test results? just wondering........
also i think the 92 might have forged pistons...I know I am running 9? pistons in my truck and they are forged.....
one way to tell if they are forged is to put a straight edge across the deck and measure how far down the piston it when it's at TDC, The forged pistons had a taller compression heigth putting the top of the piston at close to 0 deck. if the piston is like .015 to .020 down the hole @ TDC good chance they are cast....
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
Top 6 Best Deals Available on New Fords & Lincolns Right Now
Brett Foote
This Hennessey Takes the Expedition Tremor's Off-Roading Capability to the Next Level
Verdad Gallardo
Top 10 Fords at 2026 Carlisle Ford Nationals
Joe Kucinski
3 Best / 3 Worst Parts of Modern Ford Ownership
Brett Foote
10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches
Pouria Savadkouei
Every 2026 Ford Engine Explained
Brett Foote
10 Ugly Ford Trucks That We Still Kinda Love
Joe Kucinski
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Thread Starter
|
Cross-Country
Joined: Jan 2006
Posts: 85
Likes: 0
From: Talking Rock
Yeah, I did the wet compression test a few times and the results were the same everytime. No increase in compression at all each time I tried, thus the reason I took the head off and had it checked out.
I did your check on telling which pistons I have and they came close to 0 deck, so hopefully they are forged.
I did your check on telling which pistons I have and they came close to 0 deck, so hopefully they are forged.
