Reconditioned Rods Question
Thread Starter
|
Lead Driver
Joined: Mar 2008
Posts: 7,177
Likes: 377
From: Near Los Angeles
Reconditioned Rods Question
When you buy reconditioned piston rods, do they come in original size?
I have a short block that failed, and I want to break it down and determine cause. It went from 30 psi at a hot idle to 4 psi hot idle in 1k miles. On that build I had the crank and rods turned .010 over, polished, balanced.
Now I need to know what happened. I plan to tear it down and use plastiguage (again) on the mains and rods, and check the rods super closely.
Any tips?
I have a short block that failed, and I want to break it down and determine cause. It went from 30 psi at a hot idle to 4 psi hot idle in 1k miles. On that build I had the crank and rods turned .010 over, polished, balanced.
Now I need to know what happened. I plan to tear it down and use plastiguage (again) on the mains and rods, and check the rods super closely.
Any tips?
Cargo Master
Joined: Jul 2010
Posts: 2,099
Likes: 8
From: York, Pa
Reconditioning is just grinding the cap and rod end a touch then honing it back to factory specs for roundness. Not sure if you knew that or not but hardly anything gets taken off. Maybe the issue was you forgot to get bearings for a .010 under crank (not over). I wold think you woulda heard std bearings in there slapping around.
Hotshot
Joined: Apr 2009
Posts: 14,333
Likes: 247
From: Stanley, VA
Like PA74F250 said, when rods are reconditioned the bearing bore is resized to the original dimension. Also, cylinders are bored oversize, crankpins are turned undersize.
That being said, do you hear any noise in the bottom end or is the low oil pressure your only symptom of a problem?
When you pull the bearings, look at the backside of them and make sure they are in fact the correct size bearings. If your crank was turned -.010" the bearings should have 010 stamped on the back. If they are marked STD, 002, or 005 that's your problem.
If there are no other symptoms, there's the possibility that the gauge is bad.
Next, the pressure relief valve in the oil pump could be stuck and bypassing too much oil.
If one of the galley plugs had come out, I would expect it to have zero oil pressure.
That being said, do you hear any noise in the bottom end or is the low oil pressure your only symptom of a problem?
When you pull the bearings, look at the backside of them and make sure they are in fact the correct size bearings. If your crank was turned -.010" the bearings should have 010 stamped on the back. If they are marked STD, 002, or 005 that's your problem.
If there are no other symptoms, there's the possibility that the gauge is bad.
Next, the pressure relief valve in the oil pump could be stuck and bypassing too much oil.
If one of the galley plugs had come out, I would expect it to have zero oil pressure.
Cargo Master
Joined: Jul 2010
Posts: 2,099
Likes: 8
From: York, Pa
No...thank you for the reply....I see now more why you have problems.
Thread Starter
|
Lead Driver
Joined: Mar 2008
Posts: 7,177
Likes: 377
From: Near Los Angeles
I was laughing because that mistake seemed comical. I'm sorry my humor was mistaken. As so often happens on the forum, information is understood the wrong way, or personalities are different, and dispute arises.
Thanks for the help guys. I wanted to post this illustration so we know that all concerned know what undersized and oversize bearings are. If I used the wrong terminology I'm sorry. But rest assured, when the bearings were purchased, they were checked.
Oil pressure gauge was changed. Oil pump was changed to a h.v. pump. Psi continued to drop radically and the engine was pulled and changed. It has set in my garage for two years now. I'm about to break it down and go through it.
Thanks for the help guys. I wanted to post this illustration so we know that all concerned know what undersized and oversize bearings are. If I used the wrong terminology I'm sorry. But rest assured, when the bearings were purchased, they were checked.
Oil pressure gauge was changed. Oil pump was changed to a h.v. pump. Psi continued to drop radically and the engine was pulled and changed. It has set in my garage for two years now. I'm about to break it down and go through it.
Trending Topics
Cargo Master
Joined: Apr 2010
Posts: 2,600
Likes: 64
From: Billings, MT
Nothing wrong with plasti-gauge for us shade tree dudes. What were your bearing clearances on the last build? And what viscosity oil were you running?
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make
Brett Foote
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!
Michael S. Palmer
Ford's 2001 Explorer Sportsman Concept Looks For a New Home
Verdad Gallardo
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!
Michael S. Palmer
10 Most Surprising 2026 Ford Truck Features!
Joe Kucinski
Top 10 Ford Trucks Coming to Mecum Indy 2026
Brett Foote
5 Best / 5 Worst Ford Truck Wheels of All Time
Joe Kucinski
Senior User
Joined: Mar 2011
Posts: 194
Likes: 0
From: Brisbane Australia
High volume pumps were designed for racing clearance engines. They run higher clearances and hence need the higher volume of oil. If you put one on a standard clearance engine you can have issues.
Thread Starter
|
Lead Driver
Joined: Mar 2008
Posts: 7,177
Likes: 377
From: Near Los Angeles
The engine is a ford 300, inline 6, with 250 hp. I paid a friend on hard times, who is a pro mechanic, to build it. I was too busy at the time. Something went through the oil and wiped the bearings w/i a few hundred miles.
I changed the bearing from underneath. Psi started dropping. I changed the gauge. Dropped further and I changed to hv pump. When it got to 4 psi I had another engine waiting, that I built, and have been running it for ...iirc, three years now. But that first one has been itching at the back of my mind all this time, and I want to take it apart and hopefully find out what happened.
I've been running the hv pump 3 years w/o problem.
Note: It is nearly impossible to find oversize bearings for a 300.
Question: What does one do if you need to have block line bored and the crank needs to be turned down as well. Is there a combo bearing, an over/under bearing? Or do you use the dimensions of a bearing from another engine and have it machined to fit that bearing?
Cheers.
I changed the bearing from underneath. Psi started dropping. I changed the gauge. Dropped further and I changed to hv pump. When it got to 4 psi I had another engine waiting, that I built, and have been running it for ...iirc, three years now. But that first one has been itching at the back of my mind all this time, and I want to take it apart and hopefully find out what happened.
I've been running the hv pump 3 years w/o problem.
Note: It is nearly impossible to find oversize bearings for a 300.
Question: What does one do if you need to have block line bored and the crank needs to be turned down as well. Is there a combo bearing, an over/under bearing? Or do you use the dimensions of a bearing from another engine and have it machined to fit that bearing?
Cheers.
Hotshot
Joined: Apr 2009
Posts: 14,333
Likes: 247
From: Stanley, VA
Note: It is nearly impossible to find oversize bearings for a 300.
Question: What does one do if you need to have block line bored and the crank needs to be turned down as well. Is there a combo bearing, an over/under bearing? Or do you use the dimensions of a bearing from another engine and have it machined to fit that bearing?
Cheers.
Question: What does one do if you need to have block line bored and the crank needs to be turned down as well. Is there a combo bearing, an over/under bearing? Or do you use the dimensions of a bearing from another engine and have it machined to fit that bearing?
Cheers.
The machinist takes the main bearing caps and grinds a couple of thousandths off the mating surface. This makes the bearing bores undersized. The caps are then reinstalled and torqued to spec and the mains are honed back to the original spec. You use standard off the shelf bearings.
The only time oversize (larger OD) bearings are required is when the bearing is a single piece, not split. Example, cam bearings on the Ford 2300 4 cylinder. Common to spin the cam bearing, line hone to a larger ID and replace the cam bearings with oversize units.
Cargo Master
Joined: Jul 2010
Posts: 2,099
Likes: 8
From: York, Pa
My guess is and without seeing it personally the rods were the beginning of the problem. It's hard to tell if they were out of round or just too tight on the crank. The bearing material is probably what did the most damage to the mains. Still just a guess without being in my own hands.
Thread Starter
|
Lead Driver
Joined: Mar 2008
Posts: 7,177
Likes: 377
From: Near Los Angeles
Rods had ARP bolts. Are those torqued the same? The guy was experience engine builder. He would/should have known, and the crank and rods and journals should have been miched.
Although I've built a few engines, my experience is limited. Once I get it apart I'll run all the findings by you guys, and any guidance will be greatly appreciated.
Surprisingly, what I found with 2 pros I know, and also with two machine shops, is because the engine is an inline they don't seem as concerned, as though it is a toy or something.
Although I've built a few engines, my experience is limited. Once I get it apart I'll run all the findings by you guys, and any guidance will be greatly appreciated.
Surprisingly, what I found with 2 pros I know, and also with two machine shops, is because the engine is an inline they don't seem as concerned, as though it is a toy or something.
More Turbo
Joined: Mar 2008
Posts: 525
Likes: 6
From: douglasville
I had a 390 do the same thing, I just kept driving it til it started rattling so it turned out i had a 10/10 crank rolling on standard bearings. So i bought a reman crank/bearing kit and put it all back together but it still had low oil presure, got mad and bought a reman engine b/c i needed that truck on the road took the engine back to the machine shop turns out the cam bearings were also wrong,however that happened i wasted 3grand for a 30 dollar set of cam bearings and a 150 dollar crank kit. live and learn
Thread
Thread Starter
Forum
Replies
Last Post
rnelson664
1948 - 1956 F1, F100 & Larger F-Series Trucks
9
Oct 15, 2007 02:53 PM
crawlfish
335 Series- 5.8/351M, 6.6/400, 351 Cleveland
16
May 31, 2005 02:27 AM
debestuss
FE & FT Big Block V8 (332, 352, 360, 390, 406, 410, 427, 428)
12
Feb 22, 2004 08:04 AM