Question about Diesels
Post Fiend
Joined: Apr 2004
Posts: 6,473
Likes: 4
From: Lafayette, IN
My BIL, who used to be an engineer for Cummins (worked on the '03 Dodge TD), says the extra noise is from the valve train. It must be that the extra-high compression helps them to "slap shut" harder or something like that.
Jason
Jason
Postmaster
Joined: Feb 2003
Posts: 4,043
Likes: 4
I've always thought it was the fuel pump. My grand-dad had an old Oliver tractor with a diesel engine that was the smoothest running diesel I've ever heard. Absolutely NO rattles. Couldn't tell it from a gas burner. I've also heard that Rolls Royce makes a quiet diesel. I figure it's possible to make them quiet but cheaper not to.
Lead Driver
Joined: Feb 2003
Posts: 8,140
Likes: 4
From: Oak Harbor, OH
It's the TIMING of the valve train. Listen to a hopped up diesel compared to a stocker. When the 6.9IH came out in the Fords it was fairly quiet, as were the pre-powerstroke non turboed 7.3s. With the advanced timing and boost the valves basically SLAM shut from the compression. Also the explosion of the hot hyper-compressed air meeting with the cooler fuel doesn't help any.
Posting Guru
Joined: Jul 2003
Posts: 1,028
Likes: 1
From: San Antonio
my 7.3 -6.9 rig sounded like a gas when you got on it. idle was a different story. Idle drove me crazy I always wondering if the thing was missing or not(later on I cracked the 7.3 Idi block and it was missing). It never seemed like I lost any power just sounded werid at Idle.
Trending Topics
FTE Leadership Emeritus
Joined: May 2004
Posts: 18,787
Likes: 30
From: Melbourne, Aus
Not to mention the fact it isn't a spark ignited explosion, but a compression ignited one...
Injector noise has a fair bit to do with it as well - thats the main noise from the 7.3 PSD
And most diesels for that matter.
Injector noise has a fair bit to do with it as well - thats the main noise from the 7.3 PSD
And most diesels for that matter.
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
Post Fiend
Joined: Feb 2004
Posts: 10,728
Likes: 1
From: Damascus-Boring, Ore
I know I know 
Diesels work by sponaneous combustion. The fuel is squirted into the cylinder, and the pressure from the piston moving up "squeezes" it and increases the temperature for combustion to occur. On the older diesels, some of the fuel ignites before the piston has completed the up cycle, causing the characteristic diesel "clatter."
The recent diesels use a high pressure fuel delivery system (1200 lbs+ sq/in). They can inject a small amount of fuel on the pistons up cycle, then inject the primary amount towards the end of the upcycle- eliminating most of the traditional diesel noise. They also burn cleaner- which was the real reason for the switch.
Diesels work by sponaneous combustion. The fuel is squirted into the cylinder, and the pressure from the piston moving up "squeezes" it and increases the temperature for combustion to occur. On the older diesels, some of the fuel ignites before the piston has completed the up cycle, causing the characteristic diesel "clatter."
The recent diesels use a high pressure fuel delivery system (1200 lbs+ sq/in). They can inject a small amount of fuel on the pistons up cycle, then inject the primary amount towards the end of the upcycle- eliminating most of the traditional diesel noise. They also burn cleaner- which was the real reason for the switch.
Thread
Thread Starter
Forum
Replies
Last Post
joe f350
Pre-Power Stroke Diesel (7.3L IDI & 6.9L)
24
Aug 11, 2010 08:24 PM
GeneralSteve
1987 - 1996 F150 & Larger F-Series Trucks
1
Apr 28, 2008 04:54 AM