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Mar 17, 2008 | 08:51 PM

#46

Dave Sponaugle

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Joined: Nov 2003

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From: Nutter Fort, WV

My family owned the Ford dealership in my home town.

I can't even begin to tell you how many people bought that Chevy 5.7 the traded them in for Fords.

All of them ordered 4.10 gears after running the Chevy.
All of them then said what a mistake the 4.10's were, "I never have to change gears after I get to fourth until I stop".

Mar 18, 2008 | 09:36 AM

#47

ghunt

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Joined: Oct 2005

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From: Clarksburg WV

Quote:

Originally Posted by David85

Cavitation is an effect of high pressure applied to water on the metal surface. Heavy container ships need to have their props specially tested to prevent the very same thing from happening (prop can be eaten away), since there is a safe limit to how much horse power a single prop can transmit. In the case of diesel engines, the flexibility of the cylinder wall plays a big role to how vulnerable the engine may be to developing the condition. This is why the 7.3 IDI is so prone to having problems, not only is there less metal to eat through, but the rate of erosion is also higher.

I think this why 6.9s don't seem to have the problem, the cylinder wall is over 1/4" thick from the factory, I don't know what the cummins is. SCAs can prevent the condition, and considering the risk, it should be in any diesel coolant.

What I read was that the cavitation is CAUSED by vibration of the cylinder walls due to the high compression. Apparently any V8 diesel is very susceptible to this, and I have to wonder if the Cummins even has this problem since inline engines have significantly less cylinder loading on the walls. Maybe there's almost no vibration. I know when I was looking at trucks, I was on a couple Cummins forums and asked about the additive, and they were all like "...what?"

And, yeah I know what you mean about the 4.10's. I think I had my truck in 5th gear going 25 mph at one point driving it home. Could probably pull a house off its foundation with those gears.

Mar 18, 2008 | 09:59 AM

#48

Pkupman82

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Joined: Feb 2003

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From: Muskegon, MI (home)

My F250 diesel has 4.10s and it's breathing pretty heavy at 60 mph. I think 3.55s would probably be better for highway cruising. But at the same time I like the extra grunt for towing and plowing snow.

Mar 18, 2008 | 11:04 AM

#49

RCrawler

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Joined: Dec 2002

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From: Southern Oregon USA

All diesel engines are susceptible to cavitation. As Dave posted earlier, the thin walls of the 7.3 magnify the problem.

Jason

Mar 18, 2008 | 09:06 PM

#50

Dave Sponaugle

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Joined: Nov 2003

Posts: 21,285

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From: Nutter Fort, WV

Check out FleetGuard antifreeze, made for Cummins.
www.FleetGuard.com
When you click the link you will see exactly what I am saying.

The SCA addative is already in the antifreeze that Cummins specs.
Cat has ELC which also already has the SCA addative in it.
Mack and Detroit Diesel also spec coolant with SCA's in them.
The Duramax uses Dex Cool which is another SCA formulation that is more compatible with aluminum.

The higher the compression ratio, the worse cavitation potential is.
Take one of those long stroke inlines, blow a bunch of boost in the cylinder, and then compress it up that long stroke.
Huge pressure in the cylinder is the result.
Some of those on road semi engines are getting over 100 HP per cylinder at less than 2000 RPM.
Big boost numbers is how.
The only thing saving them from early failure are massive cylinder liners that are swappable.
In my engine with the base compression ratio at 20 to 1, with about 25 pounds of boost the compression ratio jumps up to over 60 to 1.

Last edited by Dave Sponaugle; Mar 18, 2008 at 09:10 PM.