[Nakkas]

Hi all,

What is this talk about 'F' and 'S' engines? What is the difference??

 

[96GMC6.5L]

Welcome to the forum new member. Check out the FAQ section of the 6.5L diesel page found at the top of the thread list. All the "sticky" threads are good to read and will give you a lot of information. If you still have questions after reading those, feel free to ask there is some very good knowledge to be found on this website. People know whate they are talking about.

Jacob

 

[Scrufdog]

yeah, read through the FAQ's, but to give a quick answer.....

F = non emissions, high output motor.

S = EGR installed, lower output motor. Slight difference in the heads as well.

 

[DavidPhillips]

S engine has an EGR valve and vacuum controls for the EGR system. It has a different intake manifold that has exhaust ports in it for the EGR system. The upper intake manifold is designed to work with the EGR system, and also has restricting intake air passages. The heads have a smaller pre-combustion chamber where the fuel is injected and ignited. The PCM is also setup for these differences.

 

[Tracy]

Anouther way to type the engines
1) Mechanical/Non computer 1992/93 years
2) OBDI computer controlled 1994/95
3) OBDII even more computer controls 1996 to 00

At least thats the way in North America in Australia not certain Mate.

 

[bkhosken]

F or S engine

Where do you see the "F" or "S"? The VIN? What position?

 

[Goldsburg]

Where do you see the "F" or "S"? The VIN? What position?

8th digit of the VIN is the engine code...

 

[Turbine Doc]

Dave you are correct but there are also some F engines that still have EGR, those would be on trucks sold in markest with tougher emissions standards. California for one had many EGR'd F trucks, also I think Canada had a few.

In addition to EGR, S engines had lower factory Hp rating and smaller pre-cup openings in the heads

 

[DavidPhillips]

Ahh,


An 'F' EGR'd engine.

So they wasn't just picking on the S engine guys after all.

Any non-EGR 'S' engines out there I wonder?

 

[Pillow]

While at lunch at Golden Corral today some of the VDOT guys rolled in with 2500 standard cab 8' bed 6.5 GMC trucks in a lovely shade of orange... But with 6 lug wheels!!!

I have never seen that one before.

 

[Tracy]

There is a light and heavy duty in the 2500 series, I think there is also a light and heavy duty in the 1500 series.

 

[Nakkas]

Thanks for the info. Lucky me, I have the 'F' engine, although it has some sought of valve from the air intake to the tappet cover...

 

[DavidPhillips]

That's the CDR valve.

It is a replacement item normally good for about 60,000 miles or so.

It keeps a slight negative pressure in the crankcase. If it is bad it will usually not flow air at all and the pressure will build up in the crankcase.