Can someone explain the difference between the 95 F and S 6.5 Engines


Thanks,
Dan

'95 OBD-I PCM takes input from EGR sensor, has outputs for EGR Solenoids on "S" - 1500 and some 2500.
"F" is some 2500, all 3500 engines - no EGR

'96 OBD-II PCM takes input from MAF sensor and EGR sensor and has outputs for EGR solenoids on "S" engines - 1500 and some 2500 series.
"F" is some 2500, all 3500 engines - no MAF or EGR

Engine mechanicals are identical. but for EGR intake manifolds.

...MAF sensors are only on 98+ light duty trucks aren't they? 94-97 you can easily disable the EGR without the computer knowing.

I have never seen a 3/4 ton truck with an EGR either.

May depend on which state the vehicle is sold in - 2500's with factory towing package got "F", for sure.

Feel free to correct, as necessary - my memory has other more specific things in the registers, iirc ;)

For sure - "S" is EGR, "F" not........

I'd recommend the "F" engine, or conversion to it. The EGR isn't such a bad thing but it clogs the inside on the intake with diesel soot and oil from the CDRV. After 10 years it's a mess. To work right the intake should have a soot trap that keeps this from happening. The Pcm can be upgraded to the "F" engine as well.

The EGR input to the PCM is very dependent on proper vacuum pump function.

"F" is for fast
"S" is for soot

Appears to be.....yep

Not sure when MAF was introduced, you can disable EGR, but swap to L65 PCM required to eliminate it, you will set a code even with a reflashed L56 PCM. EGR can be bypassed without setting code so long as vac to EGR & EGR vent and Baro sensor is still working. Just plugging ball to EGR valve may not work depending on vintage of your truck, OBD II looks for a delta of supplied vac vs vent, plugging EGR valve does not permit the change and may set the code. Shim plate under EGR alows diphragm to move so PCM is happy with feedback it gets, you are happy as EGR does not dump into your engine, plus is quickly reversable when you get back on the hiway; as I know no-one here would tamper with their emissions equipment and hiway drive.

LHD (S) 2500 series trucks do exist, those would have the EGR on them as well, not many of those built I believe limited delivery to places like Kalifornia and other tree hugger refuges.

95 S-Engine. 7200 GVW

CR what is 8th digit of your VIN F or S your sig says you are L65 is that a typo, S is L56 and F is L65.

Doh, never mind I get it now; you are driving a 2000 L65 as per your sig, and showing a pic of a 95 K2500 S.

CR you state that 7200 GVW k 2500, that would be a light duty 3/4 with 6 lug wheels I think so an "S" engine in that might in fact be correct. I don't have the numbers in front of me but GM built these truck in many different combo's.

P.S BTW Nice looking truck you got there.

Can someone explain the difference between the 95 F and S 6.5 Engines


Thanks,
Dan
In 1995,

L56
<8500GVW
180HP @ 3400rpm
360TQ @ 1700rpm

L65
>8500GVW
190HP @ 3400rpm
385TQ @ 1700rpm

Yes it is the 6 lug 7200 GVW, another very easy way to tell the LD from the HD is only the HD had the factory plastic flares on the fenders from what i've seen.

The ole 95 there is getting kinda tired, 350,000 km's now, probably sunk 8G's into R&M last year including the new head gaskets, front end parts, brakes, calipers, 1-hub, starter, batteries, blower motor, blower switch, alternators, air conditioning compressor, vac pump, stepper motor and numerous other little things.

The wife uses it as a daily driver now, its using about 3-4 ltrs of oil per change, doesn't want to start well in the cold but i just haven't had time to fiddle with it.
I'm thinking of advertising it to get rid of it. Any Canadians interested? Going cheap!

There's a 2500 light duty and a 2500 heavy duty. This is the dividing line between "S" and "F", and the easiest way to tell is the number of wheel lug nuts 5 and 6 on 1/2 ton's and light 3/4 tons equals "S" engine. 8 on heavy 3/4's and 1ton's equal's "F". *note that light duty 3/4 ton 2WD and 4WD have six lug wheels.

...Any Canadians interested? Going cheap!
Well, not quite Canadian persay, but since I am visiting atleast, how much are you asking for it?

Mine is an "S" VIN and 6 lugs but RPO says 8600 GVW. So what's that??

Mine is an "S" VIN and 6 lugs but RPO says 8600 GVW. So what's that??If yours have 6 lug and an "S" motor then it should be a LD. Where's that RPO your looking at ?
have you owned the truck sense new are buy it used?
maybe something got swapped ?

Well, not quite Canadian persay, but since I am visiting atleast, how much are you asking for it?
Well seeing your almost Canadian, how about $5000 (+ GST - Is my company truck) plus a new IP for the 00.

$5000, plus an IP $900 plus GST?

Its a '95 with a blown motor, I couldn't get 3000 for my Blazer running good right now.

Doesn't blown mean gonzo, caputz, fini.... you know, rods hanging out the bottom etc...lol. Its still driven every day and i would drive it coast to coast without a worry. Just curious here but why do you say a blown motor?

Had to start somewhere... What do you think your 94 is worth?

The ole 95 there is getting kinda tired, 350,000 km's now, its using about 3-4 ltrs of oil per change
OK, not blown, but definitely not new, 3-4 quarts is a lot considering it only holds 7!

When i first bought it @ 85,000 kms its used 2 ltrs per change, i've seen others post that use 1/2 qrt/ltr per tank of fuel. My 00 is using about 1.5 per change right now. The engine itself seems sound in the 95, but i'm not here to sell so we'll leave it at that.

Cheers!

I'm not trying to talk down your truck or anything, I'd like to have it for a toy/spare vehicle. If your serious about selling it, I'm sure we can work something out, I'm definitely interested.

I'm serious about selling it but i'm not going to give it away either, the wife enjoys driving it, all that i see that it needs at the moment is a new steering pump and a couple of glows maybe and some clean battery connections. Hell for all i know maybe the blocks cracked but i'm not going to dive into it just to see when i already have another truck. The only reason i bought the 00 to begin with was the 95 was in the shop getting head gaskets done and i needed a truck for work. I could have bought a new D'max if i'd wanted but i've had nothing but 6.5's for the last 10 years and like em.

If you want more info or pics PM me and i'll see what i can do.

I guess 5000 is about right, Kelly Blue Book says private party value is very close to that....I'm gonna have to check mine again.

"F" is for fast
"S" is for sootThat's funny but true. I met a guy who has a dealer maintained S engine 1500, 150,000 mi. nice truck but it doesn't get 19.5 mph anymore and I'm going to open the intake up and clean the soot out, then block the ports. I'll take pics.

he took it to gm to get his EGR solenoids, connectors and such redone but it never worked right. turns out the wire was broken internally just above the new buttend connector when they were installed at the dealer and the way it's plumbed if the second soleniod doesn't get power the EGR solenoid doesn't get vacuum and if the baro doesn't see vacuum you'll not make much boost.