Can someone help clarify something for me regarding model variance?

[kcobean]

I came across this site http://www.militarytrader.com/military-vehicles-news/buyers-guide-the-hmmwv which says that the 6.5L was introduced in 1994 with the M998A2.

The truck I bought reportedly has a 6.5L but was built in 1989. Is it likely that this got a new engine if the listing is correct?

 

[NormB]

Yes, very likely/possibly. MANY of the earlier engines were changed to detuned 6.5L engines. To be certain, take a flashlight and take a picture of the RIGHT front end of the engine head, the size will be embossed there. Easiest way to tell (thanks to Retiredwarhorse).

 

[kcobean]

Yes, very likely/possibly. MANY of the earlier engines were changed to detuned 6.5L engines. To be certain, take a flashlight and take a picture of the RIGHT front end of the engine head, the size will be embossed there. Easiest way to tell (thanks to Retiredwarhorse).

View attachment 686805

Ok, what do I do with that code?

EDITED: LOL, sorry, didn't catch that what's displayed there IS the size/displacement. Thought maybe it was like a date code or something that matched up a build year which could be matched to a size. WAY overthinking it. LOL

 

[NormB]

Ok, what do I do with that code?

EDITED: LOL, sorry, didn't catch that what's displayed there IS the size/displacement. Thought maybe it was like a date code or something that matched up a build year which could be matched to a size. WAY overthinking it. LOL

I thought as much. Easy to do.

I suggested taking a look just to verify what you already knew, or thought you did. I've seen several posts from guys who've bought a 6.5L only to get it home and find a 6.2 - and vice-versa.

At some point DoD guidance was to NOT repair the 6.2s and just replace with a detuned 6.5. Later models got the turbo setups for the armor/weapons loads.

The swaps were pretty common. My '92 has a 6.2L NA and I'm okay with that. So far. Still plan on buying a spare just in case sometime down the road.

 

[kcobean]

Yes, very likely/possibly. MANY of the earlier engines were changed to detuned 6.5L engines. To be certain, take a flashlight and take a picture of the RIGHT front end of the engine head, the size will be embossed there. Easiest way to tell (thanks to Retiredwarhorse).

View attachment 686805

Ok, I have looked on the right (passenger) front end of engine head. No such markings on mine at all if I'm looking in the right place. I took a pic of the same area as the pic you posted for clarification. Do I have this wrong?

 

[NormB]

I think so. Looks like you're at the right spot.

Rocker cover-head-block-water pump-fuel point gives good orientation.

I believe your numbers are underneath the fuel line if there at all.

Go back to the tach drive and look at how it's mounted. Plenty of pictures around showing which is which, I don't recall offhand.

Like here: https://halfmastpsmag.wordpress.com...ween-the-hmmwv-6-2l-and-6-5l-detuned-engines/

Maybe someone more experienced/knowledgable will dive in here.

Norm

 

[kcobean]

I think so. Looks like you're at the right spot.

Rocker cover-head-block-water pump-fuel point gives good orientation.

I believe your numbers are underneath the fuel line if there at all.

Go back to the tach drive and look at how it's mounted. Plenty of pictures around showing which is which, I don't recall offhand.

Like here: https://halfmastpsmag.wordpress.com...ween-the-hmmwv-6-2l-and-6-5l-detuned-engines/

Maybe someone more experienced/knowledgable will dive in here.

Norm

I rechecked and the numbers are definitely not present where yours are. But that link you posted is a perfect reference. My mounting bolt for the tach drive is on the right side and the turbo mount castings are present, so it looks like I do indeed have a 6.5.

 

[jeffy777]

Yours was lot 913083? That is a GEP Engine(I have been told that it the good engine) so it is a 6.5. My only concern after looking at that unit was the Oil pressure seemed a little high to me on the video and you will probably need to replace some hoses. I worry about spray paint on moving parts, I do not have enough view point to say how good or bad PlanB might have done on your rig. You may have other issues but the vehicle looks pretty good. It looks great!!!!

You can think of your oil pressure like blood pressure too high and things go bad and too low things go bad. Sometimes the things done before the video make the readings off and sometimes the gauges are off. Do not panic, it was not crazy high.

Jeff

 

[kcobean]

Yours was lot 913083? That is a GEP Engine(I have been told that it the good engine) so it is a 6.5. My only concern after looking at that unit was the Oil pressure seemed a little high to me on the video and you will probably need to replace some hoses. I worry about spray paint on moving parts, I do not have enough view point to say how good or bad PlanB might have done on your rig. You may have other issues but the vehicle looks pretty good. It looks great!!!!

You can think of your oil pressure like blood pressure too high and things go bad and too low things go bad. Sometimes the things done before the video make the readings off and sometimes the gauges are off. Do not panic, it was not crazy high.

Jeff

The gauge or the sender is bad. It reads 30+ PSI without the engine running and 60-80 PSI at idle even warm. I plan to replace it with a direct pressure gauge.

 

[Lionel]

6.5 numbers are in the back on the block just behind the right head. GEP number format is; 06 13 N, while older GM is formatted as; B017 (for example.)