Engine noise on morning start ups! HMMWV 6.5 GEP

[shawnshumvee]

Hello. I should know this answer but I'm going to throw the question out there anyways.
In the mornings my Rig Makes a pretty good noise and then it goes away after about 30 secs. The noise sounds like a machine gun or a maybe a fast knock then it goes away and she is fine all day until the next morning. Now on a civilian gasoline engine this noise is contributed to a lack of lubrication. The way i understand it is, when an engine would set for a while all the oil would drain back down into the pan (thus no oil at the top of the engine at the moment). so when you hear the noise and then it quickly goes away its because the oil pump has done its job and delivered precious oil to the top of the engine. I believe this is the issue but not to sure? So was just wondering if this is a Diesel thing? I don't think it is a diesel thing because when its all said and done, the gasoline engine and a diesel engine are both 4 stroke internal combustion engines. Any info will help? Noises are not GOOD and if left uncorrected they will take there toll on my engine.

 

[NormB]

It's a diesel thing. Preignition/irregular air-fuel mix or something.

Doesn't scare me anymore and I drive with ear plugs/muffs/headset after warm up.

 

[shawnshumvee]

Really? It sure sounds like its hammering until the oil gauge gets up there? Oh well.Thanks fro the reply.

 

[Scar59]

Yep, a diesel thing. Cold diesels sound like heck until the cylinder head temp comes up.

 

[shawnshumvee]

Thanks for the info. It sure does sound like heck! But this goes away in about 30 Secs, as soon as the oil gauge comes up to 60psi.

 

[98G]

Thanks for the info. It sure does sound like heck! But this goes away in about 30 Secs, as soon as the oil gauge comes up to 60psi.

I suspect you're right and that it's an oil thing.

I can certainly hear it on everything diesel that I drive : M35A2, M939series trucks, the hmmwv, and even my pickup truck. It clearly correlates with the needle on the oil pressure guage.

In the Ford trucks (buddies', not mine, ewwww ford yuck) you have to crank them long enough for the computer to see oil pressure before it'll enable fueling.

No action required, other than not revving it up or loading it until oil is circulating.

 

[NormB]

The MEP 802 generator starting instructions say to hit start and keep cranking until oil pressure rises (or hits somenumber I can’t recall, but once it starts it comes up FAST, like a second).

 

[Augi]

Are you sure it's not the cold timing advance? That lasts about 30 seconds if you fire the truck up and immediately pull out into the road.

Longer if you just idle it after cranking.

 

[SublimeMudTime]

I'm half thinking it's the cold start advance also. I'm going to have to see if I could wire up a multimeter to the solenoid and watch for power on it. See if my morning hammering goes away with that... Looks like it's time to dig into the TMs.

 

[shawnshumvee]

Yeah i just start it and wait i don't drive my rig until its warmed up and about 30 secs ( Give or take) It sounds like a normal diesel. The oil gauge comes up right away and it seems to clam down but don't know if thats just a coincidence? I'm from the old school and so i thought if the noise is due to a lack of lubrication because of no oil at the top of the engine right away, what can one do about that? Preventing dry start up's? I do you Lucas with my oil and they claim it sticks to the upper engine parts (cam, lifters, push rods, rockers, etc) forming a then layer of protection? You know, the same claims that Castrol and Valvoline made a few decades ago.

 

[Augi]

Well the easy way to find out is to disconnect the timing advance wire from the top of the injection pump and see if the sound changes.

Augi

 

[shawnshumvee]

Yeah, i will try that.

Well the easy way to find out is to disconnect the timing advance wire from the top of the injection pump and see if the sound changes.

Augi

 

[shawnshumvee]

I'm half thinking it's the cold start advance also. I'm going to have to see if I could wire up a multimeter to the solenoid and watch for power on it. See if my morning hammering goes away with that... Looks like it's time to dig into the TMs.

hey was just wondering if you came to an conclusion on the hamming during cold morning start up? I haven't yet.

 

[BLK HMMWV]

It's the nature of the beast.
Mine does same thing.
Sounds awful on first start up when cold.
Goes away after 30 seconds or so.

From what I remember the old 6.2 didn't make as much noise as the new 6.5 .

 

[shawnshumvee]

It's the nature of the beast.
Mine does same thing.
Sounds awful on first start up when cold.
Goes away after 30 seconds or so.



From what I remember the old 6.2 didn't make as much noise as the new 6.5 .

Awful is correct! yeah I have a 6.5 GEP Optimizer and she is loud!. It sounds like the top of the engine isn't getting any oil. I decided to do some testing of the Cold Advance solenoid (CAS) I unhooked 569a and 569b and placed them together and turned the Humvee to on/run position and then listed for a clicking sound. Sure enough there was a clicking sound. Then I tested the solenoid by use of my ohm meter just to test for continuity and there was. so its not the solenoid. But just to make sure i started the Humvee with the solenoid unhooked and the noise seemed to be a bit quieter than normal, so while the truck was running i then plunged the solenoid back in while it was still running and the noise got real loud (like normal level). So that pretty much tells me that its defiantly working. So at the end of the day I guess it's diesel thing?

 

[riderdan]

I think you're right: it's a diesel thing. I also think it has something to do with engine temps. I have a block heater in mine and when I start it on a cold morning after the heater's run for about an hour I don't get any of the usual racket. But on mornings--even warm ones--when I haven't run the heater, it's noisy for the first little bit.

 

[donquijote]

My 6.5s do the same thing. Although I switched a year ago to Schaeffer's oil and have less racket on cold starts over rotella and delo I've found. My 6.2 & 6.5 both seem to run a bit smoother.

 

[shawnshumvee]

Yeah i also use rotella oil so i will switch brands just in case and just for a little more security i will pour in some lucas also. But speaking of 6.5 GEP's. In my local CL a guy is selling is Humvee and he states in his ad that his engine displacement is a 6.5 GEP and he even state the engine is stamped with the year it was installed. so i texted him and ask him exactly were is this date at and he told me where to look and here's what i have on my block.



Any help in deciphering these number would be a great help. The pictures really don't show the complete number, so the number is 12555506. the number on the bell-housing is 3406

 

[donquijote]

http://www.steelsoldiers.com/h...ine-id.html?highlight=12555506

This thread should help you determine.

Fyi on Lucas additive... i ran it in mine as well and did not notice any smoother start than schaeffer's 7000. I ran one 6.5 using rotella w/lucas, one using delo w/ lucas and one on just Schaeffer's for 4 months.

From my observations Schaeffer's had a smoother start all around and does have a moly additive which may help. The 6.5 with Schaeffer's ate a little bit of oil in the beginning but leveled off after a couple changes. I did plan to get the oil analyzed in each 6.5, but never got around to it.

Sent from my SM-N950U using Tapatalk

 

[86humv]

Yeah i also use rotella oil so i will switch brands just in case and just for a little more security i will pour in some lucas also. But speaking of 6.5 GEP's. In my local CL a guy is selling is Humvee and he states in his ad that his engine displacement is a 6.5 GEP and he even state the engine is stamped with the year it was installed. so i texted him and ask him exactly were is this date at and he told me where to look and here's what i have on my block.

View attachment 721968View attachment 721972View attachment 721971View attachment 721969View attachment 721970

Any help in deciphering these number would be a great help. The pictures really don't show the complete number, so the number is 12555506. the number on the bell-housing is 3406

That is the wrong number....the one you need is on the right side
The GEP has a date code example : 06 10 J, ....june 10 2002