M998 6.2 litre smells bad

[wcorp87370]

My hmmwv smells very bad at idle when started or after run (I'm sure it smells when it's running too). Starts right up, no smoke, pressure 35, temp 190-215, runs smooth. Any ideas? Additives? Glow plugs, injectors?
If this is duplicate forum, sorry

 

[Westech]

Look under the truck and see if it has a cat. if it does it is a sign that it may be going bad.
option 1 is to replace it.
option 2 is to remove it.
A replacement is around $500 ish.

 

[wcorp87370]

Look under the truck and see if it has a cat. if it does it is a sign that it may be going bad.
option 1 is to replace it.
option 2 is to remove it.
A replacement is around $500 ish.

What is a cat?

 

[firefox]

There are two kinds, but I think he is refering to a catalitic converter.

 

[firefox]

cat

This is the other kind....

 

[Digger09]

I was waiting for that.

 

[wcorp87370]

Funny. I don'tthink my Humvee has catalitic converter. Smell is strong diesel smell. Makes your eyes burn

 

[Retiredwarhorses]

No cat on the early trucks...that was added mucho later on the 6.5 and turbo trucks.
That smell is normal...ur just not used to older diesel trucks.

 

[tomelroy]

I have a few m998 and one has a similar problem. It is also a little under powered compared to the others. I have read that advancing the timing may solve the problem, but that was not specific to the gm 6.2 engine.

 

[tage]

What you smell is all the NOx from high heat combustion.
I will second "not used to older diesels".
If it really bothers you, you can run a cat, DPF, SCR, and make it more clean then those dirty Volkswagen TDI's! ach

 

[tomelroy]

Mine has black soot on the end of the tail pipe and smells like someone spilled a cup of diesel fuel on startup or after a run when idiling ...It is so noticable compared to the others, i thought i had a fuel leak. Also if the wind is just right in a turn you get the super rich smell of raw diesel. It is not the same as the others...

The question: is it possible for a hmmwv to run rich? What are the symptoms and causes?

 

[patracy]

Sounds like a normal 6.2 to me. We are talking about a 40 year old diesel design. And the fact that it's a IDI system.

 

[jpg]

The question: is it possible for a hmmwv to run rich? What are the symptoms and causes?

If you had a *really* clogged air filter, I can imagine that might result in a rich condition. Or perhaps it's running the wrong IP and/or injectors? Or perhaps there's a cat stuck in the air intake?

 

[NovacaineFix]

The question: is it possible for a hmmwv to run rich? What are the symptoms and causes?[/QUOTE]


Possible if you or someone else has turned up the fuel delivery (enrichment) screws in the injection pump and/or the IP timing is off slightly, but this is assuming that it has been "tuned" up. It could be that like everyone says, you may not be used to an old style diesel running, mine smells a bit, but that keeps the riff-raff away.

The black soot is normal, if it is running really rich, it will lay down a black smoke cloud on hard acceleration or load. These trucks don't have a particulate filter like the new ones do, that is what is supposed to collect the soot.

Drive it and see what the average of your mileage is, if everything is good, you should be getting at least 16mpg, I get about 18-20 but I do a lot of freeway driving. Running rich you will get less, since it is dumping more fuel.

You could always hang an air freshener near the tailpipe, just to be courteous, lol

 

[tage]

The question: is it possible for a hmmwv to run rich? What are the symptoms and causes?

Smoke... Large particulate matter smoke. Either grey or black. Grey worse then black in diesels.

Since you indicated that your truck does not smoke, it would be reasonable to deduct that you're just not used to a diesel without emissions equipment.... Remember these engines are not epa certified for a reason.

Think of it as your machine pollutes more then 4 times as much as new diesel.

 

[patracy]

Diesel engines are a lean burn engine by nature. Additional fueling (enriching) functions to increase RPM. There's no carburetor or butterfly valve on a diesel engine to vary RPM.

That said, unburnt diesel fuel coming out the exhaust of a diesel is more typically caused by timing issues. But as I stated earlier, 6.2's routinely exhibit the unburnt fuel smell at start up, at least until they're warmed up.

 

[Scar59]

Is this the first diesel powered vehicle for the OP? His nose may be the only thing out of calibration. The burning eyes comment tends to lndicate the engine is burning coolant. Check the coolant levels and monitor any usage of coolant.
Old diesels smell like victory in the morning....

 

[Retiredwarhorses]

Excess unburnt fuel is white
Excess burnt fuel is black

White smoke can also be coolant...but goes along with decreasing coolant level in coolant bottle as well as bubbling in the coolant bottle.
As i stated and others have stated, the early 6.2 is a bit stinky...especially since these are 30yr old motors...this is not the case on the newer 6.5 GEP motors....my GEP motor at max rpm and snap acceleration produces no visible smoke of any kind.