Nice scare on the freeway...now what happened?

[Asmoday]

Hello all...

I've been off the forum for a while since I've been out on flight contracts. Nonetheless I have been using my M1009 as a daily driver and after much work six months back so far so good.

I have been running surplus Jet A I have access to for fuel and have probably 10+ tank fulls through the engine. I add a mix to the Jet A for lubrication and better performance. It's a mix of Stanadyne lubricity formula, a Amsoil cetane booster and 2 stroke marine oil. The engine seems to really pur on the mix. Starts easy...always runs smooth....hot or cold.

I actually have not had the opportunity to drive the truck much on the freeway at sustained speeds for at least 6 months since I've been using it to commute to the airport and back which is only a 5 mile drive off freeways.

The other day I needed to make a longer trip which neccessitated using the freeway to save time. I got on the freeway and set my speed at around 55 to 60 mph. I drove a few minutes at that speed but due to the fast flow of traffic here in Los Angeles, I upped the speed to a little over 70 mph so that I would not get run over...LOL. Based on the rpm the engine was spinning at I thought that was probably it's limit. I was driving at this speed, just about 75 mph now for about 10 minute when all off a sudden I noticed a slight reduction of power and immediately heard a loud clack clack clack clack sound which seemed to be at the same RPM as the engine. No idiot lights though...no other vibrations. Everything else seemed normal. It was if I lost one cylinder only.

I immediately thought I had thrown a rod as it was really really loud and definitely coming from the engine compartment and all kinds of things were running though my head. I started slowing down to get off the freeway and when I reduced my speed all of a sudden the sound disappeared and the power was back to normal.

I figured what the **** and continued on to my destination and had no more occurrences or issues for the rest of the drive.

Today I had to make a similar run on the same freeway and so I figured what the heck...? Let's see if the problem repeats itself. I maintained 65 mph during the whole trip both to and from my destination without any issues. The problem did not reappear. The 1009 ran great actually even in the 90 degree plus heat.

Anyone have any ideas what in the world happened???

I was thinking possibly a injector stopped working for a bit...???

I'm dumbfounded.....

Any advice is much appreciated including recommendations on prevention as I don't think something like that could be good for the engine....!

Thanks...

 

[Keith_J]

Probably went "over-center" on the injection timing due to extended RPM. When you slowed down, the timing went back in range. Timing advance is set by fly weights and springs. What saved you was the governor reducing injected quantity due to RPM.

Install an overdrive or drop the axle ratios if you want to run with the fast boys. Remember,, these vehicles were designed for the 55 MPH national speed limit.

 

[edpdx]

What would be a step up from the stock ratio? I would not mind running another 10-15 MPH faster without sweating a catastrophe.

How had a job is it to switch gearing?

 

[McCluskey]

With all I'm reading about guys keeping their trucks at certain speeds.... am I nuts running my '09 with 3.73s holding 75-80 on the freeways?

 

[doghead]

Yes.

 

[Sharecropper]

Instead of expending the effort and costs to change axle ratios, why not simply increase tire diameter? This would be a fast easy solution to faster highway speeds which could be reversed if desired. As you can probably imagine, I am a big fan of tall tires. Just my 2 cents.

 

[jaymcb]

Shouldn't you be able to run 70 on the m1009 Blazer....if everything else is mechanically sound?

The m1009 has the 3.08 gears and a THM400, right? It's not like you're running a 1008 at that speed. At 70 with a 1009, you shouldn't be anywhere near governor speed.

 

[corelokt]

With all I'm reading about guys keeping their trucks at certain speeds.... am I nuts running my '09 with 3.73s holding 75-80 on the freeways?

Spend good money on your oil. Put in a coolant gauge. Check those hoses and belts and the radiator. Mine would do it, but, I didn't run extended lengths of time very often.

And, I had 3:08 gears in mine.

 

[corelokt]

If I were running my 08 on highways like that, I'd be looking into some sort of overdrive. Sounds like you could use a fourth gear and different axle gearing. I generally keep mine at 55 and let people pass me. I can see on true interstate highways where that might not work so well.

 

[Red_506]

My 1009 runs well at 70; it always scares me if I go over, but I have done so with no issues thus far.

 

[91W350]

You are in the 2400 rpm range at 70 mph. 80 will kick you up to 2700 rpm, way below the governed rpm. Unfortunately, unlike a lot of diesels, the 6.2 will not survive if run for extended periods at the governed rpm. You may get away with it trouble free for a long time, you may pay the price the first time. Broken cranks and crank webbing seems to be their major downfall.

 

[Sharecropper]

Hmmmm.... Have you inspected your harmonic balancer?

 

[K9Vic]

I have probably drive 1000+ miles in my M1009 on the freeway at 65-70mph with no problems. If I have to I will jump up to about 75mph, but do not stay there for long. They can handle normal highway speeds, if your M1009 is having problems at 65-70 there is something up with it.

I have taken multiple 400 mile round trips with most of all that at about 65mph and no problems. What kind of sucks now is that allot of rural Interstates in Texas are now 75mph and as high as 80mph in far west Texas. The route I normally take to Hooks is now 75mph in areas, so I have to watch my mirrors. But even when it was 70mph, people still drove 80.

 

[SCSG-G4]

Doing high RPM's in any MV is not bright. Doing it because 'other drivers' are speeding even less so. If you are going the posted speed limit, they can pass or cool their heels till they can. Maybe it's the "University of Smith and Wesson" sticker on the rear windshield, or the "I got IT at Mike's Okeechobee Guns" bumper sticker, but them speed demons tend to back off a bit once they get to reading.

 

[jumpmasterjim]

That happened to me as well. It may be your speedometer cable. When it happens again watch the speedometer needle see if it bounces and makes the noise you described.

 

[my86m1009]

I drive mine at about 65-70 with no problems, did do about 87 and scared the s*** outta me, loose steering and unbalanced wheels.....

 

[wallew]

according to the Gear Ratio Calculator

in YOUR M1009, WITH STOCK 3.08 gears, NP208 transfer case, TH400 transmission and 31x10.5x15 tires

your rpm at

55 mph is 1940

65 mph is 2293

75 mph is 2645

if you have maintained your M1009 and everything is working properly, you are NOT harming your truck at all

is driving ANY 25+ year old vehicle at that speed safe?

that's up to you

ME?

I rarely get up on the freeways unless I HAVE TO.

but I'm old and slow and I no longer have a 'need for speed'

 

[truck1]

Have you considered a Gear Vendor overdrive? I've got one in my 1028 and I also run 37" surplus radials. At 70 mph my Tiny Tach shows 2310 rpm. I never push it above 70. I try to keep it @ 65-70. They are pricey, but work great on the highway. There was a member here that had a complete GV,TH400 and 208 TC in the classifieds not long ago. Just checked and add is still there. Search parts classifieds under Gear Vendor. It was priced right.

 

[Asmoday]

Thanks all for the info...! My M1009 has a Fluidyne harmonic balancer and I have not had any other issues. Belts, radiator, water pump, oil cooler lines..etc.etc. are all new.

I'm not sure what "over center" is so I will have to be educated on that... Can someone give me a explanation of that?

The M1009 does run real smooth though. It was just a weird thing when it happened and it really had me thinking something had let go.

Like I mentioned earlier it seemed as if I only lost one cylinder and the loud clack sound the same as RPM. It was very load and definitely coming from the engine compartment.

Could I have just had one injector stick? I've heard than when they stick it can sound like rod knock.

It did run fine all day long at 65mph and smooth. What RPM is the governor designed to kick in at?

 

[DDT]

I have a fresh rebuild on my 1009 with the banks sidewinder, 3" to 3.5" side exhaust stack, 3" round cold air filter, turned up IP pump, slightly advance timing on the pump as well. I also run the LA jungle path and usually run at 70-74.9 mph I have been getting 19.6 mpg as well