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How do you all get 6.2s to 300K miles

N

nycxjeremyy

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I hear often about 6.2 Detroits going to 300K miles and more, but can they really do that? My 1990 K5 Blazer with a swapped in 1985 6.2 Detroit Diesel w/h the ATS Turbo Kit which is at 85K miles (the vehicle itself has 279K miles) ... Already have quite a few in it with the following:

- Fluidampr swap from harmonic balancer
- 4 row Aluminum Radiator
- 4L60E Transmission (plus a Hayden external cooler)
- Spin on filter + water separator
- Radio + sound system
- Transmission temp guage
- That and other miscellaneous stuff such as new seals, bushings, window motors, hoses, mechanical stuff, new grill, etc.


The engine and transmission are fine (except for the engine leaking oil part), but this is all just normal wear and tear for a 40 year old vehicle, I just use it for regular plain old driving, no towing or anything.

I live on my installation, where damn near all my daily trips are within a 2-4 mile radius, so as of now, I change my oil every 3K miles. I use the Rotella T4 varient as (as stated prior) I leak quite a bit. Though if any other options are better, please do tell.

But for those who own similar applications, what do you all do to keep these vehicles going?

(Photos of said vehicle, including paperwork from previous owner:

https://photos.app.goo.gl/ksTMNAVU6ra73RpK9 )
 
Listen to Your injectors.
Yeah, use a long screwdrive, poke the pointy end on the injectors and place tje other end, the handle, firmly against your ear and listen to them.
See if they all sound the same, or close to that.
If You have an injector that does not sound like it pops then might want to pull that injector and test it.
A stethoscope might work good too if You have one of those:
 
Engine temp #1 killer agreed. Never over 220, running 180 is best.

If you loose an oil cooler hose thats instant engine death. I believe in high pressure hydraulic hoses like a backhoe uses.

Harmonic balancer is critical- depending how unbalanced yours is to begin with is big.
Unfortunately a rebuild is required to make it the best.


As to the low power- there is a few thing that can cause it.
Lost boost/ airflow.
Loss of fuel pressure at the ip.
Air intrusion to the ip.
At the top of the list because of black smoke is the loss of air/boost.

After that
This takes you to the pinnacle of why I suggest always have clear line on the ip return, and fuel pressure gauge tapped in metal T at the ip inlet.
If you have proper pressure at the ip- thats 1 section eliminated.
Next is throw an old phone or go-pro under the hood to record the clear line when problem occurs and watch for bubbles.
Then look for signs of fuel leaking through out the return lines to the tank. If all thats good fuel system is eliminated.
 
Will L. said:
Engine temp #1 killer agreed. Never over 220, running 180 is best.

If you loose an oil cooler hose thats instant engine death. I believe in high pressure hydraulic hoses like a backhoe uses.

Harmonic balancer is critical- depending how unbalanced yours is to begin with is big.
Unfortunately a rebuild is required to make it the best.


As to the low power- there is a few thing that can cause it.
Lost boost/ airflow.
Loss of fuel pressure at the ip.
Air intrusion to the ip.
At the top of the list because of black smoke is the loss of air/boost.

After that
This takes you to the pinnacle of why I suggest always have clear line on the ip return, and fuel pressure gauge tapped in metal T at the ip inlet.
If you have proper pressure at the ip- thats 1 section eliminated.
Next is throw an old phone or go-pro under the hood to record the clear line when problem occurs and watch for bubbles.
Then look for signs of fuel leaking through out the return lines to the tank. If all thats good fuel system is eliminated.
Click to expand...
1. Agreed. Hence why i got an aluminum radiator, it doesn't run past 190 most if at all, it creeps up to 200 when going on a steep incline, but it doesn't go past that.

2. Not sure what hoses i have, they seem okay, ill take photos of it when i can and upload them here.

3. Yup, I swapped out the harmonic balancer for a fluidampr, a night and day difference indeed.

4. Had an air intrusion issue, however, replacing the lift pump has eliminated that, i even ran a clear line and the air bubbles are gone, it runs perfectly on a flat surface, but once the incline gets steep enough, it starts to raise eyebrows
 
ak diesel driver said:
My 96 went to 305k before the crank broke. It had massive blowby, I'm assuming from getting too hot. Never did anything with the dampner, My 99 is at 285k and blowby is still OK, noticing lower oil pressure though. IMO getting hot is the main culprit with these engines
Click to expand...
Thankfully I dont have blowby on mine, or at least enough to where it becomes an issue, ive lut the oil cap on top of it, stays flat
 
nycxjeremyy said:
Not 5w40? I currently use T4 btw, heard about others, but I leak alot, so I don't know
Click to expand...
When I had the 1989 C2500 and switched to Amsoil, I called their tech number and 5w30 heavy duty diesrl engine oil is what they recommended..

I put 300,000 miles on the first engine and 500,000 miles on the long block, 6.5 GM crate engine we replaced it with.

We got 300,000 plus on all of our 6.5s. I never saw a reason to do anything different.

Injectors about every 100,000 miles. Timing chains sometime after 200,000 miles.

In .my experience, engines run on full synthetic had better compression and oil pressure in their later miles than engines run on.dino.

My racing buddies sold me on synthetic years ago after noting lower temperatures & longer engine life after switching to full synthetic.

I did run.some 5w40 Mobile in everything when they had the sale at Autozone that was just too good to pass up.
There's a couple of posts about that sale on this forum
 
Last edited:
Oil weight has a lot to do with your climate. 5-40 is more common in colder areas where 15-40 in hotter climate. use good oil not the cheapest on the shelf will also help.

keep the boost down under 12psi and as close to 0 as possible when cruising will keep your engine happier.

as for no power under load. look out your mirror and see if you are bellowing black smoke aka.. rolling coal. if so, you need more air. get you a boost gauge installed and watch it.

these engines are not power houses like the cummins, so don't expect to blow the tires off or pull a trailer house. my analogy on these is this.

the 6.2l is about the same as a 350 gasser but less horse power and more low end torque. the 6.5 and almost par with a 454 with the same less HP's and more low end torque. both with better fuel mileage too. there work horses that will pull slow and steady all day long and never give up so long as you take care of them.
 
jrsavoie said:
When I had the 1989 C2500 and switched to Amsoil, I called their tech number and 5w30 heavy duty diesrl engine oil is what they recommended..

I put 300,000 miles on the first engine and 500,000 miles on the long block, 6.5 GM crate engine we replaced it with.

We got 300,000 plus on all of our 6.5s. I never saw a reason to do anything different.

Injectors about every 100,000 miles. Timing chains sometime after 200,000 miles.

In .my experience, engines run on full synthetic had better compression and oil pressure in their later miles than engines run on.dino.

My racing buddies sold me on synthetic years ago after noting lower temperatures & longer engine life after switching to full synthetic.

I did run.some 5w40 Mobile in everything when they had the sale at Autozone that was just too good to pass up.
There's a couple of posts about that sale on this forum
Click to expand...
Id honestly use the T6 Rotella, but i leak alot and was told to use regular T4 so it wouldn't get worse (and expensive)

When I cruise the PSI stays at 3 typically, if at all slignt incline or putting my foot on the pedal it'll go to 5 PSI, but i keep an eye on the temp and oil pressure guage aswell.

I only ever rolled coal today, and even then it was slightly, and when going up steep incline (https://photos.app.goo.gl/Cxf2yAciNjtcW3MA9)

The photo attached shows the guages/layout i have, not including the transmission temp one that i have yet to install
 

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@nycxjeremyy I'm curious... you are running a 4l60E. what are you controlling it with?

keep in mind that the 4l60e is the weaker transmission. that 6.2 has the torque to blow that trans up. you might look into at a later date getting a 4l80e or having that 4l60e built up to withstand the torque. this might have something to do with your power loss.
 
nycxjeremyy said:
When I cruise the PSI stays at 3 typically, if at all slignt incline or putting my foot on the pedal it'll go to 5 PSI, but i keep an eye on the temp and oil pressure guage aswell.
Click to expand...

this is boost pressures your talking about or fuel pressure? if boost, you need more boost under load. what are you using to control the waste gate?
 
dbrannon79 said:
@nycxjeremyy I'm curious... you are running a 4l60E. what are you controlling it with?

keep in mind that the 4l60e is the weaker transmission. that 6.2 has the torque to blow that trans up. you might look into at a later date getting a 4l80e or having that 4l60e built up to withstand the torque. this might have something to do with your power loss.
Click to expand...
It's a Stage III 4L60E, it's not a stock GM one, I even run an external Hayden cooler with it to keep it cool, also, I control it with a US Shift Kit controller, the Transmission was built by Gearstar
 
dbrannon79 said:
this is boost pressures your talking about or fuel pressure? if boost, you need more boost under load. what are you using to control the waste gate?
Click to expand...
Boost pressure sir, and, honestly no idea, never touched the turbo, that was all previous owner, the link in the OG post i made shows the paperwork by the shop from the previous owner
 
dbrannon79 said:
Oil weight has a lot to do with your climate. 5-40 is more common in colder areas where 15-40 in hotter climate. use good oil not the cheapest on the shelf will also help.

keep the boost down under 12psi and as close to 0 as possible when cruising will keep your engine happier.

as for no power under load. look out your mirror and see if you are bellowing black smoke aka.. rolling coal. if so, you need more air. get you a boost gauge installed and watch it.

these engines are not power houses like the cummins, so don't expect to blow the tires off or pull a trailer house. my analogy on these is this.

the 6.2l is about the same as a 350 gasser but less horse power and more low end torque. the 6.5 and almost par with a 454 with the same less HP's and more low end torque. both with better fuel mileage too. there work horses that will pull slow and steady all day long and never give up so long as you take care of them.
Click to expand...
It was colder where im stationed, however it has warmed up significantly since, I used to use 15w30, but now I'm back on 15w40, as for the boost comment, peep the other comment I just made
 
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