Intermittent blue smoke and low power at highway speed

[mgray]

Bought this 1996 k2500 vin f truck in 2008 and it always puffed a little blue smoke at startup (slight stumble sometimes), but always smelled like fuel not oil. Longer the truck sat, the bigger the puff of smoke at startup and longer rough idle. Truck has sat more this year, only driven every month or so to warm up and move for 10-15mins. Truck started leaking what I think is diesel from front passenger side engine when parked during this summer (after driving), but has seemed to not drip as much lately as it’s gotten cooler. Injectors were replaced 5 or more years ago, and that never got rid of the startup puff of blue smoke. There would be a little smoke from around passenger side front head/injector area where it seems to be leaking fuel, after a drive when it got hot

Anyway the blue smoke at startup has gotten worse since it’s been sitting more this year, and now there’s a drivability issue at highway speeds, where I lose a decent amount of power and have thicker blue smoke (never had blue smoke while driving). But it’s seems to be a bit intermittent on how much power I’m losing and how much smoke there is. It’s not constant. It’s not really noticeable at all during slower non highway speed. Seems to idle fine.

Parked it after this highway drive and noticed oil leaking a couple drops to ground, but not much. Seems to be coming from around front oil seal, everything is oily up front. Engine has always been wet and oily at the front, but no drips, or very little. Seems this is new and tied to the recent drivability issue.

The engine just smells like it’s covered in diesel, especially after shutting down from a drive. So I'm hoping this is a stuck injector or some fuel issue, but something tells me it’s catastrophic internal damage and blow by is pressurizing the crank. The dipstick was fully seated though.

Any thoughts or ideas?

Thanks

 

[ak diesel driver]

I'd be checking the fuel supply and return lines

 

[MrMarty51]

I believe that leaking return hoses and pipes will cause a loss of power.
Also, pull those injectors and have them tested, unless You have the equipment to do so.
I’ll never again install new, or remanufactured, injectors without having them tested and balanced, ever again.

 

[WarWagon]

Pull the oil fill cap. Start engine. If it huffing or just steady blowby?

Fix the fuel leaks. Again WITH FEELING Fix The Fuel Leaks! It's the #1 troubleshooting step in the GM service manuals for a reason. Fuel leaks allow air into the fuel system. Air will compress where fuel will not compress. Air causes all kinds of problems. It's also likely the lift pump has failed and/or the OPS that powers it has also failed. Test it.

Note: The exhaust manifold can vaporize diesel that drips on it from say leaking return lines.

 

[Will L.]

Blue smoke is traditionally oil burning, not fuel. Verify that you are not sucking gobs of engine oil in through your turbo into your intake manifold and burning a bunch of oil every morning and while you drive. a runaway diesel can only be stopped by cutting off all of the air supply, because the oil becomes all the fuel it needs to become a V8 grenade. YouTube search diesel runaway if you are not familiar.

I almost never advocate installing parts without full diagnostics first.
A couple exceptions- brake fluid leaks, fuel leaks, oil leaks that are over hot exhaust parts.
The leak is already diagnosed enough. FIX IT NOW.

The truck has fuel lines that are 30 years old. We don’t even have same type of diesel anymore, now it all has ethanol in it which the original hose is not rated for & doesn’t withstand. You need SAE30R9 or higher. Take & post pics of fuel line on the engine and lift pump as many owners (intelligently) upgrade the lift pump, fuel filtering system, and enlarge the hose diameter supplying to the engine.

If stock have 3/8” hose from the tank all the way to the FFM (fuel filter manager), 5/16” from FFM to the IP. You have 1/4” returning from the ip (injection pump), which should be replaced with clear tubing (about 6” piece) from fuel-line.com for diagnostic purposes now and in the future, it is rated for the ethanol but not friction. there’s nothing that will cause friction on this line in this location so it is fine. You have 1/8” line that goes between all the injectors on the return side. You have 5/16” line returning all the way to the tank after the injectors and the IP returns together.
The best and safest answer is to bite the bullet and replace it all now. Then this problem is eliminated for the next 20 years.

If you don’t want to do it this way look for and repair the section that is leaking fuel out on the ground, and still buy an install the 1/4” clear line coming off the injection pump. With the engine, idling you watch this clear line for any contamination in the fuel or any bubbles traveling through the line, both are indications of problems.

Ideally upgrading the LP (lift pump) at the same time is a smart move, FASS is my best recommendation currently. Buy once cry once.

Also installing a metal T at the injection pump inlet post rubber hoses for a fuel pressure sensor. Mount the gauge where you can read it while driving permanently. 8–14 psi is the ideal operating range for a DS4 ip. Low fuel pressure will shorten the life of the IP, sometimes drastically. Proper fuel pressure will improve both power supply and MPG via improved efficiency.

And now that you think I’m done spending all your millions of dollars, we will talk about the injectors. In the fleets, we learned it is best to rebuild or replace them every 100,000 miles. USE CAUTION WHERE YOU BUY PARTS, MANY KNOCK OFFS AND GARBAGE IS SOLD IN MULTIPLE PLACES. My suggestion goes one step further and having the brand new injectors sent to a reputable rebuilding company and have them all adjusted to within 25 psi pop pressure of each other.
This makes for a far more balanced running engine, which improves efficiency (Aka, both power and MPG improvements).

A fuel leak will burn the truck to the ground.
Leaking, dripping, squirting (rather than misting) injectors, not only hurt power and performance, but will actually burn your pistons like a piece of plastic on the campfire.

These engines are very economical to run long-term, providing the initial investment is made properly. Otherwise, they will eat you out of house and home.
Decide if you were going to invest in it or sell it.

There are other things of concern to look at very very soon, usually recommended before the fuel system upgrade/maintenance.

Check for any signs of leaking or seepage of oil from the two oil cooler hoses.
Immediately replace them with any signs. These houses fail instantly and take out the engine faster than you can turn the key off. Some people choose to replace with factory new hoses and factory new quick disconnect ends. Some people choose aftermarket hoses, which are slightly better and adapters to go to the factory oil cooler. My recommendation is to do what the US military mandated for all of the Hmmvs being built using the same engine: use high-pressure hydraulic hoses with JIC fittings at both ends eliminating the pennypinching components the GM used.

100,000 miles intervals also replace the harmonic balancer and the belt pulley with brand new AC Delco units. The cheaper versions tend to fail around 30,000 miles.
You can choose to invest more money in better parts that will last permanently.
The fluid dampr harmonic balancer, and Leroy diesel’s billet belt pulley.
These components are to be changed in pairs as a new one will be damaged by the old unit attached to it. One or both of these having a complete failure will crack the block and or break the crankshaft. In the fleets we learned replacing these every 100,000 miles (the improved components were not available back then) completely eliminated what was known as the weakest lower and Diesel design problem. if you like the truck and plan to replace the engine when it wears out the investment of the more expensive aftermarket parts can be justified. The fluid dampr actually performs better and will create a smoother running engine that theoretically should last a little longer.

There are other things to deal with for improved longevity like cooling system but you can control that with your foot for now.
200 F is OK all day long
210 F watch the temperature gauge more than you watch the road
220F pull over immediately and let the engine idle back down to normal temperature.

In the fleet, we learned running the trucks at 180F cost approximately 0.1 MPG, but power was improved, as was longevity of the engine and transmission.

If you are on the fence of keeping it or selling it, learn what it takes to correct the cooling system if the previous owners have not already done it and add that into your cost factor.

 

[MrMarty51]

/\_/\_/\ WHAT HE SAID /\_/\_/\

 

[mgray]

Wow some great information given thank you so much, especially to the effort and detail Will put in his reply. I’ll definitely start checking everything and even think of replacing all the fuel lines. Thanks again