//// Help with new to me 1994 GMC Top Kick ////

[Andyinchville]

Hi All,
I recently bought a 1994 GMC Top Kick with a Cat 3116 Diesel and Auto Tranny.

The truck has about 485K miles (mostly highway per owner) and seems to be in pretty good shape.

The owner lost a hauling contract and kept the truck for 3 years after the loss of the contract in the hopes of getting another gig that never materialized.

The truck was started and driven around locally (in the neighborhood) to keep the batteries charged and the fluids circulating but the fuel has, per the owner, been in the truck for the 3 years the truck was more or less inactive.

I bought he truck and it seemed to run fine locally BUT when I ran on the highway and started up hills the truck bogged a lot , ran as though it was missing and started spewing smoke....laying down a smoke screen of sorts BUT without the power normally associated with rolling coal.

Anyways, this continued on many of the larger hills on the interstate and I decided , rather than pressing harder and harder on the accelerator to try to maintain speed on the hills, I would just hold the accelerator pedal at a fixed point (where it wouldn't stumble and smoke) and see how it did up hills.

As expected the truck ran fine on the flats and smaller inclines BUT as the inclines grew and the truck lost speed (remember I was holding the accelerator at a constant level), the truck speed dropped and would commence smoking and "missing".

Also interesting to note, not all hills of roughly the same steepness cause the missing and smoking.....the truck never acted up on the flats or down hill.

The truck was driven at about 55 to 60 MPH.

I did fill the tanks up and added power service at double the normal level to help lube and clean things up....I also added Wal Mart TC3 2 stroke oil to the fuel to help lube the injection pump.

FWIW the owner told me of the truck "acting up" when pushing up hills but dismissed it as the truck being made in a time when 55 MPH was the speed limit and recommened to me to keep the speeds lower.

The tach on the truck did not work so not really able to approximate the rear end ratio by MPH VS speed.

What are your thought as to what could be causing my issues?

I do plan on changing out all fluids and filters but the truck is currently in the shop getting a state and DOT inspection....I hope it passes with minimal need for repairs / parts.

Thanks in advance for any and all help on this.

Andrew

 

[Delmer]

Black, white or grey smoke? Put a boost pressure gauge on it for testing. Does this have the plastic fuel lines? check them for cracks, or leaks at the o ring joints. Fuel gets sucked out of the tank, through the first filter, to the gear pump on the gov, then to the second filter and back to the head. The suction side, tank to gear pump, is vulnerable to sucking air without leaking visible fuel.

 

[Andyinchville]

HI,

I'm not sure of the fuel line type but I will look....

There did not seem to be any visible leaks but the block was "wet" with something on the drivers side around the middle areas (not engine oil since the yellow block would have shown the black oil easily.....I'll see if I can determine what it is by smell).

As far as smoke, I could not make out the color since I was driving at night but I could see the smoke rolling out against the headlights of the following cars.

The truck does not have a boost gauge but I could probably rustle one up.....what would this help to show? (FWIW I could hear the turbo spool so I guess I am getting boost).

When I get the truck back from the shop (state inspection / DOT inspection) I'm going to check it out more thoroughly (I had to take it in ASAP to see what else the truck needs since the contract starts this Saturday).

Thanks for your input/ help

Andrew

 

[Delmer]

The top speed could be 65 at 2600 RPM so you are at the top end at 60, it should run fine though once warmed up. Sometimes a worn engine doesn't like to run smooth cold, but that's not what you're talking about here.

The boost gauge is a rough measure of engine HP, if it's not achieving the rated boost, then it's not producing the rated HP, but you already knew that. IF it IS producing the rated boost, then it makes it more interesting. If that engine is 170 HP, if you can still read the printing on the plastic label on top of the valve cover, then the boost is probably only going to be 10-15PSI at full speed full load.

You'll have to trace your fuel line to confirm, but that side of the engine being wet sure sounds like a fuel leak. Not sure it's on the suction side, but you'll find it. It sure wouldn't hurt to check the valves, don't touch the unit injectors in there though, if you knew how to do those you wouldn't be asking here. This is mechanical unit injectors, right? I was informed here that there are electronic hydraulic whatever 3116's just like the 3216.

 

[old-iron-habit]

I did not see where you changed the fuel filter. Are you sure its getting enough fuel on a pull? Although you are seeing lots of smoke but that could be the bad fuel you are getting not burning clean.

 

[Andyinchville]

HI,
I have not had a chance to change all the fluids and filters yet but will do so ASAP.
I am hoping something simple will fix it (I ado have to see what is running out on the engine block making it "wet".
Ill keep everybody posted on the progress when I get the truck back from the shop.
Thanks
Andrew

 

[DMiller]

When you change the fuel filter, before you waste the new one dump the contents of the old one. 3 years on a tank load that has been minimally used will most likely be black. If is the fuel will have to come out, algae contamination. Have seen algaecide added and then drain the bottom of the tank but you seldom get rid of the slime stopping up filters often.

 

[Andyinchville]

HI All,

In a string of seemingly never ending problems...sigh...there is an oil leak on the passenger side of the engine somewhere that has seemingly gotten worse....

There was a small oil leak on the driver side where the oil fill is located so we took that off and resealed it so that was taken care of .

What are the more probable leak points on the passenger side (it was hard to see on that side)?

The leak is not down low (not oil pan / rear main engine seal) nor is it the valve covers...it is somewhere in between....

Thanks

Andrew

PS - The truck is fine except for the oil leak and an exhaust manifold leak (exhaust leak will be tackled after the oil leak is situated since the truck is still usable unless of course we start taking the exhaust manifold off).

 

[heymccall]

Oil cooler gaskets or oil filter head O-rings. Both very common.

 

[Junkyard]

Beyond cooler and filter head you'll have two oil lines to turbo that could leak. One sees engine oil pressure and the other is a drain back to the pan.

 

[Andyinchville]

Oil cooler gaskets or oil filter head O-rings. Both very common.

Hi

I did pull off the oil filter thinking whoever changed the oil before I did may have left accidentally one of the oil filter gaskets on but there were none stuck to the oil filter housing and only one on the oil filter itself....

I'll try looking more around that area because truthfully a lot of oil with seemingly dripping down from the oil filter area which led me to think about somebody double stacking oil filter gaskets.

Thanks for the info about the turbo oil lines Etc I'll have to check those two it is pretty congested in that area of the engine that's why I guess I'm having a hard time seeing the source of the oil leak.

Thanks for the input guys and I'll check it out again ....tired of putting in gallons of oil in relatively short periods of time.

Andrew

 

[heymccall]

http://schoolbusmechanic.blogspot.com/2009/04/cat-3116-oil-cooler-repair.html

Oil cooler...leaks oil around perimeter as gaskets age.

 

[Andyinchville]

HI ,

I hate to say it BUT you are probably right about the oil cooler area leak....I could not see it because the turbo and piping was in the way but It is around that very area I see a lot of oil (when using a mirror because of all the clutter).

I guess the whole area is more accessible when the turbo is removed which may be necessary for me to do since my exhaust manifold also is leaking (sigh!).

I guess while its all apart I can kill off the last two issues on the truck....the oil leak and the exhaust manifold leak.

Thanks for all the help guys....now anybody want to volunteer to do the actual work ? HA

Thanks

Andrew

 

[Willie B]

I just bought a fire truck 1990 GMC Top Kick with 3208 Cat V8 turbo, Allison. Mine has 31000 miles plus 600 hours pumping. My intent is to put on a dump body.

 

[DMiller]

Keep the cooling system serviced in it, keep it from overheating and good fuel in it will last a good long time. When is its time to die let it and get a crate engine as I have NEVER seen a rebuild in a independent shop perform very long where even the Cat remans maybe get 1/2 original time and miles.

 

[Willie B]

Keep the cooling system serviced in it, keep it from overheating and good fuel in it will last a good long time. When is its time to die let it and get a crate engine as I have NEVER seen a rebuild in a independent shop perform very long where even the Cat remans maybe get 1/2 original time and miles.

In my case, it'll get less than 4000 miles a year. If nothing catastrophic happens, it should last longer than I will.

 

[walkerv]

HI ,

I hate to say it BUT you are probably right about the oil cooler area leak....I could not see it because the turbo and piping was in the way but It is around that very area I see a lot of oil (when using a mirror because of all the clutter).

I guess the whole area is more accessible when the turbo is removed which may be necessary for me to do since my exhaust manifold also is leaking (sigh!).

I guess while its all apart I can kill off the last two issues on the truck....the oil leak and the exhaust manifold leak.

Thanks for all the help guys....now anybody want to volunteer to do the actual work ? HA

Thanks

Andrew

If turbo is off it makes the cooler gaskets way easier , some arrangments on some models it is neccasary to even do them