Black smoke, engine overheating...(long)

[Adam King]

My 88 C1500 has been going down hill in the last couple days. It still has the EGR intake on it and I'm getting ready to swap it out with a J intake. It also has the stock inlet system which is also on my to-do list.

I had a pinhole leak in the radiator develop a couple weeks ago, but some stop leak seems to have solved that problem. My normal operating temp has always been around 200.

Once in a while under acceleration up a long hill I would get black smoke from the tailpipe. Yesterday, I was driving my sister to work in town and the truck was smoking quite a bit more and it almost felt like the transmission (700R4) was slipping and the truck couldn't decide which gear to use. I took the freeway on the way back home to see what would happen at high speed and it performed about the same. It will hit 65 - 70 mph and hold it but it seems to struggle from time to time.

Then last night I drove it about 60 miles round trip with no trouble, some smoke but not bad. No slipping either.

Today I was headed for a 200 mile round trip at 65 mph and the check gauges light came on and I was running hot, also had alot of smoke. I added some coolant to the overflow and turned the heater on to circulate the coolant thinking maybe I had an air pocket develop from the pinhole leak. The heat and the smoke continued so I pulled of the road again and pulled off the duct from the resonator to the filter housing, letting it breathe hot air from the engine bay to see if it was an airflow problem. I noticed an improvement and it cut down on the smoke as well. Once I got back into town driving at 30ish I was back down to 200 again.

I pulled the radiator cap and let it idle with no change, the radiator was full. I havent driven any further so I don't know what it will do with the duct off running at 65mph.

I have only been driving the truck for about 6 weeks now and I have no prior maintenance records. It was used as a farm and pulling truck in a previous life because I have pulled corn stalks from the frame rails and it has a 9000lb towing bumper on the back. The truck has 202,000 miles on it.

I haven't replaced the fuel filter yet since I have had it. There is about 2200 miles, mostly highway, on a Rotella 15/40 oil change. And it had a new air filter the same time as the oil change (Fram).

So, here's my theory: The black smoke is probably a combination of the stock inlet and a mechanical problem i.e injectors, EGR sytem, pump etc. This is causing the engine to work harder and thereby raising the operating temperature. It is quite possible that my cooling system is experiencing a problem too.

Does this sound logical, or at least a good place to start? If I put the J intake on and modifly the stock inlet setup, that will get more air in and may alleviate some of the smoke. Once I know I'm getting enough air in the engine I can diagnose any remaining issues easier. I will probably change the fuel filter today too, I have been running some B2 and B10 blends that may have loosened some sludge in the tank.

Is there anything I may have missed?

-AFK

[john8662]

Probably two issues here.

Cooling, could be the thermostat sticking, and could also be from a lack of cooling capacity due to a plugged up radiator either internally or externally (fins full of debris). Get the radiator leak fixed correctly and during that time have it rodded out, the radiator shop will be able to tell you whether it's rebuildable or not.

The black smoke is likely due to the EGR system, especially on a truck of that many miles, stuff breaks. To test that theory, simply unplug the vacuum line that goes into the air cleaner housing from the solenoid itself that resides on the driver's side rear valve cover. Go for a drive and see if you get any improvement in the smoke department.

For the transmission, verify it's full of fluid...

J

[Adam King]

It looks like the EGR was the issue. I pulled the hose on the solenoid side and went for a drive on the freeway to make sure it got warm and had no problems. Then I pulled over and reconnected the hose to verify, but I had no problems then either.

The next day I got going down the highway and it started with the smoke nonstop again so I pulled over and disconnected the hose again. This took care of the problem and I left it off while I drove about a 30 mile trip on the highway. Once I got back to town I went to the parts store and bought a vacuum cap assortment and installed the one I needed. The 'Service Engine Soon' light went out and it runs fine. I can't complain about a $0.20 repair bill.

I haven't had a problem with over heating anymore either but I am planning on a new radiator and a 180* thermostat from Kennedy Diesel either way. I still need to get my J intake installed and customize my filter housing...all in good time I guess.

-AFK