Cummins QSX15 Genset

Heat.

Where is it glowing? At the head? In a pipe bend? All the time? At night?

It may or may not be normal.

This happens usually at fully loaded conditions with turbochargers....at medium and lower load conditions you may have a problem... it would be prudent to check the timing after checking the performance(output) for abnormalities and also the timing of fuel injection and efficiency of turbocharging.

Our big 2500 HP fracc pump engines will do that to the exhaust manifold and turbos whenever there is a bad air leak on the intake side from a bad seal or blown intake coupler bleeding off too much of the turbochargers boost before it gets to the engine.

Check coolant and engine coolant pump.

The hot exhaust gasses from the engine. It is not an unusual things on high powered gas engines or diesels under heavy load. The old Chevy 409's. the most powerful stock gasoline engine at it's time, would regularly do it under a load. At that time drag racing cars without hoods would show it clearly while the cars were doing their "prep" immediately before their run.

To see a clear picture of where this heat comes from look (pictures or YouTube) at a gasoline fueled drag racer that has a tuned exhaust and exterior individual straight exhaust pipes at the sides (1 pipe/cylinder). Starts out as slightly yellow flames and changes to long deep blue with yellow ends similar to an oxy-acetylene brazing/welding torch. That is the heat source that turns the manifold a glowing red.

Take a high temperature range infrared thermometer and see what the actual temp is. Very, very hot!

Good Luck, Old Salt

This is not at all unusual, but if this is a new thing on this engine I will add one more item to check. If this is the only engine running on this fuel and you have no other to compare with then you must also check the fuel. I have over the years had quite a few problems with the wrong item delivered from oil companies. Things like mineral spirits instead of 10C transformer oil to mixtures of gas and diesel instead of the intended. In Albuquerque NM USA a couple years back, that was delivered to gas stations in that area extensively, and both gas and diesel tanks were affected. Quite a few engines were damaged. I am not sure the lawsuits are settled. A little gasoline mixed with the diesel will cause overheating of the head and of course the exhaust. You should check the smell and specific gravity of the fuel. If you have more than one generator on the same fuel and the others are OK you should ignore my comment.

I will guarantee that a small amount of contamination by other fuel will not be easily detected in a diesel engine. Water, yes, easily detected, but not something that will burn.

Dear Mr. diegovaz,

1. Excessive Fuel Pumping.

2. Very High Load.

3. Poor Performance of Turbo-Charger resulting in less air suction, by way of leakage etc.

4. Continuing After-Burn

DHAYANANDHAN.S

# 3 i could not agree, less air suction would result to inefficient combustion, not as hot as you think and would not end up with red hot turbo charge.

Red hot turbo charge only means flue gas that exits the manifold is still burning or in the process of combustion--it is achieved if and only if extra oxygen is still available for Carbon Monoxide and some minimal amount of Sulfur to burn.

This is a coolant problem.

Theoretically combustion is ideal at lower pressure and temperature.

High temperature combustion cylinders other than recommended ideal will not burn all fuel by power stroke. Results to after burn like this.

I had this problem on our 1000kVa cummins genset lately after it was operating for more than 500 hours.

The following was noted to have contributed to the high heat:

1. slack fan belt

2. a slight leak on the manifold

3. clogged up radiator fins

4. sludge in the cooling system

5. slow acting thermostat (open and closing)

The gen set is now operating at 85 degrees celcius and a load of 850Amps.

Hope this helps.

Thank you guys, i realy appreciate your participation, to give you much specific details regarding on this problem, here it is.: The reported problem was, the engine emmitted excessive black smoke, as i came, i have noticed that the exhaust manifold number 2,3, and 5 are glowing redhot, using the manual for this engine as reference, i've conduct evaluation, but due to the absence of Diagnostic Tool Kit, and to cut my assessment short, i extract all the injectors, and i put all these three injectors (2,3 and 5) on the rear bank (4,5,6 cylinder). I thought i've got the problem, these three injectors (2,3,5) were due for replacement. because after these, i conducted load test, and expectedly, all these faulty injectors which i'd put on cylinder 4,5 and 6 makes the exhaust manifold glow red hot, and the rest cylinder are normal. Here's the problem, after replacing these three injectors, still 4, and 5 glows but not on #6. Turbocharger already replaced, also i run the engine without air cleaner and exhaust muffler. Is it right to put the blame on the injectors? or do i have a problem on ECM? (injectors are from Cummins, Turbocharger is genuine, "brand new".)

The injectors were bad, probably from particle contamination, and are staying in a partial open, closed state. The proper or ordinary procedure is to have the injectors tested and rebuilt and replaced if necessary. New injectors should always be tested before install. It is quite normal to get bad injectors as new items, since many injectors are from China these days. My son, until he retired was involved in QC for some much larger generators and they had a very high rejection rate of new injectors failing. I would remove all injectors, have them all tested, including the original ones, rebuilt if possible. The test procedure is cheap and so is the rebuilding procedure. The damage to your engine can give you much more expensive repairs. Paticularly vulnerable on your engines are the heads and damage to them. Injectors are cheap in comparison. Do not expect to get proper results from simply installing new replacements. On the 66% failed items, the manufacturer should provide replacements, but again I would always test before installing them.