Re: 3616 Exhaust back fire reasons.

Hi Al Hunt,

Thats for your replay.May i know what information more required to you get me a better explanation of this type of failure? We have faced 4times failure in different 3 engines.Following is the incident summary


Equipment Tag: LP-2

Equipment Details: Caterpillar gas engine & Ariel Compressor

Equipment Running Hrs: - 56146



Equipment Tag: LP-2

Equipment Details: Caterpillar gas engine & Ariel Compressor

Equipment Running Hrs: - 56146

Date :-18-09-2018 Summary:-

Unit tripped due to compressor main bearing -5 temperature transmitter device fault shutdown. Operator checked the device cable tightness and tried to restart the unit, during restart time engine exhaust have back fire explosion and tripped the unit.

Issues and Resolution: -

On 18th sept 23.00Hrs unit tripped on compressor main bearing-5 temperature transmitter device fault shutdown, after checked the transmitter cable tightness, operator tried to restart the unit, gave the start command from the compressor panel, engine start sequence started pre lube, purge time starting motor engaged and engine picked up speed around 750RPM, at that time an exhaust explosion happened. two fire detectors(LP-1&2) detected the fire and tripped the whole plant. Due to this explosion left& right turbo outlet bellows damaged, exhaust stack 30’’ two bellows damaged &crack on exhaust pipe line.

This is the 3rd time exhaust back fire happened in the same unit. first time occurred in (RH-36768), Second time (RH-40555).

The first time happened on just after completed the annual PM of engine (36718). During that time, we replaced the all check valve, all spark plugs clean & re-adjusted the gap, Ignition systems cleaned, cylinder pressure checked, valve lash& gas admission valve setting carried out& valve height recorded. All values found normal, nothing found abnormal

For the corrective action of this issue we replaced exhaust bypass valve &linkages, fuel valve actuator & linkages, all combustion sensor with new.

The second time happened at the time of restart after (RH-40555)1250 hrs PM. Same scenario engine started after the purge cycle &speed reached around 750-800RPM, sudden explosion from exhaust and damaged all exhaust line bellows.





Trusted Contributor
Trusted Contributor

Re: 3616 Exhaust back fire reasons.

I think that there is insufficient information to fully answer your question, but will makes some comments.

First, Cat recommends an exhaust pressure relief to protect the exhaust system from the events you are describing of an exhaust explosion.  I think that the exhaust explosion probably is a result of the engine not being adjusted and tuned properly, resulting in excess fuel in the exhaust piping.  Further, this condition is properly made worse by the possible load on the engine from the compressor condition (bypass or recycle not fully unloading the compressor and/or compressor not fully blown down).  Cat recommends that the compressor starting load be limited to approximately 25%, yet many compressor configurations cause starting loads up to 50-60%, which makes for events like you have experienced, especially if the engine is not tuned to optimum.

It is difficult to make further comments based on the limited information you have furnished.


Best Regards,

Al Hunt

Accepted Solution

3616 Exhaust back fire reasons.

i am working in a gas compression plant,recently we are facing the engine back fire issue in startup
because of that exhaust lines damaged twice.
The engine we have here is CAT-3616 series,(Almost run-55,000 ) coupled with Ariel-JGC6
engine RPM is maximum 1000,but we reduced to 960 due to vibration issue.

i will give a brief how this is happening.
when you give a start command to the engine,ECM will initiate starting sequence,starting motor will engage & completed its cycle,(Purge,ignition,)then disengage.
during this time engine back fired twice,even though it was in startup sequence.

one of our service tech given advice,that you should keep open compressor PID controlled recycle valve bypass as well to reduced the engine load in startup.
i bit of confused that,how come the bypass opening will help,because recycle valve is already opened until unit will come on line.
any suggestion?