Cummins Marine Diesel Repower Specialists › Forums › General Discussion › 4LHA-STP engine overheating
Rob Schepis.
Hello – keen on some guidance please.
My 4LHA-STP (240hp) engine is overheating.
2000 hours.
Coolers / heat exchanger are all just cleaned and looking great.
New impellor fitted in sea water pump, water is flowing through the sea water circuit.
I am not losing any engine coolant on the fresh water side.
Not sure where to look next.
any guidance appreciated.
cheers
After cooler came out last night. perfectly clean as expected. no rubber bits or any other bits any where. no blockages, tubes clean like all other coolers from the Barnacle Buster circuit flush.
Thermostat tested – all ok. rechecked new impellor in seawater pump, looks ok.
not the heat exchanger
not the gear cooler
not the after cooler
not the oil cooler
Something has happened very recently that is a totally new and additional problem to the gradual increase in temperature from the coolers getting dirty (which I have fixed). Now the coolers are perfectly clean, temperature should have gone down 5 degrees C. Instead, temp went up to 87 / 88 degrees C.
Next option, take off the wet exhaust (custom dry riser and wet exhaust nozzle) to see if any build up there blocking flow. If not that, sea water pump will come off for a good look on the bench.
All very puzzling. My gut tells me the problem is not in the salt water cooling circuit.
whole salt water system gets fully serviced every few years, never had trouble.
Aftercooler is just next this time around (this week), expect it is clean though and just needs check and new O ring plus greasing.
No impeller pieces anywhere, didnāt fail – was changed our preventive maintenance every year.
Salt water since 2004.
Normally just needs full salt side clean out to get temp back down, just didnāt happen this time.
Can see daylight through heat exchanger, oil cooler and gear cooler tubes.
Gear cooler and heat exchanger photo attached to show how clean my tubes are.
Salt water pump to come out next.
Impeller pieces?? Acid “Barnicle Buster” does not dissolve them..
Your engine is how old in years & has had salt water in it for ???
Never properly dissembled the aftercooler? Seawater Pump tolerances / cam/wear plate.. They all wear…
Until you truly / properly service the entire seawater side of your engine , EVERY COMPONENT, top to bottom, you are chasing your tail.
The steady rise in temp indicates exactly as I am suggesting.
Tony
Hi Tony
The engine has as normal gone from 80 degrees C to 85 over about 3 years since last cooling system clean.
Last couple trips it was running hotter, to 87 at full noise so I just trolled to keep temp down.
Book says clean heat exchangers etc at 85 degrees C.
Reckon the issue is very recent.
I did a chemical recirculating clean using product commercially available for recirculating cleaning of the salt water side. (barnacle buster)
Did raw water pump impeller at the same time, just annual change out, came out in one piece as normal.
Took caps off heat exchanger and oil cooler to do annual gasket change.
Tubes all clear, no blockages or debris.
Only thing I havenāt opened yet is the air cooler which will need to come apart anyway to change the O Ring and regrease. But I expect that will be clear.
Hose runs freely through sea cock and out through intake.
Just pulling the thermostat now to test that.
Oil looks clean.
No oil in coolant.
No loss of coolant.
Annodes done every 3 months.
Donāt think it is the temp sender, everything felt a bit too hot.
Cheers
Mick
Complete history of operations, IE., when did this 1st occur? How was the after cooler, heat-x, and gear oil cooler cleaned?? Pieces of impeller- where are they? Tony
You must be logged in to reply to this topic.