engine overheating

[Paul Andrew Facey]

I recently purchase boat w/ twin cummins QSC 540hp’s. Boat travelled 1300 miles with no issues (Temp. Port 176 deg and Starboard 177 deg running at 2150rpm @24knots). Used it a week after arrival and boat ran flawlessly. Next trip two weeks later both engine temperatures start to rise port to 183 deg and starboard up to 190 deg. I pull back throttles and both temps come down immediately. I cleaned the intake strainer on bottom of boat and problem still persisting. Before boat left previous owner, both engines were serviced (oil change, belts, filters, impellers, bottom paint and all zincs). I inspected both heat exchangers, found some shells in both, more in starboard engine though, along with some small impeller fragments. The core of both looked clean. (temps still rose). I plan to change the starboard impeller and if that does not work, move on to either flushing the system with rydlime (previous owner has used this with success, however was done 6 months ago) or removing heat exchangers for a cleaning.

Am I on the right track. Any suggestions/guidance.

Topic

[Philip]

Any updates?

[Philip]

You didn’t mention the aftercooler pressure tested successfully. However without the core coming out to inspect, clean, and grease the o-ring sealing surfaces properly I would be concerned about just how long they will stay intact. Unless your pressure testing every few hours your sitting on a time bomb.

As for the HE’s they typically require much less maintenance as any saltwater that leaks past will be neutralized by coolant not to mention the pressures are about equal coolant and salt water side so not a lot of pressure differential to push one way or the other unlike the aftercooler.

I would service both sides equally.

Let’s see what others say…

Phil

[Paul Andrew Facey]

These are the HE core after partial cleaning. Dont have pictures of end result, howver mechanic said all the sclae was removed.

Paul

[Paul Andrew Facey]

Hi Phil,

The aftercooler was pressure tested before installation and was air tight. You say not to run engine.
Should I therefore take aftercooler off and get the core pressed out, cleaned and fitted back with alot of grease.

When you speak of the HE and cleaning the otherside, do you mean the other engine HE core.
For the HE core in question , it was removed and the entire core was cleaned.

I will attempt to send pictures again.

Paul

[Philip]

I only see one picture of old parts and a box… but let’s answeer some questions…

A clogged HE would certainly cause increased temps. If one is clogged I would suspect the entire cooling circuit of both sides to be of similar condition. I would get the other side apart and cleaned so you KNOW the condition baseline.

Regarding the aftercooler not coming apart my main concern is that you don’t mention pressure testing. Pressure testing is a MUST to verify you have a good seal and are not spraying the inside of your motor with salt water so tread lightly. The reason your cooler wouldn’t come apart is corrosion and that corrosion will cause your cooler to leak salt water into the engine while running at speed. Even if it pressure tested today that corrosion will creep in short time and cause it to leak. Yes a new cooler is expensive but so is a new engine and that’s what your up against….

When you mention oil provided in th Cummins kit I assume that’s oil used to lubricate the o-rings. I’m not familiar with the product but anything is better than dry but a good waterproof thick grease used liberally on sealing surfaces and the o-rings is best. That grease is what slows the corrosion and keeps your cooler from leaking in between servicing. I haven’t heard of a grease causing issues only heard that some greases slow the corrosion better than others.

I would NOT run the engine.

Finally the oil pressures in the high 50’s when cold are normal.

Phil

[Paul Andrew Facey]

Dear All,

I had my mechanic remove Heat Exchanger, Aftercooler, and Oil/Fuel Cooler from my Starboard engine. I attach pictures of HE and Aftercooler.

The HE was very clogged, and the photo shown is after rodding took place. all the scale on the exterior was removed.

The aftercooler caps were removed, and the core we could not remove. Could have taken to machine shop, however my mechanic made the decision to rinse the fins and interior with diesel oil, and then soap water, placed new seal on the end and used the oil on the O’Rings that was in the aftercooler 3pc kit as show in attached photo. I had contacted the previous owners mechanic and asked his advise which was that this is a very expensive part, and that we should only use the oil provided in the cummins kit. So thats what we ended up doing.

Have now fitted all back on engine, started it and let it idle for 10min. Sounds fine. Plan to sea trial this weekend to see if the cleaning of HE has sorted out the high temp.

I have a few questions. I was reading seaboard forum yesterday, where someone took a similar decision to me and didn’t pull the aftercooler apart, and you recommended that they should remove it and pull apart and service as per Toni recommendation. What do you recommend?, and should I sea trial this weekend?

Also, when I started up yesterday, I noticed that the oil pressure was at 58. The port Engine also runs at 59. However up to this point the pressure was at 46 on the starboard engine. The previous owner said that that is how it always was, from the day he owned the boat. Could the servicing of the Oil cooler have anything to do with this? or do you have any suggested explanation?

Regards

Paul

[Tony Athens]

You really want help?

Then, take those components off the engine, put them on the bench, take them all apart and take/post good pics of all so we can all “see” what there is to “see” .. That will tell all of us trying to help what to tell you how to clean all properly..

Tony

[Paul Andrew Facey]

Thanks Phil/Tony. I plan to remove heat exchanger and Aftercooler on Stb Engine.

Thanks Phil/Tony for your replies.

Have not yet replaced impellers. I plan to do this next week, and if ok, then plan is to remove the aftercooler and heat exchanger from Stb engine and clean. I read were you recommend using Simple Green on aftercooler and I plan to use an acid based descaler for the heat exchanger.

Here are some photos.

All the best

Paul

[Tony Athens]

Two things you left out ( but do listen to Phil) :

1) When you changed the impeller(s) –Any blades “missing”

2) Last time the aftercoolers were removed from the engines and serviced per my protocol on this web site? ( like Phil was basically says/asking)

Tony

[Philip]

Paul-

You need to follow water flow from the raw water pump linearly through the circuit. Most go raw water pump > fuel/oil cooler > aftercooler > heat exchanger > exhaust elbow. Inspect each one for debris and blockage. Also check any strainers, and the inside of intake hoses.

If you don’t find anything obvious you can try the impeller change followed by ridlyme flush. Ridlyme use if it works will most likely just buy you time until all has to be removed from engine and properly cleaned. Additionally ridlyme flushing will NOT service the aftercooler as needed.

The aftercooler needs to be removed from engine, core removed, core cleaned and pressure tested, reassembled with new orings and lots of grease, and the final assembly pressure tested again. The needs to be done every two to three years (unless your fresh water flushing).

Post a few pictures of your engine room from all angles….

Phil

[Author]

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