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

[Mike Mason]

Great thread. I am dreading pulling my aftercoolers. They will be off sometime this month. Be ready for my posts!!

[Paul Andrew Facey]

Just an update. I purchased 2 new After coolers. Had both Heat Exchangers removed and cleaned.
Got in contact with a Cummins mechanic out of Ft Lauderdale and brought him down to Jamaica. He installed the 2 aftercoolers and serviced my oil and fuel coolers. Gave engines a good check through. Temps on both engines running below 177 deg. Have been using boat and now feel comfortable with the performance.

Thanks to all for the advice.

Paul

[Tony Athens]

Starting slower:

Lower battery voltage at the starter POS terminal during the cranking process?

One cranks at 215 RPM the other cranks at 250 RPM.. Which one do you think would start faster?

Tony

[Paul Andrew Facey]

Thanks Rob,

Will follow your instruction.

Any explanation for my starboard engine starting slower than usual/
This began since the HE, Aftercooler and oil/fuel exchangers were serviced.

Paul

[Rob Schepis]

Actually moving – under load, not at the dock, get it to thermostat opening temp which is 160F for your engine. Yes as to your last paragraph but do it under load.

[Paul Andrew Facey]

Thanks Rob,

I saw that and followed it, however may not have followed quite right. When you say run up to 1000-1200rpm
do you mean at dock or actually moving or does it matter. Also for how long do I run for. The thermostat should open at 160 deg (is that correct?) What I didnt do was let her cool down and then top off. Instead I tighten the pressure cap and took for a sea trial, at which time temp went up to 185deg at 2150rpm, and engine emptied the supply bottle.

I do believe that the problem now is trapped air. My question is how to go from here. Can I simply take cap off, run (at dock or under load?) to 1000-1200 and get over 160 deg, then cool and top off with coolant, then tighten cap.

Best

Paul

[Rob Schepis]

Paul – 40/60 or 50/50… in your tropical climate either is totally fine. You’re done.

As to coolant filling, here is a prior post by me on a 6BTA:

When you refill the coolant you should refill very slowly and this will help with eliminating any air trapping. Squeeze the coolant hoses to push out any trapped air. On your first run leave the expansion tank cap loose and bring her slowly up to operating temperature to open the thermostat, 1,000 to 1200 rpm’s should do it. If you watch the temp gauge you may see a quick jump of the gauge but it should stabilize. Then let her cool down and top off and this should have burped out any air and prevent any hotspots. Never hurts to do it a second time. These small hoses (spitters) going to the coolant expansion tank are vents, although the back of the tank is higher than the front, for air burping purposes keep the coolant level in the tank a good inch or so down.

[Paul Andrew Facey]

Hi Tony,
Iput two posts yesterday. Not sure if you saw the first one. Would very much like your comments on my coolant filling up and burping. please read it and advise.

Regards

Paul

[Tony Athens]

Just stay w/ 50-50……..That is not something you need to dwell on……………………..Worry about what matters

PROPER AFTERCOOLER SERVICING

Tony

[Paul Andrew Facey]

I found this on your forum, could this be my problem.

“Firstly I made up a 40mm piece with a 1/4″ socket to which I connected a pressure gauge. This I installed in-line just after the sea-water exit from the heat exchanger. This way, I was able to eliminate a possible sea water restriction in the exhaust mixer.
I then ran the boat with the radiator cap off the expansion (header) tank, slowly increasing speed, allowing the engine to heat up slowly. Once it went above 70 deg C bubbles started escaping from the coolant.
Once the thermostat opened the remaining bubbles escaped.
I then closed the radiator cap and opened the bleed nipple until a steady stream of un-aerated coolant escaped, closed up and voila – to the amazement of the technician, the problem was resolved.
I ran the boat with WOT on one engine only, and could not force the temperature to go above 83deg C after this purge !!!
Once again, Thanks everybody!”

If I try this, can I remove the pressure cap at this stage and run boat as above to hopefully release the air? and add coolant to tank if necessary? I do not have a bleed nipple on my engine, or is this the tap at the bottom?

Also I saw your comments after filling my coolant system. 50/50 EG is what I filled up with, you recommend diluting to 40/60 EG to Distilled water. Can I simply let some coolant out at the tap and add some distilled water?

regards

Paul

[Paul Andrew Facey]

Thanks Tony,

I am taking your advice on the after coolers.

This morning I drained the coolant from both engines and flushed with water and refilled. Each draining I measures the quantity and came up with 5-6gallons each time. When refilling, i filled the bottles to the required level, then the port engine took 5 gal and the starboard took close to 6 gal. What was odd is that when I started filling the stb engine, i forgot to close the radiator tap at the bottom of engine, and clear water started to flow out. I let it run a bit until it begun to turn red, then I tightened. This may have been the reason for the difference in gals per engine. That said, I filled both very slowly and then squeezed the coolant hose as best I could. Can you tell me how much coolant these engines are to take, I read in the owners manual that the capacity is 7.7gals (this has not been my experience)

I left the pressure caps half open and proceeded to start both engines. The stb temps jumped up fast then settled while the port remained low for a while I revved up to 1000 rpm on both and the stb got up to 145deg quickly. Took up to 1200 rpm and port caught up with stb, but eventually went past and got up to 177deg while stb stayed at 145 deg (engines were on for about 6-8min.). I shut down and then tighted the pressure caps. The bottles had not reduced.

I then took for a sea trial. I wanted to see if boat was moving, things would have settled, also wanted to see what temps would go to on port engine since I had just cleaned its Heat Exchanger. Well at 2150 the stb ran at 176deg and the port climbed to 185deg. The port bottle required refilling. My question is whether the coolant filling was done incorrectly, or is it the aftercooler that has not been serviced?? I am stumped on this. I still plan to deal with the aftercoolers Though.

I need your help on this. If I have to drain coolant again I will.

best

Paul

[Tony Athens]

SWAC Diesel Engines

Paul,

Mixing EG based coolants is not a concern.. These engines are very coolant makeup tolerant.. Just be sure your final mix is 50-50, or if in warmer climates, is closer to 40% EG and 60% distilled water for the best Heat Rejection across the HX tubes…………………….. As to your aftercooler——–You are playing with fire–I’ll leave it at that as I have done my due diligence…

The aftercooler on any SWAC diesel engine of any make or color is the one component that you do not cut corners with as to proper maintenance……………………Why? Because of the mixed metal design and the environment it operates in—————-NaCl and water with a few stray currents mixed in for flavor that all work together in unison as the “ultimate corrosive medium” …….

And it’s all “Marine Age Based ( not engine hours) & and needs to start at the initial assembly of the aftercooler before it “sees” saltwater.. ……………….Cummins, ( and Yanmar, CAT, & Volvo) ) as to their factory maintenance guidelines, still have not figured that out yet.

Tony

[Paul Andrew Facey]

Dear all,

Thank you for your comments, and Tony for your advice. I am taking heed.
I really am in a learning process here and need best advice.

After cleaning the HE core and oil/fuel coolers and partial clean of aftercooler (due to not being able to separate core), I took boat for about 10min sea trial a couple of weeks ago (remember that the Aftercooler was pressure tested and was air tight), the STB engine temp. ran consistently at 174-176 deg @2150rpm, while the port had increased from the previous time from 183 to 188deg. Since then I have not tried to start the STB engine, due mainly to my concern about the aftercooler and what Phil has said and Tony re the importance of proper maintenance and the damage that can be done. Re the port Engine, we removed the HE (which was clogged however not as bad as the STB was) and cleaned the core in some pool acid and and cleaned the surfaced, before installing new O’Rings and have fit back on engine. Have not Sea trialed yet.

After reading the forums on Seaboard and boatdiesel, I realize that the aftercooler due to its design with the aluminium housing is of great concern if not serviced properly. As Tony said in a forum, even when serviced properly the life is 15 years or 15,000 hrs. My situation is that my engines are 2006 (i am now in 12th year) and only gone 900 hrs. They were last serviced in 2015 the cummins way with the oil lube provided in their kit. My annual use will probably be 100hr/yr. My stb aftercooler is on boat, however core could not come out. would need to be pressed out by machine shop. If done, could have damage to the housing which could be cleaned and machined back to spec and refitted.

I have contacted a cummins trained mechanic out of Miami to come to Jamaica and spend 2-3 days with me. I am willing to purchase new aftercoolers and have them shipped in time for mechanic to install, or do you think I should work with what I got and if necessary take to machine shop to have them resurfaced and brought back to spec.

On another note, I have read where Tony said that mixing coolant in QSC engines will not be a problem. Did I read this correctly? I have gone and mixed Red Zerex ethylene Glycol heavy duty Extended Life with the 2.5 gal that was left in the engine housing, which was a green ethylene glycol (I do not know the brand). I plan to drain and replace with the Zerex red. Can you outline the procedure to do this and should I do any flushing with water before refilling.

Paul

[Rob Schepis]

The small flexible lines are coolant vents (aka spitters). The reason the coolant tank has a sloped ceiling is so those vents can stay above coolant leave and breather. The tie-wrapped “sensor” you mention is the alternator diode based on what you are describing. Pics would confirm or you can search it here on the site as I have posted pics of this before.

I would draw a component map of each engine and do a spot temperature map of each engine recording all readings at their respective locations and see where things start to change. Using the IR gun is a bit of an art and it’s use can effect the readings. Flat paint and straight shots are best. Distance is also a factor. So be consistent.

[Harold Meyer]

I shot all those temps, but I didn’t jot down turbo or outlet of oil/fuel heat exchanger readings, but I think they were the same (which according to the picture should be 20-50F less) . I shot the heat exchanger and that was 132F starboard and 122 port. I don’t know what those little lines that come out of the expansion tank that go before and after the thermostat (with some sort of electronic sensor? tie-wrapped onto them – could they be plugged/restricted? thanks a lot for your help – Harold

[Rob Schepis]

The 100degF coolant at the starboard recovery bottle is a sign that things are not flowing “in & out”. I’d play with an IR gun some more comparing point to point between the engines

https://www.sbmar.com/articles/ir-gun-temperature-check/

[Harold Meyer]

yes I swapped 15 psi caps between engines

[Rob Schepis]

This statement seems contradicting?

“Shot temps everywhere on both engines afterwards and only difference is coolant reservoir is 100F starboard vs. 170F port. Coolant is going in and out of plastic overflows.”

Have you replaced pressure caps with new? or swapped from engine to engine?

[Harold Meyer]

Hi guys – new to Seaboard forum, but have purchased parts from Seaboard over the years. Not sure how to start a new thread, but I also have an overheating issue with starboard engine. 1998 Cummins 330hp 6BTA5.9-M3 Diamond Series 1,250 hours. The starboard engine always ran a little warmer than port, but a couple of years ago it was creeping towards 190F. End of season 2016 backflushed, installed new impeller and thermostat, changed from green to purple coolant (better heat transfer). 2017 starboard engine still ran a bit hot. 2018 out of the gate, started to hit throttles not even on plane and starboard engine goes to 200F immediately. Visually inspected all 3 heat exchangers and exhaust elbows – clean. I should say we use the boat in salt water, but it is docked in fresh water river. At dock at 3000 rpm in neutral port stays at 170F, strarboard stays at 180F. Shot temps everywhere on both engines afterwards and only difference is coolant reservoir is 100F starboard vs. 170F port. Coolant is going in and out of plastic overflows. Could it be water pump? I took drivebelt off and spun the water pump, very smooth spinning. Don’t know what else to do. thanks for the help – I need it! Harold

1 user thanked author for this post.

Gordon McIntyre

[Tony Athens]

Paul,

I’ll make this simple…………….You need a better mechanic…. Both your aftercooler & heat-X need to serviced properly.. There is not any “other way”, “partial way”, etc. if you want to do it right for the long term…………………Plenty of pics on this site as to how it should be done…..Because your aftercooler did not comes apart “easily” and could not be serviced tells the entire story–It’s on it way to failing “major” and when it does, you will be feeding / misting saltwater into your engines cylinders.. That is a 100% fact……………………It’s your call from here.

Tony

[Author]

Replies