Combustion gases, or exhaust getting into the coolant?

[Jen Wren]

Last winter while preforming maintenance on one of our QSC 540hp I discovered the coolant was black as coal. Tony said:

“There are really only three things that would cause this–Oil, combustion gases, or exhaust getting into the coolant and all of these would typically cause something external to be noticed”

After a few questions he suggested changing the turbo gasket which did in fact solve the problem.

Now I’m having issues with a QSB 380hp. This motor is in a charter boat that works everyday and is pushing 11,000hrs. Last week oil started spewing out of the airsep. Changing the coalescing filter we discovered the serpentine belt was shredded. About this same time it appeared there was excess vapor coming from the exhaust. The motor wasn’t over heating but I started paying closer attention to the temp gauge and noticed it was a little erratic depending on RPM.

First course of action was to inspect the intake of the gear cooler and it was clean. Next was to change the raw water impeller. Removing the plate from the raw water pump we discovered a deep circular gouge in it. With that I just replaced the whole pump. Keep in mind the boat is working everyday and we are systematically eliminating possible causes in the evening.

Last night we changed thermostat. It was no fun on a hot motor but we got it changed. Starting the motor the temp rose to 170 and than back down when the thermostat opened.

The alarming issue was the coolant is black as coal. There is no oil in the coolant which leaves combustion gases, or exhaust getting into the coolant. Anybody know of a way to determine which it is?

The head was replaced at 1,100 hrs because the exhaust was not built correct when repowered. The turbo was replaced about 4500hrs ago. The motor is strong and runs like new consuming no oil between service.

This morning we are still getting excess vapor from the exhaust. Turbo gasket, head gasket, cracked manifold? Any ideas?
The old thermostat looks bad. Here are a couple photos

Topic

[Rob Schepis]

Yeah, I know deep down in my pile of beer koozies is one that states —- “I don’t need the internet, my wife knows everything”

[Jen Wren]

Thanks Rob. Yes the cooler was mentioned but I truly believed this motor didn’t have one. I have been climbing all over and servicing it for more than 10,000 hours and never discovered. My wife tells me all time that I need to pay more attention. Thought to admit she is right.

[Rob Schepis]

Good that all is resolved…. but too bad the learning curve resulted in a thinner wallet and bloody knuckles….especially that cleaning the fuel cooler was mentioned here by Philip.

[Jen Wren]

Cut to the chase

Yesterday afternoon we got the new head and heat exchanger installed and went for a sea trial. To my dismay nothing had changed. We still had a vapor trail and making temperature at high rpm.

The mechanic helping was able to get the ace Mexican Cummins tech on the phone. On speaker we went over whole history and everything we had done. He patiently explained what each component did and the symptoms we should have if there was a problem. Finally he got to the fuel cooler. I told him the motor didn’t have one. It was an eye opener to learn that it does.

In the life of the motor the fuel cooler has never been looked at or cleaned. Upon removal we discovered it was full of barnacles and clogged. Bingo! We cleaned it and ran the boat WOT for ten minutes. No vapor, no temperature.

I’m more than a little embarrassed but so happy the motor is heathy again

[Jen Wren]

No, I have not. We have very limited resources here and finding help is almost impossible. I’m replacing the head and heat exchanger so that will eliminate those components. I might try to cobble somthing together this morning to test the manifold but it looks good. I was told that if it was cracked coolant should leak into a cylinder when the motor was not being operated. I didn’t remove the turbo from the manifold this time because we just installed it a couple weeks ago. I do have a spare turbo though.

Through all of this the only part I have had to buy was the coolant pump. Everything else has come from my parts inventory. It is impossiable to get parts here timely so I have had no choice but to stock pile so we can operate. Cummins is worthless here, I guy couldn’t buy a washer without them having to order it. I live in the land of manana.

The problem has slowly gotten worse to the point I was confident we would be able to eyeball something.

The boat has work Thursday and the show must go on so we need to get her back together and see what we have.

[Rob Schepis]

Starting from day one of noticing symptoms/ issues have you conducted any coolant side pressure tests? Maybe you mentioned it but I don’t recall… With things apart now you can test the components – manifold, turbo, head, heat-ex. Something more than the naked eye might be needed to inspect that head…

[Jen Wren]

Un-answered questions

We worked until after dark last night installing the new head. I will try to post some photos later this morning after the sun comes up.

It was a restless night for me. I have gone as far as pulling the top end down and still have fear the problem with this motor is not completly solved.

The last few days of operation we were loosing a quart of coolant a day. Where did it go?

A couple weeks ago when changing the coolant pump we completly drained the cooland and replaced it with blue Fleetguard. Yesterday when draining the system the coolant came out a forest green color. I’m not talking a little green, it looks strong and you can’t see through it more than an inch. How could that happen?

Weeks ago we cleaned the coolant tank and now are changing the heat exchanger becuase of contamination of the coolant side. What about the block and all the coolant passages in the whole motor? Could there be more contamination that needs to somehow get cleaned up?

I’m operating 3 twin engine cruisers with Cummins motors. All of them work hard and are high hours with 2 boats having more than 10,000. With care and good service I have managed to keep them all running and believe they still have lots of life. Guess I finally got that curve ball. This one has me stumped.

[Jen Wren]

The latest

Yes, of course the the heat exchangers and after coolers were pulled off the motors for service. I bought a 20 ton press to push the core out of the aftercooler so we didn’t have to bang on it. This is a hands on service completly supervised by me. I have tought the local mechanics a lot from your posts. We use metalube and all your kits and go step by step for service per your instructions. The info is invaluable for an operator in a rural area without resources.

We pulled the head off today and I am sad to say we didn’t find anything worthy of a photo. Looking around I went back to the heat exchanger. I went back to what Bill Desmarals said about the coolant side of the heat exchanger. It is something that is easy to over look. When I hit the coolant side with a water hose black water came out. That is after running with new coolant for 2 weeks. I broke out our spear cooler and could instantly see the difference in water flow from the garden hose. I put a little degreaser in the old cooler and it came out black. Mind boggling to me. That black crud that was in the coolant pressure tank also has hung on to the bundle in the cooler and restricted flow.

Now the motor is getting a new head which I don’t believe it needed and also a new heat exchanger which should solve the problem. If not I might shoot myself, this has been my biggest nightmare since I started boating.

[Tony Athens]

Jen,

Just one question:

When you say the aftercoolers were serviced (last year or what ever), answer this:

1) Were the aftercoolers removed from the engines for that service?

2) Did you “see” the aftercoolers” on the bench and taken apart ( cores removed, etc) ?

Plus, I want to SEE your engine from all angles and perspective as installed..

You can post here but send them to me DIRECT, all in hi-res, clear & in-focus —– [email protected]

Tony

[Philip]

Don’t forget good pictures as you go for us all to see and learn….

[Rob Schepis]

He’s been in some remote areas with iffy wifi or he’d be active here and you’d never know the difference if he was on vaca or at his desk..

Yes, do keep us posted. Thanks

[Jen Wren]

Tony, vacation? That guy works harder than anyone I know.

God bless the good people of Florida. One of my best buddies live in the keys and has elected to ride it out.

I agree the lost coolant is the vapor trail. Today will be the last day the boat works. If the motor doesn’t come apart we will will pull the boat and start taking it apart.

Thanks the comments on this. I will post what we find.

[Bill Desmarais]

The loss of anti freeze could be your vapor trail.

No obvious signs of the anti-freeze leaking out somewhere ?

By-the-way……..Tony posted a reply to one of the posts on this forum a week or so ago.

He’s on vacation this month. He was suppose to be on Long Boat Key FL next week but with Irma, he’s “on the run” !

And it looks like Long Boat Key is going to be a dead on hit tomorrow !

[Jen Wren]

At last another sign

This morning the coolant reservoir tank is down almost a quart. Looks like maybe a head gasket?

[Jen Wren]

The end is near

With a storm just passing our sea temp dropped 5 degrees but out engine temp rose 5 degrees today. Now cruising at 2200 rpm we are running 185 degrees. When we throddle up just a little the temp climes.

Last month when we R&R the turbo we also did the heat exchanger and coolant pressure tank.

Tony has not asked any questions or made any comments on this thread. He without question is the best in the business at diagnostics, Maybe his plan is to just let me self destruct and sell a re-con?

[Bill Desmarais]

Jen, I overlooked your post about “cleaning the heat exchangers”. Did you use muriatic acid or Rydlyme ?

http://www.rydlymemarine.com/

If you had black crud in the expansion tank then you have or had black crud in the fresh water circuit.

You may have residue black crud in, on, around the heat exchanger bundle on the fresh water side. Not so easy to clean.

Maybe the Simple Green circulating didn’t clean enough.

Is there a radiator shop close to you? Ultrasonic cleaning ?

Maybe you could isolate the heat exchanger and circulate Rydlime through the fresh water AND raw water sides of the heat exchanger.

Bill D

[Jen Wren]

Thanks to everyone that has replied and tried to help with this but I am still nowhere. We live in a very rural area where it is impossible to find a good mechanic. Cummins is 65 miles away and when they came and took a look their ace walked away without a solution.

I’m not really much of a mechanic but have to work on my motors out of necessity.

Looking at the fresh water/coolant side of the cooling system is it possible there is a blockage somewhere? When we pulled the turbo and changed the gasket the coolant tank on top of the motor was full of black crud. We removed and cleaned it and then ran the motor with Simple Green. After a good flush I put in automotive coolant in and ran it for a couple days before replacing it with Fleetgaurd coolant.

[Jen Wren]

Tony’s impellers are probably better and something I will consider for the future. It is a stretch to think it would solve this problem. I posted the exhaust photos so you could see the volume of sea water coming out. It appears the sick motor has better flow than the healthy one. Somthing is going on here and I don’t think it is the raw water cooling causing the problem. I can put my hand on the mixing elbow at speed and it is not hot.

[Bill Fuller]

If it were me, I would order some of Tony’s impellers and install them and see what happens. They are not the same.

[Jen Wren]

Bill,

The raw water pump replacement was brand new still in the Sherwood box. Because it had been sitting around for while we pulled out the impeller and compared it with the one in the old pump. New new one was stiffer than the old one that was still completly in tacked.

[Author]

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