6BTA 370 HP quits at 2700 rpm in 46 Maxum

[Russ Keyes]

Coming back I ran the engines up to 2700 RPM and after a few minutes the port engine quits. Close to home so go back on one engine. Mechanic comes down we start port engine runs fine, we change fuel filters, and go for sea trial. All is fine at WOT for a couple of minutes and 2800 for 15 min. When we got back noticed coolant under engine. Went back and found a small crack in head back by aft fuel injector. Had minimal lost coolant year ago, could not find leak, used stop leak went away. Since we felt we had cured engine issue decided to replace the head. Installed head went out for sea trial and port engine made 2800 RPM but quickly started to loss RPM’s and finally dies. Started back up but each time we got past 2000 it would quite but would start back up. Went back at reduced RPM all ran well. Mechanic could not figure out what was causing problem. After asking a couple of his friend questions it was suggested to remove the air filter and look at the turbo. It was dripping with oil. We had serviced the intercooler when doing the head and tech mentioned air side was oily. We then decide to pull the breather hose from the filter and go out see what happened (extended breather pipe into a bucket). Up to 2000 RPM normal when the turbo kicked in oil came out enough to fill 5 gallon bucket with 1″ to 1 1/2″ of oil. Back off to 1800 or so no problem. I had never overheated the engine but only owned boat for a couple of years. Now since the head was cracked and we have blow by it is assumed we have ring problems, but why only when the turbo kicks in. One of the shops, very reputable, I was talking to about pulling the engine suggested with a great deal of confidence that the problem was the turbo not the rings. Personally I do see how it can be the turbo but that is my question is it possible it could be the turbo? Sorry this is so long for a short question. Thanks

Topic

[Russ Keyes]

Turbo

Good Morning – He is saying 12 quarts not 13 for the low and should it be 14 quarts instead of 15 for the high as the chart shows. Mine is the older pan without the extra baffles and the newer dip stick. The pan currently has approx. 14.5 quarts in it. We sucked it dry after installing the new head put 1 quart in the filter and 15 in the pan. The two sea trials pumped about 1/2 quart out of the breather. I will drain and remark the dip stick as recommended, on both engines. Russ

[Philip]

Russ-

Keep in mind or should I say try and get your mind to understand the difference between oil PAN capacity and SYSTEM capacity. That’s where the 12qt thing is coming from that Tony is talking about. Read his article several times till you can understand it and explain it to the mechanic.

Oil Pan Capacities for Cummins Marine Engines

Phil

[Russ Keyes]

Turbo

I guess I am doing a poor job of responding. I have scheduled my mechanic to come in and do exactly what was suggested. I only meant to explain what we have done in the past. I am completely onboard with your recommendations and sure hope they work. Sorry I am more verbal than verse. Russ

[Tony Athens]

Russ,

I do not like the way you are coming back with your oil level thing… You ARE NOT following my article nor what I asked you to do………….You are adding your own flavor to how IT HAS TO BE DONE.. .. The only way is MY WAY, and it NOTHING to do with the oil filter… You need to re-read my article about 10 times until it finally sinks in as to what it is saying and leave your own interpretation out of it…

As to you engine dying because of too much oil being sucked thru the turbo or ??, I say total horse manure.. Something else it going on..

Tony

[Russ Keyes]

Turbo

We know how much was put in with oil change three weeks ago and with the oil that has come out, filled the new head and the new oil filter we are sure current is 12-13 qts. Did regular the compression test. We will now do 1 & 4 and get back. Thanks, Russ

[Philip]

Russ-

Have you done this??

1) Drain every drop of oil from that engine. Put exactly 12 quarts back in—Do not start the engine or touch the oil filter—Pull your dip stick a few times and mark it at 12 QUARTS ( not 13)

And do this and report back

4) Next for now — this will be your “compression test”—I want your engine stone cold—Maybe has not been started for a few days.. Get the fuel primed until you hear a good squeak at the injection pump. Give the engine 100% throttle ( not 75%–I want 100%) and try and start it. As soon as it starts, back down –Tell me how it started.

[Russ Keyes]

Turbo

We have installed a clear tube section in the breather hose to the air cleaner. So we can see what is happening as we increase the RPM. Up to about 1800 RPM no oil, no smoke, at 1800 when the turbo kicks in there is a lot of oil and the engine dies, but will start right back up. On a previous sea trial at 1800 plus RPM at ran a little longer without quitting and there was a lot of smoke before in finally quit. There is a fair bit of smoke on startup, both engines. I am told that is normal. I have block heaters that I use in the winter and the smoke is a lot less when they are used. It would seem we would have to be able to test compression at the higher pressure produced by the turbo to confirm this problem, is that possible to do? I believe I have done what Tony has suggested except the primed start at full throttle. Have I missed something? I would love not to pull the engine. Russ

[Philip]

Russ-

I’m no expert, but if that much oil was causing the engine to quit wouldn’t you get a TON of blue smoke? Even at 1800 RPM I would think you’d have smoke.

AND with weak rings you should be getting poor compression, slow starts, and smoke with startups…

This doesn’t sound like what you have. You state good compression, normal starts, and no smoke.

If it was me, before I went spending a lot of my money chasing things Lets get Tony’s next steps and I’ll be we can figure this out. He is trying to save you money and get you up and running quickly without spending money you don’t have to.

Have you confirmed clean and tight electrical connections from battery to engine including all harnesses and especially the circuit breaker on the back of the engine.

[Russ Keyes]

Turbo

Finally got the turbo back and in, as you thought it was not the problem. However the turbo did have some issues. Was worth a try because next step is expensive. We are left only with bad rings. Oil level right, compression OK, fuel solenoid working properly. We are very confident the engine quits because a lot of oil gets dumped into the air cleaner when turbo starts to kick in. We can see it happen. Under 1800 RPM runs great. When it does quit starts right up no sign of fuel starvation. Sounds like next step will be to pull the engine. Thanks for all your help. I’ll you know what we find. Russ

[Russ Keyes]

Met the mechanic at the boat this morning. Checked the solenoid and compression both OK. We figure with the new head getting oil, the filter, what we lost in the bucket test we are at about 13 + a little qts. Ran the engine and cracked the injector lines each one had an effect. Tested the crank case breather line at the air filter, it had no unusual pressure or pulsating compression sound.

Mechanic is very confident that it is the turbo. Especially since crank case only pressurizes when turbo kicks in. He feels the pressure is going past the seal and out the oil return line to the crank case. He says he has seen this before.

Next Monday will get the turbo back, change oil, and will do sea trial. I’ll let you know what happens. Sure hope it works.

[Russ Keyes]

Boy you sure have that right. I can’t believe the effort he went to help me out.

It is my plan to go over each one, as part of his work tomorrow. I believe you are right about the oil quantity. However it also happened before it was changed and I had run it at 2700 several times before. The fuel solenoid will get a good look.

Changed the head because we discovered a coolant leak which was a cracked head while trouble shooting the engine quitting. Do not believe it was related.

Will get back with results. Thanks.

Russ

[Philip]

Russ-

Tony gave you very specific items to check/address. He took a lot of time to help you and your specific issue. Share this stuff with your trusty mechanic if you can’t or don’t have the time to do it.

1 – sounds like you have way too much oil in the engine and your oil issues might be just as simple as too much oil. Spend some time reading this web site about how much oil goes in a marine engine oil pan.

2 – make sure your fuel solenoid is working and adjusted properly. The higher rpm could cause the boat to bounce around enough to wiggle a loose wire etc. spend some time eliminating this item per Tony’s recommendations.

3 – report back what your mechanic finds so we can all learn.

Thanks for sharing!

Phil

PS – I still don’t understand why the head was changed?

[Russ Keyes]

1.) Power dropped off quickly. You felt the loss of power and RPM went straight down.
2.) First changed fuel filters then went out for sea trial couple of days after stoppage. Engine ran fine no power loss full 3150 WOT. Got back noticed coolant on engine mat and went right back out no power loss but found source of leak. Assumed other issue taken care of so pulled head off a couple days later. Changed oil and filter (16 qts) after head completed. Went out for sea trial and engine died like before. Started right up, no priming, and happened a few more times. Went back at 1800 all was fine. Next day rerouted breather tube into bucket went out for sea trial got oil in bucket then checked air side of turbo on return and was dripping oil. Assumed that much oil cut off the air.
Mechanic will be down tomorrow will work on this stuff. Thanks very much for all your effort I really appreciate it.
Russ

[Tony Athens]

Russ,

Your second set of pics did not post, but no worries………….I think I read your post 20 times and it really leaves much to speculation as to following the sequence of events, but that is OK at this time ….. Read below as this is what I made form it………………..You did not make this easy..

Coming back I ran the engines up to 2700 RPM and after a few minutes the port engine quits. Close to home so go back on one engine. Mechanic comes down we start port engine runs fine, we change fuel filters, and go for sea trial. All is fine at WOT for a couple of minutes and 2800 for 15 min.

When the engine “quit”, did it quit like it was shut off, or did it quit slowly over a minute or so?

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When we got back noticed coolant under engine. Went back and found a small crack in head back by aft fuel injector. Had minimal lost coolant year ago, could not find leak, used stop leak went away. Since we felt we had cured engine issue decided to replace the head.
Not sure on this— It this at a later date? Did just decide to replace your cylinder head?
Installed head went out for sea trial and port engine made 2800 RPM but quickly started to loss RPM’s and finally dies. Started back up but each time we got past 2000 it would quite but would start back up. Went back at reduced RPM all ran well. Mechanic could not figure out what was causing problem.

This sounds like you are losing fuel or sucking air if the engine dies slowly. When you say it starts back up each time, is that instantly of after a lot of cranking, fuel priming?

The external fuel solenoid on the P-7100 pump—You need to be 100% it is locked in the SUCK in position or is 100% up against the stop. The fact that you replaced the head, it may need to be adjusted / reinstalled right?

Also and extremely important, the two wires under the circuit breaker—Possible loose corrected causing intermittent low voltage to the IGN circuit/that solenoid
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After asking a couple of his friend questions it was suggested to remove the air filter and look at the turbo. It was dripping with oil. We had serviced the intercooler when doing the head and tech mentioned air side was oily. We then decide to pull the breather hose from the filter and go out see what happened (extended breather pipe into a bucket). Up to 2000 RPM normal when the turbo kicked in oil came out enough to fill 5 gallon bucket with 1″ to 1 1/2″ of oil. Back off to 1800 or so no problem.

This is from the poor design of the Walker Airsep and the SINK LOOP hose in the plumbing it creates under the turbo.. Plus, you must keep the oil in the oil pan , engine off, at the dock at 13 quarts maximum.. Lot’s on my web site about this in the CCV articles—IMO, this system must go or you will always have turbo/oil issues at higher RPM’s.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

I had never overheated the engine but only owned boat for a couple of years. Now since the head was cracked and we have blow-by it is assumed we have ring problems, but why only when the turbo kicks in. One of the shops, very reputable, I was talking to about pulling the engine suggested with a great deal of confidence that the problem was the turbo not the rings.

This is not a turbo issue as nothing about it would cause the engine to shut down,. Nor was the head the reason.. For sure, the only thing that would cause the engine to shut down once it is running would be for it to run out of fuel ( air, fuel solenoid, or a combo), or a major catastrophic mechanical failure..

So at this point all I can surmise it that for some reason you are losing fuel.. The oil leak thing would not cause the engine to shut down, but needs to be addressed.. As to blow-by, that could easily be from over filling the oil pan. Lots on my web site about that too.

Your pictures helped me get a feel for things—Your exhaust system is safe which is a biggy in my book…..

So from here fwd, or next on the list, this is what I want you to do.

1) Drain every drop of oil from that engine. Put exactly 12 quarts back in—Do not start the engine or touch the oil filter—Pull your dip stick a few times and mark it at 12 QUARTS ( not 13) ………………..

2) Then, turn on the key but do not start the engine. Lift the fuel solenoid and see if it is the 100% up position. Look at all of the linkage and oil everything that moves or pivots until you can lift it up and down easily. Then un-plug the plug on it, it should drop.. Put the plug back in a lift it again—Do this 4-5 times to be sure it is working right…Maybe wiggle the wires on the circuit breaker while in the suck-in position

3) Then I want the breather hose that comes off the side of the engine behind the aftercooler that goes to the Air Sep removed from the engine. Replace it with a piece of ¾” of clear vinyl hose about 4=5ft long—Run it down below the aftercooler and then back up to above the air cleaner—Leave the top open.. This is how you are going to monitor blow by with just 12 quarts of oil in the oil pan…Look at my Envirovent CCV pic—Get your mechanic to put a “T” in the bottom of the loop with a 4-6 MM hole feeding to a catch bottle to let any oil out but all the gases still an come out the ¾” hose to monitor when you do your next sea trial.

4) Next for now — this will be your “compression test”—I want your engine stone cold—Maybe has not been started for a few days.. Get the fuel primed until you hear a good squeak at the injection pump. Give the engine 100% throttle ( not 75%–I want 100%) and try and start it. As soon as it starts, back down –Tell me how it started.
Now we can go for a sea trial and watch the blow-by and see if the engines keep running with good circuit breaker connections, a properly adjusted fuel solenoid and one that has some oil on all the linkage connections

Come back with more info and try and understand that we are here and you are there.. So try and make it more understandable as to what is going on..

Tony

1 user thanked author for this post.

Darren

[Russ Keyes]

Pictures

Few more.

[Russ Keyes]

Pictures

Attached are photos. Let me know what I missed. Russ

[Russ Keyes]

Good Morning –

No I just run them up to 27000 on the way back to port to blow the cobwebs out after each time out. The WOT is 3150. Frankly I feel uncomfortable running it a WOT.

Russ

1 user thanked author for this post.

Bill Desmarais

[Russ Keyes]

Thanks for getting back.

I’ll do pictures tomorrow. I have owned for 2 1/2 years. Previous owner 4 years. Got most of his records and talked with his mechanic, I believe he was truthful, has a good reputation around Sydney BC, where I bought the boat. He said no engine issues. This is the port engine, no issues starboard. Serial # 45687083 (Port). 2,150 hours, 150 by us, no issues with seawater or cooling. Cleaned/ inspected heat exchangers after purchased, did all the impellers, and installed block heaters. WOT 3150 22 knots, cruise 1600 10 knots. Current problem started two weeks ago when engine quit on return to home port.

Russ

[Bill Desmarais]

Russ,
In addition to what Tony has asked for information, I’m curious what the maximum wide open throttle rpms the 370s can reach?
You mentioned running at 2700 and 2800 rpms…were the rpms at maximum throttle ?
Regards,
Bill D

[Tony Athens]

mossbayco,

Yes, a long post but is really missing all that I need to even begin to try and sort this one out……….NUMBER ONE:

I need good pictures of the engines as installed in the boat– All angles & all perspectives, all clear & in-focus posted here for all to see, AND sent to me direct in .JPG attachments in med to high res.. I need to “SEE” what we are dealing with here………….,

2. I want all the complete history of operation and past issues.. That would include this at an absolute MINIMUM: Engine serials numbers, total hours, engine hours you have logged since YOU have owned it, past maintenance applicable to the entire seawater system, how many past owners, your max RPM and vessel speed at WOT loaded as you use the boat, your happy cruise RPM and vessel speed at that RPM, and off course, when the current issues started happening ..

Right now I am blinded sided as to where to start.. So help us to help you as there are many BLANKS that need to filled in..

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Tony

[Author]

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