6BTA M1 Exhaust in cooling system?

[Bill Stenger]

Hello everyone,
You all and the forum are a wealth of information! Im new to marine diesels and feel I am getting exhaust in my coolant. I have flushed coolant many times running water currently and still comes out brownish black after a little run time above 1700 rpm. I replaced the radiator cap because it wasn’t building pressure. Now I can cold start then engine bring up the throttle around 2k rpms. and the coolant hoses become pressurized immediately. release throttle and they remain quite hard. Even though coolant is still stone cold. I feel this is bad turbo gaskets from your information on the forum.

Pictures I took of the insides of the cooling system pre flushing are too big to be posted on the forum. So I posted the top of the coolant tank the brown liquid is water after a short run time. Already turning brown.

? #1 Do you agree turbo gaskets are likely bad?
? #2 Engine is a 1997 looks poorly maintained should I buy the factory cummins gaskets or the composite gaskets. Or no idea until the torn down and mounting faces inspected?

Engine serial # 45388094

cpl # 1570

Topic

[Bill Stenger]

Bought a photo tachometer off amazon. Im not certain of its accuracy. Wot no load it reads approx 2920 rpm while the tach reads 2600. What is the no load rpm limit? I read for a similar cpl 220 hp engine was 2912 rpm Is this correct for my cpl as well? I spent some time combustion testing the cooling system as I am suspicious of exhaust in coolant still. I didn’t test under load since its on the trailer atm. Passed that test so far. Curious whats causing the coolant temp @ 195 degrees @ Wot under load.

[Bill Stenger]

Here is an update on this topic. I reinstalled the turbo and cap with all new hardware and red rtv the seaboard way. I emailed you Tony to order the correct composite gasket but didn’t get a response and the bad faces are on the cap. So I figured its easy enough order one with my next purchase and swap it out.

Turbo spools much better than before. After running on the trailer for 45 minutes. It only built 8 psi of coolant pressure so the exhaust in coolant seemed to be fixed. Topped up coolant tank and took it out for a test run. @ 2400 rpm cruise it runs around 190 degrees and 195 @ WOT. Is that normal? New 180 tstat, raw water pump, and coolant pump. I don’t know when the heat exchanger was last serviced but with a laser temp gun I show 191 degrees going into exchanger and 150 approx coming out. Does this seem normal according to your gun results it seems 50 degree drop is adequate.

Next issue is if I top up the coolant tank on the engine when I checked fluids after it cooled down after testing I was 1″ low in the engine tank and about 1″ higher in the overflow bottle. So I marked the overflow bottle’s level and ran the boat again. Once again the engine tank was low about 1″ and overflow was higher about 1″. Is it normal to have the engine tank about 1″ low?

Then of coarse the fuel solenoid started acting up then died completely. Ordered one. Hopefully I can get the bugs worked out of this boat to be able to enjoy some Bahamas crossing before summer is over. My wife is a school teacher so her freedom is coming to an end. Once summer is over I can figure out what to do about a dry exhaust and whatever is next at that point.

[Tony Athens]

Late Style Cummins turbo composite gasket

No that is not the one– That is for the old engines as noted in the description (needs to made larger).

The one I would use is not on the web site as I only have about 15 pcs left–Can’t get them anymore..

You need to drop me a note on Monday.

Tony

[Bill Stenger]

Tony, do you know anywhere that gasket would be available in South Florida. Is it a factory Cummins gasket?
I would like to get it together by the weekend so I know if I can start planning trips or not.

Is this the gasket you are referring to?
https://www.sbmar.com/product/composite-turbo-charger-water-cover-to-manifold-gasket/

[Tony Athens]

Surfaces are “borderline” on 2 of the pics.. You have to use RTV.. Follow my lead 100%.

The expensive later style “composite gasket” with 2-3 re-torques would be better to use one the real bad one.

Tony

[Bill Stenger]

Finally had a chance to work on this boat this evening. Surfaces don’t look too great but should seal with some red rtv as shown in Tony’s tips. I want to at least get it back together and see if the exhaust in coolant is fixed. If not I will be tearing it down again.

[Bill Stenger]

That seems like it would work Tony.

What are your opinions on this style fitting from the pictures above? And what is the needed dry pipe size 250hp 6btam1. Cpl 1570? Also what is the safe distance from fiberglass with those fancy heatshields?

Seems like I may be able to make something like this attached image of an elbow like SBMAR did. It would need a few different angles but should be able to fit and achieve a dry exhaust.

[Tony Athens]

Look at these pics.. This was a a high-mount we did with an in-line drive that used a ZF63A.. There was no room near on the gear end to build a proper riser..

Tony

[Bill Stenger]

From what I read on here. It seems when running a high mount turbo the exhaust housing has to face the front of the engine it can’t be ran exhaust housing towards the back. I assume because the water ports don’t match the other way around. I think there is less room towards the front of the engine than the rear. There is about 3″ between the deck opening and the plumbing on the starboard side and 4″ in the front. I’m not sure what to really do here. I ordered a new turbo. I will bead blast the elbow and if there is any leaks I will repair them for now until a REAL solution is decided. Then reinstall with exhaust flapper for now. It’s made it over 20 years like this so far. Atleast then I will know if the exhaust into coolant issue is fixed.Or it may have a bad head gasket or cracked exhaust manifold which seems rare.If that issue is resolved I will run it a few trips and check the turbo. Im sure a flapper isn’t going to save it. So then hopefully we can come up with a plan to fix the exhaust. I was thinking maybe I could mock up a high dry elbow out of pvc elbows to attempt to come up with some permanent exhaust solution. Without ruining my new turbo.

Does anyone know what the minimum safe dry pipe size is? Most of Tony’s elbows are 4″ Which would be ideal. Im just not sure if I can fit that.

Also how close can the dry elbow be to fiberglass with out a chance of catching it on fire? Seems those insulating covers they make are efficient. But what is the real safe distance?

[Rob Schepis]

A high mount would be the way I would go: https://www.sbmar.com/articles/high-mount-turbo-configuration-examples/

Would be interesting to put her in the water without the elbow installed to see the actual LWL (loaded water line) … I think the visual of that would be scary, especially considering how you plan to use the boat..

[Bill Stenger]

Thank you Rob. The exhaust goes uphill from the transom then down hill to the elbow seems like a bad design to me I agree.

I recently purchased the boat and have only ran it 4 times. Yes I frequently shut down and drift in sea I likely will everytime this boat will be ran while I’m the owner. I have not experienced any hard starting or extended cranking yet. But like I said I have only taking her out 3 times besides the 80 mile run home @ initial purchase.

What’s best way to proceed? Obviously a new turbo.

Should I take the boat to the water without the elbow installed and see where the water line is? I assume this is the original turbo and elbow @ 22years. But I’m not 100% sure.

I don’t think I have the room to really make a high dry riser. But maybe Tony will chime in and say he has made them in worse situations. I obviously dont want to risk my engine even though shes old with high hours. Or ruin the new turbo.

That’s why I’m here seeking wisdom. The mixer is obviously not 12″ above the water line like required by cummins. Likely about 2-3″ at best.

[Rob Schepis]

Bill Stenger wrote:

I believe the elbow is above the waterline @ the mixer end but close.

Close only counts in horseshoes, definitely NOT here. “Just above” the water line might be fine with the engine running at the dock —- other than that, the engine is on a big time salt water diet, probably made it’s way up into the exhaust manifold and I’m surprised she has not hydrolocked at sea. Do you ever shut down and sit in a rolling sea? Ever notice the engine slow to crank when starting after sitting in a sea?

So the exhaust is going “uphill” ?

[Bill Stenger]

Here is some pictures of the exhaust routing and elbow. I believe the elbow is above the waterline @ the mixer end but close. What are your thoughts on where this water is coming from and how I should proceed. I had a few guys tell me to pull the exhaust manifold and pressure test it but I was not losing any coolant. I did seem to have exhaust pressure in the cooling system. Could coolant leaking through manifold cause this turbo damage? I figured it would have to be salt water.

[Bill Stenger]

Pulled turbo and elbow.

Ok guys, I pulled the turbo and elbow. The gaskets look terrible but don’t show a direct path where the exhaust is going into the coolant. Like I am used to seeing from a failed headgasket. Also looks like a terrible exhaust design or a bad elbow. And the turbo is trashed from salt water intake. Opinions on the elbow? Pics below.

[Bill Stenger]

Thank you Tony, I ordered stock gaskets from Kevin today. So hopefully the flanges aren’t too bad. I tried to post pics but they didn’t show for some reason.

[Tony Athens]

Start with the turbo gasket and the top of the manifold gasket.Same gasket both places…

Plenty of pics on this site as to “how to”..

If the surfaces are good, use the standard gasket as shown in the pics..

Be sure you drain all the coolant before to start taking apart the turbo..

Maybe post some pics from all around the engine too..

Tony

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