[Bob Bonser]

Tony,
After reading your article about the manifold to turbo gasket change I did some more investigation. My manifold, at the mounting surface, at the lower 1/2 is showing signs of pitting and rust. Hitting it with a wire brush cleaned it up some but nothing shiny by any stretch. The mounting surface for the turbo itself is clean, shiny and without blemish.

I did not do the gasket that sits on top of the exhaust manifold, when I do the turbo gasket again I can do that one also.

I reinstalled the turbo gasket, using the same new one that I installed from yesterday, I used the red RTV and let it sit overnight. I just sea trialed here are the results.

1. Zero drippage from turbo gasket at idle for 45 minutes and no reduction in coolant. Coolant (water at this point) was right up to the filler neck before and after.

2. got the boat to 165 (thermostat open) and I ran the boat at 2200rpm for 20 minutes. No temp change.

3. While underway I looked at the turbo and there is a steady stream of water coming from the center of the turbo mount directly between the two lower bolts. I guess its possible that the water was coming from above those bolts and collecting there but I couldn’t see any leakage from the coolant hoses, nor obvious cracks in the turbo housing.

4. After this 20 minute test I found that I lost a little less than one gallon. This seems about right for that leak. And is half the amount of loss that I incurred with the prior sea trial before the reinstall of the turbo gasket with RTV. This is making me have a little hope that the problem is at this location.

5. At this point I am unclear. I realize I could pull the exhaust manifold and get the surface milled, or at that point replace it with new. I really don’t want to pull that manifold. I can only imagine studs and bolts snapping and stripping!

6. In your article about replacing the gasket you mentioned using a composite gasket if there was pitting.

7. Are you still in favor of trying a composite gasket? If so, do I make it or can you supply? If not, what do you suggest?

Thank you again,
Bob

[Bob Bonser]

I just looked at your article related to the turbo gasket change and the SBMAR way! I wish I would have read that before I did the job. I now need to redo it. I have a leak at the lower edge, if its leaking there theres no telling whats going on where I can’t see.

I will redo the gasket the right way and report. The surfaces look clean and unpitted to me but I can’t check it for trueness.

Pressure test of the coolant system once I can find the tool.

Thanks Tony

[Bob Bonser]

Ok men. Thanks for all the help to here. After having the, aftercooler, heat exchanger, oil cooler serviced by a Ron Jago we are still overheating and still losing coolant.

Ron suggested the turbo gasket which I replaced, which did not correct the problem. Boat runs great for 30 mins then heat creeps up. Shut it down and check and we have lost about 3gal of Coolant.

It seems that at this point only the head gasket and exhaust manifold are left to blame. I don’t know how to diagnose. There is zero loss at idle even after an hour. (If that means anything to anyone)

Any ideas?

Thank you,
Bob Bonser

[Bob Bonser]

Is your current seal leaking? Why do you think you need it? Just wondering cause mine had a significant stream of seawater at rest. My box looks somewhat like yours except for all the dirt and leaves.

I loosened it, got all thre sizes from west marine, got a pigtail extractor from west marine and loosened the nut till I could access the packing.

I layed the shaft seal against the shaft and it was obvious which was the right size.

Removed all the old packing with the pigtail, cleaned, greased and put back the new.

Rotate each layer so the seams are offset. 3 layers, offset each 120 deg. I couldn’t get 3 layers in mine and still be able to reinstall. I made the last layer 1/2 thickness this may draw boos from the crowd)

Now I have only a slight drip when under way and nothing at rest. West marine sells three sizes. I have two here unused! At 12$ just get em all. I needed the smallest for what it’s worth. 40ft dorado, single inboard 6cta8.3m. 1.5in shaft.

[Bob Bonser]

Tony,

Once again thank you for all your input. I am thinking that since the HX, gear and intercooler are out I should replace all hoses. They are all at three years old and maybe 500 hours.

The main hose from the sea cock to the sea water pump. This hose is 7 years old.

2 inch wet exhaust hose. With or without wire? Corrugated? Something else all together?

Do we have a kit that contains all the sea water and fresh water hoses? They are all kinda small but I am sure not kinda cheap!

Thanks
Bob

[Bob Bonser]

Thanks for the pictures. I will be hoping for similar results. Next week I will update.
Thanks
Bob

[Bob Bonser]

Pulled the Heat exchanger and the intercooler and the gear cooler. I took the ends off the heat exchanger. Nothing earth shattering in there. A few pieces of the old impeller made it through. I can’t see this thing being the source of our problem. The other thing I found out is that my intercooler is only three years old. Ron, told me he purchased it new and installed it when he did my last service on my engine. I hope this overheat problem goes away.

[Bob Bonser]

Thank you Corey. Cooling system getting pulled and serviced. Then the proper propping!

Bob

[Bob Bonser]

Tony,

Ron told me to send his regards. Just got off the phone, he in fact is the guy who went through my motor. He put your water pump on it, and serviced the hx and intercooler. Mentioned that he lubed them up the way you like it done.

I am getting my cooling system, intercooler, hx, and trans cooler to him this week. I will post our finding if you think there is value in it.

Thank you,
Bob Bonser

[Bob Bonser]

Lol. Ron is the guy who pulled the engine and serviced it. Boat was in palmetto at the time!

I haven’t talked to him since then Because we moved the boat to St Pete. Now we are using Cummins Southeastern Marine power.

Maybe there is hope!

[Bob Bonser]

I have been reading regarding propping. Props move boats engines turn them, and Propping the Cummins 6CTA 8.3 480CE vs. 430/450 Diamond Engine.

I am trying to grasp this thinking.

A motor creates hp, but that can be manipulated with different props?

If my engines makes 2650 at 23gals and 100% load this is overpropped? I should or want to make 2750 at 90% load or 2200 rpm @ 13.6 gph.

Must both of these benchmarks be met or is one or the other acceptable?

Tony’s article mentions that the damage to these motors is done and Cruise rather than WOT. What is considered cruise ? I could not see that noted on any of the charts.

Once again I thank you so much for your time.

[Bob Bonser]

Tony as always thanks, but I did mention that both units were serviced by a Cummins guy 2-2.5 years ago. Haven’t had many hours these last 2 years.

I only took off the end caps to get all the old impeller out, and I only looked cause of this new overheat, so there is maybe 1 hour since then. Perhaps disaster is still at bay.

Let me get this hx off and sent out for service, intercooler too. If Tampa Cummins can’t do it I can box it and ship to you. The problem there is a week UPS both ways and then your shop time. I will be down for three weeks.

Once I get the overheating under control, then I can figure out if my prop is too heavy.

In your opinion, is this an OK plan?

[Bob Bonser]

Can we tell for sure if this is the 480CE?

[Bob Bonser]

Corey, hit the submit button before I made it through.

7. The thermostats May have been 160. I used the part number found on quickserve and purchased them at Cummins. But, I really didn’t feel the outlet hose get warm until 180. I need to repeat that test.

8. Knowing the weight of the intercooler and the heat exchanger, does it make sense to ship them ? Would love to have you guys look at/service them.

Thanks again,
Bob

[Bob Bonser]

Corey. Thanks again

1. I guess I need to ask if WOT always means underway/loaded or if you mean in neutral. Under load, not too heavy, I can hit 2650 with load shown as 100. I can’t really take it out to retest to make sure cause of the temps. I wouldn’t have time to get to wot and turn it about to get back to dock prior to overheat.

2. Is the heat exchanger something I service or something I bring to the local Cummins guy or ship to you? Tony says send some photos of it, this I can do too. Photos of the ends and the guts after I take off the end caps?

3. The raw water pump was from Cummins. Not sure if it was a Sherwood. But it was new in box. Installed last week.

4. Photos can be posted tmmrw . Working nights this week. Will be hit or miss. But will happen!

5. Water pump is a new in box, purchased at Cummins Southeastern Power in Tampa. Installed last week.

6. I have read the article on intercoolers and saw the comments on greasing them up.. When I had mine off the end caps opened fairly easy, but tapping the core with a wooden block didn’t make it move. I didn’t want to damage it so I rinsed it out. There really wasn’t any corrosion . Just a pile of old rubber fopeom a previous impeller failure. No tubing crud. The fins visible from the sides were not gunked up at all, but we’re discolored black.

[Bob Bonser]

Thanks for the reply.

1. The valve problem happened many years ago and it was a known mechanical issue that Cummins provided the parts and labor to repair. It’s 1000 hours of running since that occurred.
2. The engine is rated at 480hp
3. I think I am good about the raw water side. I change impellers, and the water pump is only a couple years old. I had the intercooler serviced 2years ago but I haven’t put more than 300 hours on it since then
4. I didn’t look at the heat exchanger cause I am totally unfamiliar with it. I can take it apart and see if it’s corroded
5. I have always been told by the Cummins tech that 2650 wot indicated I was propped correctly. Is that last 75 to 100 rpm so significant it means my engine is in poor condition ?
6. I am no mechanic, just a guy trying to not go broke owning a motor. I apologize if my comments may seem ignorant. Help and suggestions are appreciated. Even though you responded you didn’t suggest any way to correct. You mention looking more closely at the heat exchanger. Once I open the end caps how to proceed? Boil, scrape, replace ? I do t know.

Thanks

[Bob Bonser]

I didn’t think it applied but here is all the particular information about the vessell

1. 2002 40ft Dorado Bluewater
2. Engine 6CTA8.3 with about 1000 hours post cummins haul out and rebuilt for a sucked valve
3. WOT attainable 2600RPM 18gph Cruising speed at WOT 24 kts
4. new oil and all filters
5. has been the most reliable motor I ever owned!!
6. Typical operating temp 164deg

[Author]

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