Official Cummins 6cta 450C thread

Do you have a mechanical 6CTA or the 480CE?
 
Larry said:
Has anyone had to replace an oil pressure sending unit on one of our 6CTA’s? I am trying to find a part number or replacement for mine. Seaboard does not have them as there sending units are 2 wire units for VDO type gauge, for some reason the s
Sea Ray 4 in 1 gauge are different, these use a single wire, basically looks like your run of the mill old school oil pressure sending unit with a single stud. I just want to make sure I am ordering the correct part. Haven’t tried Marin Max yet but maybe they have one??
Click to expand...

Been working on this (but CAT engines). Best advice I've seen is to find the gauge manufacturer, and see what they specified. The senders are matched to the guages. 4-1 might be Faria, but I'm not an expert on your year boat.

Single wire senders are "standard ground" the case and threaded nipple are the ground, the single wire is the signal back to the guage. Power is supplied at the guages.
 
Last edited:
Larry said:
They are the mechanical 450C
Click to expand...
I bought one a couple years ago when I thought one of mine had failed. Turns out just the wire broke. I just looked up the part number on Quickserve and googled it and ordered online. Although I just checked and can't seem to find it on Quickserve. Maybe I just googled "Cummins 6CTA oil pressor sensor"?
 
Last edited:
ZZ13 said:
I bought one a couple years ago when I thought one of mine had failed. Turns out just the wire broke. I just looked up the part number on Quickserve and googled it and ordered online. Although I just checked and can't seem to find it on Quickserve. Maybe I just googled "Cummins 6CTA oil pressor sensor"?
Click to expand...

I looked on Quikserve too, problem is its not just a 6CTA sending unit, its different due to the dash gauge from Sea Ray. Has to be specific to the gauge..
 
Larry said:
I looked on Quikserve too, problem is its not just a 6CTA sending unit, its different due to the dash gauge from Sea Ray. Has to be specific to the gauge..
Click to expand...
Looks like flounder pounder has the matching 0-100 psi sender for the gauge. Not sure if that's the one I bought. Next time I am on boat I'll check my spares box.
https://www.searay-parts.com/Gauge-s/36.htm
 
Got them all put back together and ready to run. Need to do some clean up in the bilge but all in all not too bad of a job servicing the cooling side. A few lessons learned: the. Old zincs wreak havoc if they break apart and sit in the cooling passage. May change them mid season to stay ahead of them breaking down completely.The port side is a PIA but not too bad. Still think it’s easier than impellers on the 320. A few pics one is of the blockage I found in the oil cooler. Also painted the turbos black with a high heat paint and touched up the mains as well.Will see how she fares.
908944AF-EA74-4311-A3B7-3807B1DAB8C8.jpeg

DE24F89E-8682-4F0D-AA71-6FD0A05F79E1.jpeg
 
Irie308 said:
Also painted the turbos black with a high heat paint and touched up the mains as well.Will see how she fares.
Click to expand...

My "MAN man" paints the turbos and charge air coolers (MAN's name for aftercoolers) with black imron paint after major service. No more chocolate milk burned white paint from hi temps. I'm amazed that it is not done that way from the factory by all engine manufacturers. He paints the HE's and other removed parts with white imron. Sure makes for great "eye candy" in the ER!
 
craigswardmtb said:
I pressure tested my older core and it held 30 psi with no leaking. The newer core was also fine.
For anyone looking to build a pressure tester you can do it with about $15 in parts at home depot or a hardware store. I purchased a shrader tank valve with 1/8" mip threads. A 1/2" mip to 1/4" fip brass coupler. A 1/4" mip to 1/8" fip brass coupler. Use pipe dope and thread these three pieces together. Then thread it into one of aftercooler zinc holes. Next I purchased two 1-1/2" flexible end caps. These come with hose clamps installed. These are cinched down on the aftercooler end caps to keep the air in. Thread in your second aftercooler zinc to seal the water side off. Then hook up a bike pump and pump her up to 25-30 psi. I let it sit for a couple hours and saw no loss. I had a bicycle shock pump attached to monitor pressure and fine tune the amount of pressure in there.
Click to expand...
Hey Craig. Can you post a picture of your pressure test setup you made?
 
Irie308 said:
Got them all put back together and ready to run. Need to do some clean up in the bilge but all in all not too bad of a job servicing the cooling side. A few lessons learned: the. Old zincs wreak havoc if they break apart and sit in the cooling passage. May change them mid season to stay ahead of them breaking down completely.The port side is a PIA but not too bad. Still think it’s easier than impellers on the 320. A few pics one is of the blockage I found in the oil cooler. Also painted the turbos black with a high heat paint and touched up the mains as well.Will see how she fares.
View attachment 80792
View attachment 80793
Click to expand...
Nice job! Zincs, aka anodes, are cheap. Change early, change often.
 
I procured the dual engine boost gauge from sbmar and decided to install it where the old wired stereo remote was instead of where the synch gauge is. I decided I still use the synch gauge and the hole for the remote is the perfect size. Still waiting on delivery of 100' of air hose to connect it to the engines.
 

Attachments

  • D89DF31E-74F2-4445-862B-AAC02D758A32.jpeg
    D89DF31E-74F2-4445-862B-AAC02D758A32.jpeg
    84.5 KB · Views: 220
  • 9CA034D1-8B3D-43B5-BE56-70F0D36A31CA.jpeg
    9CA034D1-8B3D-43B5-BE56-70F0D36A31CA.jpeg
    131.5 KB · Views: 219
I finished installing the boost gauge air hoses. Long run from the helm to the engine room. Port was pretty straight forward. Ran the hose along the side then curved over to the engine air hose fitting. Starboard took a little more thought. I finally settled on feeding it through the throttle cable loom then out the end of it and up to the air hose fitting. Sea trial is tomorrow. Too windy here today.
 

Attachments

  • 8AE5A7E5-342D-4FB6-8B94-076B4A80A626.jpeg
    8AE5A7E5-342D-4FB6-8B94-076B4A80A626.jpeg
    55.8 KB · Views: 201
  • 0B011F8D-0633-4E6E-95BA-95A60E95ED0D.jpeg
    0B011F8D-0633-4E6E-95BA-95A60E95ED0D.jpeg
    124.7 KB · Views: 246
  • F01A8300-2A63-48EF-BA86-84F0545B7158.jpeg
    F01A8300-2A63-48EF-BA86-84F0545B7158.jpeg
    98.9 KB · Views: 216
Did the sea trial today. Boost was about 20 psi at cruise of 2240 rpm. Red is the port engine and has three year old rebuilt turbo and also has a slight constriction of exhaust housing due to a rust layer from a previously failed mixing elbow. Green is starboard engine and has brand new rebuilt turbo. It's boosting about 0.5 psi higher. Props are at 22.7 pitch on a 400DB.
F4DE1B75-47C5-4FDD-888D-98C65527CEA5.jpeg
 
Just a turbo boost update and the effect of load on the engine work. Mark (My3sons) educated me that the less boost at equivalent rpm, the better. Less boost means less work being done by the engine. Previous post reported a boost of about 20psi at 2240rpm. Well that was with full fuel and half water and six adults on board. Today with 1/4 fuel and 1/4 water and two adults, at the end of our cruise to Wilmington, NC, the boost was about 16psi at the same rpms.
 
Interesting. I need more instrumentation. I hate not knowing how much fuel i burn, boost, etc on my mechanical 6CTA. Kinda glad i don't have the 480ce given its known overpropping issues on the 420 and 44DB's, but i do wish i had that smartcraft data.
 
Pulled my aftercooler (6CTA)...new to me boat so don't know if they have ever been serviced. Did see where there was a warranty repair to drill weep holes...10 year ago. Port engine was tough and thought I was going to spend the weekend in there until I dropped a few pounds. Easy getting in but removing your body is tough. Aftercoolers look pretty clean...took off end caps and Rydelyme did a nice job on the tubing bundle (done last year). Trying to pull the bundle but no success yet. So why does the tubing bundle need to be pulled? Seal to outer housing is good, mating surfaces good. I have them upright with Kroil on them now....figured I would treat them for 12 hours and then flip them. How many brought these to shop for a press out? Air side looks great from what I can see.
 
EKM said:
Pulled my aftercooler (6CTA)...new to me boat so don't know if they have ever been serviced. Did see where there was a warranty repair to drill weep holes...10 year ago. Port engine was tough and thought I was going to spend the weekend in there until I dropped a few pounds. Easy getting in but removing your body is tough. Aftercoolers look pretty clean...took off end caps and Rydelyme did a nice job on the tubing bundle (done last year). Trying to pull the bundle but no success yet. So why does the tubing bundle need to be pulled? Seal to outer housing is good, mating surfaces good. I have them upright with Kroil on them now....figured I would treat them for 12 hours and then flip them. How many brought these to shop for a press out? Air side looks great from what I can see.
Click to expand...
The core problem is the copper bundle and the aluminum housing contacting each other. That sets up a corrosion nightmare over time if they aren't pulled apart every couple of years and a generous layer of Metalube grease smeared between them to minimize their contact. You are seeing the effects of that corrosion by the fact you can't pull them apart. It also causes the inside of the aluminum housing to eat away and get pitted. Eventually it gets bad enough that the o-ring seal is compromised and seawater leaks into the air side and into your engine. I had to throw one of mine away when I bought the boat and buy new when I couldn't get it apart (with a press or heat). Others here have had same experience. I just service a pair run in saltwater this weekend that we serviced three years ago and the core pushed right out with a light touch. There was no sign of any new pitting in the housing. Only way to be sure they aren't leaking is to pressure test them. Some do that every time they service them.

If you go to Tonys Tips on sbmar.com he has a whole section on this problem and his suggested solution (which I summarized above).
 
one apart and one refusing to budge....using bottle jack on a home made press. Soaking the stubborn one overnight and will try again. Sitting in vertical position with WD 40 sprayed inside and dripping down to seal surface and the top gasket surface soaking in Kroil....spraying every few hours.

Mine are 20 years old and the one core removed looks to be in good shape. Housing in good shape too. Motors have 600 hrs on them and assume they are original. I'm pushing the tubing set from the bottom end first. The one that I had success with pushed thru and then cleaned the top side and pushed back the other way. I could not remove the tube set in one direction only if that makes sense.
 
Both out....so put them on three 4x4 blocks and used a hand jack against an unmovable object. The second one was a little more difficult to get moving. Under load, I tapped the housing with a hammer and if was free. I ended up having to move the core in and out a few times and clean each side before it would slide out. The professionals use a aluminum puck the same size as the core for a push plate. I used an aluminum plate that I had to use as a push plate. Pic is the uncleaned cores as removed with my push plate
Aftercooler Core Pic 6.9.20.JPG
 
You must log in or register to reply here.

Forum statistics

Threads
113,095
Messages
1,425,832
Members
61,017
Latest member
IslandGirls1020
Back
Top