CAT 3126 Oil Consumption Issue?

[400 EC Michigan]

Hi, I have a 1997 450 Sundancer with CAT 3126 engines. I love the boat, engines and performance. However, thispast summer I put approximately 65 hours on the engines (approximately 1200miles). The starboard engine consumed nooil and the port engine used 5 quarts of oil. Wondering if this is an issue?
The starboard engine was replaced prior based upon ‘softblock’ issue and the port was okay (by previous owner and CAT). The engine serial numbers are: Port- 8NM01423and starboard: 8NM03243 (hours: 550.1 & 546.2 respectively). I purchased theboat during the fall of 2013 while in winter storage and the final payment wasbased upon successful CAT engine inspection (Michigan CAT). In May 2014 I had a crankcase blow byperformed along with oil samples and sea trial. No issues with crankcase blow by, oil samples and both engines reached 2800 RPMs with synchronizeron and 2800+ with synchronizer off. Ihad a second crankcase blow-by performed before putting the boat away inSeptember 2014 because of the oil consumption. The checks showed no issues. TheCAT mechanic has known the boat since new (the previous owner was only putting10-20 hours per year on the boat for the prior 6 years -the reason the boat wasfor sale) with no known issues. As you can tell we spent timecruising with no speed issues (28-29 MPH cruise speed at 2400RPM).

 

[Turtlesboat]

5 quarts of oil is a lot IMO. I burn no oil in mine. I would look into into this.

 

[carterchapman]

I burn no oil in mine. Do you have Walker AirSep filters?

 

[fwebster]

This is far from normal. Have Caterpillar diagnose the problem. Since you say they have done 2 blow-by tests and found the engines sound, they should feel some obligation in the resolution if they find that you now have a soft block on the other side. This is important since Cat no longer warranties the blocks.

 

[ttmott]

If engines are tight and no external leaks then suspect turbocharger shaft seal failure or turbocharger oil return line restriction.
Have Cat do another oil analysis on the engine also, in fact do everything again for comparative reasons; a problem with the engine block will show up there.

Frank - I was under the impression all of the S/N's that had problems were accounted for; don't know why I think that, maybe read something on boatdiesel..... There is a casting code denoting the French cast 3126 blocks right?

 

[fwebster]

Tom,

There is a casting code on the top edge of the block, just below the head. It would be visible, with some looking, on the front (really the back since a v-drive installation is backwards outboard side of your port engine, inboard on the stud side. I believe the casting code is FAPS on the suspect 3126 blocks.

We had a 3126 powered boat surveyed by the Caterpillar dealer in Seabrook, Texas 5-6 years ago. That dealer's impression was that all Caterpillar could tell them was that all FAPS 3126's were accounted for, but not all FAPS blocks were soft. A blowby test will determine premature wear so lost compression, oil consumption and confirming blow by test were how they diagnosed the soft blocks. Cat did handle the repair up until about 2004 (I'm not sure about the exact date), but they could not recall the engines since they didn't know which 3126 FAPS engines were soft and which were not.

Ring Power down near you was the Cat distributor who handles Cat engine sales to Sea Ray. They would have processed every warranty claim on failed engines so I'd bet their guys know the true skinny on this. I have their Service manager's name in a file in Tennessee I can get for you when get go back next week if you care to pursue it.

 

[ttmott]

Tom,

There is a casting code on the top edge of the block, just below the head. It would be visible, with some looking, on the front (really the back since a v-drive installation is backwards outboard side of your port engine, inboard on the stud side. I believe the casting code is FAPS on the suspect 3126 blocks.

We had a 3126 powered boat surveyed by the Caterpillar dealer in Seabrook, Texas 5-6 years ago. That dealer's impression was that all Caterpillar could tell them was that all FAPS 3126's were accounted for, but not all FAPS blocks were soft. A blowby test will determine premature wear so lost compression, oil consumption and confirming blow by test were how they diagnosed the soft blocks. Cat did handle the repair up until about 2004 (I'm not sure about the exact date), but they could not recall the engines since they didn't know which 3126 FAPS engines were soft and which were not.

Ring Power down near you was the Cat distributor who handles Cat engine sales to Sea Ray. They would have processed every warranty claim on failed engines so I'd bet their guys know the true skinny on this. I have their Service manager's name in a file in Tennessee I can get for you when get go back next week if you care to pursue it.

Thanks Frank - no, don't go out of your way; I was more curious than anything as this OP is concerned after so much time. Although seems his engines are unusually low in hours.

 

[The Bill Collector]

zero consumption here.....

 

[400 EC Michigan]

Okay everyone, I appreciate your input so far and not surewhat toplan for this spring. Just soeveryone is clear:
· Boat was identified as originally having susceptiblesoft blocks from the factory.
· Both engines were checked by by CAT and the Starboardengine was changed by CAT and original vessel owner.
· Boat was purchase in Nov, 2013 with escrow moneyput aside because the Port engine was tested to be ok when starboard wasreplaced I wanted assurance of no issue.
· Escrow money was released in May 2014 after the CATtest (blow by test, oil analysis and sea trial) for issues with port enginewere negative and everything showed good. In fact the blow-by test showed the port better than the starboardengine!
· No issues during the summer except for replacingleaking selector valve on fuel primer pump (port engine).
· No oil leaks on either port or starboard engine. Nice and tight and no marks on PIG pads.
· I do not remember seeing any oil / smoke residueby port or starboard exhaust outlet in hull.
· Because I noticed oil consumption after a cruisefrom Port Huron to Bay Harbor and back I contacted CAT to schedule a blow-bycheck and oil analysis again in September 2014 because if there was an issue I wantedthe winter to have the engine repaired. All tests were good. CAT did notfeel it was an issue and I should monitor the beginning of 2015 season for anyadditional oil consumption.
· The following is the oil analysis-
Element May 2014 Sept. 2014
Al 1 1
Ca 2408 1963
Cr 0 1
Cu 4 11
Fe 38 35
Pb 0 2
Mg 8 151
Mo 1 77
Ni 0 0
P 1103 842
K 0 0
Si 3 2
Ag 0 0
Na 2 0
Sn 0 1

Some of the things to do next based upon your comments-
· Have blow-by check and oil sample/test performedagain at spring 2015 oil change and launch
· Have oil analysis performed again
· Turbocharger- check turbocharger oil return line

Bruce

 

[400 EC Michigan]

One more thing. I do not have the blow-by readings from September 2014 but have the May 2014 readings which were: Port-170 and Starboard-260 taken during sea trial at speed. I was told for the 420 HP 3126 engines the 'concern' value is 630 (1.5 x HP).

Bruce

 

[ttmott]

My thoughts are if you had a blow-by problem there would be oil on the engine. As these engines are turbocharged the cylinders operate above atmospheric almost all of the time so the blow-by will tend to move oil out of the engine rather through and burn it. The crankcase vent filter would be continuously venting and oil misting the bilge. You didn't say but do you have the Walker Air-Sep air filters? Take a look at both the inlet and discharge of the turbocharger compressor; this will help determine if you have a seal leaking or return line restricted. Also, look in the turbine discharge to see if oil is coking or the riser is coated with oil; again this will help determine if you have a seal or oil return issue. These are easy things that anyone can do with a couple of wrenches and screwdrivers.

 

[Almirante]

Hi, we have engines from the same series. (8NMO1681 and 1684). I think also that 5 quarts are too much. My port engine used 1 1/2 quarts within 50 hours. The starboard engine, which was made new about 30 hours ago seems to use no oil until now.
I had the same "softblock problem" with the starboard engine. I bought the boat with this starboard engine broken. Payed about 20 k Euros for replacing broken valves, new turbo...and cylinder head overhaul. Then after some hours the engine broke again. Now CAT decided to replace the complete block, cylinder head and so on. Everything on CAT warranty now...

Stefan