6.354 oil pressure drop/ oil weight

Posted this on boatdiesel.com but thought I would see if anyone here had this experience...


We have a newley rebuilt 1978 6.354. It was originally rebuilt at TA Diesels, then suffered a severe overheat when a hose clamp on the freshwater side busted and the old guages did not catch it...after another rebuild at a local shop, all new senders, wiring, and guages from TA as well as mechanical oil/temp gueages installed, we are noticing a few things. When we broke it in we either ran 15w-40 or 30w rotella cannot remember...we where having issues with it setting off the oil pressure alarms once it was warmed up, but all the time, especially when maneuvering. We switched to 40 w. Upon cold start up, oil PSI on electric and mechanical guages is around 50 psi, dropping to 40 after warmed up. usually after about 45 minutes of running at cruise (2000 rpm) oil pressue will be around 30 psi...after cruising for a long time and while hot(178) when we drop below 1000 rpm or start maneuvering, the oil pressure drops WAY down around 10-12 psi and starts setting off our alarms. As soon as I rev it back up around 1000 it will come up enough to kill the alarms....but that means I am either shifting a little high, or listening to the alarms, which is not a good feeling...

So question is, has anyone else experienced this, what is the normal range for these engines, and what wieght are most people running? With the Shell Rotella 40w we are running now, we achieved higher pressures than 15w40 or 30 w, but not enough to keep alarms from going off at idle/shifting after a long run...around 85 hours on it now...

"10-12 psi and starts setting off our alarms."

What you experience is not that abnormal.

Simply go to NAPA and get alarm switched that contact at 5 psi, a complete range is in their catalog.

A DD used to REQUIRE the low oil light be ON ! ( 5 psi,to assure idle rpm) to engage some clutched accessories.

Once again Murphy gauges would solve the hassle.

Although so would a new set of main and rod bearings.

Tim,

my 6.354's are somewhat older than yours, probably around 1978 - 1980. 3000+ hours on the clock.
I have been using single grade*30 oil on them.*My engines run at approx 50 psi (1500 RPM) at cruising temp. When throttling back to idle*the oil pressure will drop to approx 20 psi. After**5 - 10 minutes*at idle the oil will cool down and the pressure will rise to 25 - 30 psi.

The alarm is there for a reason. Somewhere inside your engine is bleeding oil at a rapid rate.

I ran a T6.354 for many years. I used Castrol 20-50. When hot pressure would drop to 15 (ish) at idle for a few minutes then it would go back up to 25-30. It was a healthy engine.
I suggest installing a mechanical gage to understand what the pressure really is before driving yourself nuts.

*

Mine are around 50-55 PSI and don't drop much at idle. 2,300 hrs.
Running Delo 15/40

So Charles, you missing the boat yet? We're headed to Lake Charles this weekend for the grand opening party for the new marina there.

It's in the SE corner of the lake, where that little inlet is. To the far right of the convention center and pavillion. Here's a little video from the mayor where you can see what they've done to that area. Trying to attract more tourism in there.

Hi Tim,* Our 6.3544's run at a constant 60psi on straight 100 -30wt, and burns almost no oil between changes with about 4000 hours on the clock.* Idling only drops the pressure 10 to 15psi when hot.* Unfortunately, it sounds like your loosing oil pressure somewhere. When the engine was repaired after the over heat, were the bearings (mains, rods, and cam) replaced, or at least the clearances checked?* I'd check with the shop who did the work and get their opinion, but to me it sounds like there might be an issue.................Arctic Traveller

Sounds like I should switch to 30wt? I have been using the multi because previous owner did.

Thanks for all the responses. I have been up in northern*Michigan relaxing and watching all those fresh water sailors enjoy their boats from shore so away from computer for a few days. *I do have*a pair of Stewart Warner*mechanical guages on it. They are dead on with the electric guages at start up and running at cruise. I have not been in the back of the boat(engine hatch is in the cockpit, I run about a 8ft shaft off the transmission forward to a Walter V drive)*when shifting, I'll have to go get it hot and let someone else play with it in deep water....

So far the oil samples at 20 and 50 hours have shown no negative wear metals.

I have spoke with the mechanic at the shop many times about it, thats how we got to the straight 40 weight....he is an ex hatteras/Detroit Diesel guy, and if the comments about the oil pressures on those engines is correct, maybe that is part of his thinking...we did replace all of those parts...the reason I used him was because most peoples biggest complaint was that he was TOO meticulous and took to long getting things right on engines, that his standards where too high, etc.

Good to hear others have put so many hours on their engines. When we bought the boat the engine had supposedly been rebuilt and only had 30 hours on it, but in doing our rebuild, we found some suspect parts which started to make us worry about this one....

1) the head, yea that one, the rv head uses less than a cup of water to flush, no motors, pumps nor macerator and gravity dump!

Most boats have the ability to use an RV head , with a bit of prior knowledge on the part of the NA (if there ever was one) and the builder .

Just as proper easily maintaining fuel tanks were common knowledge in the 1930's , the lack of owner demand allows the boat assembler to save a few bucks.

The other , perhaps even better RV item is propane refrigeration.

Any knowledgable NA would have this option on any cruising boat , as refrigeration is the major cause of dead batteries, long noisemaker operation and dead food.

People talk abt "nevercold" it is actually that the builders do not ventilate the units so they cannot operate properly.


IF folks ever bothered to go on the Mfg site for most of the equippment aboard a new boat , and downloaded and read the installation requirements , most of the year long shake down on a new boat night go easier.