Took our boat out on Saturday, first run of the season. Boat ran excellent, great oil pressure on engines and no other issues. Did oil changes today, both engine drained the exact same amount of oil, and had the same color and texture. New filters, and fresh oil in both motors (15 quarts a piece) starboard motor had 60-65 psi oil pressure at idle and oil filter warms up like normal. Fired port motor, and it very lazily reaches 20 psi oil pressure (use to be between 65-70) and with rpm's actually drops down to between 10-15 psi. Tested to 3500 rpm on the hose. Oil filter does not warm up. It's cold to the touch, but the oil pan is warm. Oil appears to be staying clean after idling for 15-20 mins on the hose. I am stumped. I am thinking either oil pick up fell of. But seems strange it was fine on Saturday and that doesn't explain the cold oil filter. Or possibly the oil cooler sprung a leak and I am bleeding oil into the cooler and that's why pressure drops with rpm's.... But would that also cause a cold filter, and still don't seem to be getting water in the oil. Or could a faulty oil filter cause all of this. They are the CarQuest premium 2 quart filters. Same ones I ran last season with no issues also running the same oil. Problem seemed to develop as soon as i changed oil??? Oil gauges are mechanical with steel braided line from block all the way to the gauge and don't see any leaks any where. ( again fine on Saturday) Engines are 598's with chillers and 10-71's. Any input would be great.

I would change filters and see what happens.

Never had a bad filter myself but have heard about it before and killing pressure like that.

I would be changing that filter first and see what happens .

Who would have thought. It was the filter. Changed it out for a new one and am now seeing 75 psi at an idle. Talk about heart failure...... Thank you for the suggestions!!

This has to be one for the books- What could have been so bad with the filter to cause this? Did you cut open the filter to see what was inside?

very interesting -- glad you got this resolved

safe boating

3pointstar

Lol awesome to hear, where's our cold beverage ?



I kid, I kid

Rob,
My guess would be that for some reason, the filter was not flowing any oil. The oil was forced to flow through the by pass check valve in the block. That may explain why the filter didn't get hot .

Good find. I've seen that once in a Buddys old convertible GTO. He fired it up first time after sittting all winter. His oil pressure was real low, like 5-10psi at idle on a mechanical gauge. Immediately I told him the engine needs to come out. Then I thought to ask, "When was the last time you changed the oil and filter?". He looked at me like," IDK, the probably right before I bought the car a few years back". I said why dont we start there then. Sure enough, new filter and oil and all was good.

I never would of thought either, but I sure am thankful!! My filter still is not getting warm however. And now that I think about it that motor doesn't make much oil temp when cruising around either. I always assumed it was a sender or something, but I am thinking maybe I have a stuck open oil t stat. At least I will sleep tonight. Could cold oil affect fuel consumption. This same motor likes 15-20 percent more fuel at every fill up.

Does the oil temp in that engine reach at least 190* or real close to it ?