900 low oil pressure and cold filter after oil change???
 

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 ?

:party-smiley-048:

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 ?

I don't run the boat very hard. Very few wide open pulls, but I don't think it's building much heat at all. I remember the starboard motor was always up in the good heat range and then I would look over at the port gauge and it always reads much lower. I will have to pay more attention the next time we are out. Any way to test the sender and gauge??

i would agree that the oil t stat is probibally stuck open.should be an easy fix.im glad you dodged the bullet with the filter.

Rob get a infrared temp gun. Go for a run, take note of the gauge readings at the dash. Shoot the filters for temp, and the pans. See what you get.

As far as the fuel consumption goes, 15-20% seems like a lot. I know you talked about putting a wideband on it to check AFR's last time we talked last year. If you haven't done so, I recommend doing it asap. I recall when I went thru your carbs, imo it had Dangerously small jets for a blown 598 making 900+hp. I didn't wanna see ya melt it down for that fun run, so I stepped it up quite a bit for ya. My guess is you're rich, and could probably lean it down some. Plus, the wideband will get ya an idea on why one might be consuming more fuel. I've seen those old SSM props measure off quite a bit in pitch from each other, that can be an issue too. I doubt the oil temp is causing the fuel consumption issue, but you wanna make sure they are both getting warmed up oil temp wise. Good luck buddy.

Thanks bud, I do have a temp gun and will bring it with this weekend. Also will will be using my wide band gauge. I think this motor has been running cold since I bought it. I believe it may be the oil t stat. I am now trying to find out we're exactly the stat is located. My setup uses a remote filter pad to a plate cooler to a remote filter head. It must be located in the filter head.... Trying to find how I service the t-stat. And which one to buy... I still need to swap the top blower pulley on the port motor as it is two teeth smaller and makes two pound more boost. Thinking this is my fuel consumption issue.

Also props are much newer 5 blade mercury racing cnc props. So I feel they are probably decently close to the same?

I can see the blower pulley thing helping the fuel consumption issue. CNC props then prolly ok. Your oil stat should be in the remote filter housing. Can you post a pic of what kind you got? The mercury ones you can get the thermostat from any merc dealer. If you have the big hardin marine style ones you'll prob have to call them and see if they sell replacements for them. Im sure they do

I will post a pic tomorrow. It looks like mercury to me but its round rather than square like a lot of the Mercs.

Do you recall the filters they take? Like are they the big fat HP6 style mega filters, or the smaller typical thread chevy filters that are just long (2qt style)

I would try and find some oil filters that use a synthetic filter element instead of paper elements. With low oil temps you will get some condensation in the oil. The paper elements will swell with moisture and restrict oil flow. The synthetic will not. I know Mobil 1 filters are synthetic and I think K&N have synthetic elements.

I remember when I brought my Chevelles' engine home from the dyno, I put it in the car and changed the oil. It would go to 70psi then steady drop. If I let it go it looked like it would've dropped to 0.
Those were Purolator filters, swapped the filter out and all was good, then I celebrated!
I use Amsoil filters now. Glad that was your issue and not something worse!

They take just the standard chevy filter. I run the long 2 quart ones. I will be switching filter brands for sure!!

I'm gonna guess here, but I wouldn't be surprised if you had the old mercury filter mounts that do not have oil thermostats in them.

Yea I was laying in bed last night trying to visualize we're they would be on the filter head, and I think you may be right. It's pouring rain here right now so I will get a photo when it stops.