Temps and Tach
 

It seems my Starboard engine always runs a bit warmer than the Port. Is this normal and from the photo, do the gauge indicators seem close enough to not be a problem. Engines have about 350 hours of easy running. Any suggestion / input appreciated. Boat 33 Scarab AVS w 502 MAG MPI's

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Switch the gauges and see if you get the same readings.

Is the power steering pump load on the warmer engine? Are cooling systems equally free flowing - blockage, partial opening thermostat etc.

Power steering IS on the Starboard. Could that be it? As for blockage???? Not sure, mainly posted to see if it "might" be normal for them to differ a bit. Switching seems to be an easy (rather than tear down) idea. I would be switching the SENSORS ??

Oh, I know this one. Your water pressure is going to high on Starboard engine. You have (as i did) have something plugging the discharge. In my case, an old impeller chunk (i never had an impeller failure. Who knows how long that was in the block) got lodged in the thermostat housing that feed into my risers. (this is the path out) Luckily for me, none of the chucks plugged or made it to the risers. Sometimes, if you have a voltage or ground variance in your electrical system, it will cause similar issues with your gauges, but in your case the oil temp is following the water temp. Good luck

Thanks guys.... its actually cold here in Texas this year so probably time to pull some hoses, guages and thermostats off. Probable a bit of all the below. My thought of a simple, just a variance probably "ain't" just what it is.

Last quick though on your gauges. I see your oil pressure is lower on the colder engine. I just put manual Autometer gauges on mine (engine compartment only) because of this same concern. The manual results were that the oil pressure was exactly the same on both engines even though my electric sending unit style gauges tell me otherwise. Going to change my port sending unit because it's showing lower than it really is by 8 psi hot. If that doesn't correct the error i will be chalking this up to higher resistance from longer wire run.

Don't be afraid to updating the OSO world on your findings.

I definitely will let y'all know what I find and do?
: my plan of attack
1. Check for stray impelled pieces, in both lower hoses, thermostat and discharge. Ive blown a few sets over the years.

If I don't find any pieces

2. Switch out the oil sender for a start.


Wish me luck, last summer mostly spent house hunting and moving.

Looking for many more days on the water this year

is that 35psi water pressure, and 30 isn't that to high, wont it oush the intake or headgaskets out.

Seems all temps/pressure a bit high. Sitting at home thinking a clogged artery might be it.

My 502mpi's have pretty high water pressure also, but not at 3500rpms. I run about 20psi at 3500 and at WOT, they will push 35psi. Its higher than I like, but in 530+ hrs, has not created any issues

If the water presssure is that high, I doubt you have much debris/impeller pieces stuck. If I get any sizeable debris, it gets stuck at the entrance to the oil cooler and my water pressure drops about 10-15psi.

It all depends where the blockage is. Lower pressure would mean before the gauge pick up tube (usually found before the thermostat in the intake manifold). Higher pressure would indicate after the pickup. I.E. thermostat housing, exhaust manifolds and/ or risers.

As a FYI only, I never see over 12 psi. on mine.

Looks like all the starboard gauges are a smidge higher than the port. Water temp, oil temp, and oil psi. Could be a weak ground behind the dash.

In regards to the temp though, looks like they are running in the 180 range water wise. I believe they should be 140-150 with the merc thermostat?

I had a similar problem on a little different setup. (crossover w/ bypass) Port engine ran 170*F and starboard ran 160*F. To solve my problem I had to restrict my bypass a little to allow more water to flow through the engine. This increased block pressure a little but cooled the block. So what I'm trying to say is don't just concentrate on water delivery, but also water exiting. Thus a little bit higher water pressure on that engine. Flow is the inverse to pressure and flow is more important than pressure unless you have to much pressure.

Also, check your grounds.

Dam! you mild!! I guess great minds think alike!

502mpi's use 160* Tstats and mine will run between 165-175 on the guage most of the time and up to 180* after a hard run.