Putting Tow Vehicle Exhaust Underwater?

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Alumarine

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I doubt submerging your exhaust in water is causing low oil pressure. Depending on the year of the Suburban ive seen senders failing, instrument clusters failing and worn bearings or oil pump. Pretty wide spectrum right. Senders the easiest way to start id also do an oil change with a quality oil and filter and id run 5/30 which is what anything 2000 or newer specs at. While you can run a thicker oil it was designed to run on this you actually stand a better chance at oil starvation with to thick than thin. If its a gauge issue there are on line rebuilders that will repair and program them to work without seeing a shop with that tooling. If its worn bearings it will need to be tested with a pressure gauge the labor on this is almost the cost of a reman cluster for sure more than having a sender installed.

Now on to submerging your tow vehicle. For those who might have done this. Exhaust isnt an issues. But the rear diff thats another story. You drag a boat on a hot day and back the rear diff deep enough for the vent or any other place that a possible water entry point such as an axle seal which is a couple inches lower than the center of the rear wheels. Hot rear diff hits the water and cools off fast. Any air and theres lots of it contracts requiring the vent which is usually small and often on a rubber hose plugged with dust dirt or some bugs egg sack or its actually below the water line. Water gets drawn into the rear diff and if left long enough oil will float out water will take its place. Water is not a good lubricant and it doesnt play well with gear oil. The cool part is seeing this failure first hand. We had one a long time ago he burned up a couple rear ends. Come in with half the needed oil. What happens is the water boils away and leaves whats left of the gear oil a mess and a bunch of damaged parts. No real evidence of water though. Just a topic I thought id touch on in case it helps prevent someone from landing here.

Good idea to move the breather up higher then with a length of hose and some ty-wraps..
 

bruceb58

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The newer design, AC Delco pf1218, has a anti drain back valve in it.
Why would that be an issue with an engine that has a vertical filter like the 5.7L Chevy has. Where is the oil draining too?
 

72fj40

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On a vertical filter application, the anti drain back valve prevents the oil galleys from draining when the engine is turned off. It's not critical to have one in the filter, but can explain the rattle the OP mentioned on start up, and a slight delay in oil pressure.


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TyeeMan

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Doesn't the anti drain back valve prevent the filter from draining if it is mounted side ways or up side down as with mi boat?
If the filter is mounted vertically, , threads and gasket up, the anti drain back valve is kind of a non factor isn't it?

Could likely be wrong.
 

72fj40

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If the filter mounts side ways or upside down, yes the anti drain bac valve (adbv)keeps oil in the filter. The ADBV is a one way valve. When the engine is turned off and the oil galley is above the filter, then gravity forces the oil back towards the filter and the valve stops it from flowing back thru the filter and towards the oil pump. It keeps oil in the galley when the engine is turned off.
 
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bigdee

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Doesn't the anti drain back valve prevent the filter from draining if it is mounted side ways or up side down as with mi boat?
If the filter is mounted vertically, , threads and gasket up, the anti drain back valve is kind of a non factor isn't it?

Could likely be wrong.

You are exactly right. Most all filters have a anti drain valve.....more of a marketing sales pitch than being all that important. There is always enough residual oil on bearing surfaces to protect them until oil flow returns.
 

PITBoat

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The old AC Delco PF25 oil filter is what I was initially worried about causing the issue, but when I changed it to one I confirmed was correct for my vehicle, the 'problem', if one it is, didn't go completely away; that's why the exhaust question came to me.

To clarify, the indicated oil pressure is normally grand; it's only right after startup where there is a moment of nothing. So if the gauge is faulty, it's only then, unless the rest of the time it's lying to me about good oil pressure.

You guys have me wanting to check the rear diff. oil now though. Changing that's only been on the to do list for about 3 years now. And visually locating the vent while I'm under there.
 

Prophammer

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I usually shut the engine off when I leave it at the ramp to go to the dock, I always think to myself- if it slips out of park and goes under; it would be better if the engine didn't go down running , especially in saltwater , but I don't think freshwater would hurt anything if the just exhaust tip was submerged, I've had to do it once or twice myself , don't think oil pressure would be affected at at all by that, my 98 K1500 truck rattles a little but it clears up when warmed up, keeps on going " knock on wood"
 
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