Ran engine out of oil, what do you think? Mercruiser 5.7

indy440

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I have a 22' wellcraft and last year I installed a re-manufactured mercruiser 5.7 and we used it all summer and really enjoyed it. However, at the end of the season my wife and I were out with another couple, going across the lake maybe 4300rpm, I was standing and driving not looking at the gauges. The oil drain plug somehow fell out. Im not sure how long it ran without oil, as soon as the engine sound changed i looked down and saw no oil pressure and immediately shut it off. I assume the change in sound was when the lifters lost oil and began to collapse. We got towed back in and headed home. That night I found the drain plug, tightened it (not stripped), and refilled the oil. I fired it up and it was noisy until the lifters pumped back up. It ran on the hose for probably 30 mins and sounded normal so I swapped a fresh oil filter in and cut the old one open to check for bearing material, it looked good. The next day we went to another local lake to test it out. We ran it hard all day tubing and going fast. At one point i held it WOT for probably 15 mins. It seemed fine. The next week I had surgery and was done boating so the boat was put away for the winter. I just pulled it out of storage a couple days ago and havent started it up yet. I have no idea if the engine will last or if it might blow up the first time out this year... What are your thoughts? The engine probably has less than 50 hours on it total. Should I buy a new engine and keep it on hand? Pull this one, flip it upside down and check all the bearings?
 
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flipbro

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What's the oil pressure now? If you've got good oil pressure and no knocking noises I say you got lucky and run her..
 

indy440

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My father-in-law asked the same question and I couldn't give him an accurate answer because the gauge in the dash bounces around a lot (always has). He gave me an analog test gauge to connect where the pressure sending unit goes. I have not started the boat yet this season so it hasn't been tested. What should the minimum pressure be at idle on a warm engine (plan to run it on the hose for 45 mins at 2000 rpm, it wont starve for water my pressure is incredible 95-100psi out of the tap).
 

Bondo

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What should the minimum pressure be at idle on a warm engine

Ayuh,.... 10 psi, per 1,000 rpms,....

On the muffs, the motor will never really get to temp, ya gotta splash it, 'n run it under load,....

By the sounds of it so far, Ya might be just fine,.....
 

jimmbo

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You said you ran it the day after and there were no issues. Does your engine use a roller cam, or a regular tappet cam? If flat tappet, I would, remove the intake and valve cover and inspect a few lifters and lobes for galling
 

indy440

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Yes and I ran it hard all day. No easy cruising, lots of WOT and fast starts and tubing. Thats a good ideal to pull the intake, but I dont think i can do it without pulling the motor. Its kinda tucked under the rear deck and i dont think i can get the distributor out...
 

flipbro

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You said you ran it the day after and there were no issues. Does your engine use a roller cam, or a regular tappet cam? If flat tappet, I would, remove the intake and valve cover and inspect a few lifters and lobes for galling

If this worries you then just pull the valve covers. Disconnect the coil wire and crank it over the push rods and lifters should spin a half rotation. If they don't you've damaged a lobe.. Use a paint marker to mark the push rods makes it a little eisier to see..
 

jimmbo

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Yes and I ran it hard all day. No easy cruising, lots of WOT and fast starts and tubing. Thats a good ideal to pull the intake, but I dont think i can do it without pulling the motor. Its kinda tucked under the rear deck and i dont think i can get the distributor out...

I would just run it then. You gave it a good torture test and it seems to have passed.
 

airdvr1227

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^This^ run it and see what happens. Get in the habit of scanning your gauges while underway. Oil pressure and engine temp are the ones to pay close attention to.
 

indy440

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I'm going to run it so long as the oil pressure looks good on a the test gauge I have (like i said, the dash gauge bounces too much to get an accurate reading).

I also do look at the oil and temp gauges very often but a buzzer would have been ideal for this situation.

It was weird that the plug came out of it. I put at least 300 gallons of fuel through it since the last time it was out but it must have been loose...

Our summer is so short I'm still temped to buy another reman engine and just let it sit on the stand in the garage. If i blow this one i can be back out in a day, rather than waiting a week or more for another engine to ship. The last one was a complete drop in repower, this time I would just get a complete long block and swap the rest over
 

Bondo

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(like i said, the dash gauge bounces too much to get an accurate reading).

Ayuh,.... So Fix it,.....

It's either a bad gauge, bad sender, or bad wirin' connection,....

The sender will be down low port side, just ahead of the block's filter boss, or at the aft of the intake manifold, next to the distributor,...
 

Alumarine

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Do you have that in your boat? Just curious as to how it installs, and if they are adjustable at all.

I have a kit ready to install.
I decided to get one after my accessory belt broke last year. Luckily I noticed the temp rising in time.

I have a 140hp/3.0 liter and my current oil pressure port had a Tee already so I will put the oil sender there
and alongside the current water temp sender is a spare port.
They are not adjustable. Oil alarm is 6psi or less. Temp alarm is 200F or higher.
 

indy440

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Ayuh,.... So Fix it,.....

It's either a bad gauge, bad sender, or bad wirin' connection,....

The sender will be down low port side, just ahead of the block's filter boss, or at the aft of the intake manifold, next to the distributor,...


yea I agree it needs to be fixed. The sending unit is by the distributer, i remember from installing the engine...
 

MichaelinAZ

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Had a 5.7 in a bayliner that a friend of mine ran out of oil. Added oil and it ran for about two years before it finally spun a bearing.
You could tell that the crank had been roughed up a little, worn smooth and then finally gave up.
 

JerryIrons

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I have a kit ready to install.
I decided to get one after my accessory belt broke last year. Luckily I noticed the temp rising in time.

I have a 140hp/3.0 liter and my current oil pressure port had a Tee already so I will put the oil sender there
and alongside the current water temp sender is a spare port.
They are not adjustable. Oil alarm is 6psi or less. Temp alarm is 200F or higher.

Thanks for that, I have an older boat and this seems like a good idea just for the peace of mind.
 

indy440

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I took the boat out saturday and again Monday. On a warm engine the oil pressure is at 10psi @ 650rpm idle and goes to 40psi by about 1700rpm, then tops out around 45psi shortly after that. We didnt go far and only burned maybe 30 gallons of fuel in total. I ran it pretty hard in short burts, and cruised around 3500rpm for several miles at a time. I had my tubing prop on so it would over rev at WOT, I held it to about 5000rpm and then i'd let off. The engine seems fine.
 

indy440

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put another 30-40 gallons of fuel through it last weekend. Still seems as good as new...
 

R055

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put another 30-40 gallons of fuel through it last weekend. Still seems as good as new...

You should be fine, there are videos of guys running engines on stands without oil for over 5 minutes before the engine finally gives out.
 
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