Stupid me, no oil

Grub54891

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Jun 17, 2012
Messages
6,137
Had a leak on the intake myself. Had the heads re-done and they milled them flat. I used the end gaskets for the intake that came with the kit. Turns out when you shave the heads, the gasket is too thick. It squished out. My fix was to remove the remains of the gasket without removing the intake and using a good engine silicone in the area after cleaning with brake clean. Never leaked again. Had another one that the oil sender was leaking badly.
 

Lou C

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Nov 10, 2002
Messages
13,023
Just thought of another thing
Does this engine have the dipstick that hooks up to the drain plug in the pan? If so, there is supposed to be a rubber plug where the normal dipstick would go. If this rotted out or fell out you’d lose a LOT of oil! Starboard side of the block right at the bottom of the block
 

Pmt133

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Jan 6, 2022
Messages
729
Just thought of another thing
Does this engine have the dipstick that hooks up to the drain plug in the pan? If so, there is supposed to be a rubber plug where the normal dipstick would go. If this rotted out or fell out you’d lose a LOT of oil! Starboard side of the block right at the bottom of the block
My machinist actually peened in a stainless ball into that hole for that reason... think he said if that starts leaking I'll have bigger problems to worry about or something.
 

nola mike

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Joined
Apr 22, 2009
Messages
5,407
what can leak in the back of a GM V6?
Intake manifold gasket (especially where it contacts corner where block meets heads, meets intake)
Valve cover gaskets
Oil pressure sensor (if it screwed into the block back there)
Distributor missing gasket / o-ring where it enters intake
Doesn't look like any of those.

Rear main seal.

Only real bad one is the rear main. All others can be found by reaching back there and feeling for oil, start at the top and work down. Good lighting and mirror helps.
I can see oil at the rear base of the engine, that's it.
I just saw a super powerful black light on South Main Auto’s you tube. Put some dye in the oil & it will be obvious!
Well, I can see oil already. Everything forward was cleaned off, and there's nothing leaking above the head that I can see. So how would the light help? I don't think there's anything I'm missing that wouldn't require an engine pull to access.
Just thought of another thing
Does this engine have the dipstick that hooks up to the drain plug in the pan? If so, there is supposed to be a rubber plug where the normal dipstick would go. If this rotted out or fell out you’d lose a LOT of oil! Starboard side of the block right at the bottom of the block
I don't think so. I have the pan from the Blazer I pulled the motor from. Drain is on the port side, dipstick is starboard. Good thought though
 

04fxdwgi25

Chief Petty Officer
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Mar 25, 2022
Messages
583
Some reason, I only considered leaks high on the engine. What about the pan itself? Maybe the gasket got borked when installing. I have seen a couple of V6 pans crack back around the rear main area.
Did the oil pan have any rust on it when installed?

Steel oil pans and damp bilges don't get along well.
 

tango13

Petty Officer 3rd Class
Joined
Mar 10, 2015
Messages
75
Do you think your leaking a qt every 10 hours or burning? Do the 4.3's have the oil pressure sending unit in the back of the motor like the V8s? If so, maybe your leak and slightly off pressures are stemming from that.
 

Lou C

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Nov 10, 2002
Messages
13,023
Some reason, I only considered leaks high on the engine. What about the pan itself? Maybe the gasket got borked when installing. I have seen a couple of V6 pans crack back around the rear main area.
Did the oil pan have any rust on it when installed?

Steel oil pans and damp bilges don't get along well.
You really have to spray them with Corrosion X every few years. I’ve been doing that and my 1988 4.3 still has the original pan & it’s been kept on a salt water mooring for 20 seasons 5/6 months each season.
 

nola mike

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Joined
Apr 22, 2009
Messages
5,407
Ok, had planned on pulling the engine in the fall, but personal crap got in the way. Still haven't had a bunch of time, but managed to get the engine out yesterday. Everything going fine until I ran into the starboard rear mount, which was completely seized. Took me a few hours to get out. Getting dark last night, and now pouring rain on my only day to get this done for a couple of weeks...


IMG_20250414_185908.jpgIMG_20250414_191741.jpg

The mount sleeve had frozen to the flywheel cover. I guess 24 hours of being pickled on brine didn't do it any favors either. Took a LOT of force to get it out of there. I was afraid of breaking something/rounding off the head. It laughed at the impact wrench (I can see why now). Was afraid of making things worse if I cut off the head/broke the bolt, but I think I'd just be in the same place. Tough to get heat/oil to the offending area. Now need to clean out the hole, hopefully that won't be another project. Not sure why it isn't recommended to coat that in grease before install (maybe it is?)


IMG_20250414_191250.jpg

Spacer for my O2 sensor. 2 seasons. The aluminum is not liking the salt/iron combo. I still haven't dialed in my carb, so want to keep it in there. Not sure how to make it behave.

Potential leak sources:

IMG_20250414_190946.jpg
Remote oil filter. The worm clamp on the left was loose, and there was some oil at the top. This looks like the most likely suspect. Would **** me off to have pulled the engine for this.

IMG_20250414_190856.jpg
Other end of the oil filter. Some oil around the plug as well. I paid attention to this when looking for the leak. Didn't seem like it at the time, but who knows. I'll remove it and refasten.
RMS: No pics, but didn't look like a ton of oil around there. Haven't removed the flywheel cover yet. If it's clean under there I'm questioning pulling the flywheel. But it would be ridiculous of my not to replace the RMS at this point.
Want to confirm that this is the right part?
I can't find it on the mercruiser parts diagrams for some reason.
Oil pan looked OK, didn't see any specific leaking. This is all difficult since the oil has now been sitting since october and nothing looks fresh. In retrospect should have run it prior to pulling it.

Other "while I'm in there" items:
1. Bilge pump. Need to find a better way to fasten it so that it both works and is accessible/removable. Sheetmetal fastened on the side of the motor seems like the best solution, but open to others.
2. Clean off everything, repaint. I've got a soda blaster that I've been itching to use. There's a lot of rust on there.
3. Corrosion protect everything. Anybody have a favorite? Boeshield?
4. Replace spark plugs! Gotta remember that. Much easier with the engine out.
5. Steering cable. Got tight last year, again probably not helped by the dunking of the boat. I have a spare that seems ok. Wondering if I should just suck it up and buy a new one. It doesn't look impossible to get to with the engine it, but def easier with it out.
6. Flappers: These were wrong and needed modified when I put them in 5 years ago. They looked out of position, dunno if they were doing any good at best or restricting exhaust at worst.

Anything else?

IMG_20250414_191747.jpg
 

Bondo

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Staff member
Joined
Apr 17, 2002
Messages
71,079
Not sure why it isn't recommended to coat that in grease before install (maybe it is?)
Ayuh,...... It took awhile, but DonS convinced me, that any nut or bolt you think you might want to remove someday,......
Coating the threads with Perfect Seal, Works,....
Not never-seize, not grease, Perfect Seal, aka: Permatex ,form-a-gasket, non-hardening liquid,.....
 

Lou C

Supreme Mariner
Joined
Nov 10, 2002
Messages
13,023
I would for sure change the steering cable
Also unless nearly new, the starter
Next, any sign of leaking at the steering actuator? They are very tough if not impossible to change with the engine in place.
I’d also look at the joint between the Y pipe & transom mount for leaks and the steering arm for play & leaks….
Obviously the exhaust also….
 

Lou C

Supreme Mariner
Joined
Nov 10, 2002
Messages
13,023
Ayuh,...... It took awhile, but DonS convinced me, that any nut or bolt you think you might want to remove someday,......
Coating the threads with Perfect Seal, Works,....
Not never-seize, not grease, Perfect Seal, aka: Permatex ,form-a-gasket, non-hardening liquid,.....
Agreed 100% and I’ve been doing that ever since I read it in my OMC shop manual…now that you can’t really get Perfect seal or Evinrude gasket sealer (same supplier?) I’m using Permatex Aviation….
As far as sprays, I have used them all, not sure if there much difference but the lanolin ones like Fluid film or Woody Wax seem to last longer.
 

Scott06

Admiral
Joined
Apr 20, 2014
Messages
6,722
Ok, had planned on pulling the engine in the fall, but personal crap got in the way. Still haven't had a bunch of time, but managed to get the engine out yesterday. Everything going fine until I ran into the starboard rear mount, which was completely seized. Took me a few hours to get out. Getting dark last night, and now pouring rain on my only day to get this done for a couple of weeks...


View attachment 406823View attachment 406819

The mount sleeve had frozen to the flywheel cover. I guess 24 hours of being pickled on brine didn't do it any favors either. Took a LOT of force to get it out of there. I was afraid of breaking something/rounding off the head. It laughed at the impact wrench (I can see why now). Was afraid of making things worse if I cut off the head/broke the bolt, but I think I'd just be in the same place. Tough to get heat/oil to the offending area. Now need to clean out the hole, hopefully that won't be another project. Not sure why it isn't recommended to coat that in grease before install (maybe it is?)


View attachment 406820

Spacer for my O2 sensor. 2 seasons. The aluminum is not liking the salt/iron combo. I still haven't dialed in my carb, so want to keep it in there. Not sure how to make it behave.

Potential leak sources:

View attachment 406821
Remote oil filter. The worm clamp on the left was loose, and there was some oil at the top. This looks like the most likely suspect. Would **** me off to have pulled the engine for this.

View attachment 406822
Other end of the oil filter. Some oil around the plug as well. I paid attention to this when looking for the leak. Didn't seem like it at the time, but who knows. I'll remove it and refasten.
RMS: No pics, but didn't look like a ton of oil around there. Haven't removed the flywheel cover yet. If it's clean under there I'm questioning pulling the flywheel. But it would be ridiculous of my not to replace the RMS at this point.
Want to confirm that this is the right part?
I can't find it on the mercruiser parts diagrams for some reason.
Oil pan looked OK, didn't see any specific leaking. This is all difficult since the oil has now been sitting since october and nothing looks fresh. In retrospect should have run it prior to pulling it.

Other "while I'm in there" items:
1. Bilge pump. Need to find a better way to fasten it so that it both works and is accessible/removable. Sheetmetal fastened on the side of the motor seems like the best solution, but open to others.
2. Clean off everything, repaint. I've got a soda blaster that I've been itching to use. There's a lot of rust on there.
3. Corrosion protect everything. Anybody have a favorite? Boeshield?
4. Replace spark plugs! Gotta remember that. Much easier with the engine out.
5. Steering cable. Got tight last year, again probably not helped by the dunking of the boat. I have a spare that seems ok. Wondering if I should just suck it up and buy a new one. It doesn't look impossible to get to with the engine it, but def easier with it out.
6. Flappers: These were wrong and needed modified when I put them in 5 years ago. They looked out of position, dunno if they were doing any good at best or restricting exhaust at worst.

Anything else?

View attachment 406818
Whose O2 sensor Plate are you using ?
 

nola mike

Vice Admiral
Joined
Apr 22, 2009
Messages
5,407
Ayuh,...... It took awhile, but DonS convinced me, that any nut or bolt you think you might want to remove someday,......
Coating the threads with Perfect Seal, Works,....
Not never-seize, not grease, Perfect Seal, aka: Permatex ,form-a-gasket, non-hardening liquid,.....
Yeah, that's usually my go to for threaded sections. This one it looks like it seized in 2 places: The outer bushing to the flywheel housing, and the inner bushing to the bolt. I think grease would be the better choice here, but to paraphrase you, anything would be better than nothing.
 

nola mike

Vice Admiral
Joined
Apr 22, 2009
Messages
5,407
I would for sure change the steering cable
Also unless nearly new, the starter
Next, any sign of leaking at the steering actuator? They are very tough if not impossible to change with the engine in place.
I’d also look at the joint between the Y pipe & transom mount for leaks and the steering arm for play & leaks….
Obviously the exhaust also….
Starter is fairly new, though rusty. PMGR. I don't remember if it was new or I disassembled it after the dunk.
The actuator...yeah, I was trying to ignore the small leak. I'm already way behind the 8 ball for getting splashed. I'll check it out and see if I can figure out where it's leaking, but it may have to wait. (ugh, already kicking myself).
Y-pipe looks good.
Whose O2 sensor Plate are you using ?
Hardin
 

Lou C

Supreme Mariner
Joined
Nov 10, 2002
Messages
13,023
On rubber bushings with a bolt thru it I will sometimes use silicone grease because it doesn’t deteriorate the rubber.
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
71,079
Yeah, that's usually my go to for threaded sections. This one it looks like it seized in 2 places: The outer bushing to the flywheel housing, and the inner bushing to the bolt. I think grease would be the better choice here, but to paraphrase you, anything would be better than nothing.
Ayuh,...... Perfect seal woulda stopped that,....
'n the outer wouldn't have mattered if the bolt woulda turned like it was supposed too,....
 
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