Mercruiser 4.3 efi v6 ‘blowing oil leak

[James12345]

Hi,
I’ve just fitted a recon 4.3 efi v6. Had 2 hours fun and then a bilge full of oil.

I’ve an odd leak from the starboard side, when i
put my hand under the exhaust manifold at 2000 rpm it’s blowing oil out onto my hand. Just a very light splatter.

It seems to be running down and onto the starter and other electrics and blowing the middle fuse that seems to be the one that cuts the fuel pump. At least I hope that’s what’s blowing it or I’ve another problem to solve

Also it looks like I’ve another leak from the front pulley area. But it’s the ‘blowing leak that’s got me stumped.

any help much appreciated

 

[Scott Danforth]

take it back to who ever did the recon

you have two leaks, one is from them not checking the front cover to oil pan area
the other is either a valve cover leak and a bit of blow-by from the new engine, or you have a head gasket leak.

either way, the motor is coming out.

 

[Bt Doctur]

missing dipstick?

 

[James12345]

Thanks, I fitted the recon with a mechanic friend, no money back on that one, the recon was from a couple of thousand miles away, I could send it back if it turns out really bad.

But I’ll examine the other possibilities first.

the dipstick isn’t missing.

Im hoping it’s a valve cover leak, sorry for my dumbness what’s ‘blow by from the new engine’
Ive ordered a new chain cover, I think thats a likely suspect, and now I realise that should of got changed anyway hoping to get through the last few weeks of the season and then engine out.

 

[Scott Danforth]

Dont assume its your front cover. It could also be the oil pan. Read achris V6 oil in bilge thread

All engines have a bit of blow-by. New motors have a bit more until the rings seat. It is the amount of compression gasses that go by the rings and into the crankcase.

 

[Rick Stephens]

I guess definition of 'recon' motor comes into play here. I get the impression you fitted pan, front timing chain cover and other engine parts? A short block or long block and all the rest up to you? You'll have to figure out where the oil is coming from exactly to know the fix. Clean it up really well and start looking while it's running.

 

[Grub54891]

As a teenager I had an oil leak in the old Chevy. Replaced every gasket. Still had a leak, would not show up until I drove it a bit. Grandpa went to the ash bucket, sprinkled ashen all over my clean motor! Took it for a drive and viola! Oil sensor leaking, easy to find that way. And it cleaned up fairly easy. Sometimes the old timers had good ideas....lol

 

[QBhoy]

That’s where the dip stick is. Are you sure it’s not from there ?

 

[James12345]

The dipstick is on the other side (I think!) ,
the recon was a long block, so yes we refitted the pan, timing cover (didn’t know should of got a new one) , manifolds etc.
the recon looked great,everything appeared done.

 

[Scott Danforth]

here is the summary of Achris's account of the oil pan and front cover issues. https://forums.iboats.com/forum/eng...es-outdrives/561580-an-oil-free-bilge-finally

however hose your motor down with dawn dish soap and water, scrub it, then when everything is dry and clean...... sit in the bilge with a flashlight, a mirror, and your cell phone camera (because it fits where your head doesnt) and with the motor running, find your oil leak.

 

[Bondo]

and your cell phone camera (because it fits where your head doesnt)

Ayuh,.... Welcome Aboard,.... Scott beat me to it again,.....

Unfortunately, oil leaks, like water leaks are found by crawlin' in there, 'n Lookin',.....

 

[James12345]

Will do, thanks muchly

 

[Lou C]

OK just what dipstick does it have? Does it go into the block....or into the bottom of the pan....if the latter...then the hole in the block..which was for the auto style dipstick.....has to have a rubber plug in it....I know on the old style 4.3s...its on the starboard side of the block....right about where your leak is.....

 

[QBhoy]

OK just what dipstick does it have? Does it go into the block....or into the bottom of the pan....if the latter...then the hole in the block..which was for the auto style dipstick.....has to have a rubber plug in it....I know on the old style 4.3s...its on the starboard side of the block....right about where your leak is.....

Agree

 

[QBhoy]

Ok so pics show the dipstick on the other side. Must be a gasket leak as suggested above.

 

[Lou C]

sometimes those pix are reversed...I can tell you for sure on the old pre-vortec V6 its on the starboard side (mine has the plug in there) and here is a pic I pulled off of a vendor of new and reman engines...you can see....the dipstick hole is in the same place....on this vortec 4.3....starboard side...

 

[Bt Doctur]

look between the 2 core plugs just above the oil pan gasket area, I`m sure you`ll find a hole in the block there
this is where a dipstick usually goes on the v6
click to enlarge

 

[James12345]

UPDATE
thanks all for the help, there was indeed a hole on the starboard side behind the water pressure sensor that should of been plugged up! Can’t believe we missed it.

got the plug out the old block and it’s 95% fixed. Still some leaks but fairly sure it’s the rear main oil seal and the timing cover... engine out... but not until the seasons over

in the mean time, the windlass has jammed , motor blown and i hit a submerged rock so my props knackered. It’s only money eh!

thanks again