Water leaking from block but pressure tested fine?

[CLi87]

This has got me really confused, Mercruiser 7.4 Gen V I was looking and saw some water dripping from the side of the block, naturally I would think cracked block but just did a pressure test and the cooling system holds pressure fine and I don't hear any air coming out?? I looped the two exhaust tubes back into the thermostat and plugged the hose going to the oil cooler then hooked up a leakdown tester into the plug where the drain plug goes. I took out all spark plugs and I don't hear any air anywhere but yet there seems to be a drip of water down the block.

 

[Grub54891]

Did you drain the block? Water won’t make noise. Air will.

 

[CLi87]

Did you drain the block? Water won’t make noise. Air will.

Yea, I pulled the drain plug on both sides then put one back in and hooked the leak down tester to the other hole.

 

[Scott Danforth]

shut off the air source and see how long it holds 15 psi. should be forever.

additionally, it looks like there is a fair amount of rust on the cylinder heads. the water could be running down the exhaust manifolds onto the heads and pooling at the deck where you see the orange rust (vs the brown on the head)

 

[CLi87]

shut off the air source and see how long it holds 15 psi. should be forever.

additionally, it looks like there is a fair amount of rust on the cylinder heads. the water could be running down the exhaust manifolds onto the heads and pooling at the deck where you see the orange rust (vs the brown on the head)

I tried looking around but if it was coming from the exhaust manifolds and pooling wouldn't I see a rust line coming from the leak or at least some type of residue?

 

[alldodge]

I think its the head gasket, and it starts to leak when heated up and things expand.

 

[CLi87]

I think its the head gasket, and it starts to leak when heated up and things expand.

I just put new head gaskets on both sides, but even if it was the head gasket, would I not hear air coming out when pressurized?

 

[alldodge]

You shouldn't if everything met specs on install, but it is leaking and its wet on the gasket line

 

[Bondo]

Ayuh,.... In yer picture, it looks like there's a big crack in the bottom of the manifold,.....

 

[Grub54891]

Ayuh,.... In yer picture, it looks like there's a big crack in the bottom of the manifold,.....

Yeah, I was looking at that also, looks like jb weld was on there before?

 

[flashback]

I still see some JB on it.

 

[dubs283]

I just put new head gaskets on both sides

Just? Did head gaskets?

First pic is of the block/head seam, correct?

Looks like an awful lot of rust and other material there. Unless you didn't clean anything before the gasket/head install? Really appears to be fresh water leak witness/rust below the head, plus a crack in the block above the drain

 

[Lou C]

that looks like previous freeze damage repaired.

 

[Grub54891]

Is that the starter wire I see in the pic on the left? That looks like a wire for a stereo amp. If so that is not approved wiring either.

 

[nola mike]

Is that the starter wire I see in the pic on the left? That looks like a wire for a stereo amp. If so that is not approved wiring either.

Aside from being undersized if it's a starter wire, what makes it unapproved?