Pressure testing closed cooling system

Speakrdude

Ensign
Joined
Feb 25, 2004
Messages
942
I deff. have a leak somewhere.
88 Merc. 5.7 MIE.
Fill up the HE with antifreeze, not there anymore!
No signs of water in the oil.
Been reworking this boat for a while. Engine has been sitting for a while. Have a stanton psi tester. Right off the bat, there is a leak in a copper joint at the cooler. I can pump it up and hear some leakage inside the engine somewhere.

My question is, will the long period of sitting cause a little leak? Should I fire it up for a bit, then test?

Just replaced the exhaust man block off with the good gray ones. (no more green ones.) Havent run it since then.
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
70,525
Re: Pressure testing closed cooling system

I deff. have a leak somewhere.
88 Merc. 5.7 MIE.
Fill up the HE with antifreeze, not there anymore!
No signs of water in the oil.
Been reworking this boat for a while. Engine has been sitting for a while. Have a stanton psi tester. Right off the bat, there is a leak in a copper joint at the cooler. I can pump it up and hear some leakage inside the engine somewhere.

My question is, will the long period of sitting cause a little leak? Should I fire it up for a bit, then test?

Just replaced the exhaust man block off with the good gray ones. (no more green ones.) Havent run it since then.

Ayuh,..... Where, Exactly,..??..??
 

Speakrdude

Ensign
Joined
Feb 25, 2004
Messages
942
Re: Pressure testing closed cooling system

maybe down inside the manifold or in the head. Hard to tell. Should I fill up with fluid first or test with it low?
 

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
Re: Pressure testing closed cooling system

...My question is, will the long period of sitting cause a little leak?

No.

Speakrdude said:
Should I fire it up for a bit, then test?

NO!

Speakrdude said:
Just replaced the exhaust man block off with the good gray ones. (no more green ones.) Havent run it since then.

You have the pressure tester, find the leak!
 

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
Re: Pressure testing closed cooling system

maybe down inside the manifold or in the head. Hard to tell. Should I fill up with fluid first or test with it low?

Pull the hoses off the manifolds and plug them. Pressure up the engine block/heads. If that holds pressure, test each manifold.... Too easy.. :D

(I use air. If you have a fixable leak (not the block) then you aren't filling the engine with liquid)
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
70,525
Re: Pressure testing closed cooling system

maybe down inside the manifold or in the head. Hard to tell. Should I fill up with fluid first or test with it low?

Ayuh,... Do ya Hear it through the carb,..??
Pull the sparkplugs, 'n listen...
Listen through the exhaust pipes...
Listen through the oil fill, or dipstick, Whatever it takes...

Use Air, so ya can Hear it...
Water just leaks, No sound...
 
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