Grog

Guys -

I have been chasing a water/oil leak for some time now. My latest attempt at locating the problem involves a pressure check of the cooling system. I've plugged off the water intakes to the exhaust and I have also fabricated a plug at the lake water intake with includes a schrader valve to allow me to pressurize the system.
I filled the block with water, added some florescent dye, and pressurized the system to 40+ psi. Over the course of 24 hours, it leaks down to 22 psi and then to about 15 psi over 2-3 days. The dye is pretty concentrated and very visible to the naked eye. There is no evidence of leakage at my blockoff plugs so I have to conclude that the leakage is inside the block.

Now the million dollar question...... Would a "good" Gen VI block hold 40 psi pressure indefinately? At this point, I have represurized the system a couple of times and have expected to see water/dye coming out the drain plug (I have since drained the oil).

My plan is to drain the water/dye, let the block dry out for a while, then start disassembling the engine in hopes of finding intrusion of water(via the dye).

I would love some input at this point. What other tests could I run before tearing things apart?

Gen VI 502
Whipplelcharged
Otherwise stock.
removed oil cooler from system during diagnosis
Intercooler checks good. Held 50 psi indefinately.

Thanks.

Greg

Mr Gadgets

Is it possible that the air space is where the leak may be? Have you tried rotating the engine to get the air pocket in a differnet place, allowing the die to penetrate the leak? That is assuming the engine is on a motor stand.
It has been stated that intake gaskets and head gaskets could be the problem over 20psi or so. You might want to pull the intake and block off the ports in the head and do the test again. That might reveal something. Just kinda of thinkin out loud here.
Another thing would be to spray some soapy water on things, see if you can see bubbles. At times when I psi test drives, they will leak down over 24hr period. If the leak isnt obvious, I dunk the whole drive in a tank. It takes a while, but small bubbles will appear after awhile and it may take several seconds to a min for the next bubble to appear.. So a slow leak over a 24hr period can be very small and not very obvious.. Good luck on your search!.. and let us know what you find..

Hope this helps..

Dick

Chris Sunkin

I'm going to assume this is a closed system and you have no water in the crankcase oil.

A block crack would leak water into the crankcase

Heads are a different story. A small crack in a valve seat area could leak as you describe. Try pressurizing with air and using a compression tester adapter & a piece of hose, listen to each cylinder for hissing. I'm assuming you have the exhaust off of the engine- check there as well.

Most likely it's a head gasket or a cracked head.

Mbam

Yes, use air only. Pull the valve covers, pull the plugs, pull the exhaust. Get a couple of feet of windshield wiper hose that you can use like a stethescope and start poking around. You can pretty much see in the intake valley once the valve covers are off.

What is it that makes you think you have a water leak?

Chris Sunkin

Yeah- forgot that one. Cold water won't go thru tiny cracks in a cold motor without alot of pressure. 20 to 30 psi is plenty. more will possibly cause more harm than good.

MOBILEMERCMAN

leak test and use a hose as suggested to verify combustion areas, that is nice because you don't have to disassemble much, also the intake cross over area can easily leak. Do you know what your water pressure is a speed?

offthefront

you say water/oil leak ? could you expand on that ?

Grog

Hello guys. Thanks for the interest. I hope I remember to respond to everyone's follow up questions.

I am fairly certain that I am getting water into my crankcase due to the fact that I get chocolate milkshake for oil after every time or so out. It is an open cooling system, and the motor is still in the boat. My WOT water pressure is about 18 psi.

I have been pressurizing the system to 40+ psi (block cooling passages filled with water/dye) and watching it leak down to around 18 psi over a few days. Since there is no evidence of dye outside of the block, I have to assume that it is leaking inside. Although not positive that only air is leaking, I think I did a good job of filling the block with dye/water because during the filling process. I made sure that I saw dye coming out of the dump fittings located at the rear of my intake manifold (these were added with the SC installation) when filling the block.

Since my initial post, I have removed the oil cooler, exhaust manifolds, valve covers, and supercharger. The oil cooler pressure tested fine. And so far, I see nothing in terms of water/dye, including some soapy water spray testing around the intake manifold and block-off plugs.

I will try the stethascope test in the cylinders, but I am afraid that the leak is so small, that all I will hear is the neighbors damn dog barking. Will let you know though.

If all else fails, I will hopefully see evidence of dye/water when I remove the intake.....or maybe even the heads. Boat problems suck.

Chris Sunkin

This is why complete information up front is so helpful...

Water in oil-

60% chance it's intake, 40% head gasket.

Be careful with your disassembly- you should be able to see if there has been gasket failure or improper installation of the intake gasket. Regardless of what you find, I'd have the heads checked for flatness and skim-resurfaced if necessary.

You can skip the stethoscope test.

Grog

ttt