Mercruiser milkshake :( 305 288 CID - how to test for cracked block?

[swfleur]

Hey guys - I love this site - need some help please...

Could someone do me a sketch or tell me how to air test the block? DO pressurize the oil side or the water side?

This motor is drained of oil and water - replacing gaskets on head and exhaust.

We had the milkshake spewing out of the valve covers on both sides and had to shut her off and pull her back to shore and dig into the cause.

Water was drained out before winter so I'm wondering what the hell ??

Hoping new gaskets will fix it but would like to know how to check the block with the 'ol 15 psi test ???

Help with that or advice on this problem would be greatly appreciated

The temp never got hot and oil pressure was 25- 40 while it was running.

 

[darrincates]

Re: Mercruiser milkshake 305 288 CID - how to test for cracked block?

Hi all! . I'm the boat owner and my awesmome friend is helping me out ....

Just a little history: Although I did drain all 4 pit cox valves last winter, the winter before that, being a new boat owner) I didn't open/drain anything, and had a boat shop repair the two cranks on the outsides of the manifolds (between bolts 2 and 3 of the four, both sides). Boat shop had it from June1st until Aug 16th ... 7 oil changes, and he left extra oil in it (it measured a little high on the stick). Ran it twice end of last year, an hour each time, and the boat went well except for the very end of the last ride last year when it sputtered for about a minute, so I idled it around and came out of it, so I trailered it, (drained all four) and that was it until yeterday. Filled lower unit, and put in for 1st time. Idled out a ways, lifted the hodd while idling, and got milkshake (more from port side perhaps?) motor ran great through the whole ordeal, got it back home, drained oil and got a couple gallons(?) of hot water and oil ... then we removed port side manifold and I ran hose through the water ports, and the exhaust ports stayed dry .. am fighting with one bolt on starboard side now to remove manifold .. I have 2 long manifold gaskets, and two square gaskets for the pieces that site on the manifold ... I am going for head gasket now .... Any advise/instruction on the block pressure test would be greatly appreciated! .. Thanks!

305 CID Mercruiser ...

- Darrin

 

[RogersJetboat454]

Re: Mercruiser milkshake 305 288 CID - how to test for cracked block?

You pressure test the block through the cooling system.

Typical way of doing this is blocking off the hoses to the manifolds. Tapping into the inlet hose (from the drive) with your tester, and pressure testing with compressed air through a regulator/gauge assembly that should be easy to make after a trip to your favorite local big box home improvement store.

But...
You had cracks in the manifolds. You clearly have allot of water entering the oil. I am very doubtful that a head gasket is going to solve this conundrum. If it were me, I would be pulling the intake manifold, and looking in the lifter valley for cracks, as this is one of the most common places for it to occur after freeze damage.

 

[swfleur]

Re: Mercruiser milkshake 305 288 CID - how to test for cracked block?

Thanks for the tips Jetboat - OK - we will hold off on the head gasket and focus on the intake - we have already pulled off both the exhaust manifolds ( v 8 engine ) and these seem to be ok -

we will put new gaskets in while we are there - Pardon my ignorance but ... ? the lifter valleys ? Is this something we might see under the valve cover also? thanks and all others please keep the info coming - feel free to chime in if you have ever had to resolve the gray milkshake in a 305 or 350 - Holt cow we had a lot of milk coming into both valve cover gaskets - we had to un hook the EGR hoses and let the spew/ drain into the bilge while we limped back to shore slowly - pretty good stream of milky gray water and oil mix -was coming out both of the valve covers

 

[RogersJetboat454]

Re: Mercruiser milkshake 305 288 CID - how to test for cracked block?

That's right, the lifter valley.

The part in the middle of a V configured block thats not level with either bank of cylinders. Both cylinder banks are cast in such a way that they slope to the middle, like a valley, it's also where the lifters live, hence lifter valley.

Don't be ordering or replacing any gaskets yet. Just pull the intake manifold off, and start looking for cracks, including on the bottom of the intake.

 

[swfleur]

Re: Mercruiser milkshake 305 288 CID - how to test for cracked block?

Here is an update on the mystery of is my block cracked.....

Tested the engine like this ......

The highest point that water can be is the thermostat housing - Pulled the bolts and exposed this cavity at the front and top of the engine.

Pulled the drain plug and drained out whatever oil was left in the engine - ( needed to do that anyway since the milkshake of water and oil was inside the valve covers and everything internal.

With the engine off and cooled and ( battery removed for safety - dang starter scares me ; )

Poured water into the thermostat housing on top side of engine - until it appears to be "topped off" - or let the garden hose trickle the water in and hang out and wait -

if water tops off inside thermostat housing - then stop adding water and let it sit - any cracks will allow water to seep in and drain out the oil plug screw on bottom side ( which you have already removed - right ? ; hint - hint )


If water comes out your drain plug ( immediately or during the fill or 1 hour later - you got serious issues inside the motor - We did this on this motor and she is bad news Water poured right out of the oil drain hole - proof of some serious internal cracking

I'm thinking its time for another motor - Probably not possible to repair and feel secure about the repair ???

 

[darrincates]

Re: Mercruiser milkshake 305 288 CID - how to test for cracked block?

Thank you to my master machinest friend .. he got oily out to pond, and and worked with me on this motor till the wee hours of the morn' .... a good friend is what is truly priceless. ... now, can I borrow a few grand for a new crate motor? :facepalm: kidding of course! .... I all ready found a couple close by on craigslist, and I am calling Marshalls, Sun, and Rinauldi for prices!

 

[RogersJetboat454]

Re: Mercruiser milkshake 305 288 CID - how to test for cracked block?

Probably not possible to repair and feel secure about the repair ???

Nope.

If funding is lean, you can use a healthy truck engine from the same era (needs to match to a 2 piece or 1 piece rear main seal depending on what year the 305 is in your boat), providing all the marine parts (electrical/fuel) from the original engine are used on the new engine. Should also install brass core plugs, and marine head gaskets. Would also be a nice opportunity to swap in a 350.

 

[HT32BSX115]

Re: Mercruiser milkshake 305 288 CID - how to test for cracked block?

Here is an update on the mystery of is my block cracked.....

Tested the engine like this ......

The highest point that water can be is the thermostat housing - Pulled the bolts and exposed this cavity at the front and top of the engine.

Pulled the drain plug and drained out whatever oil was left in the engine - ( needed to do that anyway since the milkshake of water and oil was inside the valve covers and everything internal.

With the engine off and cooled and ( battery removed for safety - dang starter scares me ; )

Poured water into the thermostat housing on top side of engine - until it appears to be "topped off" - or let the garden hose trickle the water in and hang out and wait -

if water tops off inside thermostat housing - then stop adding water and let it sit - any cracks will allow water to seep in and drain out the oil plug screw on bottom side ( which you have already removed - right ? ; hint - hint )


If water comes out your drain plug ( immediately or during the fill or 1 hour later - you got serious issues inside the motor - We did this on this motor and she is bad news Water poured right out of the oil drain hole - proof of some serious internal cracking

I'm thinking its time for another motor - Probably not possible to repair and feel secure about the repair ???

Howdy,


I just want to add for others viewing this thread that the above technique while working in this instance, won't work for everyone.

An engine with "tight" cracks won't leak enough with just "head" pressure to detect leaks reliably.

The best and most effective way to test for cracks is to pressurize the block cooling system with air using a gage and valve.


And yes. There is no cost effective way to reliably "fix" an internally freeze cracked cast iron block. It might be cost effective with a super expensive (Big) diesel but Small Block GM engines are plentiful and cheap..............AND there's nothing wrong with using a "truck" 350.


Regards,


Rick

 

[Silvertip]

Re: Mercruiser milkshake 305 288 CID - how to test for cracked block?

Just a little correction: The title of your post says "305 288 cid". 305 cubic inches is the displacement that engine. 288 has nothing to do with that engine..