Rebel_Heart

A couple of weeks ago, I wrote about what we thought was a water pressure issue when I found excessive water in the oil. We installed a Mercury relief valve which did its job - water pressure never made it above 12 psi. We pulled the sticks after several runs and found again a milk substance!

Engine builder seems to think that the Gen VI block is not holding up, he wants to switch to a Dart Block. Another person states that he is very sure that it must be reversion. I am looking for thought here. Thanks.

BadDog

Cam specs? Timing and idle speed? Do a search on reversion, much info on diagnosing.

Rebel_Heart

These are 540s with Jim V. heads (Dart Pro Ones). The cam is a Crane 139651. Boat is a 35' 2001 Classic Fountain. Exhausts exit under swim platform near the water. Is it possible that I could be getting water backing off trailer or at idle? CMI e-top headers, with CMI tails - water introduced at transom as far back as possible. There are no internal baffles or external flaps. Engine builder stated that water could not make the climb?

He wants to replace the block, thinks that the block is not holding up. I would appreciate any thoughts on this.

JCPERF

Pull the intake manifold off it and replace the gaskets.Excessive water pressure will push out the intake gaskets.

GOODT

I have to agree with JC pull intake and check gaskets I have a hard time beliving its the block other then maybe a bad head gasket,you could also pull a header/manifold and check for water trails to check for a reversion issue

waterbum

What a bummer. When I saw you pull out of the shop Saturday morning, I was hoping to hear all was good.

Is it happening to both motors? Hard to imagine bad gaskets on both, but I guess anything is possible. Any chance the headers are leaking - have you had them pressure tested lately?

Just curious - does anyone know what a max CR ratio would be for Gen VI with aluminum heads? Does the Dart block have a different head bolt pattern? Maybe that's why he mentioned the Dart blocks.

Good luck. Hope it is a simple fix.

Doug

SB

iTrader: (1)

Run engine with fuell exhaust and wet on the dyno, idle it down for a few. Pull risers/headers off and look for water. If you can do this easily in boat, then do it there.

Also, as mentioned above, possible intake gasket leak. If your block and/or head surfaces have been machined and the intake manifold hasn't, you could have water posts not aligned well and showing it's ugly face with any sort of pressure.

The 502 blocks can hold up to what you are doing with them, but it's always possible you are having issues with yours - be it from machine work or on their own. Both on their own? Would be strange, but schit happens.

This issue needs to be strongly investigated before you have no hair left.

I'll mention this again - I do not like the 651 cam, but since many do I may be off kelter with my opinion.

SB

iTrader: (1)

I just noticed this.

Yes it can !!!! Both ways.

Wobble

Pressure test the blocks cooling system at say 25psi, it will take a little rigging, but can be done by blocking all the t-stat housing hoses but one and sealing off the hose from the raw water pump. Use a radiator tester.

If that's good then I'd look to oil temps and crankcase ventilation.

When you say water on the sticks, do you mean water, or milky oil, or scum.

I had a stopped up crankcase vent (Pinched hose) and my oil was milky after a 30 mile run with a mile of idling. New vent and problem went away.

Not saying it's not reversion, but there are other possibilities.

do you have flaps in your exhausts.

Rebel_Heart

Thanks for all of your input. I do not have flaps on the exhausts because I was told they were needed. They are a cheap fix, should I have some installed? The engine builder is pressure testing the blocks today. It was a milky oil after only 15 minutes of running. We varied the speed to test the water pressure and everything was ok there. The starboard had a little more of the milky oil on the stick than should have been with just oil. The port engine also had a milky residue, but the total volume hadn't increased much.

SB - you are right, the cam is liked by some and other feel that it has too much duration. Could this be a cause? I know this is the cam the engine builder has used in all of his 540 configurations.

We did replace the copper gaskets last time. The first time it appeared you could see the trail of water on the gasket.

The engine builder did say that he had this issued once before on a blower applicaiton where he replaced the block with a Dart block and the issue went away. That is the reason that he is leaning toward the block issue.

waterbum - good to meet you Sat. morning, there seems to be a different head bolt pattern. The Gen V and VI motors have a lot more material taken out of the block as compared to the Dart or even a Gen IV with regard to the head bolts.

Again, thanks for your replies and help.