syringa

A while back I posted about a water/oil problem I am having. Gen VI 502 (modified) Imco powerflows, Merc HP 500 intake, SS crossover. Engine ran perfect for 18 hours then the milk came (prev post).. I pressured up the engine with air to 50 psi and it will hold for 8 hours.Done comp, leakdown,r&r'd heads checked for cracks ,replaced intake gskts etc.etc.etc. I can run it at 3000 rpm all day long without a problem. Punch it to 4500,engine temp 120-130 w/30 psi water pressure and I am 2-3 gts overfull with oil/water within 2 min of running. My engine builder says it is VERY doubtful block/heads r cracked as it would show something at 50 psi. I've run out of ideas ???????

syringa

excaleagle42

it tough to figure a problem out like yours without ALL the engine info. who keeps taking the engine apart , you or the engine builder? what do the spark plugs look like at normal running before the water problem? after the engine gets loaded with water are the plugs still the same color? there is no water in the cylinders? are you using any sealant on the head gaskets? what kind? what type of intake gasket and what kind of sealant? what torque spec and pattern on the intake? when you remove the intake, is there water puddled in the lifter valley that isn't emulsified? has your torque wrench even been calibrated? you said the engine is built. has the block been decked? the heads shaved to raise compression? what head gasket including thickness? are the heads a matching pair? one is not newer, correct? was the intake angle cut to match? have the heads been ported? was the block ever clearanced for a stroker crank? was the block hydro tested prior to being built? (my local machine shop charges $90 but well worth the money on a marine engine) i assume the gasket sealing surfaces are flat with no signs of previous corrosion? are you running an oil cooler? where is it installed? has that been tested on both sides? last question; have you tried a test run without the thermostat installed?

syringa

exceleagle 42> THks for the reply.Good questions i'll try answer them. I t's me that took the engine apart. The plugs look the same color and there is no water in the cyls. Plugs appear to lookfine. When I reassembled the engine I didn't use any seaalant on the Fel-Pro head gaskets Used RTV sealant on the water ports(both sides)and on the ends of the Fel Pro (#1275) intake gaskets. Torqued heads in 3 steps, intake in 4 or 5 . The heads weren't shaved but were ported. The block wasn't hydro tested prior to being built but it was aNEW 502 GenVI crate engine. I'm running a oil cooler and a merc oil thermostat but bypassed the cooler when the problem started.I also pressure tested the cooler (removed in water tank). I didn't run it with no t-stat but ran it with a 5/8 restrictor never went over 25 psi water pressure and didn't get a rise on oil level but the oil was a bit milky (residual water). But then punched it over 30 psi and the problem returned. This is the puzzler to me.
1) The engine was perfect for the first 15 hours and I pounded it pretty good at times. I didn't have a pressure gauge then but i am assuming it was very high.
2) If the block will hold 50 psi air for 8 hours why can't it take 30 psi for 2 min? without puking??

I should add I'm in Western Canada and the lake water temp is about 60 degrees so with a SS crossover system it's hard to get the water and oil temps up. But this is not a condensation problem.

syringa

cat n around

Do you have evacuators on your exhaust,I had this problem last year my evacuators valves was bad

excaleagle42

syringa,
you held 50 lbs. of air pressure on your water side of your engine, completely isolated from your air source after the initial pressure up and it held 50 lbs. for 8 hours with no loss at all ? is that correct?

syringa

Excaleagle>> This is how I did it>> Joined both tees(to exhaust manifolds) together. Plugged inlet bypass port, plugged one end of bypass, put air in the other with t-stat removed. Set the regulator on the compressor to 50psi. I have a 35 psi Gaffrig water pressure gauge ,the neddle went past almost to the stop. Marked the needle position with a felt pen. Crimped off the compressor hose with vise grips and shut off the compressor. Double clamped all connections. Sprayed with soapy water no leaks. In the morning the water pressure gauge was EXACTLY in the same place. What do you think ???? thks for the interest this has me beat so far!!

syringa

syringa

I just read my post and my explanation is a bit confusing.. I meant to say I plugged the water inlet on the crossover,then the tees,then bypass hose.
syringa

excaleagle42

so you shut the compressor off with the vice grips pinching off the hose. did you notice the guage on the tank? usually a air compressor will have over 100lbs. the regulator would still work. my point is, if you had a small leak in your engine somewhere, you pinched off your hose and it still leaked air into your engine a bit, it would maintain 50 lbs. until your tank pressure equalized with your 50 lbs. of air in your engine.

syringa

Good point>> I don't think it would leak back but just to be sure I hooked up the test the same way only this time pinched off and disconnected the air supply from the compressor. We'll see what happens in the morning. It's past midnight here so it's time to get some sleep

syringa

BadDog

Isn’t your engine a little warmer when you are running it than when it is sitting in the shop? Look at it this way, your combustion chambers are very hot, the incoming cooling water is very cold relative to other components of your engine. Thermal expansion and contraction is simultaneously occurring from start up to full operating temperature. Sealing surfaces are moving around during this process. Testing with air pressure is a good place to start. If you see a loss all you have done is confirm a leak. If you do not find a leak you have not proved that is does not leak through these temperature changes.

Since it did not leak initially I would still suspect a gasket leak. Something is shifting around when hot.

Tim T.