bIzzare steam effect from valve covers, Help please

[Patronus]

I have a 1987 Volvo Penta out drive bolted to GM 350 with all penta aux systems. <br /><br />Today I put the boat in the water and sparked off the engine. As a habit I reached down and touched the Impeller housing, It was cool but not cold. I headed out and started heading to full power. At around 3800 My pressure cap on my heat exchanger ruptured and spewed coolant and steam in all directions. I shut down the boat. I troubleshot the problem back to the thermostat and yanked it out to run straight back to the dock. The impeller had heated up but not destroyed itself. Everything seemed fine on the transit home <br /><br />HOWEVER, I now have a fair amount of steam coming from the crankcase breather tubes on both cylinder banks. To add to my confusion , the oil is not emulsified (bad spelling) Infact it seems unaffected. I had assumed the head gasket was toast (along with this boating season) But Isn't there sposed to ba Coolant mixed with the oil if that happens. <br /><br />I hope someone has the skinny on what I am seeing. I am hoping that if the Main engine is shot than maybe I can nurse her threw the 4th, and then hunt for a new plant. <br /><br />As A side not. I do not know what the temp at the time was. I know it was above 212 F. (steam) <br />Could the metal in my heat exchanger get so hot that is is boiling the sea water in my tubing bundles?<br /><br />Thanks for any help you may provide. <br /><br />-Chris (Patronus)

 

[Boomyal]

Re: bIzzare steam effect from valve covers, Help please

Could the metal in my heat exchanger get so hot that is is boiling the sea water in my tubing bundles

The answer is no. I would speculate that you overheated and blew your head gasket. You do not necessarily get coolant in the oil when you blow a headgasket.

 

[Haut Medoc]

Re: bIzzare steam effect from valve covers, Help please

Welcome to I-Boats ... I agree with Boomer, sounds like a blown headgasket. It would take awhile for water and oil to mix...Your engine isn't toast... yet....Unfortunately a blown headgasket cannot be normally be detected by a compression check. The engine will run at normal temperature at low R.P.M., but will overheat at speeds over 3000 R.P.M....J

 

[Patronus]

Re: bIzzare steam effect from valve covers, Help please

Say it aint so.....<br /><br /><br />the only thing i don't understand is why I would have steam showing from the crank case breather but still have perfect viscosity. <br /><br />I drove it back to the dock and ran it at the dock and still it was just a bit of steam. <br /><br />My father said it didn't smell like Coolant steam either. <br /><br />I am not questioning you because i don't believe you. I just want to fully understand before I spend the rest of today and tommarrow tearing down that engine. <br /><br />So my question is this. <br /><br />Where is the steam coming from that it would vent only from the crankcase breathers? Why am I not seeing collant spraying all over from the head? (where the headgasket would have ruptured) <br /><br />Thanks guys for your advice. <br /><br />-Chris

 

[rodbolt]

Re: bIzzare steam effect from valve covers, Help please

if you have closed cooling and popped a head gasket you will start noticing a coolant loss. vapors from the vent area are common, more so if the t-stat is out. the only path for combustion gasses to access the crankcase and oil pan or valve vally area is from a blown head gasket, cracked cyl head or a cracked block or cyl or blow by passed the piston rings. most will start dumping coolant from the pressurized closed cooling into the oil very rapidly. fix the seawater pump, replace the t-stat and keep rolling. a leak down test can find any coolant leakes related to the cyl or combustion chamber area rapidly. if you suspect a coolant leak and do a leak down test remember to remove the coolant fill cap. a radiator pressure tester can find leaks in the closed cooling portion of the system.

 

[Patronus]

Re: bIzzare steam effect from valve covers, Help please

Hi everyone<br /><br />Thank you for all the input. <br /><br />We have discovered 2 things today. <br /><br />1 the water that started showing up in the oil and the cause of the steam, is seawater. <br /><br />2. The impeller was not moving much volume into the heat exchanger. <br /><br />I am working now on the assumption that the shaft seal between the impeller drive gear and the Block has weakened or failed. This is supported by the fact that no coolant appears to be present in the oil. <br /><br />I read that this can occur in some volvo penta (johnson) seawater pumps. <br /><br />Am I on the right course?<br /><br />Thanks again <br /><br />C