Water in Oil - Mercruiser 5.7/Alpha 1

qystan

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Apr 26, 2004
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Engine is a 1989 Merc 5.7<br /><br />I am getting water in the oil. Not enough to make latte, just a little can be seen in the hollow areas at the top of the cylinder heads. <br /><br />Exhaust manifold are good, checked those out. <br /><br />Recently the port cylinder head cracked and was replaced, likely the stbd is on its way? <br /><br />I had an overheat when flushing, warning buzzer came on and was shutoff almost immediately, temp went slightly over 200F - would this be problem?<br /><br />Where are the other likely fail areas and what do you recommend to isolate this that can be done in phases. I am trying to avoid the kill-all method of removing all the heads and skimming them and changing the gaskets at one go. Gaskets alone will burn a big hole. Or I am done for and this is the only way :(
 

Don S

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Re: Water in Oil - Mercruiser 5.7/Alpha 1

If your engine is fresh water cooled, you could try pressure testing it and listening for the leak.<br />If it's raw water cooled, the only thing to do is start taking it apart and looking at each item. Since the port head was replaced, I would do the other one first. If raw water cooled, was a MARINE head gasket used? If not that could be your leak.<br />Some things you can't skimp on.
 

waterone1@aol.com

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Re: Water in Oil - Mercruiser 5.7/Alpha 1

Qystan, You said that it overheated durring flushing. Did you notice anything out of the ordinary the last time you had it out ? Perhaps something like running a little hot at idle, but would cool back down as soon as you raised the rpm's ?<br />A little bit of background would help; Is it raw water cooled ? Used in salt water ? How many hours are on the engine ? Have you pulled and checked the spark plugs ? Any signs of oil or water on them ?
 

qystan

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Re: Water in Oil - Mercruiser 5.7/Alpha 1

Head gasket was from Merc, so shud be ok.<br /><br />Engine is raw seawater water cooled - yuck. Hours unknown, but in my area not likely to be high, its usually corrosion that kills off engine around here. The saltwater and high humidity, engine is always rusting.<br /><br />At idle temp holds steady at 150F, flush or on water. Cruise at160-170F. Impeller is ok. Also just changed to SEI drive, comes with new pump-same.<br /><br />Spark plugs look ok, dry no water. Maybe I should look again.<br /><br />Taking it apart - sigh! Last time I did the port side, ended up with helicoil insert.
 

Don S

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Re: Water in Oil - Mercruiser 5.7/Alpha 1

Last time I did the port side, ended up with helicoil insert
Where was the insert? <br /><br />Did you use sealer on the head bolts when you installed the port head?
 

waterone1@aol.com

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Re: Water in Oil - Mercruiser 5.7/Alpha 1

Before you flip a coin and tear off a head, there are two tests that might help narrow this down. I have to underline might. The first would be to pull the lower hose off of both exhaust manifolds and plug the hoses, then pull the hose from both risers and plug those hoses. Next connect a garden hose to the water inlet hose that is normally connected to the outdrive.Remove all spark plugs and remove both valve covers. Turn on garden hose just a little, leave hose a little loose where it connects to faucet ( the idea is to have enough preasure to make large hoses on engine feel a little firm, but not blow anything).<br />Watch for any signs of water around heads and from spark plug holes. If nothing after a few minutes, turn engine over slowly again looking at spark plug holes for any signs of expelled moisture.<br />Another test that might tell you something: If you have access to compressed air and have a hose adapter that will screw in to a spark plug hole<br />( I use a detachable compression tester hose with the check valve removed), you could do the following:<br />Remove valve covers, loosen all rockers, with all spark plugs out, one cylinder at a time connect compressed air, listen for where air is leaking. If anything sounds suspicous, you could also remove the thermostat housing and watch the water to see if it rises or bubbles at any point. Also be on the lookout for leakage from one cylinder to the next.<br />In more than one case this test has helped me to localize or narrow down where to look. One case I had a very small corroded hole from the cylinder wall to the water jacket, engine still ran fine but was sucking a small amount of water into cylinder and was ending up in oil.<br />Another case was a blown head gasket. And still another a hairline crack in head.
 

qystan

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Messages
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Re: Water in Oil - Mercruiser 5.7/Alpha 1

Thanks for the help Don And Waterone.<br /><br />The helicoil is the 2nd (from front) in the lower row. Yes, sealant on helicoil and all bolt threads.<br /><br />The compressed air method sounds promising.<br />I'll give both a try this weekend. <br /><br />Again, thanks guys.
 
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