89 merc 3.7 draining water out of reservoir

[atwall2011]

Hey posted a topic earlier don't think I worded my question right. Problem number one: With the motor turned off and cold I can fill the coolant reservoir up to the top off the filler neck and it will stay there. As soon I fire the motor up the water starts draining out of the coolant reservoir. With the motor still running I poured more water into the reservoir, at this point the reservoir starts to fill on its own and gurgle out of the to of the filler neck. This is all done with flushing muffs on. After all of this and shutting the motor down the water drains out of the reservoir and the coolant reservoir cannot be filled due to the water draining out of it, at least not until the motor has completely cooled down again.can anyone explain this phenomena?

 

[Bt Doctur]

Did you remove the exaust riser? And your supposed to be using a 50/50 mix of regular anti-freeze

 

[stonyloam]

Sounds like it is leaking out of the exhaust, or into the raw water part of the exchanger.

 

[atwall2011]

A little history on the motor... Was bought last year and installed in the boat. Was not able to hear it run before purchase, but the oil was checked at the time of purchase and it was at the correct level and looked in good shape. After installation it was fired up with muffs on, same situation a in the first post existed at this time as well. after a few minutes milky oil started spraying out of the vent hole on top of the valve cover. Deteriorated head gasket was the culprit. Removed exhaust riser, exhaust manifold, intake manifold and head. Had head resurfaced and checked for cracks, all good. Reinstalled everything with new gaskets per service manual specs. The exhaust riser did not get a new gasket the one that came in the kit was not right we reused the old one and permaseal.

 

[atwall2011]

I'm also getting water in the crankcase, the oil when it comes out of the dipstick tube is milky. Could a leaking exhaust riser cause this symptom?

 

[Bt Doctur]

 

[stonyloam]

you need to put a new gasket on the exhaust elbow. either aluminum manifold http://www.mercruiserparts.com/showSpecialPicture.asp?pn=18272 or cast iron http://www.mercruiserparts.com/showSpecialPicture.asp?pn=856705 depending on which one you have.

 

[NHGuy]

Terry is correct about the gasket. Exhaust manifold to riser gaskets have to be perfect or you can ruin valuable engine parts.
However, I think the likely reason it holds cold and drains warm is the thermostat. But something or things are still wrong.
Your motor might be ok if it's just the oil cooler leaking coolant out into the oil. And that is where I would look.
Here is a link to the parts page https://webapps.brunswick.com/litera...atureSearch.do,
Go to Mercruiser, 1989, 3.7, Cooling, for a look at the heat exchanger assembly which contains the oil cooler.
Once you have it identified, remove it and check it for leaks. You can block one end and send water or air in the other. It should hold 15 psi forever. If it leaks it's either fix or replace.
BTW that is the definitive source for original equipment part numbers. I often pull part numbers there to confirm I have the right thing. Or I pull and Google them to get good buys, local quick sources, etc.

 

[atwall2011]

So there is an oil cooler on that motor?

 

[atwall2011]

Because we saw a cooler close to the rear of the motor that looked like the oil cooler in the diagram in the link you posted but trace it back to the power steering pump (power steering fluid cooler?)

 

[salty3rd]

So there is an oil cooler on that motor?

Not Necessarily, the stock 470's don't usually have an oil cooler, but the upgraded 4 barrel models would..I agree with the above and change that exhaust elbow gasket. If that doesn't work I would be suspect of the cam shaft seals on the front of the engine, which is a common problem on the 470.

 

[stonyloam]

Yes that is a power steering cooler in the line between the exchanger and the exhaust elbow. Salty is correct, only the 4bbl 470's have engine oil coolers.

 

[atwall2011]

Thanks guys still do some more investigating and report back

 

[NHGuy]

My bad. Wish they labelled it ps cooler on the image!

 

[atwall2011]

Confused me too

 

[atwall2011]

Hey guys, update on mercruiser 470. Confirmed that water draining out of reservoir is due to a leaking heat exchanger by pressure testing the motor and observing water being pushed out of the seawater outlet behind the boat. Bypassed the heat exchanger and pressure tested again, held pressure with slight leak down, inspected exterior of block, hoses, exhaust system,.and water pump weep hole. All is week except for seepage around exhaust riser gasket, and a few small leaks around hoses. Inspected heat exchanger, found one tube leaking profusely. Next steps, repair heat exchanger, replace riser gasket, double check and tighten hoses, test task, WATER TEST!! Any ideas on heat exchanger repair no radiator shops in my area and not enough $$ for another one. Also what about the pencil zinc for HX?

 

[atwall2011]

Oh yeah water in crankcase theory... spark arrestor tube was blocked(dirt dauber) when installed it created to much base pressure in motor causing oil to be pushed out of dipstick tube as well as breaking the seal between the camshaft and water pump. Cleaned spark arrrstor and reinstalled ran motor for 30 45 min, no oil out of dipstick tube and no water in oil.

 

[atwall2011]

Hey guys, update on mercruiser 470. Confirmed that water draining out of reservoir is due to a leaking heat exchanger by pressure testing the motor and observing water being pushed out of the seawater outlet behind the boat. Bypassed the heat exchanger and pressure tested again, held pressure with slight leak down, inspected exterior of block, hoses, exhaust system,.and water pump weep hole. All is week except for seepage around exhaust riser gasket, and a few small leaks around hoses. Inspected heat exchanger, found one tube leaking profusely. Next steps, repair heat exchanger, replace riser gasket, double check and tighten hoses, test task, WATER TEST!!??Any ideas on heat exchanger repair no radiator shops in my area and not enough $$ for another one. Also what about the pencil zinc for HX?

Oh yeah water in crankcase theory... spark arrestor tube was blocked(dirt dauber) when installed it created to much base pressure in motor causing oil to be pushed out of dipstick tube as well as breaking the seal between the camshaft and water pump. Cleaned spark arrrstor and reinstalled ran motor for 30 45 min, no oil out of dipstick tube and no water in oil.

 

[stonyloam]

Thought I posted earlier, but the post seems to have vanished. I suggested a screw and JB Weld, Eric suggested solder. If you can find a brass tube the right diameter (hobby shop) you might be able to slip it inside the bad tube and solder the ends. Losing a single tube in a 4" exchanger is no big deal.

 

[Eric 3.7LX Alpha 1]

He's got two threads going.

http://forums.iboats.com/forum/engi...2-89-mercruiser-3-7-milky-oil-out-of-dipstick


I keep getting confused about this one and the the guy with the 3.0 engine noise he has two or three going also.