89 mercruiser 3.7 milky oil out of dipstick

[atwall2011]

I have an 89 mercruiser 3.7 replace head gasket intake game exaughst gasket all pier manual specs ran fine at start up and for a quite a good while after 30 min or so noo issue. Put breather on and connected vent tube from breather to valve cover and milky oil started coming from the dipstick tube. Any theories on what is causing this and how to repair it? Thanks inn advance

 

[stonyloam]

Is the oil in the crankcase milky? Can you smell antifreeze in the oil? How are your water pump cam seals?

 

[atwall2011]

Not that I can tell, after shutting the motor down at the sight of milky oil, and letting the eng cool four about ten minutes or so I checked the dipstick and there didn't seem to be any milk on it, but also my oil level was way low barely on the stick,I has just put five what's in. No antifreeze in the boat just straight water was drained last winter in the middle of rebuilding just now messing with it, it's a project boat. The resovoir will not hold water believe it is running out of the exhaust ports like the seawater does and think it may be the heat exchanger leaking but not sure. When you fill the reservoir up and crank the motor with the muffs on, water pours out of the reservoir like it's pulling in seawater but it will not do that if you don't first fill up the reservoir. Water pump cam seals?

 

[stonyloam]

Yeah that engine holds closer to six quarts, so you need a little more oil. Cam seals, read this http://www.sterndrives.com/470_coolant_leak.html. You will want to get antifreeze in the engine, as the water will rust the cam seal surfaces, where the antifreeze is less prone to causing rust. You might want to pull the exchanger and take it to a radiator shop for a check.

 

[atwall2011]

I thought about doing just that but not any radiator shops around my area anymore that I know of. 10-4 on the antifreeze going to read the link you posted now

 

[atwall2011]

Just read the post, that makes sense but I feel like if that was the case I would be seeing water leaking from the front on the motor, and I don't. You don't think it would be a cracked block do you?

 

[stonyloam]

Well you could pull the front end cap off of the exchanger, then pull the two inside (antifreeze) tubes off and clamp one closed and feed a garden hose into the other, and see if when you turn the water on, water comes out of the open (raw water) of the exchanger. You could also use air pressure, and listen for a leak. If you had bad seals you would see water leaking out of the weep hole on the lower starboard side of the engine waterpump. 470 engines are usually filled with antifreeze so they don't crack, but if yours was filled with water, it could have, if it had been drained it should be OK.

 

[atwall2011]

I will try that the next time I get a chance to work on it and report back. What do you think is causing the oil/water to push out of the dipstick tube like that?

 

[Bt Doctur]

water entering the crankcase and mixing with the oil creating a emulsified mix .It aerates, grows, and escapes thru the dip stick

 

[atwall2011]

That's what I would think but I'd that was the case wouldn't the dipstick read full/over full instead of empty? And it only comes out when the breather vent tube to the valve cover is connected?

 

[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.

 

[stonyloam]

If it is only 1 tube you can plug it at both ends and you will be OK. if it is a 4" exchanger losing one tube won't make much difference. The best way would be to take the exchanger to a radiator shop and have them do it. You might be able to make plugs with a couple of screws (that bite into the metal a bit, because the coolant side is under about 14 PSI pressure) and some slow cure JB weld. That is probably what I would do, but I would never suggest someone else do it.

 

[Eric 3.7LX Alpha 1]

Can you solder? if not do you know any plumbers? or boiler repair men?

I am a plumber and soldered a tube closed on mine... on both ends.... piece of cake, wire brush it shiny, some flux and 50/50 solder, but you have to have the heat just right, small flame using propane.... too much and the solder will just turn to liquid.

Where are you located?

 

[stonyloam]

Solder would be great, you could stuff a little steel wool down in a little ways to hold the solder in the last 1/2 inch or so. Pulling the exchanger out would make it way easier to do in either case. Just make sure you solder both ends of the SAME tube LOL! I could see me making that mistake.
Just a thought, you might be able to go to a hobby shop and find a length of brass tube that you could slide into the bad tube, then just solder the ends to repair the tube and keep almost all of your cooling capacity.

 

[atwall2011]

Eric 3.7LX ALPHA1... I can solder, a plumbers helper myself. I'm located in New Bern, NC did you shoot your heat straight down the tube? And did you take the end castings out to do this?

 

[Eric 3.7LX Alpha 1]

I just removed the end caps. sanded shiny, hit it with some flux and slowly filled the hole with 50/50. Had the exchanger horizontally and worked my way up. Just keep the heat on the low side, aiming at the edge of the tube.


You can pressure test it before putting it back in. Put the end caps back on, cap off one line and air test the other using a test gauge that you'd use to test piping in a house.


I do like Terry's idea though about sleeving the broken tube with another pipe. Maybe a piece of 3/8 OD" copper thru the split tube, a small flare on the ends, and solder it up. This way you don't loose as much cooling ability.

I have the 4" heat exchanger. The older years had a 3". Your's being the '89 should also be a 4". I can tell you with a good impeller in the outdrive, my engine won't budge off 160? all day long no matter the speed with that one tube closed off.

 

[atwall2011]

I gotcha doesn't seem like it'd be that hard. I was thinking about using the marine jb weld(putty) type, put a bit in the tube, follow that with a piece of 1/4in wooden dowel rolled in jb, to act as positive stopper, followed by another ball of jb on the end. And do both ends of course. The tube I have leading is right in a corner and hard to get to. Any thoughts on that idea?

 

[stonyloam]

Sounds good to me. Just make sure you clean and rough up the area you are going to epoxy.

 

[atwall2011]

Fixed the heat exchanger, plugged the tubes work jb weld lol. Now a new problem... B.O.AT. ughh!! Was pumping seawater fine good and strong, and the just stopped, then picked up again then stopped.that that was the other day. Today it was pumping good hard and strong and then just quit and wouldn't pick back up. No blockage in inlet or outlet.