Water in Oil - Leaking intake gasket?

GordOnTheWater

I have a new-to-me 1991 Rinker 236 with a 7.4/Bravo 1. I bought it off a mechanic. He mentioned he'd replaced the seawater pump impeller the end of last season. I had a problem with overheating, which turned out (after a few hours of troubleshooting) pieces from the impeller he replaced caught in the power steering cooler and clogging the water flow. So, I got that cleaned out and got out on the water for the first run with the boat. A good hour and a half of cruising around the lake. I stopped for a bit of a break and within a minute or so, the overheat alarm went off. I got towed home. When I checked it out there was no signs of clogging anywhere, and I found milky oil on the dipstick. According to the book, and the mechanic I bought the boat off of, this is most likely an intake gasket issue. Anyone have any suggestions or guidance? 

PickleRick

Cracked head, cracked block, intake or head gaskets.

I got water in my 350 from a slight over heat and killing the engine, this allowed the cold lake water to suck up into the exhaust.  Took 3 oil changes and engine flush to get most of the water out.

An over heat can eat the exhaust flappers which is how the water was able to enter my motor.

212rowboat

if guessing most likely from the average pool of causes, your exhaust manofold leads the charge, resoundingly defeating cracked heads and intake manifolds.... 

YOUR story, however, could be pieces of impeller in the elbows allowing exhausting water to stream instead of spit, and stream back into the manifolds and resting on an exhaust valve just waiting to open to be ingested. 

GordOnTheWater

@212rowboat I pulled all the water lines and checked for debris, thinking this was the issue. They were clear everywhere. That's when I happened to check the oil and it was milky. I'm still leaning on intake manifold gasket, partly because I'm psyching myself and it's the easiest repair lol. But also because when I was still running strong at about 3000 RPM, about 15 minutes before I stopped and it overheated, I noticed the performance being a little sluggish when I increased the throttle. I played around with throttling up and down between about 2800 RPM and 3500 RPM just trying to figure out if it was actually sluggish.....it was. Stopping was just a random thing, but it lasted only about a minute before it overheated. I may be wrong, but I'll start there and see where it ends up. @PickleRick that's interesting. I've read about sucking water in through the exhaust at idle, and have wondered about it. The only reason I don't think it's the issue here is that I seem to have been sucking water in at higher speed before I stopped. The engine temp stayed normal when I was cruising and it only overheated when I stopped. 

rasbury

Ok, I can ask a dumb question here cause I'm not looking at someone that can laugh in my fact- how is an exhaust valve ever exposed to water?

aero3113

@rasbury, remember no stupid questions on this forum. Water can go right in the exhaust ports on the transom. The rush of water when coming off plane can go in and up.

aero3113

@GordOnTheWater , why are you thinking intake gasket and not head gasket? Take compression readings to find out.

rasbury

yes but water does not go on top of the valve, it goes around the head in water areas, but can't get down to the cylinder unless it is a gasket right? And then if it got in the cylinder, still does not get it into the oil??

aero3113

Think of the path of the exhaust , where does that exit the engine from and where does it exit the boat?

rasbury

yes but worse case it gets to the cylinder....not the block/oil?

PickleRick

If an exhaust valve is open when the water hits then it has access to the cyclinder.

Since piston rings are not water tight the water will flow down into the crankcase and mix with the oil.

aero3113

Exactly @PickleRick

PickleRick

Unfortunately i dealt with that my first week on the water this season.

Thank god it was fresh water so no damage done.

If it happens when running you can bend or break a rod, damage the head piston and or cylinder.  Just a lot of stuff.  Air compresses, water does not.

Also, a 236 with a BBC??? I have a 235 with 5.7.  A 1992 to be exact.  I bet that boat moves.

GordOnTheWater

@aero3113my first thought was head gasket. It may very well be that. However, both the mechanic I bought it off of and the Mercruiser Sterndrive Service manual say it's more likely intake manifold. The idea is, the gasket gives out and water starts leaking into the cylinder. A side effect is that water also starts leaking into the valley under the intake, which is how it get's into the oil. So, I'm rolling the dice. Intake has to come off either way, so if nothing else, I'm being the optimist in hoping it's the intake gasket 

212rowboat

Not really rolling dice... if its intake manifold which it could very well be then you'll be needing those gaskets... if it is heads, you'll still be needing those gaskets because you gotta get manifold off to get heads off... 

Ras: if you shoved a water hose in your trucks exhaust pipe, it'll do the same thing. Just take longer and more pressure.. park facing downhill, and you'll do it faster.  Boat exhaust is just shorter and doesn't have the drops cars and trucks do. 

69fastback

Judging by some of the things happening here, I would take the word of mechanic you bought the boat from too seriously. 

aero3113

Check compressions this way you don’t pull off the wrong head if it’s a head gasket. Unless you replace both gaskets at the same time.

GordOnTheWater

A bit of an update. I've been busy...got married on the weekend so the last couple of weeks have been focused on other things. I picked up a hand oil pump that screws onto the dipstick. It's not working. The thread turns on the dipstick, so not getting any suction.  I can't do anything until I get some fresh oil in it as there's definitely water in the oil, and even on the heads (checking through the oil add hole). I'll play around with the hand pump a bit when I get some time, but I'll probably have to pull the oil pan drain plug, with will be a PIA. I've realized when it comes to pulling the intake, I'm not up for that myself, so I have a mechanic lined up. I'll check some things like compression test, and check which cylinders have water in them, and a few other things my mechanic suggested. I'm hoping for a fairly simple answer/solution but time will tell. My new wife is ready to sell it, so I need to get cracking on solving this problem. I'll keep you posted.

Aqua_Aura

You can try putting the suction house down the dipstick and doing it that way. 

rasbury

Sell? Sounds like you need another new wife already!

PickleRick

If the boat is on a trailer just pull the drain plug.  You want as much out as possible. 

I then flushed my motor out with a blend of gasoline and motor oil a few times.  Still took 3 oil changes to get rid of maybe a few pints of water.  

GordOnTheWater

PickleRick said:

If the boat is on a trailer just pull the drain plug.  You want as much out as possible. 

I then flushed my motor out with a blend of gasoline and motor oil a few times.  Still took 3 oil changes to get rid of maybe a few pints of water.  

I have enough oil right now for 3 oil changes, and I'll get more if I need to. It may take more than 3 so I'll just keep cycling through until it's clear. I'm going to try seafoam in the second oil change as it absorbs water. Might help get more water out quicker

GordOnTheWater

Time for an update. It's been a long summer, and I spent a total of 1 1/2 hours on the water. That sucks. But, I've made progress and I think It's all good to go. I hired a mechanic to replace the intake manifold, as it was more than I could handle. I sat n the boat with him and helped out when he needed it, and learned quite a few things. Previous mechanic/owner didn't replace some of the parts that I would consider standard procedure for a rebuild, but it is what it is. So, here's the list:

Replaced the intake. The mechanic was good, and a mobile guy so he came out to my place to do the work. Half way through the work, a thunderstorm rolled through, along with a torrential downpour. I held a tarp over us and the engine bay while he worked. Got the job done. I think he rushed a bit when checking/resetting the timing, but partly because there was zero water flowing through it. He had to leave (spent 6 hours in my backyard) so I took that troubleshooting task on.

A little troubleshooting and it was clear the seawater pump impeller had completely disintegrated. This was the part he replaced a year before I bought the boat. So, this is why it suddenly started overheating after 1 1/2 hours on the water. I definitely didn't expect that, but it is what it is. There was a spare that came with the boat, so I installed it, and ordered another for a spare. This solved the overheating issue.

I've changed the oil several times, and as far as I can tell all the water is out, and there is no evidence at all of adding water to the oil. The last one I added a can of seafoam, because I believe it will help clean the oil system and also absorb any leftover moisture. So far, I've been in the backyard with the hose hooked up for cooling. Hopefully today I'll get it in the water and verify. After 10 or 15 minutes, the temperature slowly rises up to the 200 degree mark, at which time I shut it down. My theory is this is a combination of using the hose (rather than in the lake) and I think the timing is off a little, which could make it run a little hot. Just a theory, though. 

It's time to winterize the boat, as I live in Alberta, Canada and winter is sneaking up on us. I will do 1 more full oil and filter change just for peace of mind (and because I have the stuff already), and drain the block. I will take it to a mechanic for the last part of the winterizing, mainly because I want to get the timing checked and the throttle looked at.....it seems to be a little sticky after the gasket replacement project, and idles high (1300 - 1500) unless I manually push the throttle down.

I also had to replaced the water shutters in the exhaust. Possibly where the water got in, but based on the lead up to the issue on the water, I'm still of the opinion it was thee intake gasket. Either way, II replaced them both. During this process, I realized the ex-owner didn't bother replacing the rubber exhaust tubes even though they are pretty worn out with cracking and hardening. I have replacements on order. I also have replacement on order for the nylon ball/spring/long screw assembly in the cooling system (sis below the thermostat). No idea what is called, but the nylon balls are severely warn so I'll replace that.

Otherwise, I'm fairly certain this boat is finally seaworthy. I'll feel better after the in-water testing.

As I said, I'll hopefully get it in the water today for a shakedown. Beyond that, it will be in storage until next season. I definitely appreciate all the guidance I've received from this group. I've learned a lot about this boat which is the bright side of the experience. I'm sure I'll be back with more questions next year. Have a great winter!

GordOnTheWater

PickleRick said:

If the boat is on a trailer just pull the drain plug.  You want as much out as possible. 

I then flushed my motor out with a blend of gasoline and motor oil a few times.  Still took 3 oil changes to get rid of maybe a few pints of water.  

@p@PickleRick in the end this is exactly how I did the oil changes. A little messy, but it worked out great. Thanks for the tip!

GordOnTheWater

rasbury said:

Sell? Sounds like you need another new wife already!

Nah, she came around. It's a great boat, it was just the frustration of making the investment, doing everything we could to make sure it was a solid purchase, and then sitting on the deck listening to all the boats on the water, all summer long, while ours sat in the backyard not running. As long as this thing is finally good to go, it's a keeper....and so is she lol!

Pat310

Are you sure you got all the bits and pieces of the old pump impeller out? Could block water passages and be causing it to heat up running on the trailer. 

GordOnTheWater

Pat310 said:

Are you sure you got all the bits and pieces of the old pump impeller out? Could block water passages and be causing it to heat up running on the trailer. 

Yes, i flushed all the lines out with a hose and got as much as I possibly could. I was able to get it over to the boat launch....didn't get a run n, but was able to run it with the leg in the water. When I put it in the water/in the lake, it ran with a steady temp at varying RPMs. So, I'm pretty confident I got it cleaned out. This is where it all began, with the previous owner/mechanic NOT cleaning out the debris from the exploded sea water pump impeller. So, I pay very close attention to how much debris I pull out, to be sure I get it all.