Couple of questions

[ccoon520]

Ok so this weekend was the first time I was able to get the boat out on the lake since I purchased and did some repairs to it. I have a few questions. The motor is a Ford 351W (Mercruiser 233) SN: 4677439 and it is hooked up to an MC-1 outdrive (do not know the SN all the stickers are very worn).

First off Saturday it started really hard then ran rough when in gear and stalled repeatedly. So retrailered it and brought it home for some troubleshooting and repairs (hopefully). I had filled it with what I thought was ethanol free 93 but noticed at the pump friday that it had a 10% ethanol sticker in it. So the boat had a combination of about 5-10 gallons of fuel that was lord knows how old (but it started and seemed to run fine without load) and 20-25 gallons of 10% ethanol 93 that was 3 weeks old. So when we got home we drained the fuel and changed all the spark plugs. The old plugs were carbon fouled. We then found a station with ethanol free 91 (triple checked it this time) and filled the boat up with a couple of cans of Seafoam as well (28.5 gallons of fuel, 32 oz Seafoam, the remainder of the 30 gallon tank left over old fuel and probably some water). Took it home and started the boat up and it ran 100x better. To be completely honest I thought about changing the spark plugs and draining the fuel immediately after I brought it home but talked myself out of it because I'm smart (s-m-r-t) like that.

Now onto today, I put the boat in the water and it started first try no additional throttle needed, idled great, and went into gear no problem. I added throttle and it got on plane (a little slower than expected with just me, a cooler of water, bag of towels and a small toolset just in case) but the engine didn't seem to want to go above 3k RPM even with trim. I tried to get on plane again after this but I think I forgot to lower the trim because it just sent the nose to the sky. So I probably screwed up my attempt to replicate the situation. Does this sound like a carb issue or the prop being too steep (picture of prop pitch below).

Brought it off plane to pick up the wife and I noticed the temp gauge was in the red (no idea what temp that is the gauge is just yellow then green then red). I immediately shut off the motor then went and lifted the cowl. It was arguably cool in there and the I didn't feel any heat even radiating from the engine. I started the boat to see if letting it idle and pull water with no load would help and the needle sat in the red for a second then jumped to smack dab in the middle of the green bar. Then it sat there for a while and jumped back to the middle of the red bar. It never pegged all the way to the end of the gauge only ever to the middle of the sections. It also never gradually went to the spot it was always a jump in the blink of an eye. I have attached a picture of the temp gauge below. Any ideas on what the issue could be here? I do not have a temp gun to point at the engine and it seems odd that it would jump back and forth.

When we got back from the lake I decided to drain the engine oil because I had not changed that between me owning it and the previous owner as well. Below are pictures of what was pulled out via the dipstick tube. It is definitely murky and has water. it was about a 1/16" (maybe an 1/8") over full on the dip stick when I pulled it to check. Today was the second time the boat was in the water since I have owned it and only for probably 2 hours total. it has been on muffs for probably about an hour or 2 as well. Does this seem like a manifold leak or is it more likely that there was water in the oil from condensate for sitting for a couple of years and then when it ran it emulsified it? I've seen other posts about water in oil but they seemed to me to be a different color than this.

Mods let me know if I was supposed to split this into multiple posts and I will do so. I couldn't see to find the preferred method for multiple questions at once in the rules and apologize if I missed it.

 

[ccoon520]

Is there any input on this or should I split it into multiple threads?

 

[nola mike]

Cracked block, leaky manifolds are the usual suspects. How was it winterized? Salt or fresh water?

 

[ccoon520]

Cracked block, leaky manifolds are the usual suspects. How was it winterized? Salt or fresh water?

Fresh Water, and I do not know how it was winterized. I got it this spring with the outdrive off. It had sat a couple of years before I got it.

 

[76SeaRay]

Did you do a compression check? Milky oil usually says water in the oil. Cracked head/block etc? If you changed the oil, did it get milky again? I would definitely replace the temp gauge with one that gives you the actual temperature along with replacing the sensor at the same time. Make sure you have solid conductivity in the wire from the sensor to the gauge.

 

[ccoon520]

Did you do a compression check? Milky oil usually says water in the oil. Cracked head/block etc? If you changed the oil, did it get milky again? I would definitely replace the temp gauge with one that gives you the actual temperature along with replacing the sensor at the same time. Make sure you have solid conductivity in the wire from the sensor to the gauge.

I have not done a compression test. I can rent a compression tester from the auto parts store and probably do it this weekend. Dumb question but wouldn't the compression test just say there is a leak and not differentiate between a bad gasket, cracked block, or cracked intake or is there something I am missing?

Also I just pulled the oil for the first time yesterday I have not changed it since I got the boat (I probably should have but I got focused on other things and the engine oil slipped my mind besides checking that it was there).

Any specific Gauge that you would recommend or would any oil temp gauge with specific temps work?

 

[Scott Danforth]

do a compression test - all cylinders should be between 135 psi and 150 psi

then do a leak down test (to determine where the compression is being lost)

water in the oil could be leaking manifolds and water running down the cylinders which would also have low compression from rusty valves and valve seats on the back most cylinders

water in coil could be busted block and heads from poor winterization

also do a cooling system pressure test (15psi).

not sure what you are doing with the seafoam, there is no magic mechanic in a can. if your fuel system needs cleaning, it must be manually and mechanically cleaned.

 

[ccoon520]

do a compression test - all cylinders should be between 135 psi and 150 psi

then do a leak down test (to determine where the compression is being lost)

water in the oil could be leaking manifolds and water running down the cylinders which would also have low compression from rusty valves and valve seats on the back most cylinders

water in coil could be busted block and heads from poor winterization

also do a cooling system pressure test (15psi).

not sure what you are doing with the seafoam, there is no magic mechanic in a can. if your fuel system needs cleaning, it must be manually and mechanically cleaned.

Ok I will see what stuff I need to get for the leak down, and cooling system test and see if I cannot knock that out this weekend as well.

Seafoam was to act as a stabilizer (hence being around the 1 oz per gallon mark rather than the >2oz per gallon in the instructions for cleaning). It was mostly just a stop gap step after draining the old fuel from the system and not knowing how long the boat would be laid up for while troubleshooting. I figured if the carb needed cleaned it wasn't going to take care of that and I would need to rebuild it and clean it manually.

 

[ccoon520]

Also to confirm the order of operations here (because I could not find anything in the Adults Only section. Do a compression test on all cylinders and any that do not sit in the 135-150psi range do a leak down test on. This will isolate the cylinder(s) that have the issue. After that do a cooling system test at 15psi.

If compression is good, leak down is good, and cooling system is good it is probably condensate from sitting for a couple years.

If compression test and leak down is good and cooling system is bad then it is probably a cracked block.

My question is how to differentiate between a bad gasket/rusty valves/cracked manifold and a cracked block with a bad compression/leakdown? Is that then determined from the cooling system check (aka if cooling system holds pressure it is a bad gasket/rusty valves/cracked manifold, inversely if the cooling system does not hold pressure it is a cracked block)?

 

[nola mike]

Any specific Gauge that you would recommend or would any oil temp gauge with specific temps work?

The temp gauge is water temp, not oil. Get an IR thermometer to see where/if there's a problem. In the meantime clean up your connections at the sender and gauge at least.

Also to confirm the order of operations here (because I could not find anything in the Adults Only section. Do a compression test on all cylinders and any that do not sit in the 135-150psi range do a leak down test on. This will isolate the cylinder(s) that have the issue. After that do a cooling system test at 15psi.

Yeah, although what people call a leak down test is a bit misleading. In my mind a true leak down test involves measuring air in vs. air out. Seems that around here, most consider a leak down test to be simply pressurizing the cylinders and listening for a leak. That's probably adequate here; if the compression is down then you can see where you're losing it. Cooling system would be similar, not sure how easy it is to isolate the leak. If it's leaking you need to remove the risers/manifolds anyway though, and can test them off the boat. Bad HG could be seen on compression test, but not necessarily.

 

[Scott Danforth]

its hardly ever a bad gasket

if the leaking air is coming out the exhaust, you have rusty valves or valve seats. this would indicate a breach in the manifolds leading to water running in the cylinder and causing rusty valves

if the leaking air is coming out the breathers, you have leaking rings or a crack in the block or heads

the cooling jacket pressure test will confirm above

 

[ccoon520]

its hardly ever a bad gasket

if the leaking air is coming out the exhaust, you have rusty valves or valve seats. this would indicate a breach in the manifolds leading to water running in the cylinder and causing rusty valves

if the leaking air is coming out the breathers, you have leaking rings or a crack in the block or heads

the cooling jacket pressure test will confirm above

Thanks, I'll see if I can't get together rental tools from the auto parts store and test this stuff this weekend.

 

[ccoon520]

The temp gauge is water temp, not oil. Get an IR thermometer to see where/if there's a problem. In the meantime clean up your connections at the sender and gauge at least.

My bad, I was typing faster than I was thinking and put my foot in my mouth on that one.

Will the IR work on muffs? I'd think not since the water coming out of the hose is very cold and it isn't recommended to go above idle on them. Let me know if I am wrong. Unfortunately any lake that allow motors are an hour away from me so it may take a while before I get to the thermometer thing.

Also I just noticed that in that bulletin on the adults only section about water in oil it said to change the oil and run it at 1300 RPM until motor reached temp then check for water again. Is this something I should do before the other tests or should I do compression and leak downs first?

 

[nola mike]

My bad, I was typing faster than I was thinking and put my foot in my mouth on that one.

Will the IR work on muffs? I'd think not since the water coming out of the hose is very cold and it isn't recommended to go above idle on them. Let me know if I am wrong. Unfortunately any lake that allow motors are an hour away from me so it may take a while before I get to the thermometer thing.

Also I just noticed that in that bulletin on the adults only section about water in oil it said to change the oil and run it at 1300 RPM until motor reached temp then check for water again. Is this something I should do before the other tests or should I do compression and leak downs first?

Compression test is always a good idea just to get a baseline for the engine. Sure, change the oil and see if water comes back. Won't hurt anything.

 

[Rick Stephens]

First priority is to change oil and filter and run it to see if it gets water back in the oil. If so, then you search for the cause. The cause can be as simple as the engine cover left open and water dripping in through the carburetor. I hate to see you waste time on compression and engine tests if you have a cracked block. Most often, a cracked block will not show up on a compression test.

If your motor clears up the oil, then you proceed from there with whatever tests make up a balanced look at your motor.

If your motor oil fills back up with water, then very next step is pressure test the cooling system and find out where the air leaks out.

 

[ccoon520]

First priority is to change oil and filter and run it to see if it gets water back in the oil. If so, then you search for the cause. The cause can be as simple as the engine cover left open and water dripping in through the carburetor. I hate to see you waste time on compression and engine tests if you have a cracked block. Most often, a cracked block will not show up on a compression test.

If your motor clears up the oil, then you proceed from there with whatever tests make up a balanced look at your motor.

If your motor oil fills back up with water, then very next step is pressure test the cooling system and find out where the air leaks out.

If I run the engine on muffs is that adequate to see if water gets back in the oil or does it need to be under load?

 

[Rick Stephens]

On muffs is fine. I sure wouldn't bother taking it out for a cruise. Pay close attention to oil level before and after. If getting water in it will show up as overfill on the stick.

 

[ccoon520]

On muffs is fine. I sure wouldn't bother taking it out for a cruise. Pay close attention to oil level before and after. If getting water in it will show up as overfill on the stick.

Perfect. I can do that this weekend. I have 2 gallons of oil on the way and a new oil filter as well. I'll check the temp gauge connections and what wiring I can see to make sure no critters have gnawed through it and look into a new temp gauge that shows actual values.

 

[ccoon520]

Ok so I'm still around life just got in the way. Did a compression test and both banks were low (no cylinders significantly lower than another though all within 5 psi) and the motor needs rebuilt but that will need to come later due to a list of reasons the top of which is space, time and money. I could not do a leakdown test because none of the auto stores in my area had one for rent and the compression tester I did rent had a check valve on the spark plug port so I couldn't even pressurize the cylinders with it. So in order to move forward I pulled the intake and heads and started looking at the block for signs of cracks. I found no visible cracks across the top of the cylinder block between the water and oil passages.

Attached is a picture of the oil passage (lower circular hole) behind Cylinder 8. There appears to some dark lines sweeping back and forth and I can't tell if this is just one long hairline crack or something else. In my head if the block cracked due to expansion it would be at least linear-ish but what is in the picture seems to snack back and forth I also cannot see a corresponding path on the water passage side but that doesn't really mean much. Has anyone seen anything like this before is this a crack?

 

[achris]

With the amount of work (and money) that is going to be involved in refurbing an almost 50 year old power train, and at the end of it, you'll still have a 50 year old power train. I would be looking for a donor boat with a good, working late model 5.7 and Gen II drive. Anything north of 1991.

Chris........