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U used 318 Marine Block purchase

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scottyjean

New member
Good Afternoon

I have an opportunity to buy a used 318 marine block.

The cylinders were bored (.020)out last September and winterized for the winter. (by the owner)

Unfortunately water got into the last two cylinders leaving rust in these cylinders. The rust has been removed using fine emery cloth.
but there are rust stains in the cylinder walls. Cylinder walls are smooth.

The Block is otherwise in very good condition. Second opinions on whether to buy this Block or not would be greatly appr

Thankyou for your time
 
To tell you the truth I am not sure.

Ran the Engine for about 20 minute and then let it sit for awhile . Check oil level and it was up. A couple of days later I checked the level and it was down ??

Upon further evalulation of the Engines performance I have found a lot of other problems

Upon start up Blue smoke exits exhaust - gasoline can also be seen on water - there are shooted plugs - wet plugs - there is now a clanking noise coming from the under the Valve Cover. (could be a lealing exhaust manifold. )

Today I am going to perform a Compression Test, both wet and dry. I am also going to remove the Valve Cover and see what I can find.(springs something loose)

Yesterday I ran the engine again and today I am going to check th oil level again. I am also going to take a sample from the Oil and see if any water or gas are present. I will not run this engine again

Your help is appreciated
 
Until you zero in on what’s wrong the engine, I would advise against a plan of simply transferring your current components and internals to used block (a somewhat questionable one at that). Even if your block is, in fact, toast,there may also be other sketchy parts that shouldn’t be transferred over.

Buying a block-only, that someone says has been bored-over,is always a risk. I’m not saying the seller doesn’t have good intentions but there may be backstory that he’s unaware of, etc.. So, if you buy it, you’ll want to pay to have it magnafluxed, confirm the bore and, most likely, have it honed. You don’t want to put the time and money into that block if it’s a loser. Also keep in mind that, if your current block hasn’t been bored, you’ll need to shell out for new pistons to match the overbore of the “new” block.

I know it’s very easy to suggest how someone else spend their money but, having done a couple of tear-downs/rebuilds (both the right and the wrong way) and having purchased a remanufactured longblock, it’s really hard to advise someone to go the rebuild route with a 318……..because the longblocks are so reasonably priced. Again, it’s different story if you’re 100% certain that everything you’re using for the rebuild is in good shape.

I would continue with your efforts to narrow down what’s going on. Never know…..you may find that you’re only in need of a new riser, etc.
 
Last edited:
Thankyou for your reply

You are correct I must find the source of the problem.

AS I said above I ran the Engine for about 20 minutes - 24 hours later I checked the oil level and it had not moved
Also I took a sample of Oil from the Crankcase and found evidence of water.

Spark Plugs all were black a little bit shinny - two were sooty

Compression Test- 2 at 135 - 5 at 120 and one at 100 ( cylinder # 8). No evidence of water in the Cylinders. Going to perform a wet Compression today


Exhaust Manifold had a couple of loose nuts. Sufficent amount of water is being pumped out of the Boat. Going to replace gasket and tighten.
If there is a breach in the Exhaust components I believe that I should should find water in the exhaust ports of #7 or #8

With cylinder #8 at 100 - I am concern that this is a Cylinder head gasket problem or a ring problem

The engine runs good but I believe that there is an Ignition misfire. Engine needs new Spark Plug wires.-will replace

Thankyou for your time
 
Having run a 318 with a cracked block, it doesn’t sound to me like that’s your issue. Obviously, it depends on the size and location of the crack but, typically, those things fill up fast and make quite a milkshake out of the oil.

From what you’re describing, it seems more likely that water’sgetting into the cylinder(s) via the heads as opposed to directly into the oil via the block. I think you’re on the right track doing some further investigation into the exhaust, head gasket, etc.
 
In your original thread, I mentioned checking the oil coolers (if you have oil coolers). A cracked oil cooler will introduce small amounts of water into the oil, and it's a very easy fix.

Do you have oil coolers, and if so, did you check them?


-JJ
 
Hello

There is water in oil and when I last checked the oil level it was down. I don't understand this. I had only run the engine about 20 minutes. I did not find any water when I pulled the Plugs. I found no milkshake but the Oil was brown . I took a sample and this is when I found the water. I had to let the sample sit for several hours.

I will try one more oil change and check for water in the Cylinders . If this does not work I will look at the Exhaust System the Intake Manifold and Cylinder Head gasket.

Oil Cooler. I inspected the cooler visually and saw no leaks. This is transmission oil and the level was right on. Will take another look at it.

As always thank you for your time
 
Hello and Good Day

One thing that confuses me is that after taking the last oil sample and letting it sit for a couple of hours a grey sludge appeares at the bottom of the sample glass. The rest of the oil is a dark brown. A small level of water appears at the top

I took the sample from the bottom of the oil pan and I now assume that the bottom of the oil pan is filled with this Grey Sludge. I had not changed the oil from last Summer until this Spring.

The engine does not fill up fast with milkshake oil and when checking the oil level it appears clean

What would be the colour of new oil and water mixed be?

This is most confusing as I am trying to decide on whether or not to do a couple more oil and oil filter changes before a teardown. I am concerned about doing damage to other engine parts

Any comments or experiences are appreciated
 
It is a huge mistake to put a marine engine away for the winter without changing the oil.

It IS possible that an oil change or two now might get rid of that sludge and your problem, but...

Jeff
 
scottyjean said:
Hello and Good Day

One thing that confuses me is that after taking the last oil sample and letting it sit for a couple of hours a grey sludge appeares at the bottom of the sample glass. The rest of the oil is a dark brown. A small level of water appears at the top.
Click to expand...

Wait a minute here... water has a higher specific gravity compared to oil, and therefore will sink to the BOTTOM of the vial. If you see a fluid on top, it is not H2O.

-JJ
 
Gasoline floats on TOP of motor oil. You have GAS in your oil my friend.

Easy way to find out for sure...smell it and check to see if it's flamable.

-JJ
 
scottyjean said:
To tell you the truth I am not sure.

Upon start up Blue smoke exits exhaust - gasoline can also be seen on water - there are shooted plugs - wet plugs - there is now a clanking noise coming from the under the Valve Cover. (could be a lealing exhaust manifold. )

Your help is appreciated
Click to expand...

I'd check to see if you have an extreme rich mixture condition, or if you're getting spark at all the plugs. Sounds like you're not burning the fuel getting into the cylinders.

-JJ
 
Hello

I am happly to report that after 4 oil changes the engine nows maintains its proper oil level.

However i cannot understand where all that water came from. I admitt that I did not change the oil at fall haulout but there was an increased oil level with new oil in the engine.


Thankyou for your time
 
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