Mercruiser 160/165 cracked block

[gregg_a_g]

Got a "free boat" with 1974 Mercruiser 165. The outdrive appears to be in very good shape (said to have been rebuilt about 5 years ago). The boat has been sitting for the last 4 years - not winterized, and it got in the 20s for several days at a time, several times. The engine had about 4-1/2 qts of "oilish type substance" (ha, ha). It was so thick it was hard to drain - gray emulsified
mess with lots of water. I can't imagine that the block is not cracked. Solenoid pulls in, but the starter is completely frozen. Removed exhaust manifold and cylinder head and they both look pretty good. Carburetor looks crummy.

Just after I got the boat and determined the engine condition, I was able to get a very nice looking Mercruiser 160 and outdrive. The exhaust manifold on this one looks good, but it has the "reverse flow" setup, minus the elbow/adapter going into the side of the exhaust elbow. The carburetor looks pristine. It looks like the owner was going to do some maintenance or possibly replace the exhaust elbow, but never finished. The 160 was in a Reinell (looked immaculate) that was sitting in a heated garage for the last several years. The owner developed Alzheimer's/dementia, so the boat just sat. Anyway, I got the motor and outdrive for $200 and figured it was worth it to take a chance that I could get one engine running!

The oil in the 160 looks like it just came out of the jug. There is literally no grease or grime on the engine. It turns over easily. Now my questions.

It seems that it might be easy to get the 160 running without too much effort or expense, so that's my Plan A.
1) I could use the 160 engine with it's existing manifold (reverse flow, but I would need to find an adapter to thread into the exhaust elbow), OR I could use the manifold from the 165. Any pros or cons that some of you might know about? I guess under certain conditions, some of the 160/165 manifolds would develop "hot spots", hence the "reverse flow" kit. From what I have been able to find online, it doesn't seem that the "reverse flow" was used much.
2) The 165 carburetor looks crummy, the 160 carburetor looks very good. Both are Rochester 2GC, but the configurations are slightly different. The 165 has a fuel inlet, and a valve cover breather hose connection that goes into the flame arrestor. The 160 has the same fuel inlet, but no breather hose to the flame arrestor. The valve cover on the 160 has a breather cap.
Also, the 160 carb has a tee on the starboard side with one line going to the valve cover, and then another going to the bottom of the Carter fuel pump. I am planning to use the 160 carb, but wondering what the purpose is of the 2 lines on the tee?
3) I think I can figure out the electrical connections, but there are a couple of differences on the 160. There is a FloScan fuel sensor inline from the fuel pump to the carburetor. I guess these are used to calculate fuel consumption/efficiency. I'm assuming I can just delete this all together. The other difference is some kind of solenoid on the port side of the block. It has 4 wire connections, but I don't see anything else. Anyone know what this might be?

I've finished removing the 165 from the boat, and cleaned up the hull/floor. Debating whether or not to remove the transom plate an replace the u-joint/exhaust bellows or leave as is. The owner that gave me the boat said there was a small amount of water accumulating and that he had to run the small bilge pump now and again. Don't see any other "leak candidates", so thought it might be one of the bellows (or maybe he just had a bad boat plug).

My next step will be to decide on the final configuration and then try and run the 160 engine out of the boat. Any help with the questions above, or other advice will be greatly appreciated!

Gregg G.

 

[achris]

Got a "free boat" with 1974 Mercruiser 165.

The most expensive way to boat ownership!

Just after I got the boat and determined the engine condition, I was able to get a very nice looking Mercruiser 160 and outdrive. The exhaust manifold on this one looks good, but it has the "reverse flow" setup,

That's not a 'but', that's an AND!

The oil in the 160 looks like it just came out of the jug. There is literally no grease or grime on the engine. It turns over easily. Now my questions.

Engine-wise, the 160 and the 165 are the same.

1) I could use the 160 engine with it's existing manifold (reverse flow, but I would need to find an adapter to thread into the exhaust elbow), OR I could use the manifold from the 165. Any pros or cons that some of you might know about? I guess under certain conditions, some of the 160/165 manifolds would develop "hot spots", hence the "reverse flow" kit. From what I have been able to find online, it doesn't seem that the "reverse flow" was used much.

The reverse flow kit was only made available after the 165 had stopped production. However, if you bought a new manifold (back in the day) it came with a reverse flow kit IN THE BOX!

2) The 165 carburetor looks crummy, the 160 carburetor looks very good. Both are Rochester 2GC, but the configurations are slightly different. The 165 has a fuel inlet, and a valve cover breather hose connection that goes into the flame arrestor. The 160 has the same fuel inlet, but no breather hose to the flame arrestor. The valve cover on the 160 has a breather cap.

Use the flame arrestor from the 165. Check the specs on both carbs and respec the 160 carb for a 165.

Also, the 160 carb has a tee on the starboard side with one line going to the valve cover, and then another going to the bottom of the Carter fuel pump. I am planning to use the 160 carb, but wondering what the purpose is of the 2 lines on the tee?

Line form the bottom of the pump is a diaphragm rupture line. If the diaphragm ruptures, it floods out the engine and stops the pump form filling the engine oil pan with raw petrol. Not a good thing!

3) I think I can figure out the electrical connections, but there are a couple of differences on the 160. There is a FloScan fuel sensor inline from the fuel pump to the carburetor. I guess these are used to calculate fuel consumption/efficiency. I'm assuming I can just delete this all together.

Ok relocate the display to the new boat.

The other difference is some kind of solenoid on the port side of the block. It has 4 wire connections, but I don't see anything else. Anyone know what this might be?

Probably the starter solenoid.

I've finished removing the 165 from the boat, and cleaned up the hull/floor. Debating whether or not to remove the transom plate an replace the u-joint/exhaust bellows or leave as is. The owner that gave me the boat said there was a small amount of water accumulating and that he had to run the small bilge pump now and again. Don't see any other "leak candidates", so thought it might be one of the bellows (or maybe he just had a bad boat plug).

Have a look at the yoke and unis on the front of the drive. Rusty? Uni bellows leaking. Not rusty, your leak is elsewhere, and I would definitely be removing the transom plate and gimbal housing. At the very least you can check the transom for rot.

My next step will be to decide on the final configuration and then try and run the 160 engine out of the boat. Any help with the questions above, or other advice will be greatly appreciated!

Gregg G.

 

[gregg_a_g]

Hi, achris - thanks for your reply and all the info! Ah, so the "reverse flow" was an afterthought of sorts, but a good way to fix uneven manifold temp - got it! I don't know why it was partially disassembled, but it looks like the riser elbow was getting long in the tooth and kind of rusted. I'll plan on using the riser elbow from the 165 - it looks like I just need to remove one of the plugs and put in a 3/4" npt x 1" hose fitting to reattach the cooling line from the front of the manifold. Is that how the "kit" came back in the day, with an elbow to replace one of the 3/4" plugs in the riser?

I didn't know that a slave solenoid was sometimes used, but now understand why and can verify that it's working fine.

If I use the flame arrestor from the 165, would it make sense to also use the valve cover from the 165 so that I have the right breather connection?

If the line from the bottom of the fuel pump on the 160 is a safety in case of diaphragm rupture, why doesn't the 165 use one? If I use the valve cover from the 165 it doesn't have a fitting for the return line from the tee in the carburetor. Would it make sense to add a fitting to the 165 cover and use the 160 carburetor with the tee and extra line from the fuel pump? Or would it be better to use the fuel pump from the 165 without the extra line? I'm not quite understanding the situation... If the fuel pump diaphragm ruptured, wouldn't the fuel pump just stop pumping?

The outdrive universal joint and yoke are pristine - no sign of corrosion whatsoever. The exhaust bellows looks pretty clean as well. The only other place I can think of that might be leaking (evidently it was a small leak) is the water tube or bell housing to transom cork gasket/seal. Is that where I should be looking when I take off the plate?

Is this what a cracked block looks like? This is the goo that came out of the oil pan... I think the carb on the 165 was just about toast, so it was running very poorly. The previous owner got frustrated and just left the boat instead of draining the block and manifold before the cold weather.
"Free boat" is expensive, huh? Ha, ha!

Thanks so much for your wealth of knowledge!

 

[nola mike]

. The only other place I can think of that might be leaking (evidently it was a small leak) is the water tube or bell housing to transom cork gasket/seal. Is that where I should be looking when I take off the plate?

The issue is that when the transom rots it flexes, allowing water around that seal.
You need to drill into your transom to check its condition. Basically take a ¼ drill bit and drill in an inch or so in multiple places, particularly down low and around the transom cut out. See if you get wood shavings or wet mush.

 

[gregg_a_g]

Hi, nola mike - thanks for the suggestion! The hull of the boat looks so good, and the transom area looks and feels very solid. I'd be surprised if there was rot, but I have very little experience so I'll have to give it a try. Best case outcome - there is not rot, what to do then? Epoxy over the test holes? Then keep looking for other leak paths?

Worst case outcome - "mush" as you say. Does that mean I would have to replace the whole back of the boat? The transom is one piece of wood that covers the whole back? Whew, the "free boat" is costing more already!

 

[nola mike]

Hi, nola mike - thanks for the suggestion! The hull of the boat looks so good, and the transom area looks and feels very solid. I'd be surprised if there was rot, but I have very little experience so I'll have to give it a try. Best case outcome - there is not rot, what to do then? Epoxy over the test holes? Then keep looking for other leak paths?

Yeah, epoxy or 5200

Worst case outcome - "mush" as you say. Does that mean I would have to replace the whole back of the boat? The transom is one piece of wood that covers the whole back? Whew, the "free boat" is costing more already!

Yes, plus your stringers as well probably. Unless you're a masochist, you dump the boat at that point and pay for one that floats and runs. What was wrong with the boat you pulled the engine from?

 

[gregg_a_g]

An elderly couple had the boat, but due to health reasons hadn't used it in quite a few years. They called a salvager to haul it off. The salvager expected to find it overgrown with weeds - was shocked to find it in a garage. The boat was in very good condition, so a friend wanted to use it for crabbing (this is in Seattle area), but wanted to put an offshore bracket with big outboard. The salvager carefully removed the engine and out drive, even saved all the nuts, bolts and bits. The oil in the pan looks like it just came out of the jug, carb and plugs super clean, no grease or grime anywhere. Cranks easily - so I'm thinking I'll get the cooling reconnected and see if I can get it to run on the platform I have it bolted on.

The "free boat" I got is great cosmetically - clean seats, floor, hull not dinged, so I'm hoping the transom is ok!

 

[Scott06]

An elderly couple had the boat, but due to health reasons hadn't used it in quite a few years. They called a salvager to haul it off. The salvager expected to find it overgrown with weeds - was shocked to find it in a garage. The boat was in very good condition, so a friend wanted to use it for crabbing (this is in Seattle area), but wanted to put an offshore bracket with big outboard. The salvager carefully removed the engine and out drive, even saved all the nuts, bolts and bits. The oil in the pan looks like it just came out of the jug, carb and plugs super clean, no grease or grime anywhere. Cranks easily - so I'm thinking I'll get the cooling reconnected and see if I can get it to run on the platform I have it bolted on.

The "free boat" I got is great cosmetically - clean seats, floor, hull not dinged, so I'm hoping the transom is ok!

Check for rot which is common in boats of this age. Possible if stored inside it is not rotten but that is the first thing to check before you put much time and money into it. Drill in bottom of transom stringers around the engine if they are ok plug as mentioned .