Mercruiser 165 6 Cyl. Good, Bad, Okay?

[sreiner]

I am looking to purchase and older boat that has a Mercruiser 165 6cyl. engine. Are these generally good engines? Any particular strengths and weaknesses? The boat is 18'7" tri-hull cuddy and approx. 2500 lbs. It will be a fishing boat and occasionally tow a tube or wakeboard. Any thoughts would be appreciated. Thanks.

 

[thunderroad]

Re: Mercruiser 165 6 Cyl. Good, Bad, Okay?

Whenever I look at older boats for a project, I'm always happy if they're a 140, 160 or 165. Maybe it's because they're simple...who knows. But the consensus I've read around here is that the engine is very reliable. I have one in a 69 model boat and it runs great.

 

[achris]

Re: Mercruiser 165 6 Cyl. Good, Bad, Okay?

I had a 165 for about 8 years and yes, they are quite reliable. The only thing to make sure is that the manifold water reversing kit is installed. If it doesn't then put it on before the manifold gets cracked, particularly if you plan on doing any water sports (skiing, tubing ect). Another thing I would recommend is the put electronic ignition on it. Points were ok in their day, but.... go electronic. And last but by no means least, and this applies to all I/Os, is the exhaust elbow. They have a lifespan of about 5-7 years and when they fail, they fill cylinders with water Replace it when you buy the boat, it's cheap insurance, and go genuine, the after-market ones last about half the time.

Chris...........

 

[sreiner]

Re: Mercruiser 165 6 Cyl. Good, Bad, Okay?

Guys, thank you very much for the input. I agree about the electronic ignition and I will take your advice with the other items as well if I get it. I am assuming it will have adequate power for a boat this size. I don't need anything spectacular, but would like to be able to get on plane and cruise at 25-30 mph or so with a full load. It seems like it would be a nice little motor and more fuel efficient than a V-8. I am trolling the vast majority of the time so quiet and smooth running are also important to me. Thanks again!!

 

[achris]

Re: Mercruiser 165 6 Cyl. Good, Bad, Okay?

My 165 was in a 20' Bertram Bahia Mar (cuddy) that weighs around 4,000lb and she would do 34mph at WOT. Just remember you're buying more than the engine, make sure everything with the leg and transom plates are ok too, otherwise you'll have your hand in your pocket more often than you would like . I also ran a prop that allowed the engine to spin at 4300rpm at WOT. These engines hate being over propped.

Chris.........

 

[sreiner]

Re: Mercruiser 165 6 Cyl. Good, Bad, Okay?

Sounds perfect. Thanks for the input - I really appreciate it as I've never been around this engine.

 

[79Glastron]

Re: Mercruiser 165 6 Cyl. Good, Bad, Okay?

That engine (GM 250ci) is a great engine, very smooth, you'll love it!

 

[HT32BSX115]

Re: Mercruiser 165 6 Cyl. Good, Bad, Okay?

That family of engines from the 60's to the 90's or so was probably the best inline 6's ever built. ( 230/250/292 I-6 )

They were perfect for a stern drive.

Mine was a 1966 Mark Twain, 150hp (230 cu-in), Mercruiser #1 drive. Dad bought it new and we ran it from 1966 - 2005. It never had the head off and the coupler lasted 38 years. The hr meter broke in the 80's at around 1500hrs. The only reason I sold the boat was to get a larger boat!

I told the guy that bought it, that if he ever wanted to sell the boat I'd buy it back from him!!



Cheers,


Rick

 

[sreiner]

Re: Mercruiser 165 6 Cyl. Good, Bad, Okay?

That's a great story! This boat is a major upgrade for me in size and power. I plan to keep it for many years so it sounds like this engine will be a winner provided it's in good shape of course. I baby my equipment also so it should last me a lifetime. Thanks again for all of the input. I am getting excited to get this boat!!

 

[ziggy]

Re: Mercruiser 165 6 Cyl. Good, Bad, Okay?

provided it's in good shape

do a compression test on the engine, from memory, 140 is spec, min is a 100. range of all cyl. within 20psi + pressure test the drive to 15 psi. it should hold it.......a long time......

i'll agree with everyone else. it's a good engine, great durablity, as easy as it gets to service ..... i like mine too.....

when i was a kid our 165hp in a 2500lb trihull did 40ish..... i was more than happy that the boat i got to replace it had the same engine in it..... my second 165hp mercruiser..... good luck with yer adventure........

 

[Akira]

Re: Mercruiser 165 6 Cyl. Good, Bad, Okay?

I own A 1969 19 1/2 Dorsett with the 250 160 hp inline six. Rebuilt the boat this summer plus the engine. Man this old heavy fishing boat is sweet in the ocean and river. Engine uses very littel fuel. And they last for years if you take good care of them. I found all new parts off the web to rebuild everything. It runs out at 43 mph @4300 rpm wot. Good luck with yours

Carl

 

[baytro23]

Re: Mercruiser 165 6 Cyl. Good, Bad, Okay?

6 in a row can go (great engines) - my dad had 1 in a 19'er back in the 70's, only problem we ever had was the ignition coil went bad. It would be erratic when hot and we had to run awhile, let it rest, run, rest. Finally made it back in.

 

[davidwjacob]

Re: Mercruiser 165 6 Cyl. Good, Bad, Okay?

Hello All,

Im new here jsut bought a 1972 Four winns 19 ft with a mercruiser in it. its says 165 on it, but has no other identifying numbers or tags. im downloading a manaul for all motors from 60 something to 73. this is my first boat.The engine turns but the previous owner thinks the crank is shot in it. i have a few questions maybe someone can help with:

1. if i post a pic of it here does anyone think they can identify the engine 100% or can you just tell from the 165?

2. and does anyone know where i can get parts for this engine?

thanks in advance and i look foward to becoming a active member on this forum

thanks
DAve

 

[ziggy]

Re: Mercruiser 165 6 Cyl. Good, Bad, Okay?

dave, ya should probably start yerself a new thread so folks can see your
question, not someone elses..

i had an unknown 165 in my last boat. probably a truck engine. i just used service manual #1 also. seemed to suffice. the 165, L6's, internally seem to be mostly the same. look for your serial number above the starter. a mercruiser tag. fyi, drive s/n is on the 165 sticker on the mercruiser sticker. also stamped into the drive under the sticker. i think port side.

parts for your 165 can be obtained at your local mercruiser dealer, or here at iboats, or many other places on the www. dougrussell, bam, many others....

and i look foward to becoming a active member on this forum

yer gonna love it here. many knowledgeable folks frequent the fourm..... welcome.


​

 

[MikDee]

Re: Mercruiser 165 6 Cyl. Good, Bad, Okay?

Hey, that's a great engine, had one in my old 18' Wellcraft airslot trihull, had to rebuild it to specs (it was siezed originally), it did 45mph, and only sipped gas, sorry I don't still have it.

 

[MikDee]

Re: Mercruiser 165 6 Cyl. Good, Bad, Okay?

Hello All,

Im new here jsut bought a 1972 Four winns 19 ft with a mercruiser in it. its says 165 on it, but has no other identifying numbers or tags. im downloading a manaul for all motors from 60 something to 73. this is my first boat.The engine turns but the previous owner thinks the crank is shot in it. i have a few questions maybe someone can help with:

1. if i post a pic of it here does anyone think they can identify the engine 100% or can you just tell from the 165?

2. and does anyone know where i can get parts for this engine?

thanks in advance and i look foward to becoming a active member on this forum

thanks
DAve

Chances are it is the 250 cu in/165hp 2bbl carb version, of the original Chevy 250/150hp 1bbl truck, and 70' Chevy 2 Nova engine I had.

 

[EZDuzIt]

Re: Mercruiser 165 6 Cyl. Good, Bad, Okay?

I had a 165 for about 8 years and yes, they are quite reliable. The only thing to make sure is that the manifold water reversing kit is installed. If it doesn't then put it on before the manifold gets cracked, particularly if you plan on doing any water sports (skiing, tubing ect). Another thing I would recommend is the put electronic ignition on it. Points were ok in their day, but.... go electronic. And last but by no means least, and this applies to all I/Os, is the exhaust elbow. They have a lifespan of about 5-7 years and when they fail, they fill cylinders with water Replace it when you buy the boat, it's cheap insurance, and go genuine, the after-market ones last about half the time.

Chris...........

What is this manifold water reversing kit you speak of? I bought a 76 Apollo with the Merc 165 straight six last year and am slowly restoring it. It does a little bit of everything from no wake speed putting along fishing to cruising to water sports. I'm looking for every upgrade to make it as reliable as possible. Electronic ignition is definitely on my list. Going to be doing a lot of work to it before next season.