Need some motor advice 165 Six OMC

[metalwizard]

I have a 73 arrowglass with 165 hp omc outdrive.

when I got it there were some Drive and tilt problems. had to change out the intermediate housing and some minor stuff. got it all taken care of.

Put the motor back in hooked up some water to her and Water is pouring out from under the int/exh manifold. I get in there with the flashlight and a freeze plug is missing. THis is odd because no leaks (that I new of ) before I pulled the motor.

So I pull the manifold put in a plug and fire it up again. STILL LEAKING (very minor compared to what it was)

I get the flashlight out. and I have a hairline crack about 1/2-1" below the head gasket in the block. AARRRRGH!!!

Ok the motor is old. so First off I am wondering if it was that way when I bought it and I got suckered, I only had it in the water once and got about a cup or two of water out when I pulled it out and pulled the plug. So I think it is possible it was bad beforehand.

Just a note I did drain the two petcocks on the side of the motor before it got really cold. But It is possible i was to late. and it's my fault. Either way. I got to do something.

My question. I have never owned a straight six. When you run them out of the water are they noisy? (i know nothing to do with my leak. i will get to that) I understand no muffler, so its going to be loud, but the motor itself seems loud to me.

Ok. if it's supposed to be quiet, It seems like i should just go with a new (used rebuilt etc) motor.

If I do that can I use a 250 Chevrolet CAR engine? (long block only not carb dist etc)
If so I heard I need a special head gasket, IS this true? is there anything else I need to make sure of or change to be Boat ready? or is this idea BAD..

When I talked to my wrecking yard they said they also have 292 Straight six motors. that should be the same externally. Dose that sound correct? and is this something I should or should NOT do? I cannot read the HP rating on the tag. it is just plain worn gone.

THe boat is a 73 Arrowglass Viper. 17.5" foot long. I don't know what else is needed to figure max HP..

Thanks in advance for your input. If any more info is needed I'll do my best.

 

[HT32BSX115]

Re: Need some motor advice 165 Six OMC

Howdy,


Yes, the crack is from frozen water left in there during winter. Did it happen before or after you got it? Anybody's guess.

Bottom line is you need to find another one.

You can basically use any 250 truck engine (to get the closest cam-profile to a marine cam) that has the correct mounting points. Look at the way your engine is mounted.....you'll need to closely inspect any engine you find for those same mounts........ It can be a 230/250/292 as long as it has the same mounting arrangement.

There are some 250/292's with vastly different heads. You have to use your current head in that case.

The 292 is about 1" taller(deck) than the250/230 engines and that might make matching up the exhaust problematic and it may not fit at all so finding a 250 might be the best (and easiest) bet.

When I went looking for 250/292 engines at a local truck parts wrecking yard, they had something like 15 engines for me to look at and several of them were suitable.

In the future when you drain an engine block, ensure that you always use a piece of wire or other "poker" to get all the rust flakes and other debris that can keep you from completely draining the block. DO it on the manifold too.


Good luck,


Rick

 

[metalwizard]

Re: Need some motor advice 165 Six OMC

Thanks Rick.

Honestly I don't know if it was ME or it was that way when I bought it. Nothing I can do about that now. I will tell you, the guy I got it from did NOTHING to maintain the boat. it was pretty crappy shape when I got it.

I only saw 2 drain points on the engine. both on the port side, near the rear below the exhaust/intake manifold. am I getting all of them.

I have heard about using anitfreeze How much of a pain is that? It does get below freezing here. but not that often (I know it only takes once.)

I poked around and found a 165 hp MARINE engine rebuilt ready to stab in long block for $1900 ish shipped to my door, no core charge.

I may end up doing that. then I know I am 100% good to go.

 

[GLENN M]

Re: Need some motor advice 165 Six OMC

$2000 ish rebuilt,shipped to your door.sounds like the best way to go if you buy used truck engine you have to change head gasket and frost plugs.chances are its pretty close to wore out anyway.my dad had a little pump ran off a drill he used to pump antifreeze through motor after every run in salt water,you would be amazed how much longer manifolds lasted.not for freezing but to stop rust,winter he drained after flushing.

 

[metalwizard]

Re: Need some motor advice 165 Six OMC

Glenn,

I am pretty broke for extra money but I agree that might be the best thing to do. then I know it is done right. and I am NOT going to have any other problems. At least theoretically.

Wat kind of pump did he use? and wht kind of antifreeze. I only do lakes. but I am sure it would help

 

[GLENN M]

Re: Need some motor advice 165 Six OMC

its bein a long time but it was just a cheap pump i think he got from canadian tire,it ran off of a 3/8 drill.he put a container under drive to catch antifreeze,he used regular auto antifreeze just was careful not getting any on the ground.his first manifold started flaking rust second year had boat plugged riser,it was his first i/o 120 merc so it gave him fits he was master gm mechanic so no one touched his stuff,although he wasent above asking questions anyway manifold lasted 2 more yrs.next one lasted 10 yrs still on when sold boat he swore by flushing then antifreeze.

 

[HT32BSX115]

Re: Need some motor advice 165 Six OMC

Glenn,

I am pretty broke for extra money but I agree that might be the best thing to do. then I know it is done right. and I am NOT going to have any other problems. At least theoretically.

Wat kind of pump did he use? and wht kind of antifreeze. I only do lakes. but I am sure it would help

If you're only a lake boater, draining the block is a sure way to prevent freezing. (I think Bondo says; AIR DON'T FREEZE......I tend to agree.)

My previous boat had a 230 GM I6 in it. (1966 Mark Twain that Dad bought new) While it was getting tired after 39 years, it still ran OK. I just drained the block & manifold every year.......

There's nothing wrong with using a truck engine. Those 250's last a "good-long-time". Just do a compression check before you use it. Most wrecking yards will ensure that you get a "good" runner if you ask for one.

If you're only running in fresh water, you wouldn't have to worry about the head gasket. It probably wouldn't be a bad idea to change the soft plugs but even that's not all that required either if you're not going to run in salt....

 

[proshadetree]

Re: Need some motor advice 165 Six OMC

Fresh water boater here with a Gm truck 305. Same head gasket same core plugs. If you had a good motor see if you can have it welded. I welded both my manifolds. Some also use JB weld. I have only used this on automotive radiators but I still have one 25 years later that dont leak. If you do a JB weld repair keep an eye on it. Only use the pink rv antifreeze. If someone sees green driping out of your boat before you hit the lake EPA may be on you.

 

[metalwizard]

Re: Need some motor advice 165 Six OMC

I was thinking about the JB weld thing. the crack is really minor. I heard best thing is to drill small holes at the end of the crack first so it does not spread.

I think the nosiey engine is the gear drive. I have NO idea how old the motor is or hours on it. but it ran good.

 

[86 century]

Re: Need some motor advice 165 Six OMC

Those old i6 eng no matter who made them will last a long time.

I have seen those things beat to two or three times and they still run may not have much power but will get you home.

I am confident enough in a cracked 165merc that I am putting it in latest projects.

 

[metalwizard]

Re: Need some motor advice 165 Six OMC

Just my experiance, when an old engine makes a lot of thrashing noise it's tired in a lot of ways. I don't know that I would spend much time or effort resurecting it. Chances are, any repair you make to the crack is temporary at best. Have you checked with any local rebuilding shops to get a price? There are no "marine parts" other than the cam, casting plugs, and head gasket. You or they can order all the parts from the normal auto parts market.

If I replace the motor I found a good rebuilt MARINE shipped to my door paying shipping and for the core it was $1895. Right now I have some ex wife and court issues so spending that much is not a good option.. it might be but I would rather wait. so YES changing it is in the near future. BUT until then I wanna take it out. so at least a bandaid for the crack. and a few more trips this spring. and I am happy , if it blows it blows. the lakes by us are not that big that I am worried about being stranded.

Those old i6 eng no matter who made them will last a long time.

I have seen those things beat to two or three times and they still run may not have much power but will get you home.

I am confident enough in a cracked 165merc that I am putting it in latest projects.

are you saying you have a welded repaired block and it is going strong or at least you trust it and you will be using it?
That is good information.

 

[GLENN M]

Re: Need some motor advice 165 Six OMC

use to be a product you could buy at drug store called waterglass it was an egg perservitive,had an 6 inch crack in an 86 olds engine right along water jacket.poured waterglass in 5min later not a drip for two years till sold car.ive taken heads into machine shop and they brazed crack,not sure of total procedure but guy there didnt flinch when should him crack i had it back next day worked great.i think cost me $45.

 

[fishrdan]

Re: Need some motor advice 165 Six OMC

For that old of an engine I'd do the JB weld thing and hope water doesn't appear in the oil.

Here's something to check out, craigslist, roll the dice...

http://mohave.craigslist.org/boa/2183333984.html

When you say the engine is noisy, how and where is it noisy? Drive noise, gimble bearing, Ujoints, water pump, alternator, valves, rods? If that engine is original it probably has the fiber timing gear, those are supposed to run quite.

 

[86 century]

Re: Need some motor advice 165 Six OMC

If I replace the motor I found a good rebuilt MARINE shipped to my door paying shipping and for the core it was $1895. Right now I have some ex wife and court issues so spending that much is not a good option.. it might be but I would rather wait. so YES changing it is in the near future. BUT until then I wanna take it out. so at least a bandaid for the crack. and a few more trips this spring. and I am happy , if it blows it blows. the lakes by us are not that big that I am worried about being stranded.



are you saying you have a welded repaired block and it is going strong or at least you trust it and you will be using it?
That is good information.

yes i have early 70's 165merc (250 chevy) that has a large crack just below the deck.

She runs great i put around 10hrs on it last summer no problems at all.
Some have a big problem with external cracks I don't.
My opinion would be to run it see what happens worst thing you are out a hour or two.


i have a 140 merc 4cly that has a nasty crack in the same place you describe that my parents ran all last summer with no issues at all. Some pics of the 4cly before and after jb weld.

 

[metalwizard]

Re: Need some motor advice 165 Six OMC

Just my experiance, when an old engine makes a lot of thrashing noise it's tired in a lot of ways. I don't know that I would spend much time or effort resurecting it. Chances are, any repair you make to the crack is temporary at best. Have you checked with any local rebuilding shops to get a price? There are no "marine parts" other than the cam, casting plugs, and head gasket. You or they can order all the parts from the normal auto parts market.

For that old of an engine I'd do the JB weld thing and hope water doesn't appear in the oil.

Here's something to check out, craigslist, roll the dice...

http://mohave.craigslist.org/boa/2183333984.html

When you say the engine is noisy, how and where is it noisy? Drive noise, gimble bearing, Ujoints, water pump, alternator, valves, rods? If that engine is original it probably has the fiber timing gear, those are supposed to run quite.

thanks for the link I will check that out seems to be Flagstaff, Ny daughter lives there...
as for the noise. No its up front. I am thinking timing gears. had a neighbor with a 4 cyl chevy same noise. gears went out.
I figure once the leak is fixed I will look into that more. Pull the dist cap rock the crank back and forth see how much slop in the gears.
Should be an easy fix only one belt and pull the balancer and you are there..

yes i have early 70's 165merc (250 chevy) that has a large crack just below the deck.

She runs great i put around 10hrs on it last summer no problems at all.
Some have a big problem with external cracks I don't.
My opinion would be to run it see what happens worst thing you are out a hour or two.


i have a 140 merc 4cly that has a nasty crack in the same place you describe that my parents ran all last summer with no issues at all. Some pics of the 4cly before and after jb weld.

WOW nice repair. JB weld it is..

 

[fishrdan]

Re: Need some motor advice 165 Six OMC

thanks for the link I will check that out seems to be Flagstaff

Nope, Golden Valley AZ. Between Kingman and Bullhead City, AZ.

 

[metalwizard]

Re: Need some motor advice 165 Six OMC

I called 3 times.. no answer.. Must be in a hurry to sell LOL

thanks for the hook up. if I ever get a callback

 

[metalwizard]

Re: Need some motor advice 165 Six OMC

Well I tore the motor apart. my outer crack is not that bad. BUT I have water in my oil. so it's a lost cause.

I did get a hold of the guy in the add. I have one question Are ALL gm 165 hp straight six marine motors the same? or at least interchangeable?

Mine is OMC, his is Black so I am thinking it's mercrusier (but I am not sure and I don;t think he is either)

The things I am worried about, engine mounts. bellhousing, intake exhaust fit etc.

I attached the pictures he sent me so far. they are pretty crappy but better than nothing.

I told him if I can hear it run, ANd I am sure it will work for me I will take it. He is about 4 hours drive from me,
So I want to know what I am looking for (fit wise) before I go.

Thanks for any input.

 

[Bondo]

Re: Need some motor advice 165 Six OMC

I have one question Are ALL gm 165 hp straight six marine motors the same? or at least interchangeable?

Ayuh,.... 1st off,.. Do you understand the difference between a complete motor, 'n a Long Block,..??

The Long Blocks are the same, 'n completely interchangeable....

You'll need to reuse All of the OMC accessories swapped over to the Merc Long Block, after you've removed all the Merc accessories,...

The Merc motor mounts, manifolds, alternator, igntion, etc are No good for the OMC....
None of it'll line up, or bolt up, or hook up properly...

 

[metalwizard]

Re: Need some motor advice 165 Six OMC

Yep I know the difference. I actually used to be a Heavy Line technician for Jeep ans Chevrolet. So I have done my share of motor work.

I was worried about bolt holes and bell housing bolt holes aligning up Also my intake exhaust is pretty rough, so I was hoping I could use the one off the "new" motor..

anyways. If the long blocks are Identical. I believe I am good to go as long as the motor is in running condition.

Thanks for the input Bondo.. that was the answer I needed. I hate when two motors are the same EXCEPT one little detail.