Mercruiser 165 Rebuild

[finisher88]

Hi! All nice site here I have enjoyed looking around, I have 1978 SeaRay with a Mercruiser 165 , in line six. The engine has severed me well over the years but is getting a little tired with an excessive amount of blow by. So it is time to rebuild it. Actually replace it, as it has raw water cooling and has been running in salt water, for many years. I tried GM for crate motor but the parts guy laughed and said they have not been available for a long time. So my next step is to buy a used core and rebuild it. My question is what is the difference between a 250 and a 292 block,will either one work, which would be the preference if a pro was going to do it. In my area a long block core goes for about $300.00 to $400.00. Is there anything in particular I should look out for when buying the core, I.E a specific head,etc. Thanks for your reply.

 

[woosterken]

Re: Mercruiser 165 Rebuild

check this out,plenty of info.
on left they have marine stuff http://www.jasperengines.com/marine-overview.htm

woosterken

 

[ziggy]

Re: Mercruiser 165 Rebuild

the 292 was only used for one year by mercruiser. i don't know why. but could be a heads up. the difference between them i think is the stroke. longer on the 292.

get a truck engine. if i remember right, the car engines may not have the boss ya need to mount our mercruiser front engine mount.

since it's all most winter, and ya got a fresh water cooled engine. ya could rebuild your exisiting engine. then ya'd know yer starting with the right block and head.

when i get to the point of rebuilding my engine. if someone else does it, i think i'm gonna want a build sheet i think it's called. a sheet that states the specs of the rebuild. so i'd know it was within spec. some rebuilders put new parts in them and say their rebuilt. it seems there's different levels of how it was rebuilt.....

 

[finisher88]

Re: Mercruiser 165 Rebuild

Thanks for the input guys, I am at the beginning of this and will continue to post as I move along. My first steps are to find a good core and an engine re-builder. Good point on the build sheet and a 250 truck block. Cost is not the driving point here but rather a professionally rebuilt motor,that will purrrr for many years.

 

[joeyr]

Re: Mercruiser 165 Rebuild

Hi all,

Finisher, I have the same enigne (1977) GM 165 - with the same problem. I have the grey blow by happeneing as well. Really effects the performance I am finiding espeacilly after long usage. Do you know where your problem is? Ie simple gaskets or something along those lines, or is it time to rebuild as well? - I should be pulling my engine within a couple weeks. Keep in touch. joeyr@vianet.ca

 

[finisher88]

Re: Mercruiser 165 Rebuild

Hi all,

Finisher, I have the same enigne (1977) GM 165 - with the same problem. I have the grey blow by happeneing as well. Really effects the performance I am finiding espeacilly after long usage. Do you know where your problem is? Ie simple gaskets or something along those lines, or is it time to rebuild as well? - I should be pulling my engine within a couple weeks. Keep in touch. joeyr@vianet.ca

Joeyr in my case its just an engine that is 30 years old, the rings are gone I am sure and it has been running in salt water with no fresh water cooling for many years. so it is time for a new long block.

 

[finisher88]

Re: Mercruiser 165 Rebuild

I have been looking for a long block 250 with no luck to date. There seems to be a few Mercruiser 4.3 engines around and I like the idea of a few more horses. Does any one know if a 4.3 will bolt up to the 1978 gimbal ( I know that the motor mounts would have to be redone) and would the Y exhaust hook up. There are probably a few more things that would have to be done any input would be appreciated. The main question is it possible without changing the Gimbal and drive,

 

[ziggy]

Re: Mercruiser 165 Rebuild

stick with yer L6. rebuild what ya got. whatever. a v6 and a stright 6 ain't got to much in common..... short of 6.............

 

[finisher88]

Re: Mercruiser 165 Rebuild

I have finally made a decision and made a purchase after much switching back and forth from a 165 to a 4.3 and back to a 165,I purchased a fresh water running 165, from an outfit in Mi. it should be here in a week or so, I will do a compression test and from that decide weather to rebuild it or just run it any suggestions on this.

 

[finisher88]

Re: Mercruiser 165 Rebuild

Can some one explain why an engine overhaul gasket set for a 250 GM engine can be had for $20.00 while a Mercruiser 165 cost $280.00, now I know there is probably a difference in the head gasket but the rest of the gaskets should be the same.

 

[chiefalen]

Re: Mercruiser 165 Rebuild

Your gonna do the rebuild yourself?

About the gaskets got me.

It says marine or merc on it 10 times more.

 

[finisher88]

Re: Mercruiser 165 Rebuild

Not sure if I am going to rebuild it ,most likely I will, In the event I do, I have a good local machine shop, that I will get to do the machining and assembly. Are there any performance parts for the Inline 6, I.E pistons,valves, lifters, rockers etc?

 

[Fishermark]

Re: Mercruiser 165 Rebuild

In the event I do, I have a good local machine shop, that I will get to do the machining and assembly.

Have them get the gaskets. Tell them this is a marine engine. I recently rebuilt a 165 and used the marine gasket set. (This was for my father's boat and he bought the set before I knew he did. I would have told him not to bother as you mention, the only one to worry about is the head gasket, and you can buy that separate). Have the machine shop install brass freeze / core plugs.

 

[Don S]

Re: Mercruiser 165 Rebuild

One other thing that all the OEM manufacturers recommend. DO NOT bore the cylinders more than .030 oversize. The walls can get too thin and with an engine running under a heavy load at 3500+ rpm for hours on end, it's just not worth it.

 

[finisher88]

Re: Mercruiser 165 Rebuild

Thx for .030 bore tip Don, I am awaiting the engine arrival, hopefully I get what I paid for.

 

[Bondo]

Re: Mercruiser 165 Rebuild

Are there any performance parts for the Inline 6, I.E pistons,valves, lifters, rockers etc?

Nope....

 

[abj87]

Re: Mercruiser 165 Rebuild

http://www.cliffordperformance.net/

 

[180shabah]

Re: Mercruiser 165 Rebuild

http://www.cliffordperformance.net/

You can appearantly get an aluminum intake manifold but it is only going to net a few horses and it won't last very long in a salt water environment.

So refer back to Bondo's post.

 

[chiefalen]

Re: Mercruiser 165 Rebuild

Na, Na , Na, you ain't supin up a L6, forget about it.

There are guys on here got serious hp, if you had anywhere the motor to do it they got the real dope how to do it.

Not the L6.

 

[180shabah]

Re: Mercruiser 165 Rebuild

...if you had anywhere the motor to do it....Not the L6.

If you really wanted to make some power then a small block V8 would have been the way to go, but this could easily set you back $6-7k.