Break in procedure for new '77 Merc 140hp

[SheldonZ28]

Hi Everyone,

I have done a ton of research on this, but still have a couple questions.

I am buttoning up an extensive restoration of my 1977 Sunray 17' with a Mercruiser 140hp 3.0L/181. I have build a new engine for it which was a .030 overbore with new pistons, rings, bearings, lifters etc.

Reading through many different write ups on the initial break in of a flat tappet cam engine, everything notes that the initial startup should be a 20-30 min run time with 1500-3000rpm fast idle variation with engine break in oil, followed by an oil change before the second part of a 10hr break in with a bunch of variation of RPM and several other speed variation guidelines, also using break in oil. The second part I am not worried about.

For the first start, I am about 40min drive to the closest lake I can put the boat in to for a 20-30 min fast idle variation, and given the amount of fresh parts on this boat, I would prefer to do this at home in my driveway where I have all my tools to solve any potential problems as they may come up.

I have read some mixed information on whether I am running risk of water supply by doing this initial run on muffs with the garden hose. My hose water pressure is excellent, however I am unsure if normal 1 side fed muffs are acceptable? Is there a specfic muff that someone might advise for use of this, or am I running a high risk and need to be doing this with the back of the boat in to the water?

Appreciate all input, very excited to have this boat done and finally bringing it out on the water, however I have a significant amount of time and money in this and I am wanting to break this in properly so I can enjoy it for years to come without going through another engine build for it.

Thanks!

 

[Scott06]

Hi Everyone,

I have done a ton of research on this, but still have a couple questions.

I am buttoning up an extensive restoration of my 1977 Sunray 17' with a Mercruiser 140hp 3.0L/181. I have build a new engine for it which was a .030 overbore with new pistons, rings, bearings, lifters etc.

Reading through many different write ups on the initial break in of a flat tappet cam engine, everything notes that the initial startup should be a 20-30 min run time with 1500-3000rpm fast idle variation with engine break in oil, followed by an oil change before the second part of a 10hr break in with a bunch of variation of RPM and several other speed variation guidelines, also using break in oil. The second part I am not worried about.

For the first start, I am about 40min drive to the closest lake I can put the boat in to for a 20-30 min fast idle variation, and given the amount of fresh parts on this boat, I would prefer to do this at home in my driveway where I have all my tools to solve any potential problems as they may come up.

I have read some mixed information on whether I am running risk of water supply by doing this initial run on muffs with the garden hose. My hose water pressure is excellent, however I am unsure if normal 1 side fed muffs are acceptable? Is there a specfic muff that someone might advise for use of this, or am I running a high risk and need to be doing this with the back of the boat in to the water?

Appreciate all input, very excited to have this boat done and finally bringing it out on the water, however I have a significant amount of time and money in this and I am wanting to break this in properly so I can enjoy it for years to come without going through another engine build for it.

Thanks!

If you have good water pressure and a good size hose you wont have any issue doing the cam break in on the trailer. I don't think you need to go quite as high as 3 k normally I have done 1-2 k. Make sure to use ZDDP additive or an oil that has it for break in. I use these style muffs no issue-

Amazon.com

Just make sure you have a working temp and oil pressure gauge , you can get decent mechanical ones at the auto parts store for about $25 each.

If you run into any issues etc just shut it down you can stop the break in part way through if need be.

Most of the the flat tappet cam issues you see now are due to poor machining not incorrect break in, neither of which you can control....

let us know how it goes. What you lay out in terms of break in and oil changes is correct.

 

[Scott06]

Hi Everyone,

I have done a ton of research on this, but still have a couple questions.

I am buttoning up an extensive restoration of my 1977 Sunray 17' with a Mercruiser 140hp 3.0L/181. I have build a new engine for it which was a .030 overbore with new pistons, rings, bearings, lifters etc.

Reading through many different write ups on the initial break in of a flat tappet cam engine, everything notes that the initial startup should be a 20-30 min run time with 1500-3000rpm fast idle variation with engine break in oil, followed by an oil change before the second part of a 10hr break in with a bunch of variation of RPM and several other speed variation guidelines, also using break in oil. The second part I am not worried about.

For the first start, I am about 40min drive to the closest lake I can put the boat in to for a 20-30 min fast idle variation, and given the amount of fresh parts on this boat, I would prefer to do this at home in my driveway where I have all my tools to solve any potential problems as they may come up.

I have read some mixed information on whether I am running risk of water supply by doing this initial run on muffs with the garden hose. My hose water pressure is excellent, however I am unsure if normal 1 side fed muffs are acceptable? Is there a specfic muff that someone might advise for use of this, or am I running a high risk and need to be doing this with the back of the boat in to the water?

Appreciate all input, very excited to have this boat done and finally bringing it out on the water, however I have a significant amount of time and money in this and I am wanting to break this in properly so I can enjoy it for years to come without going through another engine build for it.

Thanks!

If you have good water pressure and a good size hose you wont have any issue doing the cam break in on the trailer. I don't think you need to go quite as high as 3 k normally I have done 1-2 k. Make sure to use ZDDP additive or an oil that has it for break in. I use these style muffs no issue-

Amazon.com

Just make sure you have a working temp and oil pressure gauge , you can get decent mechanical ones at the auto parts store for about $25 each.

If you run into any issues etc just shut it down you can stop the break in part way through if need be.

Most of the the flat tappet cam issues you see now are due to poor machining not incorrect break in, neither of which you can control....

let us know how it goes. What you lay out in terms of break in and oil changes is correct.