break-in procedure for a rebuilt powerhead

[GlasV162]

Hi all,

I have a 1990 Evinrude 90 hp with a newly-rebuilt powerhead; new pistons, rings, bearings etc. It has been lake-tested and all works fine; I'll be picking the boat up later this week and am wondering what the break-in procedure is; specifically, how long before I can run at wide-open, and how long before I can pull skiers and kids on the tube. Also, do I run extra oil in the gas in addition to the VRO? Thanks for the input.

 

[tfbrown1270]

Re: break-in procedure for a rebuilt powerhead

Wow, thats a coincidence, I am picking up my rebuilt 92 Johnson 90 hp (VRO) next week from the shop and was going to post the same question...cue the X-Files music!
I had mine done locally (Winnipeg Canada) and paid $3000 for the work (bores .040 over, new BRP pistons/rings and VRO pump plus 1 year warranty), is that anywhere close to what you paid or did I get scr--ed?

 

[Dhadley]

Re: break-in procedure for a rebuilt powerhead

The break-in proceedure will be according to what the machinist / rebuilder uses for specs on piston to wall clearance, what they used for a cylinder wall finish, if they cut the deck and/or heads, what they have the timing set at, what fuel they want you to use, what rpm it's set up for, etc. You'll need to get that info from the rebuilder. Try to get it in writing. If they prefer a "tight" clearance you'll need to be very careful during the break-in period. If the clearances were on the "loose" side it won't be as critical.

Yes, it's normal to use 50:1 in the tank as well as the oil injection until you can verify the oil injection is working properly. If the oil line was purged properly it should be fine. Make sure the oil tank was drained and cleaned.

The #1 most overlooked part of any rebuild is finding out the cause of the damage. A damaged piston is a result, not a cause. If the piston was damaged - something caused it. They just don't do that for no reason. If the cause isn't found and corrected, it has an excellent chance of a repeat performance.

 

[GlasV162]

Re: break-in procedure for a rebuilt powerhead

Thanks Dhadley.....I'll check with the shop for break-in. The cause of the damage was "lugging" over a period of time and I didn't know it. WOT rpm was only about 5000 rpm. It caused carbon build-up which led to part of a ring breaking off. Lesson learned. It's a 16' Glastron and the motor has a 17 in. prop, which I've been told should be the right prop for that boat. If I still don't get 5500 rpm out of the motor after the rebuild, what do you recommend? Thanks.......

Tfbrown, I hope you have good results from your rebuild. Mine was about $1700.00 in U.S. dollars, however that didn't include a new vro pump; that was replaced just last year and works fine. They also rebuilt the carbs.

 

[Dhadley]

Re: break-in procedure for a rebuilt powerhead

Playing with the set up can gain a lot of rpm and therefore efficiency with the same prop. A V4 crossflow on a 16 Glastron seems close, depending on which 16 Glastron it is. If it's a GT160 a 17 is way small!

BTW -- carb rebuilds and a water pump kit are a standard part of any rebuild.

 

[tfbrown1270]

Re: break-in procedure for a rebuilt powerhead

Thanks for the reply, sounds like I got a spanking but considering the alternative (buying a new 90ish hp at about $8000) I won't complain too long if this turns out to be reliable...
I too am anxious to hear about the correct "method" to break this engine in...common sense dictates no WOT for a few hours and varying the rpm.
But how long should I wait before pulling a tube around the lake or trolling for that matter....
thanks GLAS162 for bring this up!

 

[Scaaty]

Re: break-in procedure for a rebuilt powerhead

Real easy for 4 hours (I did 1/2 hour shots on muffs), then variable throttle for the next 6.. avoid wide open accept for short burst in those 6. Then ya also can lay off the heavy oil.

 

[GlasV162]

Re: break-in procedure for a rebuilt powerhead

Thanks everyone............Dhadley, my boat is a '78 V162 Futura; actually she's a few inches short of 16'; I've seen the GT160 and that's a longer boat than mine. When you say way small, do you mean I would be better off with a 19 or 21 inch pitch? Also, how many hours of running before it's safe to pull tubes/skiers? Thanks..............

 

[GlasV162]

Re: break-in procedure for a rebuilt powerhead

Anyone have an idea what pitch I should run on this rig? Thanks..........

 

[Willyclay]

Re: break-in procedure for a rebuilt powerhead

Go to Mercury's website and find their Prop Selection model. Play around with the different parameters until you see a tight range of choices develop. I found that by inserting weights instead of using their generic hull-types, it gave results that I could verify with existing boat/motor/prop combinations.

 

[Dhadley]

Re: break-in procedure for a rebuilt powerhead

What I'm saying is that a 17 pitch prop on that boat seems about right. The GT series is a little more of a performance boat so the 17 would perhaps be a bit small. If you aren't getting enough rpm's with the 17, I'd play with set up before spending money on a prop.

 

[GlasV162]

Re: break-in procedure for a rebuilt powerhead

What is there to adjust for setup other than the pitch? Thanks..........

 

[wilde1j]

Re: break-in procedure for a rebuilt powerhead

Motor height on transom ("X" dimension), kickout can be adjusted. If motor is turning too slow at WOT, stop moving higher a hole at a time until you get some cavitation in tight, high speed turns. Adjust kickout until boat just starts porpoising at WOT.

 

[tfbrown1270]

Re: break-in procedure for a rebuilt powerhead

GLASV162...
as you may recall I have the same motor (nearly) just rebuilt as well...
I had it out this last weekend and got 5000 rpm max as well with the same prop.
I believe my boat is probably lighter as well and it was just two guys in the boat...please post if you get to the bottom of this issue since I need an answer as well.
Could you please tell me how yours idles, mine seems VERY COLD BLOODED, I mean it was a bear to get idling, I set the fast idle lever about 1/2 up, started using the primer (push in the key) and found it would start, race to 4000 rpm, then fall back to 2000 then 4000 as I pushed in the key to try to keep it going, pushing as it died out, I was to bring the idle down over a period of 2 to 3 minutes as it warmed up...BUT... as long as the fast idle lever was up it ran ragged, like the timing was off. After 4 to 5 minutes I was able to drop the fast idle lever all the way and it settled into a 600 rpm idle (in neutral). However when I put it in gear the idle dropped to 500 and away we went. It will troll at 500 rpm for hours with only the occasional shudder that makes me expect that its going to stop but it doesn't.
HOWEVER...anytime we stopped to fish and let the motor cool for more than 5 minutes I had to start the whole procedure over because it would NOT IDLE, it would start, but required the fast idle lever up about 1/2 way to keep it running till it was warm, any attempt to shorten the warm up cycle resulted in an immediate stall......aaaaaaaaaaaaaaaaaaaaagh!.
I posted a question about the 5000 rpm max with some additional info.
I too will keep you advised what I learn from this end, I am frustrated since this engine was to provide dependable power...its not as of now!
Note; after the engine warmed up and I was able to drop the fast idle lever it RAN WAY SMOOTHER, it seems that this device not only controls RPM but changes timing..is it supposed to run like crap with the lever up even a tiny bit?
Its a Catch22 here, need to have the lever up to keep it running when cold, but it runs like crap, put the lever down even a moment too soon and it dies, perhaps because the idle is too low. and I can't put it in gear to start moving with that lever not locked down.
and to make a long post longer...I tried to bump the idle up with the set screw on the throttle arm...it made no difference.

 

[GlasV162]

Re: break-in procedure for a rebuilt powerhead

Well, the break-in is going well so far; however, it's idling low, about 700 rpms and wants to stall after a few minutes at that speed. I suspect this can be cured by just adjusting the idle speed up a bit??? Also, I'm still only getting 5000 to 5200 rpm at WOT. I'm wondering if my tach is not accurate, because she's screaming at that speed; any advice??