Time for rebuild? 1978 115

[77_starcraft]

Sorry for the long story, but here's the 30 yr history....

I have a 1978 Evinrude 115 that seems low on power. The boat has seen a lot of use since about 1990. Don't have an hour meter but I'm sure there are a lot of hours now (200-300?). It has had good routine maintenance and some various repairs (carbs, ignition) over the years. Performance seems to have slowly slipped over the years.

Primary use is a ski/air chair tow boat, but won't get a slalom ski out of the water. I have aerated the 19" prop, which helped a lot. A 17" prop is worse in both takeoff and top speed. The aluminum hulled boat will only do 35mph(GPS) at about 4400rpm (w/ 3 adults, good conditions). Full of gas, it probably doesn't weigh more than 1500 pounds. I have a planeing (sp?) fin that helps out on slow cruise speed, but doesn't effect top end much (anymore).

What should the compression numbers be for this engine? My dad put some thicker head gaskets on it 15 years ago to run in 87-89 octane gas (still did 40 mph+ back then). My plan was to run the engine a few min with muffs and then do the test.

Anyone know of a good outboard shop in Phoenix AZ?

I was also thinking of stock head gaskets and upgrading to 140 carbs. was this the only difference between the 115 and 140?

Does the boat need to be at WOT in the water to check the timing? can I use a regular automotive timing light hooked to #1 cylinder?

 

[iwombat]

Re: Time for rebuild? 1978 115

There were lots more differences between the 115 and 140 than the carbs. Those 140 carbs will probably rob you of power rather than gain you any. The smaller head gaskets will help out though. You can run 87 octane with the stock gaskets all day long. Not sure what the rationale was for swapping them out.

300 hours is just breaking it in.

Have you done a decarb recently?

You can check timing statically out of the water by removing plugs and grounding out the wires. Put the throttle in full advance, and crank it over. Using a timing light on #1, set the timing to 4-degrees less than full advance.

 

[77_starcraft]

Re: Time for rebuild? 1978 115

Ok, thanks for the advice.

The thick head gasket was recommended & done by Tom's outboard in Olympia WA. long ago. Can I put regular gaskets back on myself (I've done auto engines before)? I have some manuals, I'll go look tonight.

Engine had never been de-carbed. ever.

why ground out the wires for the timing test? all or just #1?

Thanks

 

[iwombat]

Re: Time for rebuild? 1978 115

Ground all the wires. With the plugs out, and fuel shooting out the holes, ungrounded wires make engine go FOOM!

decarb your engine, that's probably all that needs to be done to it. And do it now, before you catch a ring on an exhaust port.

If you've ever replaced a 4-stroke head gasket, a 2-stroke head gasket is 900-times easier.


nine hundred times


And I don't exaggerate - never ever ever.

 

[tashasdaddy]

Re: Time for rebuild? 1978 115

have you ever done the carbs? you ought to be turning 5000 -5500 at wot. had a 115 on an 18ft glass boat, 42mph loaded 45 1 person.

 

[iwombat]

Re: Time for rebuild? 1978 115

That's a good idea too.

You say it's had good routine maintenance over the years. It might be time to pull out some receipts (assuming shop did the maintenance) and figure out what has been done recently. If you can't find anything that says impeller, add that to the list while your at it.

 

[iwombat]

Re: Time for rebuild? 1978 115

So, reiterating . . .


Do a decarb, like now. No, like RIGHT now. There's various methods in the FAQ. I prefer the 3/4 gal premix and 1 can seafoam in a portable tank method since it gives the carbs a thorough cleaning too.

After that . . .

1) Take a compression reading (while warm). Assuming good numbers proceed to.
2) Check all fuel hoses and fittings, replace any that are suspect. This may be an air leak problem after all is said and done.
3) Install a new impeller (if you can't find a record of one in the last couple years)
and maybe on to
3) Carb rebuild depending how the boat-test of 1-3 turn out.

 

[Solittle]

Re: Time for rebuild? 1978 115

Throw a new set of plugs at it while you are putterin around.

 

[emdsapmgr]

Re: Time for rebuild? 1978 115

Your engine, when new, should normally run 125 lbs compression. Your year 115 already had the intake stuffers-a performance plus. A set of 140 heads and carbs will pick up some increased performance. If you are only running 4000 rpm's, you are lugging the engine. You need to prop it to run 5500 for optimal performance, engine life and fuel economy. Spark check all 4 plug wires.

 

[77_starcraft]

Re: Time for rebuild? 1978 115

Ground all the wires. With the plugs out, and fuel shooting out the holes, ungrounded wires make engine go FOOM!

Ah, yes I had to discharge a fire extinguisher inside my garage for something similar (alternator sparks).

I read the de-carb info in FAQs and bought a can of seafoam. Its going to take a few weeks to get around to doing the job. (hey, its hunting season too)

I had/have an intermittent warm start issue, so I replaced the fuel pump (per my repair manual). A piece of the new pump gasket found it's way into one of the carb's float valve, so I rebuilt the carbs (~2 yeas ago). I put new plugs in every year, and change the lower gear oil. All coil assemblies were replaced about 10 years ago.

I believe the impeller was replace once long, long ago.

Thanks for the help. I will post the results of the comp test when I get-r-done

 

[77_starcraft]

Re: Time for rebuild? 1978 115

I did a de-carb at the lake this weekend, then did a compression test. All holes are at 88-90lbs. seems low but it does have thicker head gaskets.

I also checked the timing. throttle pickup was 2 degrees (idling in gear) and max advance was 17 (cranking with advance lever held at max). from my manuals it looks like it should be 4/24 degrees(28-4?). I still need to replace a ball/socket joint so I did not adjust or test drive.

fuel system doesn't appear to have any leaks and the engine is firing all cylinders.

My next step is to replace the B/S joint, do the whole syncro adjustment and take it for a test run.

 

[iwombat]

Re: Time for rebuild? 1978 115

90lbs while isn't great it isn't bad either. You've certainly got a long way to do before I'd be thinking about a ring job. I think the 17-degree timing is the real issue here. Fix the timing, and spend $30 on some new stock head gaskets and I think you'll be pleasantly surprised. It could also be that you're due for a carb rebuild, but unless you're getting sputtering at wot i wouldn't be going there right away. You should be shooting for 5500rpm at full throttle and you may need to put that 17-pitch prop back on to do that.

Also, replace that impeller (w/ a water pump kit) if you haven't already. It'd really suck to get it running right only to have the pump go. It's about a 1-hour job on that motor if you haven't done one before.

 

[CharlieB]

Re: Time for rebuild? 1978 115

The shop installed thicker head gaskets to reduce compression and retarted the timing following the factory service bullitin published when the lead was being phased out of our fuel to prevent detonation and heating issues at the time.

Since then, we haave learned NOT to lug/prop the engine so low and the timing and compression could be restored to original.

Clean carbs, new plugs, repair that linkage, replace head gaskets.

Set timing to original specks.

CHANGE THAT IMPELLER, every two years, three at the most, whether you've run it or not, they die the motor dies.

Hang on

Prop as needed to run 5500 - 5600 WOT with your 'normal' load of passenger, baggage, etc.

 

[77_starcraft]

Re: Time for rebuild? 1978 115

Thanks for the input. I am in the process of digging for part numbers.

Looks like I have to remove the lower drive to do the pump impeller. besides just the impeller, which of the repair 'kits' do I need to do the job? any other gaskets needed to finish the job?

Also, the motor leaks oil and the tilt/ exhaust housing gets filthy quick. looks like a vent hose that goes into the bottom of the air silencer base is oozing oil. I plan on replacing the silencer gasket. Is there a deeper problem here? I went through the carbs recently (hence the leaky gasket)

AND... the motor is a bear to lift. goes down great, but can't raise it from inside the boat. the shock/spring is $240, is this my only option beside a $500 aftermarket power trim/tilt? Those extended handle jobs may have to do.

the linkage was damaged before I got the boat. I screwed with it for a while but never got it reliable. I can launch/load with it in the locked down position but can't get the motor back up without getting into the water and releasing the hooks (which are now screwed up too). I would like to get to the point were the motor can be raised from inside the boat again.

 

[iwombat]

Re: Time for rebuild? 1978 115

The water pump kit is all you'll need to change the impeller. There's a slight chance you may need to replace the rubber rectangular gasket around the exhaust housing. Do a visual inspection when the lower unit comes off and see if it's been smooshed or kinked.

 

[Mr.Stuart]

Re: Time for rebuild? 1978 115

I've got a 78 starcraft with a 78 Evinrude 115 HP, mine will do 45 MPH, and the compression is right at 150 per cylinder, these guys know what their talking about, follow their advice, you'll have a pretty sweet running outboard when your done, mine runs like a Swiss watch now, very strong dependable engine.

Stuart

 

[emdsapmgr]

Re: Time for rebuild? 1978 115

If you go back to stock head gaskets, likely you will pick up compression. That's good. In regards to the leaking oil in the cowl, replace the airbox hose and it's cover gasket, but also check to make sure the base gasket is not leaking. Common on those engines. That will actually let exhaust smoke into the cowling and exhaust oil drip down from the base of the engine onto the midsection. Timing is set on those engines at 5000 rpm. If you are testing max timing at idle, it will read low. Once the rpm's get up, the timing will show further advance, so watch how you are setting it.

 

[77_starcraft]

Re: Time for rebuild? 1978 115

.. but also check to make sure the base gasket is not leaking. Common on those engines. That will actually let exhaust smoke into the cowling and exhaust oil drip down from the base of the engine onto the midsection...

which base gasket? exhaust cover to housing? I see several in the exploded diagram.
http://epc.brp.com/default.aspx?brands=ej&lang=E&dealerlocator=no
link doesn't work; 1978 115 893C
thanks

 

[iwombat]

Re: Time for rebuild? 1978 115

I think he's referring to cylinder block to exhaust adaptor.

 

[77_starcraft]

Re: Time for rebuild? 1978 115

Ok, I'll check that too. I bought the parts I need and read both my manuals on impeller replacement and head gasket RR. Looks fairly straight forward;

head gasket-
remove stuff attached & bolts
remove head, clean surface
install new gasket dry
torque bolts in steps in order.

impeller-
remove lower unit
remove pump cap
install new impeller
put back together.
open beer

can I leave the oil in the lower unit? I just changed it.