Info on a 1998 merc 115 elpto

[jponfrank]

I am interested in purchasing a 1998 115 hp merc elpto. Are there are problems with these motors. The owner told me that when first taking off they start on two cylinders and at wot they hit on all four. I have never heard of that. Should I ask him if he has a bridge for sale. Any info would be helpful.

[Markus]

The Mercury inline 4 was designed for walleye fishing. It therefore has the 2 cylinder idle that makes it a better trolling engine, but is frustrating for non-trollers.

Other than that, it does not like more than about 5300 rpm because of harmonics at higher rpm, and the block and head is casted in one piece. Together, that means that the engine cannot be modified for higher hp.

Supposedly, the resale value is pretty low because a lot of people do not like those features.

If used for its intended purpose, it is not a bad engine, but I would go for a Yamaha, Bombardier-built Johnson or Tohatsu if I was getting a 4-cyl engine.

[Capt.Insane-o]

Loved it. Never had a problem with the "concept 2+2". Used it primarily for wakeboarding and fishing. Ran 8 years on the original plugs. Lots of torque, quiet, good on fuel. No rpm though. Ran it on my HST to check it out before I sold it to my bosses uncle and it pushed it 64. Wish I had a dollar for every mile I put on that motor.

[2springers26]

that Motor is the bread & butter @ our shop ... no real issues... Runs On 2 cyls til 1800 rpm's.. then switches to all 4 cyls....... Put One on a vector for a guy.. Pushed it almost 70... mph with a 24 p trophy

[mk30h]

Its a great engine, good mileage, lots of torque and farily quiet too. Never had a problem except with a defective stator that Merc replaced. As for its 2+2 its good for trolling doesn't smoke- also burns a lot less gas when trolling as it's only using two cly.

As for the block, never have to worry about a head gasket, Very tight block, like the old mercs.

Use mine everyday from may till november - about 7 miles a day. Have been doing this since 97- runs till the ice forms.

[GelcoatJoe]

wat is the deal wit the apache? left ya a few p.m...is it sold?

[C-Webb]

Originally posted by 2springers26
that Motor is the bread & butter @ our shop ... no real issues... Runs On 2 cyls til 1800 rpm's.. then switches to all 4 cyls....... Put One on a vector for a guy.. Pushed it almost 70... mph with a 24 p trophy

Was that 70mph push with a 115 or 125??

[2springers26]

2001 115 4 cyl..... we were having issues with the motor So we gave the customer a loaner... We had a vector w/o a motor... perfect for testing the engine.... NO this was NOT gps....... speedo.... it was impressive against my vector with a 150...

[durhamd]

I came out here looking for some advice myself.

I bought an 2001 18' Nitro F&S about 2 weeks ago that has the 115ELPTO. I was concerned I might not have enough hole shot to pull up a skier. A buddy of mine said he had skied behind a '79 115 inline 6 for years on a similar size/weight of boat, so I bought the boat.

I can't get any hole shot out of it. I saw another post under "Worst motor ever" that said something like "takes about a week to pull up a good sized skier". Definitely can't argue that. In fact, it's so bad, I haven't even attempted to come up on a ski behind this boat.

I've tried the following props:
22 pitch LaserII
20 pitch HighFive
17 pitch Ballistic
17 pitch Michigan Match

They all took more that 7 seconds to get to 20mph on the speedometer.

Also, I can't get the motor to rev over 5400 rpm, it starts getting "choppy", almost like there is some sort of rev limiter on it.

I looked at Merc website for prop recommendations. Based on the weight and hull style of the boat (bass), thier top speed matches what I got out of the HighFive and LaserII. So it seems like the motor is working as designed.

At idle, it runs extremely rough when trimmed all the way down (like those 2 cyls are really working to turn that big prop at low rpm). It would drive me nuts to troll with this thing. Is there something wrong with the motor, or is it working as designed?

Any and all advice welcome.

Bull Durham

[Jeff_G]

I've had a few that have had carb issues, from sitting. Rebuild your carbs first and run some power tune through it. Yes they have a rev limiter, surprised you would hit it easily with some of those props.
They can be a pain if not cared for but once right they are OK.

[durhamd]

Thanks for the info Jeff. Are there any tests I can perform to verify the carbs really do need rebuilt? The boat doesn't look like it's been used a whole lot over the last few years. It very well could have been sitting a lot. I don't have any history because I bought the boat at a repo auction.

I probably should have included in my original message that I really think the motor may not be big enough for the boat. The boat is rated for max 175hp. I really think the motor would probably run much better on a lighter boat. When I trim the motor up to releave some of the load at idle, it idles much smoother.

What we've noticed from the hole shot to is that it will rev up to anywhere between 3200 and 4000 rpm (depending on the prop), and it sounds like the thing is really working, but just won't go anywhere.

Also, the only props we hit the rev limit on were the 17 pitch.

[Markus]

Durhamd, if you read my earlier post on this thread, you will understand why the rev. limiter is as low as it is on that engine.

[durhamd]

Thanks Markus.

I did see the earlier reply about not liking anything above 5300, but I didn't know there was actually a rev limiter on it. I definitely won't try to turn it off.

I'm going to see how it idles after I re-build the carbs. If it's still rough, I may seek some advice on how to turn off the 2 cyl idle so it idles on 4 cyls.

[durhamd]

We pulled all of the carbs apart last night. All clean as a whistle.

Any other advice would be appreciated. Next stop is the shop on Monday so they can run some diagnostics on the electronics.

Bull

[jponfrank]

I just got my back from the marina,did a compression test replaced plugs and adjusted the carbs,the motor idles like a cement mixer,but that is the way they run. I have a 17ft pro line with a 115 merc,at 5400 rpm top speed is 34mph with four people on board. I just have to get use to the horrific idle. I also asked about changing the 2/4 setup,but was told couldn't do it.

[sho305]

34mph? Is that a huge hull? I can run over 50 with my 17' vee at 930lb hull weight with a 150 inline that is +/- 115hp. I ran a 19' deckboat that weighed more with a 85hp V4 that went over 30, 34 on the speedo that seemed close to the right reading. My 80hp merc on a 16' at the time could not stay with that giant deck boat and read 32mph. I can see the 18' Nitro getting big for that motor. I wish I could have raced a 125 at my lake with my inline, but he was never out when I was. It was on a momba(?) and ran pretty nice by the looks of it. What is your top speed with an empty boat?

[Rodney Nance]

I have one on a 24 foot pontoon that is on it's 9th season. Idles fine and turns 5100 rpm. Only repairs have been a new stator. Junior Eaves told me what ever you do don't run it hot. The sleeves do not bottom out in the block. If it gets hot the sleeves will fall down in the block letting the rings go above the top of the sleeve. Instant lockup.

[Raceman]

One of my lake neighbors has had one on a pontoon boat since it was new and loves it. The rough running at low speeds takes some getting used to, but when he hits the throttle it's responsive and runs good.

[durhamd]

To JPONFRANK - "Cement mixer" - good description! What kind of prop are you running? What does your motor do at 5400rpm? Does it start "surging" or getting "choppy"? When I tested the 17 pitch props, all I could get out of my boat was about 34 - 35mph.

I took it out by myself after rebuilding the carbs. Had the 20 pitch HighFive on it. Popped up nice (about 4 secs to plane and 4.5 to 20mph) and ran WOT 44 - 45 mph, but I think if I get the additional 600 lbs of load back in it, I'll be right back where I was. I need to get it weighed. According to Nitro's site, the total package weight of the new ones is 2600 lbs. Don't know how they get this number unless something changed since ’01, because the hull is supposed to be around 1600 lbs., motor is around 350 lbs according to NADA guides, and I had the trailer weighed and it is definitely 800 lbs. I've requested some technical specs from Merc comparing the 115 inline 6 w/ the 115 inline 4. Hopefully they can come up with something.

I took mine to the shop last night to have it checked. I figure I’ve got nothing to lose. If he can find something wrong, hopefully, it'll be enough improvement that I can keep the motor. If not, I can sell it with confidence. Hopefully will have an answer by the end of the week.

Bull

[sho305]

45mph sounds a whole lot better, but I fear that is just too much boat for it. A planing aid will help get it up but nothing for wot. I have near nothing but a 10lb anchor and the required stuff in my checkmate.

Get a case of beer to attract friends, then take a run with and without the weight. Some hulls it really kills and others not so much.

[jponfrank]

Proline is a heavy boat,if im not mistaken the hull weighs 2000lbs. I can get it up to 40mph if I'm by myself. The prop is a 17pitch.It revs at 5400,if I start to trim it up the motor sounds like it is going to blow up. When backing off the throttle the motor sounds like a chain saw. Like I said before,I had the whole motor checked out,because it is still under warranty until end of June. Thats how the motor was made. I still don't know if I can get use to it. Joe

[sho305]

Should go faster trimmed, are you hitting the rev limiter at 5400?

I never noticed that 125 at our lake sounding different.

[durhamd]

Got mine back about 2 weeks ago. Runs much better. He put it on a dyno and made some adjustments. The only thing I can remember him mentioning was timing, but I know he said he made some other adjustments. He said the timing was about 4 degrees off at both ends. Part of the problem was the indicator was off by 2 degrees. He told me that there is no rev limiter on the motor though. He said that it was running too rich at WOT and that is why it was acting weird at 5400 rpm. He said this was only affecting top speed, not acceleration. He explained why, but I can't remember the explaination. He said if I wanted to keep the motor and get as much top speed as possible, I could bring it back to have him rebuild the carbs. He said it probably wasn't worth the money for the little bit I would get out of it. After the adjustments, the motor pulled me up (I weigh 210 lbs) on a slalom ski on the first try with a full tank of fuel, and 600+ lbs of guys still in the boat. I was able to get up, first time, with the 20 pitch highfive and also with the 17 pitch Michigan Match props. Didn't, and won't, attempt to get up with the 22 pitch Laser II that came with it. The motor idles MUCH smoother now too. I wouldn't want to try to teach a 200 lb guy to get up on a slalom behind this boat, but it will do for just about anything else. I'm content. The boat is useable until I sell it.

Oh, one more thing. I asked about changing the 2/4 setup. He said he did it for one customer. $1000 later, the customer had a motor that performed the same, but idled on 4 cyls. Definitely not recommended.

Bull Durham

[sho305]

That guy with the 125 was trolling around the lake last weekend, so I ran down there and listened:) Yep, it kinda chugs like a twin but it seemed to be ok and not that bad. 4 degrees is quite a bit of timing. I wonder how it got off like that.

[Markus]

A friend bought a new 125 hp Mercury last week and took me for a test ride. On that engine, the rev. limiter hits hard at 5400 rpm and there is no way getting past.

[Capt.Insane-o]

My 100 was on a 17 ft Tri hull. Used to take 4-6 people out skiing/boarding all the time. Easily pull two wakeboarders up. I found they don't like stainless props, idled with aluminum props the best. Less rotating mass at idle speeds. Puts along at 550-600 all day long without complaint. Older guy I sold it too loves it.

[Markus]

My friends engine had a really high idle for that kind of engine: About 1000 rpm. I guess it needs to be adjusted. Are there any special tricks for adjusting the idle rpm on an I4?

[Capt.Insane-o]

They adjust the same as most other mercs, a screw on the throttle arm. Get it good and warmed up, bring it to idle and tune it in. With a 19 p aluminum mine would idle all day at 550 ish in the summer heat and about 600 on a cold fall day (35-40 degrees) during salmon season. If you have to adjust the idle mixture be very patient, make very very small adjustments, let the motor run a couple minutes after each adjustment to let it stabilize.

[Murph]

Been running a 30" inline Merc Chopper for 10 years. 4 years before that I had a 26" Laser II that would hit 5800. Take off with the chopper alone can hit 6000. She's always running near 5500. When you get to playing around with the chopper you can scream her. Idles so smooth you can hardly hear it. I do have to trim up at idle do to spinning such a big prop or it will fight the engine. I would never know that the engine cuts down to 2 cyl. My boat is very light compared to your basic setup that this motor would be used for. That may be the difference but I really think the biggest problem is these motors don't develop a good hp curve untill you get them moving which doesn't happen on most setup's. No complaints here.

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