Merc 135 Twins all sorts of problems

MikeV4

Seaman Apprentice
Joined
Sep 18, 2006
Messages
47
Hi all, as I am new here on the forum, I will quickly introduce myself and tell about the probs on the bottum.
I am from Holland but live in Abu Dhabi in the emirates, I have a '84 Wellcraft 166Elite with a Johnson 175 Faststrike:
DSC01385.jpg


And since a short time this Gulf Craft Ambassador 24" with two Mercury 135 Black Max.
scan0001.jpg


The Wellcraft runs like a dart and hasn't given me any problems at all.

Now the Gulfcraft:
Like said it's twin engined and it does not seem to have enough power, it's not coming on to plane and doesn't accelerate. The props easily vent and the engines make a hell of a noise. Could the engines be too close to each other, what are the settings for twins?

The boat leans to port side aswell, but this might be bcs both engines rotate the same.
 

tashasdaddy

Honorary Moderator Emeritus
Joined
Nov 11, 2005
Messages
51,019
Re: Merc 135 Twins all sorts of problems

on first thought, i would think the boat is waterlogged. but, in the picture it is not sitting low in the water. with twin 135's it should fly. have you checked compression and spark on on both engines, a picture from the stearn would help and the year and serial number of the engines.
 

MikeV4

Seaman Apprentice
Joined
Sep 18, 2006
Messages
47
Re: Merc 135 Twins all sorts of problems

Guess it is al engine problems:

This morning we went out on the coastline, engines at 3200rpm and about 25mph :/ , suddenly the port side engine just stopped, tried to restart and heard the starter engage, but pulled back immediatly. Opened up the cover and tried to rotate the crankshaft but that was stuck, this engine is dead. Okay, we have a twin and go home on the other engine.... started and reved up at 2200 rpm, and started moving the boat, not even any speed and the rpms dropped below 1000 and the engine stopped :% :%, started again and the same thing happend again. Than let it run on idle power and directed to shore, throw out the anker and the engine stopped again, anker not fixed on ground and by the waves and strong current we were washed at the beach, which was full of coralrocks :'( :| So the boat was pushed further on the beach and rocking by the waves on the rocks. Me and my wife were not able to push the boat back in to the water to anker it, thanks to some great folks who passed by, we got it of and they towed us in to the marina. What a day :^

As the port engine is seased, I believe there must have been a cooling problem, but I never got the alarm nor was the temp ind high. This will proberly end up with a powerhead replacement.
THe starboard engine, I don't know what is going on with it, it runned fine when both engines ran, but alone it doesn't have power and droppes dead.

P engine S/N C254658 is a '90 and SB engine S/N OD935574 a '94?
 

MikeV4

Seaman Apprentice
Joined
Sep 18, 2006
Messages
47
Re: Merc 135 Twins all sorts of problems

Tomorrow I will pull it out of the water and check the damage on the bottom aswell.
 

alana

Seaman
Joined
Feb 3, 2006
Messages
71
Re: Merc 135 Twins all sorts of problems

are both motors connected to the same fuel tank
 

MikeV4

Seaman Apprentice
Joined
Sep 18, 2006
Messages
47
Re: Merc 135 Twins all sorts of problems

Yup, I only have one fueltank.
 

MikeV4

Seaman Apprentice
Joined
Sep 18, 2006
Messages
47
Re: Merc 135 Twins all sorts of problems

Got the boat out of the water yesterday and moved it to the workshop. It is one big disaster:

On the port engine the lower gearcase is stuck, so this will have to be replaced completely, the inside is one big mess, they tried to recover the shafts but thay are totally gone. This is totally due to bad or no maintenance, the seals are gone saltwater inside and hardly any grease.
After removing the lower engine part from the rest, the engine moved freely again and compression is good. I will have this now replaced by a counter-rotating gearcase.

On the SB engine a piston rod went through the engine case, so this one will be a powerhead replacement. More $$$$.

Uptill now I will have following replaced:
1 lower engine unit by a counterrotating unit.
1 power head.
2 ss props
Engine controls (due to counterrotating unit being installed)

The guy I bought the boat from had a bunch of invoices from the engine services he had done over the past years, guess the workshop who had done this were not so very good, but at least he is willing to make a deal with the repair coasts.
Will post some pics of the damage soon.
 

alana

Seaman
Joined
Feb 3, 2006
Messages
71
Re: Merc 135 Twins all sorts of problems

(hardly any grease)!!! should be oil in gearbox. get a manual and at least learn to change the oils, then you know it has been done.
 

MikeV4

Seaman Apprentice
Joined
Sep 18, 2006
Messages
47
Re: Merc 135 Twins all sorts of problems

Grease/Oil, all lubrificants....
 

MikeV4

Seaman Apprentice
Joined
Sep 18, 2006
Messages
47
Re: Merc 135 Twins all sorts of problems

OKay, boat is back in the water, engines up and running again.
I have had the rest of the engines fully serviced now, and the carbs have been cleaned. They have installed 2 ss 17" props. But now that the engines are running good again, I can go for the rest.
The result of the prestations on the (extremely salty) water is: 4600 rpm at WOT with max speed of 45MPH. When I trim out the bow starts to get extremely high and jumpy, this with a boat dry wt of approx 2000lbs, 80 gallons of fuel and 40 gl water tank and 2 pers. I think the performance could be better for this boat. (okay the speedbrake on the top to keep us out of the sun will reduce performance for sure)

Is there anywhere to calculate or find out what the correct height of the engine installation should be for twins?
 

gss036

Commander
Joined
Jan 18, 2003
Messages
2,914
Re: Merc 135 Twins all sorts of problems

You have the wrong size props if you are only turning 4600RPM. You should try at least 2 inch smaller props, that should get you up to about 5000rpm, maybe 3 inch smaller, then you would be at about 5200 where you should be at WOT. You will damage your motors when they are over propped and lugging the engine down.
Sounds like you have power trim, with the engines trimmed up so that they are level with the water, it should push the bow down and give you more speed/rpms, maybe you need trim tabs?
 

MikeV4

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Joined
Sep 18, 2006
Messages
47
Re: Merc 135 Twins all sorts of problems

I can only keep the bow down when the engines are trimmed in, the moment I trim out the bow comes up. Before I start with trim tabs I want to be sure the engines are in the correct position.

Interesting what you say about the props, they have installed 17" pitch Mirage Plus propellors, I can't find the diameter for these on the net, will have to look at the props themself.(could only find 15.250" diam for the 19"pitch, would the diam be the same for 17"p?) What I also found on the net is that the Mirage Plus are for engines rated 150HP plus, may be I should talk to the guys in the shop (this is the official Merc dealer here)
 

gss036

Commander
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Jan 18, 2003
Messages
2,914
Re: Merc 135 Twins all sorts of problems

Manufacturer: Mercury, Mariner, Sea Ray
Description: Mercury & Mariner 135 HP V-6 Gearcase (Thru Hub Exhaust & 15 Tooth Spline)
Horsepower: 135 HP
Year(s): 1987 & Newer
Max RPM: 5000-5600 RPM

I am not a prop expert by any means. Maybe somebody w/knowledge will jump in here and offer some good advise.

http://www.iboats.com/mall/propfind...id=306&session_id=308380083&cart_id=698913698
Click on this link and then look to right side of the page prop information and explanation of props.
I don't know how high twins should be mounted but the above indicates where your RPM range should be. I would suggest trying somewhere around 14 1/2X15 props.
 

MikeV4

Seaman Apprentice
Joined
Sep 18, 2006
Messages
47
Re: Merc 135 Twins all sorts of problems

MikeV4 said:
I can only keep the bow down when the engines are trimmed in, the moment I trim out the bow comes up. Before I start with trim tabs I want to be sure the engines are in the correct position.

I mean that the bow is allready to high when the engines are trimmed in and once I push the trim buttons the bow starts jumping straight away.
 

MikeV4

Seaman Apprentice
Joined
Sep 18, 2006
Messages
47
Re: Merc 135 Twins all sorts of problems

I have installed the engines one bolt-eye higher and could go now to a 19" prop, running 5200 RPM, looking very good and will keep it there.
Less bowjumping aswell, but might think of trim tabs on a later stage.
The engine-axes were installed parallel and I have them now a bit convex. Between front and rear there is 3/4" difference, which decreased the venting and noise.
 

05GlastronSX

Chief Petty Officer
Joined
May 29, 2005
Messages
437
Re: Merc 135 Twins all sorts of problems

im glad you got all of the problems resolved mike. It took time and $$$$, but that pic seems to make it all worth it bud..have fun and be safe!d:)
 
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