Mariner 135-2 dead cylinders

[SuperNova]

I am looking at purchasing an early 80's Checkmate Diplomat with a probably same vintage Mariner 135. The owner tells me that he had a tune-up done and leak-down test performed and was told that 2 cylinders were weak/dead. What might I be looking at getting myself into on this thing? I think they probably ran it without mixing the oil, unless this is a common problem on these. Thanks in advance. Any additional information would be appreciated also.
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Stan

 

[roscoe]

Re: Mariner 135-2 dead cylinders

$300 for a blown head gasket.........

Or $4,000 total rebuild.

The motor is worth scrap/parts value. $300 max.

 

[SuperNova]

Re: Mariner 135-2 dead cylinders

I have extensive experience rebuilding engines including 2 strokes outboards, but mostly 4 cyl Omc brands. So if I do it myself, my question I guess is in general are parts ridiculously expensive or hard to find for these outboards?
Thanks Again for your time. Also, is it even worth rebuilding; is it a good motor? It is a v-6 not an inline 6. Who actually made it. I know some were Mercury, but were they all made by mercury?

I answered the parts availability question myself, right here in iboats catalogue.
--
Stan

 

[Laddies]

Re: Mariner 135-2 dead cylinders

Heres parts lists and prices
http://www.mercruiserparts.com/selectSerailRange.asp?doc_nbr=V-135

 

[SuperNova]

Re: Mariner 135-2 dead cylinders

Well, I bought the boat. It turns out the motor is a '93 150 hp disguised as a 135. I test ran it and it sounded fine and ran about as smooth at 600 rpm idle as I would expect a 2-stroke to run. No odd sounds or smoke. I am going to do a compression test on it tomorrow night and a leakdown if the compression isn't right, but I am not too worried about it. It sounded good. The boat on the other hand, is an '84 and needs a lot of TLC. I gotta admit I am looking forward to the project.

--
Stan

 

[SuperNova]

Re: Mariner 135-2 dead cylinders

I did the compression test and it showed 125 psi on all cylinders and that was without opening the throttle up. I ran it on sunday and I did notice that between 1100 and 2200 rpm it runs rough and feels like it's missing, but it idles fine and runs full throttle fine, no excess smoke or noises. At 3100 it surges about 100 rpm, feels like it is dropping a cylinder and picking it back up again. The plugs are surface gapped and look newish, but I am going to install a new set anyway, what about coil packs? Any thoughts would be appreciated.
--
Stan

 

[j_martin]

Re: Mariner 135-2 dead cylinders

First off, you don't know what's wrong with the motor, other than the guy told you that 2 cylinders were dead. Your own compression test belies what he told you, so you start over at ground 0.

If it has an oil alarm module, you can move the wire that goes to the switchboxes to any cylinder. If a cylinder is misfiring, the alarm will go off at that time. You can move it from cylinder to cylinder and see if they all stay strong at speed. If the alarm goes off, you can swap coils around to see if it's a bad coil, or a bad switchbox.

If it patterns, all on one side, it's likely a switch box. If it goes bad on one side above or below about 3000 rpm's, it could be a stator. If it dies on cylinders 1-4, or 2-5, or 3-6, it's a trigger.

If the spark is there and good all the time, you're looking at fuel. Probably time to take the carbs off and throw kits in. Then a formal link n sync to set everything up right. BTW. I'm assuming you have discarded any old or dirty fuel and replaced it.

With compression numbers like that, you probably have a pretty good motor. All the above is relatively minor, especially if you have the moxy to do it yourself. When running right, that's a pretty sweet motor.

hope it helps
John

 

[SuperNova]

Re: Mariner 135-2 dead cylinders

John, Thanks a lot! Your information will certainly help. I am pretty comfortable around mechanical things. I am a professional auto tech and have been fooling around with boats for over 30 yrs now. The problem is the last 10 yrs I've focused on Mercruisers. The last outboards I messed with were all 70's up to mid 80's Johnson and Evinrudes and maybe one straight six Mercury. So this is another learning process for me. I understand the mechanics of the thing, but the bells and whistles I'm not familiar with. I am going home tonight with an HEI type spark tester to see if any of the cylinders show me weak or no spark. Your idea with the alarm sounds good, and yes it does have an alarm, but I honestly don't know what you mean by "switch boxes" or which wire I move around. I am reasonably sure when I get home and pull the cowl it will be somewhat apparent to me. I'm going to print your advice and see if I can put it together. And youa re also right that I don't really know anything about this motor. I checked the lower unit gear oil and it's not milky, but there are metal flakes in it. The lower looks brand new, but who knows. I'll drain it and refill it and see what happens. If I end up having to take it apart then so be it.
--
Stan

 

[j_martin]

Re: Mariner 135-2 dead cylinders

The ignition is all controlled by 2 switch boxes stacked one on top the other on the starboard side of the engine. Each box has 3 ignition circuits in it, 2 charge coil inputs, a kill circuit, and a bias circuit. Timing is by 6 leads from the trigger, and each ignition circuit feeds it's own coil and plug. Charge coils (stator) supply the power, and the bias circuits keep things in sync, and are modified by timing modules and such.

The oil alarm module is hooked to one of the coil primary circuits, and to a pulse maker in the oil pump. If pulses are available at one place, and not the other, the alarm sounds. You can put the switch box lead on any coil wire and check for misfire with your ear. If you move things around on the switch boxes, make sure all the grounds are tight and the mounting screws are tight before you crank. They like to fry with a bad ground.

2 cycle is easier to fix than 4 cycle. It goes squish-bang. If it ran once, has compression, fuel, and spark, it will run. Simple as that.

On the LU. I would run Merc High performance gear lube, not the normal stuff in that engine.

Are the flakes steel or aluminum. Mine had a few al flakes in it. Turned out to be from a wrench monkey forcing bearings and seals in crooked. I noticed excess end play and had a good mech go through it. No major parts, but 'bout 100 in seals and stuff and 300 labor. Steel flakes would be something actually spalling. If it's a few and you're lucky, just a bearing. If you let it go, and flakes get into the gears and cause metal to metal contact, they will spall and catastrophically fail.

I have a 2.4 XR4. It is a unique sounding and strong, swift machine. It was intimidating at first, but after I saw what the wrench monkey did to the lower unit last fall, I took it down to the long block and checked everything out during the winter. If you're patient, and do things the best way instead of the fastest way, it's actually pretty easy to work on.

hope it helps
John