1988 Mariner 135 overheating at lower RPM's..

[Baja18man]

Greetings to everyone!! My first post here is a problem with my 1988 Mariner 135 that has been professionally rebuilt. I have studied all threads here to obtain as much info as possible but I need some imput. I believe (based on my knowledge gained from reading threads) that I have a "popet" valve stuck in the open position. My engine begins running hot (per temp gauge) when I operate below about 2500 RPMS. Any RPM's above that it seems to run about half scale on the temp gauge. I recently had my water pump replaced (professionally) due to failure. My mechanic has stated this is normal operation but I am not sure I believe what he is saying on this. My question here is basically this: Does this sound like the problem and if so how hard is this to do yourself. I have fairly good mechnical skills but not alot of boat engine maintenance background. If this is the problem, if I obtain a good manual, can I attemp this repair? Thanks to everyone who can help!!

 

[Baja18man]

Re: Problem with 88 Mariner 135 overheating at lower RPM's..

Re: Problem with 88 Mariner 135 overheating at lower RPM's..

Hey to all.....Any chance someone can offer some help on this problem...I really could use a helping hand on this....Thanks in advance for any help!!!

 

[ifixf18s]

Re: 1988 Mariner 135 overheating at lower RPM's..

Is there a thermostat? It might need to be changed, had the same problem with my motor even though it was a 25 HP 2 stroke. Is there a good stream of water coming from the pee-hole at the lower RPMS?

 

[Baja18man]

Re: 1988 Mariner 135 overheating at lower RPM's..

Thanks Ifix....I think there is a thermostat and there is good flow out of the pee-hole as the water pump was just replaced before this problem began..so I think that is ok for now

 

[Baja18man]

Re: 1988 Mariner 135 overheating at lower RPM's..

Guys...Any ideas on this??? I could really use your help on this....any Mariner 135 experts out there???

 

[Faztbullet]

Re: 1988 Mariner 135 overheating at lower RPM's..

First check that the hot horn is operating. If is is operating and not sounding is is not getting hot and install new t-stats(I do on every rebuild). Throw that temp guage away and install a water pressure guage, these temp guages cause problems when there isnt any. If you dont like the reading on guage just back it up a half turn off block and it will read cooler.

 

[j_martin]

Re: 1988 Mariner 135 overheating at lower RPM's..

To answer your question, the poppet valve might be stuck open, or have some chit in it, or whatever. It's pretty easy to work on. Just get the gaskets and diaphragm and have at it. If you need other parts, like the seal doughnut thingie in the block, you can get it later. It's easy to get at once you've been there.

Does your tattletale spit a bit of steam at idle. That's a clue the block isn't filling because it's spilling out the poppet.

Temperature does jump around a bit on these v6's as the cooling system design is a SWAG (scientific wild *****ed guess) design, or a series of approximations partially moderated by thermostats.

hope it helps
John

 

[powrguy]

Re: 1988 Mariner 135 overheating at lower RPM's..

Okay; that's it. You sound like you might have a good handle on the Mariner 135. (I have a 1990 model)

I have very little dribble out the "weep hole" at startup but plenty of flow out the hub. It takes at least 10 minutes at idle/fast idle to get the temperature to move off the cold mark, but once it does, the stream from the weep hole is okay.

My question for ya is "where is the poppet valve"?

My second question would be "should it take that much warmup time before I can put it in gear without stalling"?

thanks

 

[j_martin]

Re: 1988 Mariner 135 overheating at lower RPM's..

What yer describing sounds like a stuck poppet valve. A pressure gauge would make it easy to see. Best "view" of your cooling system anyway.

It's on the starboard side, low on the block.

Just get a diaphragm, and the gaskets (2 I think) and pull it apart. Look for something stuck in it. The seat may be loose and getting cocked in the hole, in which case you get a new one and swage it into place with a center punch.

4 bolts probably, ten minute job if you know what yer doing, maybe an hour if you have to ponder it.

hope it helps
John

 

[powrguy]

Re: 1988 Mariner 135 overheating at lower RPM's..

Okay; that's kinda what I was thinking, but needed someone more knowledgeable to confirm it. I'm going to FIRST get a factory manual, as this motor is new to me and I wanna read up on it a bit.

thanks for the help

 

[sschefer]

Re: 1988 Mariner 135 overheating at lower RPM's..

Okay; that's kinda what I was thinking, but needed someone more knowledgeable to confirm it. I'm going to FIRST get a factory manual, as this motor is new to me and I wanna read up on it a bit.

thanks for the help

The guys have you on the right track but you mentioned ordering a Service Manual.

Make sure you order the one for the Mariner and not the V135 Merc. Almost everything is identical and most of the parts will cross over without any problem but you're bolts are all metric and all your threaded parts have metric threads. If you need to replace something threaded or a bolt make sure you use the Mariner parts list.

 

[powrguy]

Re: 1988 Mariner 135 overheating at lower RPM's..

Actually, this motor is a 1988, I found out, and the Serial No. is OB383775. I also found out the Manual is not the same as most for the era, and of course, harder to find.

Was this motor one of those that were made by Yamaha for Mercury (hence, the metric fasteners, etc.)?

I guess the manual I'm looking for is 90-97658--3, which I can't seem to find cheap ($120 or so at Marine dealers). I'm keeping an eye out on Ebay, though, so maybe one will pop up.


thanks

 

[Dukedog]

Re: 1988 Mariner 135 overheating at lower RPM's..

Steve you missed it. All tha V6 Merc and Mariners are identical in every way except in color. Through tha Seloc away........
First thing I would ask is about the water pump. Was the complete water pump changed or just the impeller? Were the parts OEM or aftermarket? The pump housing and base plate, even though they have stainless steel parts, they do wear down and need to be changed along with the impeller. Some don't agree with this but your already in the pump and its not many more $ for peace of mind. Aftermarket pump parts are a crap shoot at best.
The water pressure guage is the best thing to rely on. Just make sure your heat horn is working.............D

 

[j_martin]

Re: 1988 Mariner 135 overheating at lower RPM's..

I agree with D. The manual even says Mercury and Mariner.

scheffer has worked on exactly one Mercury v6 in his life, so he's now an expert.

I also agree that often the water pump will lose it's goodie from a bad base gasket, or the bottom plate is grooved, or the housing is distorted from either heat or overtorqing. BTW, I can't get it to the book torque specs without distorting the housing. I just tighten it till it looks and feels right, and it's always been good for me.

If you're not sure about things, a second opinion from someone that's been there is always a good thing. Post close-up quality pictures here, and you'll have a few hundred pairs of eyes worldwide checking your work for you.

hope it helps
John

 

[powrguy]

Re: 1988 Mariner 135 overheating at lower RPM's..

Steve you missed it. All tha V6 Merc and Mariners are identical in every way except in color. Through tha Seloc away........
First thing I would ask is about the water pump. Was the complete water pump changed or just the impeller? Were the parts OEM or aftermarket? The pump housing and base plate, even though they have stainless steel parts, they do wear down and need to be changed along with the impeller. Some don't agree with this but your already in the pump and its not many more $ for peace of mind. Aftermarket pump parts are a crap shoot at best.
The water pressure guage is the best thing to rely on. Just make sure your heat horn is working.............D

Well, now I'm confused. Is the 1988 Mariner 135hp "Marathon" built by Yamaha, with metric fasteners/fittings, or not? Does the "Mercury-Mariner" Factory manual say anything about this in regards to interchangeable parts for Mariner and Mercury? Does ANYONE know which Factory Manual I'm looking for to be the one for my Mariner motor?

thanks

 

[Dukedog]

Re: 1988 Mariner 135 overheating at lower RPM's..

If your motor ia a V6, which I'm sure it is, its built by Merc. Nothing metric about it. The parts numbers are even the same. Tha only time you see a different part number between Merc and Mariner V6 motors is if tha part is a PAINTED piece. The smaller merc/mariners or a different story.......D

 

[CharlieB]

Re: 1988 Mariner 135 overheating at lower RPM's..

Poor cooling at low engine speeds are most commonly caused by low water pressure from the water pump.

I wholly agree with the previous posters statement about the prior water pump repair, changing the lower plate/pump body AND the upper pump body may be required to ensure adequate impeller sealing and restore low RPM water pressure and flow.

This is a very common error made by many people hoping to save a few bucks on repairs. Don't make this mistake.

Bite the bullet and do the job RIGHT.

I also cast my vote for installing that water pressure gauge.

 

[powrguy]

Re: 1988 Mariner 135 overheating at lower RPM's..

If your motor ia a V6, which I'm sure it is, its built by Merc. Nothing metric about it. The parts numbers are even the same. Tha only time you see a different part number between Merc and Mariner V6 motors is if tha part is a PAINTED piece. The smaller merc/mariners or a different story.......D

Thanks. What I intend to do (if it ever stops raining here), is just take a few sockets and nuts and check some bolts and threads to determine metric or SAE fittings/hardware.

I, too, feel that this is a Mercury with a Mariner paint job/decals.

Thanks

 

[sschefer]

Re: 1988 Mariner 135 overheating at lower RPM's..

I agree with D. The manual even says Mercury and Mariner.

scheffer has worked on exactly one Mercury v6 in his life, so he's now an expert.

I also agree that often the water pump will lose it's goodie from a bad base gasket, or the bottom plate is grooved, or the housing is distorted from either heat or overtorqing. BTW, I can't get it to the book torque specs without distorting the housing. I just tighten it till it looks and feels right, and it's always been good for me.

If you're not sure about things, a second opinion from someone that's been there is always a good thing. Post close-up quality pictures here, and you'll have a few hundred pairs of eyes worldwide checking your work for you.

hope it helps
John

Not sure where that came from John. I do happen to know a little more than you might think about Mariners. Ever seen a Belgium made Mariner 100 hp 2+2 fishing motor. I doubt you even knew they existed. All the fastners are Metric. I'd invite you over for a thread checking party but I doubt you'd come.

Here's a Belgium built Mariner, all metric fastners, Serial #09655784, inline 4 same as the merc 100hp that runs on two cylinders up until the accellerator pump kicks in and adds fuel only to 3 and 4 (approx 1800 rpm) via two 5 lb check valves in the fuel ports.

Oh yeah, that would also be mine and in my shop and hanging from my hoist but now it's on my 18' fully restored 91 MonArk Legend which I'm taking fishing Sunday morning while the new to me North River is being rigged for my E-Tec 115 H.O. As for the V-135, it's a fun motor, just something to use to learn more about V-6's.

 

[j_martin]

Re: 1988 Mariner 135 overheating at lower RPM's..

So, is a 2 + 2 a V6

Sorry, you missed big time on the metric V6 bit.

John