Overheating with ear muffs

EM2

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Aug 15, 2009
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16
I've spent a few days researching now, so I feel adequately prepared to finally ask this question.

Quick background:
Bought this boat 2 weeks ago. It's a 2001 Glastron 5.0 Volvo/penta I/O. It overheated on me once in the water, which I thought was because I sucked up some reeds. I pulled the stern drive up, found no reeds, lowered it, temp went back down, trucked right along all day. Slow speeds, 45mph, etc. No probs. Ran it 3 more times, each time I would flush it thoroughly.

I pull the boat in on the trailer, attempted flushing, water wouldn't come out. It just sprayed out the sides of the muffs. The engine begins to over heat with the muffs on. If I flush water in the port on the side of the engine, it runs cool all day.

Now, I have pulled the thermostat, replaced it, verified that all passages are clear (including the bypass port). I also pulled the raw water pump and saw that it was, in fact, brand new. No leaks, it pumps just fine.

So I begin wondering if I can get flow up to the engine, so I pop off the intake hose (at the raw water pump) and run flushing water to the stern drive. No water.

I ran to Lowe's , made myself an adapter and ran water from the inlet hose (still disconnected from RW pump) and watched in amazement as clean water flowed out of the inlet holes in the stern drive.

Water still won't make it up to the pump. I pulled the clean out cover (yup, I found that one) and it's clear.

So... help?
 

BRICH1260

Lieutenant
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Jul 6, 2011
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1,342
Sounds like your raw water pump is not priming, not enough water pressure, bad muff seal, or you have an air leak on the raw water pump itself,
( bad o ring seal).
 

EM2

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Aug 15, 2009
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16
But why would I be able to get water out the inlet holes when backflushed with my adapter, but I still can't get water up to the RW pump?
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
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pull the drive and inspect the raw water inlet fitting (where the hose attaches to the outdrive)

while you have the drive off, inspect the bellows, u-joints, gimbal, etc.

also look at your power steering cooler. that is bolted to your transom plate on the inside. if you have a large chunk of debris, this would be the first place that it would get stuck in the system
 

Lou C

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Nov 10, 2002
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Keep in mind that it is a bit more difficult for a system that uses an engine mounted impeller to prime. The water has to travel up about 18" and then forward about 3' to make it to the impeller housing. The Merc Alpha probably is the easiest to prime because the impeller is right above the water intakes, just like outboards. On my Cobra, the water has to rise about 18" to make it to the impeller housing, which is in the upper gear housing. I recently had to replace my old set of dual inlet rectangular muffs and here's what I found....whoever makes them for Tempo, Sea Choice, etc is making the cups out of rubber that is too stiff. The do not seal as well as the older ones did when whey were new. So I switched to the Merc/Quicksilver ones that have the steel wire clamp that pushes through the water intakes and gets secured on the other side. Much better sealing. Also, I came up with a way to make sure that the Cobra pump primes right away, esp if it has not been started in a while, and can be used on a Volvo or Bravo with the engine mounted impeller:
​Hook up muffs but do not turn on the water yet.
​Go up to the front of the engine, disconnect raw water intake hose and fill it till you can hear water running out around the muffs (if you have a Volvo or Bravo, this is the hose that goes from the impeller housing to the transom mount).
Then reconnect that hose, turn on water
Start engine
​this way it fills the water intake hose from the thermo housing (or if you have a Volvo or Bravo system the hose from the impeller to your transom mount) all the way to the water intakes. The pump will prime much faster this way and you will have less impeller wear because it gets water almost instantly.
 
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bruceb58

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Keep in mind that it is a bit more difficult for a system that uses an engine mounted impeller to prime.
It's actually very easy on the water since the raw water pump sits below the water line. Agreed that it is a little further when on muffs.

It is totally normal for the water to be squirting out the side of the muffs until you start the engine.

I would be checking the hose that goes from the pivot housing to the transom assembly to make sure it isn't kinked.

To the OP, I use these type of muffs. If you don't have them, I suggest getting them.
https://www.walmart.com/ip/Attwood-U...&wl13=&veh=sem
 
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Lou C

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Nov 10, 2002
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​Bruce, I bought a new set of the one you posted (used the old one for years without a problem) and the rubber is just too stiff for it to seal. I switched to the one in the link above and it primes much better and runs cooler. It barely hits 150 degrees on the muffs now. And the Merc design cannot fall off or get loose. The rubber on the Merc/Quicksilver muffs is noticeably more pliable than the Tempo/Seachoice/Attwood rectangular muffs.

​I agree that the Volvo design primes easily in the water due to the level of the raw water intake hose & hydrostatic pressure but on the water muffs, it can be difficult. I bet in some cases if you disconnected the raw water hose at the impeller and had the muffs on with the hose on full the water might not even make it all the way to the impeller housing, unless they fit really well and the bow of the boat is down slightly.

 
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bruceb58

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I have never had a problem getting water to the engine in the 15 years I have owned my boat. I used the exact same type for 12 years with my OMC Cobra.
 

Lou C

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I see that they have changed the water intake design from the first run of the SX which had simple holes like a Merc Alpha. Now they have what looks like removable screens so you can clean out the water intakes I guess.
 

bruceb58

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I see that they have changed the water intake design from the first run of the SX which had simple holes like a Merc Alpha. Now they have what looks like removable screens so you can clean out the water intakes I guess.
Mine is an LK which is close to the beginning of the joint venture. No screens.
 

EM2

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Well, I haven't had time to play with it since I posted, but I've been doing some brain storming and came up with exactly everything you all have posted.

I think the best plan forward is to block off the suction inlet and fill from the hose at the engine to see if I have a leak somewhere. I may have sucky muffs and be currently chasing a wild goose.

Thanks for the info!
 

sogood

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May 11, 2016
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You mention that it overheated once while on the water , with no apparent cause. So you may still have an issue separate from your muff. Did you check the oil cooler for blockages ? Maybe old exhaust flaps broken off and stuck in the bottom of the exhaust pipes ? Just a thought .
 

bruceb58

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Have you pulled your drive recently? If not, I would probably pull it and force water from the hose at the water pump and see if it comes out the pivot housing.

You should be pulling your drive annually anyway so even better excuse to pull it.
 

EM2

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Aug 15, 2009
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I've only had it for a couple weeks now. The gentleman I got it from pulled the out drive and (supposedly) did all that. I'll probably pull the out drive before too long.

I'm fairly sure that there were dead reeds stuck to the inlet ports that fell off when I shut the engine off and picked it up, which is why it overheated.
 

QBhoy

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Mar 10, 2016
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Hi
Make sure you have the right muffs. I had the same problem with my VP 4.3 and 290dp drive. Wasn't easy for the engine driven pump to pull the water up initially...unless you have the right correct and proper sealing muffs. Even if you sit these drives in a big tank of water, they struggle to pull the water up. They really aren't good at this and rely on water pressure by means of being truly submerged in their natural 3ft of water pressure (i.e. When the boat is in water)
Just my experience anyway.
 

EM2

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Aug 15, 2009
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You are absolutely correct. The muffs don't work.

I filled the inlet hose with water after taping the ports off. I didn't have any leaks, so I took it out for a run today and had zero cooling problems. Lesson learned I guess.
 

Lou C

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What I said right? This design is just hard to prime on the water hose with certain muffs, where the rubber is too stiff. The water has to raise up about 18" and go forward 3-4'. That takes a good amount of pressure and minimal leakage.
The normal muffs that will work with outboards and Merc Alphas sometimes do not fit well enough to pressurize that entire raw water circuit from the drive all the way up to the engine. Another thought:
​Get a big set of wood working clamps, that you can use to clamp the muffs, tight enough that they will not leak much. Kind of does the same thing as the Merc muffs do, but can be used on lower units where the Merc muffs with the rod and clamp cannot be used. Then do as I said above, disconnect the raw water intake hose from the impeller, stick a funnel in it and fill that hose till it is full. Re-connect the hose. Then go and look at the muffs and adjust them till there is minimal leakage. I tried this on my Cobra and it worked better but the Merc muffs are foolproof. Once installed properly they cannot come off or move out of position. With the engine running there is nearly no leakage.
 
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