Cooling problems, continued

[cutwater]

I pulled the freeze plugs to drain the anti-freeze in the block, then ran the Minx (SBC) for a total of about 10 minutes on the hose with the T-stat REMOVED. I got strong, normal water flow out of the exhaust tips. When I removed the water input hose to the Circ Pump, it smelled like pure anti-freeze!! Do you think I have a blockage in the Circ Pump, and the raw water was just going through the bypass? I KNOW that the block filled up with fresh cold water (I guess since there was no T-stat, it could have filled the block from the top to the bottom, instead of through the Circ Pump). It was just the big hose to the circ pump that still had anti-freeze in it. If not, why wouldn't it have cleared the anti-freeze in that main hose??

Last season I had trouble burning holes in my exhaust hoses, never got it completely fixed. It seemed like good raw water flow was intermittent. At one time I shredded an impeller and never found all the pieces (even when I backflushed the oil cooler). Maybe this is the problem? Should I tear into the circ pump?

[MOP]

Revised as per Red Dog! Should read better and not talk on the phone while posting, no Tstat and no circulation make me think the impeller on the circ pump may be spun and not doing its job!

Phil

[RedDog]

The Tstat many times will not open well on the cold water from the hose, so it can take quite awhile for the block to fully flush out. Let it run for awhile longer at op temp, if all is well it should clean up in 15-20 at op temp.
Phil

Read the post again - the t-stat was removed - I guess that could be a reason it didn't open?

[MOP]

Revised thoughts above:hangum:

[cutwater]

I kind of thought that at first, but I always heard that if the circ pump went bad, it just acted like a crossover. If this were the case, then the anti-freeze still would have cleared out, right? That's why I'm wondering if there is debris in the circ pump inlets. I guess I'll try to tear it apart tomorrow.

I hate the thought of buying a new circ pump, as I was wanting to go to a crossover system. On my OMC setup, though, I would have to relocate the fuel filter, oil pump, alternator, etc. to get it to fit :hangum: :smash: Can you tell I'm not happy about it?? :wink:

[cutwater]

Did ya block off the bypass when you removed the t-stat?

Poodle -
I only had the T-stat out for winterization so I did not block off the bypass. Normally I run with a 160* T-stat. Are you thinking that the bypass is a less restrictive path, so the water just went that way instead of through the block? I've thought about that a little bit, but I was assuming that after 10 minutes most of the coolant would have been cleared out regardless, especially if the circ pump was creating pressure in the system like it should.

[cutwater]

By the way - on this OMC setup, I don't think there is any way to block off the bypass to run correctly w/o T-stat because the circ pump input cannot be isolated from the block outlet... :confused:

[cutwater]

Here's a pic. The T-stat housing internals are a little hard to 'splain... anyone got experience with these?

Like this one:
http://www.a1discountprop.com/glm_omc_cooling.htm

Here is mine:
Right-click and open in New Window to read labels...

[VetteLT193]

Check Eddie marine for crossover/t-stat setups. They have thermostat kits that should work for your application without relocating half of your accessories. They have one in particular that is setup for 3/4" NPT fittings so you can route the lines away from your alternator.

Back to your current issue though...

With the inlet at the T-stat the water pump has to create good pressure otherwise the water will just flow out the exhaust. I'm wondering if your problem with the exhaust meltdown is because the water pump suddenly starts doing its job at a certain RPM, which causes the block to evacuate blistering hot water that gets further heated in the exhaust causing the hoses to melt. I'm guessing you can put it back on the hose and get the antifreeze out by running the rpm's up.


Bottom line is all signs point to the water pump in my opinion

[cutwater]

With the inlet at the T-stat the water pump has to create good pressure otherwise the water will just flow out the exhaust.

You are right. I didn't even think about this until recently because I had been making some incorrect assumptions. I can get a GLM replacement pump for around $70, so I'm going to give this a shot.

I've spent way more than that replacing the burned exhaust hoses several times.

[VetteLT193]

You are right. I didn't even think about this until recently because I had been making some incorrect assumptions. I can get a GLM replacement pump for around $70, so I'm going to give this a shot.

I've spent way more than that replacing the burned exhaust hoses several times.

$70 is pretty cheap but after seeing your engine a crossover seems worth the coin. It looks like changing the water pump on that thing is a day long job... at least a stainless crossover wouldn't go bad on you again. :wink:

[cutwater]

$70 is pretty cheap but after seeing your engine a crossover seems worth the coin. It looks like changing the water pump on that thing is a day long job... at least a stainless crossover wouldn't go bad on you again. :wink:

I'd really like a crossover... So, if I went to the eddie marine t-stat housing and used a 90* angle NPT fitting so that I could avoid the alternator on the port side, would I get good water flow to the port exhaust manifold? It seems like having the stbrd water outlet straight and the port outlet 90* turn would cause uneven cooling.

Also, do the crossover inlet bars lay closely to the block, or would I have to worry about the alternator belt hitting the crossover?

[cutwater]

Stainless Marine :) :)

That's what I have been looking at for a few months, but to use a Stainless Marine T-stat housing, I would have to relocate my alternator (which is now upper-port, as in the picture), and several other accessories would have to move as well. I think that's why the Eddie Marine one was suggested, because it provides plumbing flexibility.

Currently, alternator is upper-port, pump is lower-port, and fuel filter is lower-starboard.

[VetteLT193]

I'd really like a crossover... So, if I went to the eddie marine t-stat housing and used a 90* angle NPT fitting so that I could avoid the alternator on the port side, would I get good water flow to the port exhaust manifold? It seems like having the stbrd water outlet straight and the port outlet 90* turn would cause uneven cooling.

Also, do the crossover inlet bars lay closely to the block, or would I have to worry about the alternator belt hitting the crossover?

I would set up both sides the same way even though you have room on one side. That will keep it balanced.

The crossover at the bottom is pretty far in, here is a pic of my brother's engine. it's BBC but similar enough to get the idea.

http://www.donzi.net/forums/attachment.php?attachmentid=31858&d=1190818239

[cutwater]

It's not the inlet I'm worried about, it's the t-stat housing outlet hoses that go to the exhaust manifolds - the upper-port mounted alternator is right in the way. Is there any SM solution that won't require relocating my accessories?

[VetteLT193]

Stainless probably has a kit that will work, I'm guessing one of the blower kits, but it's hard to tell based on your pic. I have a hard time visualizing the base of the T-stat area and the depth of everything.

Take a look at how far forward my brother's stat housing comes... Can you run underneath the alternator with that style? Are you taking into account at how much smaller the Stainless housing will be?


The other option you have is to keep your current stat housing and block off the big hose inlet, then make sure you get a crossover that has the bypass. Hook the bypass up to the current raw water inlet in the T-stat housing, connect the raw water line to the crossover, and you are done. You won't win any awards but it will be functional.

[Air 22]

What are the Pros and Cons of a Crossover on a basically stock motor vs. a working Circ pump providing an evenly distributed water PSI throughout the block?? ie steam pockets etc? Not sure if this applies but I have heard several views on this b4...:smash::nilly:

[VetteLT193]

What are the Pros and Cons of a Crossover on a basically stock motor vs. a working Circ pump providing an evenly distributed water PSI throughout the block?? ie steam pockets etc? Not sure if this applies but I have heard several views on this b4...:smash::nilly:

Some have problems with crossovers, most do not. The few that do have problems are the loudest.

That said, with a stainless crossover you will never have a water pump failure again. It eliminates hoses, complexity, weight, and it looks a hell of a lot better:) You also have to pick up a few horsepower from not having to spin the pump.

I'll post before and after on mine after it comes in the mail...

[Air 22]

Some have problems with crossovers, most do not. The few that do have problems are the loudest.
That said, with a stainless crossover you will never have a water pump failure again. It eliminates hoses, complexity, weight, and it looks a hell of a lot better:) You also have to pick up a few horsepower from not having to spin the pump.
I'll post before and after on mine after it comes in the mail...

I have seen the look b4..it is cleaner for sure...Why then do most stock marine engines come with a Circ pump? I guess that raises the question WHY even have a circ pump to begin with? I see the points NOT to have one...:smash:

[VetteLT193]

I have seen the look b4..it is cleaner for sure...Why then do most stock marine engines come with a Circ pump? I guess that raises the question WHY even have a circ pump to begin with? I see the points NOT to have one...:smash:

To start off with Merc builds engines for everyone in every climate. If you run in ice cold water, not so of an good idea.

I run my boat when it's warm, and even if I get the itch to run when it's cold it will still be warm compared to Maine in winter...