OVERHEATING

[larglo]

Hi all,

In my last post I mentioned I overheated on my trip out. Today I went to the boat to see about winterizing the engine. My son removed the thermostat first to see what it looked like. Here is what I found.
First of all I too my thumbs and depressed the center down and it went less than 1\8 inch and stopped. Using further pressure, it clicked and I was able to push the probe further down.
When we were out during the overheating, we did see a very small amount of water coming from the exhaust.
Could I surmise then that this was the problem which caused the overheating?

Second, when removing the intake hose, after shutting off the seacock valve, my son said the hose was cracked and appeared rotten. So I fell lucky we found this out now, and it will be replaced next spring.

As for winterizing, and now with the thermostat out, could I just place the intake hose into a 5 gal bucket of anti freeze and start the engine, letting it draw the fluid threw the engine until I see the antifreeze coming from the exhaust and then stop the engine.
We tried to remove the drain plugs from the rear of the exhaust manifold and couldn't budge them. I think I read on one of my replies that this is how they did it?

I could really use some advise on this concerning my thoughts for the reason it overheated being the thermostat and winterizing the engine or anything else that may come to your mind.

Thanks very much in advance.

Larry

[rooferdave]

http://www.trojanboats.net/wforum/viewtopic.php?t=3996
that would have helped before you started winterising, if you are still in the water maybe you can

if not use an i.r. gun and put the stat in a pot of water on your stove or other source of heat and when it opens take a reading of the water temp. The stat itself should have the opening temp on it, i.e. 142... 160 etc

[rickalan35]

Overheating can be the thermostat or a water pump impeller. In my case, as most know on the forum here - this past summer it was my impeller. If either is half-ass functioning you may not overheat at idle speeds but will indeed when you ramp it up.

Winterizing - in regards to my engines, I usually just drain both engines and leave them. I know where all the plugs (drain cocks) are located on my Fords - I just make sure to get to every drain plug.

I do run marine/RV water tank antifreeze thru the fresh water system before draining the whole system, as much as possible. I unhook the line at the water pump. I pour a little anti freeze into the water pump. I leave antifreeze in my toilets. I have straight drainage from all sinks - no traps.

I have vacuflush heads and they vacuum tank always makes me nervous. But so far so good, flush antifreeze thru it.

I run antifreeze into the shower drain as well and then pump it out. The remaining antifreeze in the shower pump must work because it's always fired up each spring.

If anyone has more to add that I might also take advantage of, please do.

Cheers

Rick

[rbcool]

Larry, you and I are both praying it's the thermostat. More than likely impeller or that hose was collapsing, still easy. But many times I've found it was the risers and manifolds. How old are they? Is there a heat exchanger?????

[prowlersfish]

You said it was not pumping much so it could be your pump or could be the hoses sucking air hopefully the risers are ok being in fresh water

[rossjo]

Larry,

Is you systems SeaWater cooled (open) or FreshWater Cooled (closed with a heat exchanger)?

... Ross (former King)

[prowlersfish]

Your still the King

[larglo]

I don't have a heat exchanger. I have a seacoak shutoff valve in the hull floor with a hose going up to the engine. That hose seemed to be rotten, from what my son said, right at the valve.
If I remember right, after first starting the engines this summer, I always checked to see if there was a good stream of water coming from the exhaust, which there always were. That to me, would mean the thermostat would not have to be open yet to get the water flow? Is that correct?

This is where I'm confused, how does the system work, to get water flow out the exhaust, having the stat still closed?
I was told, and it looks to be, a brand new water pump on the engine when I bought the boat. At most, I only have 8 to 10 hours on the engine myself.

The drain plugs, or what we thought were drain plugs located in the back of the exhaust manifolds required at least a 1" or larger socket wrench to remove, does this size sound about right? We only had an 8" adjustable wrench and couldn't budge the plug.
Any thoughts on this?

Larry

[rossjo]

Larry,

You have a "Sea (or Raw) Water Cooled" setup (for future reference).

Even if the thermostat is closed, water bypasses it (not through the engine) to go out through the manifolds.

Flow:
Scupper > Seacock > Seawater Pump > Engine Water Pump > Engine/Thermostat > Manifolds > Exhaust

I'm looking for a Raw Water diagram ...

Don't remember what engine you have (Chrysler 318?) to help on manifold. Typically, you'll have a tapered pipe thread plug on the bottom of the manifold you can drain. I installed brass/stainless shutoff valves in the manifold drains (1 per side) on my 26 so I can drain mine anytime. I often pop them open right after starting the engine to verify water flow, since the 26 is a Bravo-1 I/O.

[larglo]

Now, I'm getting somewhere!

So, if water does (should) pass thru the exhaust when the stat is closed, and on mine, is does not, what would be the most obvious reason for it not to, or first place to start checking to find cause?

I havs a Chrysler 318, 225 HP engine.

This is a great help, thank you. If I can get thru this winter, I will deffintly look into the drain plugs, seems like that would be a great help in winterizing the engine.

Larry

[rossjo]

Cooling Diagrams:

Cooling Diagrams for Most (6 cyl and v8 ) Mercruiser engines:
http://RNR-Marine.com/Meruiser-SeaWater ... 94hg6a.pdf

Most have this in their Trojans:
Mercruiser-V8 Fresh-Water-Cooled, Raw-Water-Through-Manifolds Water-Flow-Diagram:


Typical (7.4L/454 in tthis case) RAW Water Cooled:


Rare: Mercruiser-V8 Fresh-Water-Cooled, Fresh-Water-Through-Manifolds Water-Flow-Diagram:

[larglo]

Is it possible to pour marine anti-freeze directly into the thermstat housing area that would mix with any water inside the engine and safely protect the engine from freezing up?

I'm asking this in case I'm unable to remove the plugs to drain. Could I also remove any hoses to the manifolds and pour anti-freeze into them also?
Anything I may do, I will also place a marine bilge heater into the engine area.
I used this heater all last year without winterizing anything and it worked fine. But I spent most of the winter worring about a power outage. We had a very cold winter last year and the lake froze all around the boat.

Thanks

Larry

[kallen]

Just removed my exhaust manifold on my raw water cooled "318". Had a issue of steam from one engine ( just noticeable under way) Was not overheating but the steam did discolor the pin stripping. Found that the distribution tube in the exhaust manifold was blocked by 2 pieces of water pump impeller.This was causing a hot spot in the manifold. Lack of suffient flow. The tube can only be removed by disassembling the manifold at the elbows or remove the complete manifold. As for winterizing use a 5 gallon pail with antifreeze mixed to the stongest concentration. Run the mixture in thru the seacock hose.Catch what comes out the exhaust & measure the freezing point. Plumbing anti-freeze is less expensive but u will need a different type of tester available from a RV store.

[aaronbocknek]

dont forget your hoses etc when you do the winter layup. last year when john helped me, after everything was completed, the very last thing he did was use a squirt bottle with a diluted soulution of wd40 and water. he spritzed it all over the engine and the hoses. as the water dries, it leaves a little coating of wd40 on linkages, hoses and everything else so nothing dry rots over the winter. simple solution for a very real problem.

aaron in baltimore

[k9th]

dont forget your hoses etc when you do the winter layup. last year when john helped me, after everything was completed, the very last thing he did was use a squirt bottle with a diluted soulution of wd40 and water. he spritzed it all over the engine and the hoses. as the water dries, it leaves a little coating of wd40 on linkages, hoses and everything else so nothing dry rots over the winter. simple solution for a very real problem.

aaron in baltimore

Great advice!