Headless 170 boat...where to go from here?

[66200i6]

Check with Stewart Warner and find out what the readings should be for the sending unit. You can also check the gauge in the same way based on their specs. Confirm the gauge reading when your running is correct.

T-Stats have been known to stick open. That would explain the cold temps at idle but not the high temps at cruse. A clogged block would cause warmer temps at cruse even with the T-stat open. I wonder if you had two problems?

I'm sure something like that has never happened to anyone else before.

Ric.

 

[64 inboard]

The new SW gauge I installed a few years ago is a mechanical one, altho I never tested it. I will try the "hot water" test on it. While I'm at it, I will retest the t.stat.

 

[Lazy JW]

...... If the t.stat is working correctly, and the water is flowing thru the block, up to the head, how can the temp sensor read "cold" if the t.stat is still closed? Shouldnt the water temp raise if its setting there? .....

I misunderstood about the temp sensor being located in the head; HOWEVER, it is still at the rear of the head, and therefore the water will not have had much chance to warm up. With cold water running through those cylinders, it really isn't going to warm up very much due to the fact that the cylinders simply don't get that hot to begin with; the real heat is developed in the head, and you are reading the water temperature FAR AHEAD of the thermostat in a system that does not recirculate. I see no way that this system will ever give a reading any where near the "rated" thermostat temperature in its present configuration.

Why doesn't the water temp raise if it's just sitting there? It would, if it were, but it isn't, so it doesn't. As soon as any flow goes through that thermostat, be it from a drilled hole or just slight leakage (they aren't all that tight) then the water at the sensor is being replaced WITH COLD WATER! And it's something like 100º colder than the water leaving the head!

Don't count on those cylinders to warm up the water very much; a very small percentage of heat is lost through the cylinder walls. So why can't you hold your hand on the side of your fully warmed up car engine? Because it has a recirculating cooling system. I'm guessing that you could indeed hold your hand comfortably on your boat engine in the cylinder block area (which could be readily verified with the infra-red gun) but it would be much hotter near the thermostat housing.
Joe

 

[69.5Mav]

It has been my experience that the 170 runs perty cold blooded. What I have found is that the thermostat area must be 110% clean in order for the mating surfaces to seal. I use a scotch bright wheel in order to remove everything down to bare metal. Even then the 170 still runs cold and takes a long time to come up to temp. I am using a 10" electric fan and a fan switch mounted in the bottom radiator hose.

I was driving down the tristate tollway in Illinois in september at 55-60 MPH. The air temp was 75 the sun was up and the radiator was 1/2 blocked with cardboard. The Alternator light came on. I kept driving for another 50 miles. The car didn't overheat untill 4 blocks after I left the tollway. I had a broken fan belt. I replace it and drove away.

I think what may have happened to you is you had a good sealed up thermostat that went bad. when you replaced it you did not and have not got a good seal on it. Without a good seal and pulling in cold lake water you will have a hard time getting the engine up to temp. Next time that engine is together pull the thermostat housing apart and clean those mating surfaces as if your life depends on it then use RTV to get a good seal on the grove in the housing and on both sides of the gasket. I think that may cure your problem. Also make sure both sides of the housing are flat with a straight edge.

 

[JackFish]

I'm wondering if it's possible to install the thermostat backwards?

 

[64 inboard]

I just checked the SW gauge and the t.stat in water. I heated the water to about 170 degrees, then dropped the 160 stat in it. The stat opened fully in about 30 seconds or so. I ran cool water in the container and it closed as the water cooled.

When I put the SW mechanical sensor in the water, the gauge registered...it read between 5 and 10 degrees colder than the infrared thermometer, but definately moved.

so, as of now, I guess the only thing to do is get the head rebuilt, installed, and see what happens. BTW, the t.stat was installed correctly and the gasket shows no signs of leaking.


I do thank all of you for your input so far.... hopefully this new head will help...for whatever reason?

Now on to pulling the head apart to do a little grinding.... probably wont do much...just clean up some rough casting flash.

 

[Lazy JW]

.....

When I put the SW mechanical sensor in the water, the gauge registered...it read between 5 and 10 degrees colder than the infrared thermometer, but definately moved......

That's plenty close enough.

Use that infrared thermometer when you get the boat out on the lake; check at various locations and right down the readings, then PLEASE report your findings
Joe

 

['68falconohio]

Now on to pulling the head apart to do a little grinding.... probably wont do much...just clean up some rough casting flash.

There's a sticky in the HardCore section with porting tips for the log heads, if you're feeling froggy.

 

[fordconvert]

FWIW
I was chatting with an 'old timer' at a job site today and we got talking about boats so I asked about this one. He said he remembers them and said you got to use the 'special' stat, not a 'regular' one. I asked if he knew what was special about them and he said he did not know he only knew that if you used the special one they worked fine. Not much help but may be worth more research to find out what was special.

 

[JackFish]

I too have read that marine stats are different.
And it was mentioned that a hole was drilled in one that was used.
I can see the benefit of this in a closed automotive system, but what effect would it have in a marine system that has what I would think would be less pressure? Would it not allow the continual passage of cold water right from the start, thereby not allowing the engine to reach operating temp.

 

[Lazy JW]

...... Would it not allow the continual passage of cold water right from the start, thereby not allowing the engine to reach operating temp.

That's my thinking. It may even allow for reverse flow through the hole for a while, depending on the dynamics. Does all of the water drain from the block/head when the engine is shut off?

Just speculating: I wonder if the marine thermostats have some difference to compensate for the fact that they are dealing with non-circulating coolant. Think about it, in the photos above, it shows the "T" connection at the thermostat housing which will put COLD water to the outflow side of the thermostat, and this water will be KEPT cold by the continual flow of water past it; I'm not sure just what this will do or how it would affect the design, just throwing it out there to think about.

 

[jamyers]

Hmm...did some online poking around, can't find an online manual, but did find where you can buy the owners, tech, and repair manuals for something like $68 at MarineEngine.com. Seems like that'd be a cheap investment, if only for a picture of the cooling water flow.

I'm thinking there's some difference between the marine thermostat and an automotive one...I know on the Chris-Craft t-stat setups, the t-stat (diverter valve, iirc) does more than just open up and allow flow, it completely re-routes the flow directions.

Also, I'm thinking that the raw water oughta go up-and-back through the exhaust manifold BEFORE going into the block, for 2 reasons: 1. cool the exhaust manifold, and 2. pre-heat the water. Then, after it comes out of the engine it oughta hit the t-stat to be regulated, with "cold" water going back through again and "hot" water going straight into the exhaust flow and overboard.

I'd invest in a set of manuals, or beg/borrow/steal a diagram of the water flow from somebody in the old boat world. (Have you contacted Correct-Craft, they may well have some good info)

 

[jahearne]

Surprised there's no circulating pump for the motor. You need to have the correct thermostat because without a pump it acts as a check valve. The water comes from the raw water pump into that T fitting. Cold motor the t-stat is closed so no water flows through the stat housing. So cold water flows in through the lower (car water pump would be) adaptor into the block because it has no restriction. The 1/8" line acts like a small bleeder so a little water will always flow. Once the water heats up in the head, the t-stat opens and hot water has no place to go but out the open t-stat. If the raw water pump's pressure overcomes the hot water coming out the t-stat it will cool and close; therefore, acting like a check valve.

Very important that the correct t-stat is installed and 1/8" copper line is not plugged. There's no raw water strainer, so silt can deposit in the block and heads not to mention raw water (no anti-freeze or corrosion inhibitors) will corrode passages especially in the exhaust manifold and adaptors on either end, which may attribute to your original overheating problem. A lean mixture due to all those cracks in the head might cause over heating. If you can, pressure test the exhaust manifold because if it corrudes through water could get in past the valves are do all kinds of damage, hydro lock, etc. I imagine the marine manifolds can be hard to find.

That 170 boat motor is cool! All my boats have small block Chevys; flywheel aft! not backwards. The only other engine options at the time were Ford 427.

Take care,