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

['68falconohio]

I replaced the original electric gauge with a new SW mechanical gauge. The sensor is in the "back"(if on a car) of the head, right along the alternator. If you look close, you can see the end of the sensor sticking up ,just under the throttle cable, in the bottom pic I posted above....

Okay, nobody had asked so I figured what the hay. It's always the little things that get me.

fordconvert,
I 'think' he already has the system you're trying to show. I could be wrong and if I am, the waters have now been muddied. First pic.. Boat 170 rebuild/repower... info needed!?

Best of luck

 

[Lazy JW]

......... The sensor is in the "back"(if on a car) of the head, right along the alternator.......

Ahhhhh......... so it is sitting right next to the cold water inlet....... is this correct?

Am I also correct in assuming that the water does NOT re-circulate through the engine, but is simply a "bring in cold water-----dump out warm water" system? If so, that gauge reading will ALWAYS be low due to the fact that the water in which the gauge is placed will never have an opportunity to get warm.

I don't like this method, if I am interpreting it correctly. Seems to me that some means of circulating the water would be better, then use the thermostat to dump the hot water into the lake. But I'm not a boater and know virtually nothing about boats.
Joe

 

[64 inboard]

The sensor is on the opposite end of the head from the t.stat. The wierd thing is, I never had a problem with it until about a year and a half ago. ... At that time, the engine actually overheated, we were 5hrs from home, so I replaced the original stat with a 160 automotive one....still overheated. We removed the stat so we could use the boat that weekend and it wouldnt run any temp. Undestandable with out a stat.

When I got home I ordered a 140 stat (the manual recomends) ..no temp...Ive tried another 160...nothing. BTW, the boat temp does come up when Im idling, in a no wake zone. So thats why we are wondering if the raw water pump is forcing the stat's spring open?
I am in the process of trying to find a cooling system diagram for the engine so we can verify the water flow routing... The head definately has issues that need to be addressed, but I still need to figure out why we cant get any engine temp...

 

[Stubby]

The 385 series Mercuries have a water to water cooler on some of them. It's not a very large system, might be worth retrofitting.

 

[66200i6]

With the T-Stat installed correctly I don't think water pressure could force it open. That is, in an automotive application.

The temperature sensing portion of the T-Stat is toward the block. The heated water affects the packing of the housing and allows the spring to "pull" the plate away from the opening toward the packing. If the block side is pressurized it would actually try and force the sealing plate closed.

Ric.

 

[Stubby]

Looks like it may work backwards from conventional systems. It may bypass cold water then close to cool it down. Hard to tell with the pics. I tried to look at more photos on your link.

I would trace the water system and think it thru. You'll figure it out.

I looked at your old pics, before and after resto. It looks like something is missing.

http://outdoors.webshots.com/photo/2135 ... 9384zkfPqZ

In this pic, the water comes from pump to a water manifold. One port into block (where car water pump would be) manifold continues to head (this appears to be the thermostat housing) then on to the exhaust manifold.

If water manifold is plugged between block port and return from Tstat, pressure might force the Tstat open.

In this pic, I do not see the Tstat housing. Maybe it's just the pic clarity.

http://outdoors.webshots.com/photo/2014 ... 9384WvgxNL

Am I missing something?

 

[Stubby]

http://www.marineengine.com/boat-forum/ ... hp?t=13823

About half way down this page is some info.

Wow, It's an interceptor 170, 100HP.

http://www.correctcraftfan.com/

Scroll through their diaries and classifieds. Cool boats.

 

[64 inboard]

Im one of the "old timers" on Correct Craft Fan. Problem there is most of the boats are v8s, not six bangers. I hafta laugh a bit... I just about didnt buy this boat because of the 6, some of the guys thought I was nuts when I did anyway....(all my other boats are v8s). Now, last fall when I started talking of a v8 swap, all the guys told me to keep the 6!

I would LOVE to try one of the alum heads on this old girl..... besides a strained budget, carb CFMs and exhaust could be potential shortcomings. But, man would a couple hundred ponies be fun!

As for the t.stat, the pellet does go in the block. I think the t.stat housing is where water actually enters the block(if the stat is open) from the RWPump hose, otherwise I think it just dumps into the ehaust elbow.

 

[fordconvert]

Any idea what sort of design the water pump is? Any idea if its self priming? Or is its physical location below the water line? If the plumbing has not changed since you have owned it I may be looking closer at the pump itself. Im not clear on the current design but it almost seems like the stat actually stalls the flow which I think could be hard on the pump (depending on its design).

So the inlet to the block is that fitting above the trans? That would be the waterpump on the car and the normal inlet. Then the stat is on the head just like the car? When does it hit the exhaust manifold? Could you walk us through the what was the current flow design again? It seems like there has to be some form of a bypass somewhere for if the stat is closed to allow full flow of the suction pump and cooling of the exhaust manifold. Was there any signs of sand or mud in the head or block that you have seen so far? I know in my area you can end up with a lot of that in the block especially if running in reverse in shallows because the pickup is in front of the prop so running in reverse all the crap that gets kicked up blows right past the intake so some gets sucked in. 2 years ago I picked up an extra person at a beach and that was enough extra weight to not let it float. Rather than get out and push or make everyone shift I figured I could just power off. Bad idea. Now im sure my water pickup pump is chewed up from the sand. Like you were saying in a no wake zone it starts getting pretty warm if I leave it at idle. If I can kick it up about 200 rpm it still climbs but its alright. At cruise its fine. Takes about 45 seconds to go from 200 back to its normal 120 when you plane it out.

Most of the other boats like yours are V8's? Most of the classic boats I have seen around here are all inlines. That could be just because the lakes are smaller so the boats are smaller so maybe they just are not big enough for 8's.

The reverse turning engines are interesting to work on. I have done some work on a pair of 454's and silk? drives. Thats where the motors sit backwards with a transmission gear box in the front that then has the prop shaft point out the back. Who ever worked on the backwards motor did not know there was such a thing. If you ever look in any sort of a marine parts catalog its hard to miss.

 

[64 inboard]

The water pump is above the water line and is self primimg. It uses a rubber veined impeller. I think Ive got the water flow figured out. The water comes from the water pump into a "t" fitting at the t.stat, where it enters the motor. (if the stat is closed, it goes into the exhaust manifold). The fitting where the water pump would normally be in the block is where I think the water exits the motor. I have some pics but probably wont get time to download them for a day or so.


As for the other v8 boats...some "wierd" things there as well. MY 62 Higgins is powered by a 327 ci ,AMC/Hudson . The other boats are all Correct Crafts, 1966 Barracuda SS powered by a 318 Chrysler "Poly" , the 1968 Barracuda has acChrysler 360, and a 70 Wildcat,powered by a Chrysler 318 "LA" . I also have a 283 Chevy engine with tri-power...just waiting for the "right" hull.

BTW, all of these V8's are flywheel aft, RH (reverse) rotation, with 1:1 Velvet Drive trannys. I know its not a ford Six, but heres a pic of the "backwards-running" 360 in my 68 cuda. It shows how it uses a bellhousing to mount the trans... Notice how the starter is mounted backwards above the trans so it will spin the motor right

 

[Thad]

Rubber vane pump, much different from a centrifugal pump. It is a positive displacement pump and can make more press than a centrif. It could be "blowing" the thermostat open. You mention at one time having a overheating problem. If the t'stat was installled backward it could pressure up and keep it from opening properly. In a closed loop cooling system (car, truck, etc) there a hole in the t'stat so pressure is equalised both sides. Whereas in you boat set up the discharge side of the t'stat the pressure is near zero.
Suggest changing pump drive pulleys to spin slower, thermostat on discharge end of cooling system, a pressure "pop off" from pump discharge side to intake side or exhaust jacket with a pressure relief valve set at 14-16 psi should be about right.

 

[64 inboard]

I have always drilled an 1/8" hole in the t.stat base before installing them, so they cant "airlock". As for the stat, the pellet end has always been in the head.

I keep coming back to the pump having too much pressure and blowing past the spring, but there is a bypass fitting in the t.stat housing that goes directly into the exhaust elbow. It's hard to belive it can build that much pressure. Here is a pic showing the adapter...



There is also a fitting in the t.stat adapter that goes directly into the block, where a car water pump would normally be. You can see that "T" in the above pic, right at the lower elbow of the adapter, (below the green tape marked "cooling",where the boats raw water pump hose mounts)

Heres the waterpump to block adapter where that fitting goes....




in the exhaust manifold the cooling water from the t.stat adapter bypass- runs in one jacket , to an end cap at the flywheel end,then back thru another jacket , back to the exhaust elbow where it exits thru the "tailpipe.







FWIW, there is also a small 1/8"copper line exiting the end freeze plug on the head that also goes into the end cap of the exhaust manifold. This probably also helps from airlock.





So, as of now, thats what I have figured as far as the cooling flow .




















.

 

[66200i6]

Good pictures.

Something seems wrong to me. From your other post you provide a good view of the inlet and outlet hoses attached to your pump.

In order to cool or transfer heat from the block and out your exhaust you must have an Inlet and Outlet. According to the view from your other post, there is only one water supply or inlet from your pump to the special fitting shown in the first pic. The only two paths from this one supply are at the T-stat Housing and the adaptor (shown in the second picture down with the short piece of hose still attached). One of these must be the inlet and the other must be the outlet. I would be willing to bet that the T-Stat Housing is still your outlet. You have an arrow in your picture showing that the T-Stat Housing is and inlet.

If your inlet is plugged you probably just don’t have the flow through the block. If it were flowing normally the block would pressurize and hold coolant until the T-Stat opens normally and release the heated coolant into the lower pressure exhaust path.

Good luck, Ric.

 

[fordconvert]

I think Ric has got it and it is the same function as the Mercuriser and home made setups I was trying to describe. In your photo the arrow on the stat needs to be reversed so flow would be out and the same as it would be in a car. The inlet is into the (car water pump hole) so the flow is the same as it would be in a car. You have the water inlet from the pump then you have the first T that goes into the engine. After that continuing up to the stat housing I am betting there is a slight restriction either in the casting or an actual plate. This is to generate a slight resistance so if the stat was open the easier flow path would be through the engine. If that path was easier to flow than the engine you would never get any flow in the engine. If the stat is closed it just continues through that assembly on its way to the exhaust. There would have had to be some sort of a small bypass around the stat or you would never have any flow around the stat to heat it and make it open smoothly not to mention get the air out every time you ran it. Is there any sort of notch around the stat in the housing? Perhaps there was a matching notch in the original head? Or I wonder if the original stats had some special sort of bypass method? Figuring out what size that hole should be would be a trick in the field. You need enough flow to get the air out and get water up to the stat but not too much to let it do too much cooling. This would all have to be in balance with the incoming water pump pressure, that restriction in the casting between the inlets and the stat housing, and the 'back pressure' after that in the exhaust manifold. If the exhaust manifold is all full of sand / mud and not flowing freely it may be creating back pressure in the system and not letting that balancing act happen properly.

 

[64 inboard]

Thanks for the input!!!!! I posted those pics in a hurry last night... After looking things over again, I think you guys are right about the water flowing into the block, then out of the t.stat housing at the head(my arrow should be turned around) . I ran water thru the water jackets in the exhaust manifold and they all seem to be open. I havent checked the block for restrictions yet.


Remember, my problem for the last year or so has been not being able to get any engine temperature when running on plane. Doesnt this suggest water isnt slowing down long enough in the engine to build up temperature? Wouldnt any restictions tend to build heat? After looking over the flow again, I probably wouldnt need to drill the 1/8" hole in the stat for air lock. The small copper tube running from the end of the head into the exhaust should prevent that?


FWIW, when I took the head off last week a couple of the water passages(in the head gasket) between the head and block had scale build up and were just about plugged.....

...On a positive note, I am hoping to get the heads "CC,d' later this afternoon. now if we could just get the temp figured out.

 

[JackFish]

Remember, my problem for the last year or so has been not being able to get any engine temperature when running on plane.

"Any" is a rather vague term. What does the temp guage actually read, and where is the sender located?
Hold cold is the lake water? Marine engines never really get as hot as in an automobile.
Running cold is normal, IMHO.
I doubt that my V6 I/O engine ever gets any hotter than, oh maybe 150°, and that's after a long idle-up and 20min run out to the camp. Especially when it's late in the season and the water is about 40°.

 

[64 inboard]

Remember, my problem for the last year or so has been not being able to get any engine temperature when running on plane.

"Any" is a rather vague term. What does the temp guage actually read, and where is the sender located?
Hold cold is the lake water? Marine engines never really get as hot as in an automobile.
Running cold is normal, IMHO.
.

Sorry, should have been more specific.. in my start of this post I had stated it rarely moves of 100 degrees when on plane.... which is too cold. I'm running the factory recommended 140 stat. It will bring temp up when idling in a no wake zone. I have run it with a 160 stat, no difference. I've run the boat in 55 degree lake water and 80 degree river water, again, no noticable difference.

I replaced the original electric gauge with a new SW mechanical one . The sensor is mounted in the head on the opposite end of the t.stat. I cant believe the old junk head I just took off could have anything to do with it? ..... btw, the head I took of was a 62cc one with a Victor gasket....hopefully after the replacement head is rebuilt, it will help give the old girl a little more "spunk".

 

[Lazy JW]

.....


.

I think this picture tells most of the story: the incoming flow from the raw water pump divides at the "T" junction; the flow inertia will naturally send the majority of flow to the exhaust manifold and a minor portion will go backward through the block, then upward through the head, and finally forward through the head to the thermostat. When the thermostat opens, the flow will go outward, re-joining the flow to and through the exhaust manifold.

With the temperature sending unit installed in the rear of the block, it will be sensing the temperature AHEAD of the major hot spot in the engine, namely, the combustion chambers and especially the exhaust valve portion of the chambers. No way will the cylinder portion inside the block ever reach the temperatures found in the head, therefore the temperature indication will always be significantly LOWER than what would be found at the thermostat housing area, at which point the water will indeed be at its very hottest.

If possible, I would attempt to install a sensor at the thermostat housing, or at least as close as possible. If this is impractical, purchase a hand-held infrared non-contact thermometer and take direct readings on the surface of the thermostat housing. I strongly suspect that you will find significantly higher temperatures at that point than is currently being indicated by your gauge. Then you can decide if a hotter thermostat is appropriate.
Joe

 

[66200i6]

Once working properly the T-stat will not begin to open until it begins to reach it's rated temp. Use a candy thermometer and boil your T-Stat before installing. You will see when it begins to open and at what temp it is fully open. These two temps should be with 15 or 30 seconds after it begins to open.

The temp your reading on your SW gauge should be within that range. It should also not matter what the ambient water temp is. The T-Stat should maintain your engine temp.

As far as operating temp, I am one of those who believes, that a healthy 180 - 200 degrees is the best for combustion no matter what the application.

Good luck, Ric.

 

[64 inboard]

I do have an infrared thermometer and have checked the t.stats with hot water before installing them... they are pretty much dead on with open/closing temps. The temp sensor is in the head, not the block and located at the opposite end of the t.stat. 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?

another thing in the "FWIW" catagory, I have changed the rubber impellor in the raw water pump every other year or so...

also, not that it probably matters, but when the bypass water enters the exhaust manifold, it still travels thru the manifold's water jackets, forward thru the front manifold cap, then back thru another jacket ,back to the exhaust elbow where it exits into the exhaust.