Why do I have two thermostats?

[ashedd]

I replaced all the hoses on my starboard engine and in the process discovered two thermostats. I'd like to know why, and try to figure out if I might have installed one backwards(I reused the old thermostat). After I replaced all the hoses I refilled the antifreeze and now it seems I'm running hot, even though the temp gauge shows normal. All the coolant hoses were very warm and a couple were so hot I could only touch them for a second or two. The sea water side was ice cold. The bottom of the heat exchanger was cold, the top very hot. The manifolds and risers were hot. So I'm wondering if I installed the forward thermostat backwards or something. The forward thermostat housing didn't really have a "groove" or seat for the thermostat, it just kinda sits there over a hole, you have to be careful installing the top of the housing or you'll disturb the placement of the thermostat. I understand that I can have air in the system, but I know I'm pumping sea water. I have a receipt in the boat showing a FWC exchanger being fabricated and installed about ten years ago. I'm not sure if it used to be RWC and was coverted to FWC or what. Perhaps the forward thermostat was left over from the RWC system... The aft thermostat is one of those big ones and I never removed it. The forward stat is small like the standard automotive size. The engine is about(not sure what year, perhaps as old as 1968) a 1974 International Palmer Ford 351. It's very hard to find info on these engines. There are a couple pics of the same engine in some early 70's correct craft or slick crafts or something like that. All those pics show RWC systems. This motor runs great.. My portside engine is a 2001 Crusader 350, it's and interesting setup to say the least.



Forward housing



What are those "caps" on the bottom of the housing? Think I should replace them? Is there something better I can use? Would that be a good place to plumb in a red dot heater?

 

[alldodge]

Don't know about two thermostats but the raw water should come in, go thru the Heat Exchanger (HE) and then out thru the exhaust elbows. Yours looks like the raw water comes in and then is connected to the engine circulating pump. If this is the case, your pumping raw water into the motor where the antifreeze should be

 

[alldodge]

Here is the Merc layout and I used the rear mounted HE instead of the front mount because of the layout. Note the raw water comes in on one side and goes out the other end



Where does this hose come from on your layout?

 

[Scott Danforth]

AD, it looks like the OP has glycol cooled exhaust manifolds and risers cooled with the discharged raw water. the only reason to use 2 thermostats with this setup that I can figure out would be to allow the exhaust to come up temp faster than the block. who knows, as the Palmer engine cooling shown would have been developed in the early 60's. however the heat exchanger is much more recent. the 255 came out in about 1965 with the 265 coming out in 1967 from what I can tell from old brochures which then became crusader engines in the early 70's

it looks like the circulating pump is pulling from the rear mounted hx and not raw water.

I did find a discussion board on the old palmers http://www.oldmarineengine.com/discus/messages/3430/3430.html and http://www.correctcraftfan.com/forum/forum_posts.asp?TID=13737&PN=5

 

[ashedd]

Don't know about two thermostats but the raw water should come in, go thru the Heat Exchanger (HE) and then out thru the exhaust elbows. Yours looks like the raw water comes in and then is connected to the engine circulating pump. If this is the case, your pumping raw water into the motor where the antifreeze should be

The larger hose(largest in the system) comes from the aft right bottom of the HE and goes to the circ pump. Raw water comes up from underneath the engine and goes into the raw water pump. It's a orange hose from sea **** to raw pump(it'll eventually need replaced too). From the raw water pump it goes to transmission HE and then along the top left side of the motor(between valve cover and intake manifold). It's the new black hose with blur stripe in the pic. That hose goes to the bottom left side of the HE.

 

[ashedd]

Here is the Merc layout and I used the rear mounted HE instead of the front mount because of the layout. Note the raw water comes in on one side and goes out the other end



Where does this hose come from on your layout?

These hoses(there are two) go from the manifold/riser to a T fitting on the back of the HE. The other side of the T goes to the portside HE just like the starboard side shown.

 

[ashedd]

AD, it looks like the OP has glycol cooled exhaust manifolds and risers cooled with the discharged raw water. the only reason to use 2 thermostats with this setup that I can figure out would be to allow the exhaust to come up temp faster than the block. who knows, as the Palmer engine cooling shown would have been developed in the early 60's. however the heat exchanger is much more recent. the 255 came out in about 1965 with the 265 coming out in 1967 from what I can tell from old brochures which then became crusader engines in the early 70's

it looks like the circulating pump is pulling from the rear mounted hx and not raw water.

I did find a discussion board on the old palmers http://www.oldmarineengine.com/discus/messages/3430/3430.html and http://www.correctcraftfan.com/forum/forum_posts.asp?TID=13737&PN=5

Not sure why the pics don't show in my quoted replies. But thanks for the info so far....

The way you describe the setup sounds about right from what I'm seeing. I wonder if I can omit the 2nd thermostat? Also it's currently overheating, from what I can tell. Do you think that's like air in the system?

 

[Scott Danforth]

for your overheating, I would start with the basics. pull the end caps on the heat exchanger and clean out the tubes. check the raw water impeller. check the thermostats. check your coolant level. you do have the burp tank connected, correct? that heat exchanger shown doesnt have an expansion tank volume of the 10% system volume that would be needed.

without knowing the why things were plumbed the way they are, its hard to guess. If it was me, I would check everything first, then if needed, re-design the system.

 

[ashedd]

I'll look it over.. is the burb tank the same as the expansion tank? I found some pics of the same motor with RWC setups and it looks exactly like the forward part of my cooling system. I forgot that the engine tag says thermo electron, you more hits on google with that in the search criteria. I'm afraid to wrench too hard on some of these fasteners in fear that they'll break. Can I replace those crazy looking manifolds with any generic 351 manifolds and risers?

 

[alldodge]

Real hard to see the routing so I just accept it is as it should be and not worry about that part.

With stuff getting real hot, water isn't circulating. Which ones or the hoses are getting hot?

You could remove the thermostat to see if the heat is reduced. Also place the thermostat in a pan of water and heat it up on the stove with a thermometer. Then watch when the thermostat opens.

They make manifolds for the 351 but you will need to compare if your system can be reworked to use them

 

[Scott Danforth]

Those manifolds were common fair in ski boats in the late 60's and early 70's

 

[Bondo]

Ayuh,.... Where are the 2 t-stats,..??

I'm guessin' one is at the front of the motor where they most always live, which controls motor temp,....

I'm Guessin' the 2nd is in the t-stat housin' lookin' piece by the H/E tank,..??
If so, it's my guess that one used to control the heat of the water sent to whatever appliance that used to be hooked up to the blocked ports on the bottom of that housin',....
If true, that t-stat is doin' Nothin', the way it's now plumbed,....

 

[dingbat]

The over heat problems could simply be air trapped in one of the circuits. There should be a purge fitting(s) in each circuit. I didn't see any in the pictures, but common locations are the high points in the circuit. I would check around the thermostat housing on the block and the upper portion of the heat exchanger. Check to make sure your expansion tank isn't saturated. A saturated expansion tank will cause cooling problems as well.

One thermostat controls the water temps in the heat exchanger, the other temps in the block. Removing either thermostat will throw the systems out of balance. Check to make sure the thermostats are opening and closing at the proper temps and move on.

 

[ashedd]

Ayuh,.... Where are the 2 t-stats,..??

I'm guessin' one is at the front of the motor where they most always live, which controls motor temp,....

I'm Guessin' the 2nd is in the t-stat housin' lookin' piece by the H/E tank,..??
If so, it's my guess that one used to control the heat of the water sent to whatever appliance that used to be hooked up to the blocked ports on the bottom of that housin',....
If true, that t-stat is doin' Nothin', the way it's now plumbed,....

I've been sick in bed or I would have looked at it by now. As it stands I didn't go a check everything last night because I'm sick. It was 20 something last night and when it's below freezing I go start the engines at night and let the engine bay warm up. I'm sure I'm fine with the heater in the cabin and drop light by the engines, plus the water temp is about 42 and won't ever freeze. I think it froze 100 years ago last.

You are correct about your assumed thermostat housings. I've found more pics than ever online since now I know crusader and palmer were owned by thermo electron at the time. The pics show the front stat housing bottom ports with hoses(on RWC engines, which I guess they all were). The bottom left port went to the raw water pump and the bottom right I'm not sure. It shows a hose going down and under the starboard manifold.

 

[ashedd]

I'm not sure what a heat saturated expansion tank is...

Some of the pics I've seen show little purge valves but they're all at low points, but I'll check them out.

So in regards to the front thermostat(small automotive type), is the proper stat orientation "upright". That is to mean the longer end down and "hat" to the top?

I wish I would have paid more attention to that system before I replaced hoses. I know the temp sensor stayed at around 150, like it still does now. I do know that this engines manifolds go hotter than the port side crusader. For being a 2001 crusader classic xp it looks brand new. I can touch pretty much all parts of that engine when it running. It also stays at about 150.

The really hot hoses on the palmer are the top two right and left hoses on the aft thermostat housing. The rest got very warm but not unbearable. This was after 15 mins of run time. Good news is the replacement choke cap works great. It fired right up with one second.

The over heat problems could simply be air trapped in one of the circuits. There should be a purge fitting(s) in each circuit. I didn't see any in the pictures, but common locations are the high points in the circuit. I would check around the thermostat housing on the block and the upper portion of the heat exchanger. Check to make sure your expansion tank isn't saturated. A saturated expansion tank will cause cooling problems as well.

One thermostat controls the water temps in the heat exchanger, the other temps in the block. Removing either thermostat will throw the systems out of balance. Check to make sure the thermostats are opening and closing at the proper temps and move on.

 

[alldodge]

Correct, The long part of the thermostat goes toward the block and the hat part is toward the HE.
The water circulates thru the thermostat and into the bottom of the manifolds, then out the top elbows and into the top of the HE. Your thermostat housing should have a small bypass hole to allow air and water to go around the thermostat when it is closed

 

[Scott Danforth]

The over heat problems could simply be air trapped in one of the circuits. There should be a purge fitting(s) in each circuit. I didn't see any in the pictures, but common locations are the high points in the circuit. I would check around the thermostat housing on the block and the upper portion of the heat exchanger. Check to make sure your expansion tank isn't saturated. A saturated expansion tank will cause cooling problems as well.

One thermostat controls the water temps in the heat exchanger, the other temps in the block. Removing either thermostat will throw the systems out of balance. Check to make sure the thermostats are opening and closing at the proper temps and move on.

purge fittings shown on top the manifold elbows.

 

[dingbat]

purge fittings shown on top the manifold elbows.

Ya, I saw those but thought it would be too easy.

Then again, my experience comes from the water to water closed loop cooling systems used on our equipment. Nothing is that easy on them

 

[ashedd]

I've been sick all week and haven't left the house. I got something to do for work tomorrow that can't be avoided and will go check on the boat. I'll try those purge fittings... how do I work those? Crack them open and wait until coolant spits out when it's warm and running?
I also forgot to mention that this engine is also plumbed in to the water heater, I guess that probably would have been good to mention early on. I may go get an IR thermometer and get a true reading of the manifolds. I need to get an idea of their condition since they look so old. There is an hour meter that is the same vintage of this motor that says 1200 hrs. Like I said before, the 2001 crusader on the portside looks literally brand new, so I don't think it's has many hours. The original engines according to the placard where Chrysler M45's, whatever those are. Not sure if the Palmer went in after those, and I'm not sure what happened to the portside Palmer, if any. Wish they would have done a full repower when that crusader went in. I'm sure cost, as is now, was an issue.

 

[alldodge]

Appears the M45 were 331 cu in Hemi's

http://www.jalopyjournal.com/forum/...-chrysler-m45-marine-hemi-engine-pics.501916/