chrysler 440 closed system cooling help

[mlcorry]

Am converting a 1970 Cary 28 to closed cooling. Previously was on Lake Erie and now going to saltwater in Florida. I am using a Sen-Dure 1250 heat exchange on 1985 chrysler 440's to convert to closed cooling. The thermostat housing has (2) 3/4 inch lines and (1) 1 inch line coming from it which is capped off since it was the recirculation line. I routed each of the 3/4 inch lines to the exhaust manifolds which then return to the heat exchange. Therefore, the cooled water from the heat exchange goes to the centrifugal pump (on the front of the engine), then through the block then out the thermostat housing through these (2) 3/4 inch lines which go to the manifolds then back to the heatexchange. I am using a sherwood G7 (1-1/4 inch) impeller pump for the raw water supply. The thermostat is 160 degrees opening temperature. I have set up both motors this way on the Cary and they both run hot. 180 degrees at idle and rise to 210 degrees with full power and therefore I slow down to cool them back down. Do I need to get a different thermostat housing which has 2 larger outlets? Anyone with experience with 440s and the Sen-dure heat exchange? Would appreciate any help.
Thanks,
Mark

 

[jehardiman]

You're not getting enough heat taken out of the system (as if you didn't know). This could be because there is not enough flow through the cooler (which is my bet), or that the cooler is too small/not enough raw water flow.

First, have you talked to SEN-DURE?
SEN-DURE PRODUCTS , I N C .
6785 N.W. 17th Avenue
Fort Lauderdale, FL 33309
Phone: (954) 973-1260
Fax: (954) 968-7213
e-mail: sen-dure@worldnet.att.net
web site: www.sen-dure.

Second, are you using the maximum size hose to the manifolds? 2x3/4 seems a little small for carrying all the cooling for single engine especially if you are cooling the manifolds also. What was the hose size when it was an open system? Was it a wet exhaust? Is it still?

Check the coolant temperature coming out of the exchanger, it should be significantly lower than the thermostat setting and the raw water should only see a 5-10 degree rise through the exchanger. If the coolant is comming out cool and the raw water is also not getting a significant rise, then it is a coolant flow issue and you need to plumb the recirculation line back to the cooler. If the coolant is comming out hot and the raw water has a significant rise, then the exchanger is too small or not getting enough flow.

 

[mlcorry]

thanks Jehardiman

I will measure the temperatures of the raw water and the coolant water exiting the system tomorrow. Originally it was raw water cooled with a 3/4 inch line coming from the thermostat housing to each manifold then exits the manifold with a 3/4 inch line to the wet exhaust. There was a 1 inch recirculation line which connected from the thermostat housing to the intake of the centrifugal pump. The water first went through a 1-1/4 inch impeller pump(Sherwood G7) to the centrifugal pump then throught the block and out the thermostat housing. Now I am using the G7 pump for the raw water and the centrifugal pump for the closed system circuit. When I feel the exiting raw water it is warm to the touch but not hot. The water reservoir on top of the heat exchange is very hot and the lower section where the tubes run through is also very hot but cooler on the exiting side. I will check the temperatures tomorrow to be more accurate. If the raw water is not too hot (5-10 degrees warmer than the seawater), then most likely it is a closed circuit circulation problem. How much of a difference in temperature should there be between the closed circuit entry fluid from the exit fluid?
Thanks,
Mark

 

[jehardiman]

I'm begining to think that you may have a heat balance problem because not enough flow is going through the exchanger (either coolant or raw water but most likely coolant). Are you still using a wet exhaust and where does the water come from? In the open system, the water after passing through the manifolds was exhausted and cool make up raw water was fed into the block and recirculated before discharge. Now all coolant is recirculated. Normal exhaust gas tempatures are above 700F, and the manifolds get very hot. Now that heat is no longer going out the back, but must be removed by the exchanger, as well as the block heat. The way you have it piped means that coolant into the exchanger is 1) limited to the flow through the manifolds, and 2) much hotter than the water in the block. I think the problem is the the returning coolant is 1) too little and 2 ) too hot.

Check the thermostat housing. Do the manifold supply lines exit before the thermostat? If they do, here is what I would do. I would pipe the recirculation line out the top of the thermostat housing (discharge side of the thermostat) back to the coolant inlet side of the exchanger. This is how it would function: When the coolant temp was below the thermostat setting, all the flow is directed through the manifolds. When the coolant reaches operating temp the thermostat opens and some block water is bled back into the manifold water to reduce the coolant inlet temperature and increase flow. This will reduce the coolant temp to the engine.

There is the possibility of two other issues. 1) the raw water pump is too small or 2) the flow loss through the tube bundle is too much for the engine's water pump. In the first case this is easy to tell, the tempature of the exiting raw water will be hot and very close to the tempature of the exiting coolant, which does not appear to be the case. The second should manifest itself as the tempature of the exiting raw water will be cool and very close to the tempature of the exiting coolant.

The temps you want to take are raw water in, raw water out, coolant in, coolant out. If everything is working right at the exchanger, there should be a significant drop in coolant temp and a slight rise in raw water temp. If you still are having a temperture problem, then that means that there is not enough coolant flow; either the mainfolds are limiting or the pump is.

 

[bilgeboy]

This is a very nice thread, guys.

It could almost fall under the rubric of "DIY Marinizing", and there are too few good threads there.

I would love to see some pics of your set up, Mark, especially of the t-stat housing and the size of the exchanger relative to the engine. Would you mind posting a couple?

Thanks,

Mike

 

[mlcorry]

Thanks Jehardiman

Didn't get to measuring the temps. Had to do some family stuff. I think you are right. I think the flow problem is probably on the closed circuit portion. The closed ciruit flow to the manifolds origninates after the thermostat. The thermostat housing has three outlets. (2) 3/4 inch and (1) 1 inch. When I ran it with the 1 inch line returning to the heat exchange, the engines would overheat after I came down from full power. I assume this was because the manifolds were not getting enough flow and therefore the water would start to boil in the manifolds, yet the engine temperature was 190 degrees before I backed down from full power. Shortly after backing down form full power, the temp would rise to 210 degrees. I am wondering if part of the conversion to a closed cooling system would have been to exchange the thermostat housing to one with 2 larger bore openings to feed the manifolds. Since I have never converted 440s to closed system, I don't know what I am supposed to have. The flow goes to the manifolds with a 3/4 inch hose then exits the manifold with a 3/4 inch hose to the heatexchange. The raw water discharge goes from the heatexchange to the exhaust elbows attached to the back of the log style exhaust manifolds. Sure do appreciate your help and insight. I can't wait to measure the temperatures and start to check things further but my neighbors probably wouldn't like me starting the motors at 1100PM. Would also post pictures but not sure how to do it.
Thanks again,
Mark

 

[Thisisit]

I would, get an aftermarket water pump to move more water 1st.
You need to move volumes. Larger hoses are a good start. but means nothing if you cant fill them .
Does the water pump you have now have 5 fins or 6.? was it from an air conditioned car?


Dont know much on the boat adaptation of the 440 but have a high perf 440modified in a street car. Have been working on that size eng for years.

Try this. http://www.440source.com/waterpumps.htm

 

[mlcorry]

Thanks Jehardiman

Thanks to everyone for their input. Went over the temperatures in and out of the heatexchange. The raw water exiting the heat exchange had very little increase in temperature and the closed cooling exiting water was cool. The holding tank on the top of the heatexchange was very hot. Therefore, what was happening is that the closed cooling circuit was not circulating fast enough due to restriction in flow. Called a friend who knew a friend who owns an engine repair shop locally who was the dealer for chrysler inboards in the 60's thru 80's. He was great and invited me over to his shop where he had a couple of 440 engines with similar heat exchanges made by sen-dure. Sure enough it appears my problem is the thermostat housing which needs to be exchanged when converted to a closed cooling system from the raw water system. The new housing has 2 one inch hoses coming from it. Hopefully, I can install them this weekend and let you know how it went.
Thanks again,
Mark