Hi All,
I've got a 21' Sleekcraft with a 460, Berkeley JG, an Edelbrock Performer 460, and Indmar Marine thru-transom exhaust. At cruising, the temp reads about 160F (which I heard should be around 110F), but at idle, goes to 220F. I've checked for blockage on the water lines and have found nothing so far. I thought I'd double check with the experts here to see if the plumbing is done correctly.
The main line from the jet goes to a 3/4" hose and heads toward the front of the motor. It then goes into a T fitting (I believe it's brass) which has two 5/8" hoses coming out of it. Each of these two 5/8" hoses goes to either exhaust manifold. From the exhaust manifold, it goes into the housing which usually houses the water pump. Water then goes through the engine and out the intake manifold where the thermostat usually resides (although I do NOT have a thermostat). Two hoses coming out of the intake manifold then go to the rear-most portion of the exhaust manifold and out the transom.
From what I've previously read on the posts here, I would think that this is plumbed correctly. Otherwise, please let me know.
The question: Could I run the cold water directly into the water pump housing without preheating it through the exhaust manifold? I could then run the water into the exhaust manifold after it had gone through the block. This might solve my overheating problem at idle. However, I was concerned about thermal shocking the motor by feeding it cold water. Plus, will my exhaust manifolds get too hot since I am now feeding it hot water?
Thanks for all you expert advice. This is such a great board.
Augie
[QUOTE]Originally posted by Inciong_A:
[B]Hi All,
The first thing I would check is that the sending unit and gauge are working properly. I wish I could get my engin that hot.160-185 is perfect temp to run an engine at and 220 shouldnt hurt your motor.
Are you running a gate valve out of the pump? Normally, to get those kind of temps, the water has to be restricted. I agree, check the guage and sender. Also, if you can, check the pressure coming from the pump. If your pump is worn excessively, you may not be getting enough pressure and flow to keep the engine cool. I don't think it's a good idea to run lake water directly to the heads, but a lot of guys do it anyway. Your plumbing setup sounds right for your application.
SteveM.
Your plumbing is right ,what I would check is the hose that hooks up to the last part [exhaust riser manifold inlet},there could still be some blockage, or there's a smaller orifice [reducer]installed to raise the water temp.However 160degrees temp is the right operating temp.Without thermostat this temp will drop sligthly under higher speeds, depends on incoming water temp you're boating .If you shot the engine off after a hard run right away, the temp will rise to 200-220 ,because there's no volume going through the engine,thus your gage indicates a rise in temp.I always let the engine idle a bit before shut off.
[This message has been edited by spectras only (edited May 25, 2001).]
[QUOTE]Originally posted by Inciong_A:
[B]Hi All,
I've got a 21' Sleekcraft with a 460, Berkeley JG, an Edelbrock Performer 460, and Indmar Marine thru-transom exhaust. At cruising, the temp reads about 160F (which I heard should be around 110F), but at idle, goes to 220F. I've checked for blockage on the water lines and have found nothing so far. I thought I'd double check with the experts here to see if the plumbing is done correctly.
The main line from the jet goes to a 3/4" hose and heads toward the front of the motor. It then goes into a T fitting (I believe it's brass) which has two 5/8" hoses coming out of it. Each of these two 5/8" hoses goes to either exhaust manifold. From the exhaust manifold, it goes into the housing which usually houses the water pump. Water then goes through the engine and out the intake manifold where the thermostat usually resides (although I do NOT have a thermostat). Two hoses coming out of the intake manifold then go to the rear-most portion of the exhaust manifold and out the transom.
From what I've previously read on the posts here, I would think that this is plumbed correctly. Otherwise, please let me know.
The question: Could I run the cold water directly into the water pump housing without preheating it through the exhaust manifold? I could then run the water into the exhaust manifold after it had gone through the block. This might solve my overheating problem at idle. However, I was concerned about thermal shocking the motor by feeding it cold water. Plus, will my exhaust manifolds get too hot since I am now feeding it hot water?
Thanks for all you expert advice. This is such a great board.
you might want to put in maybe a 160 or 180 degree Thermostat, i've ran my boat with this and my truck, and when it's blistering hot out, this will help so you don't tack to hot.....
thermostat alows more of flow than the stock one.....
Montrone,if it's aint broke,dont fix it! I ran my boat for 25 years with the proper setup,and I haven't overheated once!If you don't have a thermostat or a gate valve at the pump,your temp most likely will be around 110-120F running wide open,and around 150-160 at idle.The reason for a thermostat is to maintain constant temp at 160.Most hot boaters run their boats in the summer so the thermostat is really not that important.If you don't see oily residue or smoke on your transom at your exh tips, your engine is running close to the right temp .If it's running a bit cooler, only your fuel consumption will suffer,yet you may gain a bit of performance.Theoretically your rings and cylinder walls would suffer with lower temps,but unlike a car that you expect a lot of milage out of it,a boat engine is rebuilt between 1000-2000hours before any major problem anyway.
I run a thermostat in my 460 which keeps the temp at 160 at w.o.t and cruising. The temp does come up to about 190 - 200 after a hard run, but like spectra said I always idle around a bit to cool it down. 160 is perfect, don't change a thing.
Thanks for all of your responses. A previous call to GS Marine led me to believe that my jet pump needs rebuilding. Greg told me that there is only about 1/8" clearance between the impeller and the fitting through which the water goes toward the engine. He said that a bad thrust bearing will cause the impeller to shift forward, enough to block the fitting. So, I went with this assumption.
As I removed the bowl, I realized that I've got quite a new pump. The impeller is still all green and without any wear on the blades whatsoever. I called CP Performance to order bearings and seals. I was told that if I truly had a bad thrust bearing, I would be able to rock the impeller back and forth. I could not rock it back and forth. Plus, CP said that if I truly had a bad thrust bearing, the heating problem should be worse under load, which was not my case. He highly suspects that I've got blockage in my water path.
So, this weekend, I replaced all of my 3/4" and 5/8" hoses and found no blockage in any of the hoses. I also fed water though each of the exhaust manifolds to try to discover blockages. Found none so far. While in the process of connecting hoses, I temporarily hooked up the fresh water coming in to the thermostat housing. I thought of this as an effort to backflush the engine to see if there was some crud in the exhaust manifold which was causing my blockage. The dirty water then came out the fitting in the exhaust manifold into which the fresh water usually enters. I did one manifold at a time. For the first one, I got quite a bit of rusty water coming out. I thought that this might be the answer. I waited until it was clear and then I did the other manifold. No rust came out of the second manifold. I then realized that the rust came from the block and that flushing the other side first got rid of the rust.
I then had an idea. Ding, Ding, Ding. What prevents someone from permanently plumbing a boat just as I explained? Water through the thermostat housing (I don't have a thermostat, remember?), through the motor, out to the water pump housing, out to the exhaust manifold and out the transom. Afterall, who says the water in a boat engine should flow the normal direction? Since jet boats don't run water pumps (and no thermostat in my case) like cars do, this should be feasible. I could even install solenoids to be able to switch from the normal configuration to this "new" configuration.
Does this sound doable? Are there flaws to my theory? Also, do you guys know what's causing my motor to run at 220F at idle?
Thanks again to all of you guys.
Incoming ..
I'm no boat mechanic, but if it were me I think I'd try pulling the hose (briefly) off of the gate valve to determine if you are getting water from your pump. If you are then you know the problem lies downstream from there. I kinda like to figure out what's wrong and leave things the way they are :-)
so would you reconmend me taking out the 160 thermstat (abrv). i have in my engine now?
i appreicate the info and feed back, i also have learned alot day by day from experts like you guy's.
thanks again....
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