Running hot & overheating

[StealBlueZ]

I need help with a heating prob. 509, 6/71, cam driven magnaflow water pump, new impeller. Motor runs 190-220* but after a few passes or sustained rpm’s it will overheat. Hoses are ½� ID. on the inlet and overboard and 3/8� from pump to the block. Should I use bigger hoses and fittings? I have experimented with different thermostats and restrictors but nothing seems to help what else can I do…

[Infomaniac]

StealBlueZ:
I need help with a heating prob. 509, 6/71, cam driven magnaflow water pump, new impeller. Motor runs 190-220* but after a few passes or sustained rpm’s it will overheat. Hoses are ½� ID. on the inlet and overboard and 3/8� from pump to the block. Should I use bigger hoses and fittings? I have experimented with different thermostats and restrictors but nothing seems to help what else can I do…Those hoses sound a bit small to me. Do you have any pics of the entire cooling sys.?
What kind of exhaust do you run? Restrictive exhaust will do this also. Late timing also

[Rexone]

I agree, from what I've experienced, your hoses and fittings are too small. The inside of a fitting that accepts 3/8 hose is really tiny.

[HM]

How about the location of his water pick-up(s)?
Granted, the hoses are very small, but if he is not picking up water from the cav plate area, that could be why it over heats on speed passes as the water pick-up may not be picking up.
I had this problem - my orginal water pickup was built into the strut. I also had the too small of hoses problem, but did not know that until I started running more serios HP.

[StealBlueZ]

pickup tube is 1/2" and is welded on the side of the rudder about 3" from the bottom. I rekon that I never even considered the fittings, and I can see where the 8AN's would be restrictive. Here's a link to a good pic, only difference is that the headers are not plumbed.

[StealBlueZ]

pickup tube is 1/2" and is welded on the side of the rudder about 3" from the bottom. I rekon that I never even considered the fittings, and I can see where the 8AN's would be restrictive. Here's a link to a good pic, only difference is that the headers are not plumbed.
http://community.webshots.com/photo/30803882/30975936pasxTzwNuu

[sgdiv7]

The water pump impeller, why was it replace? if the impeller came apart did you account for all the pieces? if thats ok I would check the fuel mixture and the timing. I think you have big enough lines from the water pump to the block, reason being two 3/8" lines put together are bigger then the 1/2" dump line. you might want to check for a bad head gasket. Cylinder could be blowing exhaust gases past gasket. just some more things to think about.

[GofastRacer]

From what I can see from the pic, your inlet line is way too small. That Magnaflow pumps more water than that line can supply!!. I run a #12 from the P/U to the pump and #8 to the block and the outlet line!!...My .02...

[dossangers]

do you have a outbourd rudder? i had the same problem im running old neovane pump the back of rudder is low pressure area you need to weld small scoop 2 in below rudder in clean water my problem went away plus plum no 8 lines those look like washing machine hoses?

[63stevens]

Remember that on any system where you have a suction side and a discharge side the suction is always much bigger than the discharge side. half inch is not very big. I would at least go bigger on the suction side. also look at timing and possible head gasket leaking.

[SK48]

I have pretty much the same system on both of my V-drive boats. I run a 16 line to the Magnaflow, and then # 10's to the motor. I think your inlet line is way to restrictive. You are not getting enough volume to the pump.

[Rexone]

Your -8AN lines from the pump to the block should be adequate. The supply line however, as others have stated appears small. As well as the water pickup on the rudder. Although I've never seen a water pickup welded on the rudder I can't think of a reason it wouldn't work "if its large enough". Now boat handling could be another issue. But as far as cooling, your inlet line size is only as large as the smallest point in it. It appears small and if there's even one restrictive fitting somewhere in that circuit, that is limiting your water flow to that size hole. Generally, a -12 or -10 at the very least should be supplying the Magnaflow, which has a 3/4 pipe inlet. I can see from the pic you have this inlet stepped down with a reducer. My opinion is that would be the first thing to change. If the pump can't pull enough water, to supply those 2 -8AN lines, you will overheat running hard. Hope this is helpful.

[Rexone]

The fact that you're running a blower compounds the need for adequate water flow as the engine creates more heat than maybe your average carb engine. You mention you have a 509. Is that a Merlin Block? If you have a siemese type block, they are even more prone to overheat from inadequate water flow. Have you always had this problem or is this a new setup?

[dossangers]

if hes running a hydro the water pick up is on the rudder out board steering like mine because the back of the boat is out of the water. i have a brand new merlin you need to force the water in the pick up thats why i welded a little scoop on bottem of rudder has no effect on steering it cured my problem even with my old neovane pump and it flows less water i use no 8 lines all around

[HM]

I always wondered how hydro's picked up water!

[HM]

Damn, you guys are real fart stinkers!
Hydro Pic (http://community.webshots.com/rs1/7/58/3/30975803mBIAwOwWkT_ph.jpg)
The link worked earlier here, but for some reason the picture stop posting. I edited it to be a web link now.
[ September 08, 2002, 11:24 AM: Message edited by: HolyMoly ]

[Rexone]

Never even thought of it being a hydro, stupid me...

[HM]

Here is a rear shot of StealBlueZ:
(StealBlueZ - I assumed you wouldn't mind if I posted a couple of your pics- it is a very nice boat and should be seen by many!)
hyrdro pic (http://community.webshots.com/rs1/0/39/30/30803930QLoqUbFXBp_ph.jpg)
There are some nice in-progress shots if you flip though all the pics.
[ September 08, 2002, 11:26 AM: Message edited by: HolyMoly ]

[pgf127rt]

StealBlueZ:
I need help with a heating prob. 509, 6/71, cam driven magnaflow water pump, new impeller. Motor runs 190-220* but after a few passes or sustained rpm’s it will overheat. Hoses are ½� ID. on the inlet and overboard and 3/8� from pump to the block. Should I use bigger hoses and fittings? I have experimented with different thermostats and restrictors but nothing seems to help what else can I do…If it were me I would not run a thermostat on a boat with a neovane pump, I have owned numerous v-drives and have never ran a thermostat on any of them, as has been mentioned the supply line is suspect, and have you checked the impeller, to see it has shelled out and stopped up the water passages, just a thought.

[vdrivenman]

hi stealbluez,
the tube was the same as the ski hydro so when the boat is up it will not be out of the h2o.that is the bigger h20 pump than was ran on the sanger and the same size lines.it worked fine. a bigger suction line should help. i tired to figure some type of colllector at the bottom of the tube.that was copied off a couple other hydros. i wanted it bent and down past the end of the rudder.never ran a blown motor in it so don't know about the heat.i have had the impellars come apart & restrict the flow, however i would not run w/o a thermostat that motor needs some heat to operate properly, but u know that. u'll figure it out !
any bites on selling it ?