Overheating at idle under load

commonarcwelder

Petty Officer 2nd Class
Joined
Oct 8, 2007
Messages
103
1996 225 Vindicator. My problem is this. When idling in gear for say 100 yards the alarm goes off. The pressure gauge reads 12lbs. at 5500 RPM's and 2lbs. at idle under load (650-675 RPM's). It will run all day long above idle with no problems. Just bought the motor and it SUPPOSEDLY has a new impeller....The telltale has a good stream coming out of it.....Thermostat? Thanks Guy's! Also has low water pickup if that helps at all.
 

HighTrim

Supreme Mariner
Joined
Jun 21, 2007
Messages
10,486
Re: Overheating at idle under load

Your problems usually indicate a t stat issue, they control the temp at idle. If you're into them though, you might as well replace the poppet valves as well, save you some time and money the next time it overheats at high speeds. I would never trust somone else when it comes to the impellor being replaced, can be very expensive if it fails,on any new motor I would replace it right away. Good luck.
 

commonarcwelder

Petty Officer 2nd Class
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Oct 8, 2007
Messages
103
Re: Overheating at idle under load

Thanks guys. I'm gonna go ahead and change the impeller, thermostats and the poppet valves.
 

commonarcwelder

Petty Officer 2nd Class
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Oct 8, 2007
Messages
103
Re: Overheating at idle under load

The poppet valve. Is this what bombardier refers to as a blowoff valve?
 

HighTrim

Supreme Mariner
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Jun 21, 2007
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Re: Overheating at idle under load

the poppet valve is located beneath the t stat in the t stat housing, it is essentially a rubber valve that opens at high rpm, it will have a large spring against it.
 

CH1968

Petty Officer 3rd Class
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Oct 15, 2007
Messages
80
Re: Overheating at idle under load

I have read that some cut their poppet spring in half.

What advantages woudl this give?

Cam
 

tashasdaddy

Honorary Moderator Emeritus
Joined
Nov 11, 2005
Messages
51,019
Re: Overheating at idle under load

i have no idea, as i have never done it. it was engineered to run with complete spring, and never had any problem.
 

Dhadley

Supreme Mariner
Joined
Feb 4, 2001
Messages
16,978
Re: Overheating at idle under load

Your motor doesn't have the poppet valves but rather the single blow-off valve.

Your readings are extremely low. Verify that the line for the pressure gauge is connected to the adaptor housing (lower starboard side). Make sure both t-stats are there and working properly.

If all you're changing is the impeller, go ahead and replace the rest of the kit. Make sure you have the high pressure pump.
 

commonarcwelder

Petty Officer 2nd Class
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Oct 8, 2007
Messages
103
Re: Overheating at idle under load

Thanks Alot Dhadley. That explains why I couldnt find them on the parts diagram or the motor. LOL....What should the pressure gauge read at idle and at WOT? Thanks Guys!
 

Dhadley

Supreme Mariner
Joined
Feb 4, 2001
Messages
16,978
Re: Overheating at idle under load

Let us know where the line is reading from. If it's not reading from the adaptor housing then we'll have to get it there.
 

commonarcwelder

Petty Officer 2nd Class
Joined
Oct 8, 2007
Messages
103
Re: Overheating at idle under load

OK....I'll do that tomorrow. Boat is in my barn. Was cleaning out my barn this afternoon after work and heard alot of hissing in the corner. Turned around and there was about 10 copperhead snakes!! Not sure what to do about them yet....Maybe I'll kill them tomorrow......Thanks DHADLEY!
 

commonarcwelder

Petty Officer 2nd Class
Joined
Oct 8, 2007
Messages
103
Re: Overheating at idle under load

Still havent had a chance to pull the cowling off and see where its reading from. I went ahead and ordered a water pump kit though. It's a Sierra kit, part number 18-3392. Any opinions on using the aftermarket kit versus OEM?
 

Benny1963

Lieutenant
Joined
Sep 17, 2006
Messages
1,476
Re: Overheating at idle under load

hi keith i live in denham springs la. i have a 150 v6 rude
i crossed over the 18-3392 to sierra and used it .
works great , put pump kit in fired it up and thermo started leaking.
went with full sierra thermo kits they work fine ,
bennyb
 
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