Water Pressure Issue
06-03-2008, 07:27 PM
#11
Registered
Thread Starter
I can't believe with the relief valve and the 1/2" intake dump you are still seeing that pressure, even if the t-stat is the hold up. Where are you dumping the water from the relief valve out? Is it a dedicated dump and is it the full 1" dump or did you reduce it down? I fail to see how the recirculating pump can build any pressure that you are seeing. (Maybe a couple psi??) It isn't a positive displacement pump, and can simply 'freewheel' with in the water. Dumb question, but you do have the valves plumbed up right? In your main 1 1/4" water line, before your t-stat housing with the 1" port your dump. (just covering all bases)
I'd also remove the stat and do a run. Might try the drilling the stat or using a restrictor plate instead, but with the relief valve, you should be fine. With the stat closed, the bypass circut within that housing might be too restrictive. Don't know, just thinking the same as the Merc 2 hose housing which is probably about the same as what you have.
Out of curiosity, when you see these high pressures, what are your engine temps?
I'd also remove the stat and do a run. Might try the drilling the stat or using a restrictor plate instead, but with the relief valve, you should be fine. With the stat closed, the bypass circut within that housing might be too restrictive. Don't know, just thinking the same as the Merc 2 hose housing which is probably about the same as what you have.
Out of curiosity, when you see these high pressures, what are your engine temps?
Anthony
06-03-2008, 08:15 PM
#12
Ginger or Mary Ann?
Charter Member
I'm at a loss. When I was dialing my valves in and cut the springs to short (lower spring pressure) I had way low WP.
Your stats are installed correctly and not being held from opening fully, such as bottoming out or hanging up in the intakes? Have to believe they are not bad since it occurs in both motors.
Do you have the stock Merc stat housings to retry? or pull the stat and run. At least it'll eliminate the exhaust and point to the SM stat housing design.
Do your intakes have the small bypass hose connecting to the top of the circ. WP?
Your stats are installed correctly and not being held from opening fully, such as bottoming out or hanging up in the intakes? Have to believe they are not bad since it occurs in both motors.
Do you have the stock Merc stat housings to retry? or pull the stat and run. At least it'll eliminate the exhaust and point to the SM stat housing design.
Do your intakes have the small bypass hose connecting to the top of the circ. WP?
Last edited by US1 Fountain; 06-03-2008 at 08:18 PM.
06-03-2008, 08:27 PM
#13
Registered
Thread Starter
I'm at a loss. When I was dialing my valves in and cut the springs to short (lower spring pressure) I had way low WP.
Your stats are installed correctly and not being held from opening fully, such as bottoming out or hanging up in the intakes? Have to believe they are not bad since it occurs in both motors.
Do you have the stock Merc stat housings to retry? or pull the stat and run. At least it'll eliminate the exhaust and point to the SM stat housing design.
Do your intakes have the small bypass hose connecting to the top of the circ. WP?
Your stats are installed correctly and not being held from opening fully, such as bottoming out or hanging up in the intakes? Have to believe they are not bad since it occurs in both motors.
Do you have the stock Merc stat housings to retry? or pull the stat and run. At least it'll eliminate the exhaust and point to the SM stat housing design.
Do your intakes have the small bypass hose connecting to the top of the circ. WP?
06-05-2008, 07:09 PM
#14
Registered
Thread Starter
Today I tried a little test in the driveway.After much thought and talking with a ton of people I am coming to the conclusion that my circulator pump is causing the excess pressure in my engine.The only way it could build pressure is to dead head against the thermostat.So with a thermostat in place I ran the motor at 2000 rpm for a minute and recorded 5 psi on the gauge and on both motors.I removed the thermostat and tried same test again and the needle just moved off the stop pin.I think with this test proves that the exhaust headers flow with no restriction and without a dead head for the pump it all just flows out the exhaust.This would explain why my merc. dump valve dont open because it is located before the circulator pump and is not seeing the added pressure.So now do I try a bypass and eliminate the circulator so I can run a thermostat?Anyone have any thoughts?
Thanks Anthony
Thanks Anthony
06-06-2008, 07:11 AM
#15
Registered
Join Date: Jan 2002
Location: south jersey
Posts: 230
Likes: 0
Received 0 Likes
on
0 Posts
Nordic, I would single gauge survey the system if you can. But if it's to be accurate, use one gauge and forget what your dashboard gauge is telling you for now. I'm not familiar with your exact plumbing system but generally speaking get a NEW mechanical pressure gauge, take a reading after your raw pump, after your cooler/ coolers, at the circulation pump inlet (unless your cooler location is the same), and off the block or back of the intake. You can also try it without your t-stat. You should figure it right out.
Also, could your raw water pump pulley have been changed to a smaller diameter?
Good luck,
Excal
Also, could your raw water pump pulley have been changed to a smaller diameter?
Good luck,
Excal
06-06-2008, 08:14 AM
#16
Registered
Today I tried a little test in the driveway.After much thought and talking with a ton of people I am coming to the conclusion that my circulator pump is causing the excess pressure in my engine.The only way it could build pressure is to dead head against the thermostat.So with a thermostat in place I ran the motor at 2000 rpm for a minute and recorded 5 psi on the gauge and on both motors.I removed the thermostat and tried same test again and the needle just moved off the stop pin.I think with this test proves that the exhaust headers flow with no restriction and without a dead head for the pump it all just flows out the exhaust.This would explain why my merc. dump valve dont open because it is located before the circulator pump and is not seeing the added pressure.So now do I try a bypass and eliminate the circulator so I can run a thermostat?Anyone have any thoughts?
Thanks Anthony
Thanks Anthony
06-15-2008, 07:58 AM
#20
I have excacly same problem on my 500 hp 454. I have bin all the way as you describe and still have way too high pressure. Thought it was the Headers that was the problem but its not. When turning 3000 rpm the big hose from cirkulationspump to T-house starts to expand like a ballon.
Is it possible that the pressure comes from a leaking headgasket ?
Is it possible that the pressure comes from a leaking headgasket ?
