C_Spray

I have a pair of Innovation/Volvo 540 ci/600 hp engines with closed cooling (except for the Eikert exhaust manifolds). The engines are injected, not supercharged. This setup seems vulnerable to exhaust system damage if the raw water supply is interrupted, since the water in the closed system will prevent the engine from overheating immediately. In the meantime, there is nothing flowing through the manifolds, so they could get too hot real fast.

I'd like to install water pressure gauges and warning lights, but the question is where to take the measurement. I am thinking that I want to read it on the way into the exhaust manifolds, after it has gone through all the various fuel/oil/steering/engine coolers. Any thought on this, or what the number should be?

Also - when measuring oil temperature on the hot side of the sysem, where is the best place to install the sensor?

C_Spray

Spoke to a Volvo rep yesterday who told me that they deal with this on the 496 engines (also closed-cooled) by putting overtemp alarms in the exhaust manifolds. Just insert a high-temperature switch into each manifold, hook the signal wire up to the master alarm circuit and -presto- you're all set. Anyone else ever try this? (Might be a good way to save a set of headers one day, too.)

Kentz

My HO's have a pressure sensor in the raw water housing. No gauge, part of merc's audible alarm system. Don't know the set point.

Kentz

Pump, that is!

FlyFast

C spray,

I have full closed cooling on a sbc. I have a pressure guage that is attached to the top of the t-stat housing. Normal pressure is 5 to 10 lbs with a 14 lb cap. This guage on my dash tells me more about my engine cooling than the temp guage. It reacts faster than my temp guage. Once you have a block pressure guage you would never go without one. If my pressure rises over 10 lbs I know I need cooland before my engine gets hot. I have my temp sensor on the bypass line and my overtemp alarm in the intake manifold.

My last eengine was toast before the temp guage showed 180 degrees. I look at the block pressure guage as cheap insurance.

Let us know what you find out.

Mbam

I have closed cooling on my 1000's, and just as you say have overheated a set of headers before the engine temp even begins to climb. I put pressure gauges on the header feed after all the coolers, etc as you have already figured out. It has been a while since I have run the boat, but I think I remember 8-10 lbs. If there is reduced flow, the pressure will drop at first and then climb and bounce around as the water in the header boils.

formula31

Yup, good thinking, those PF/Eickert headers melt quickly. A pressure switch in the line feeding the headers is the key. Hook it up to the alarm system. I dont know what the pressure setting was. The guage works too, but they melt so fast without water that the alarm is more reliable.

C_Spray

In their 496 engines, they measure the temperature of the casting itself, not the water. If you put a water temperature alarm switch in, even if you set it at 210 degrees, it may go off when you come off of plane and the water supply is suddenly cut way back. Also, you run into galvanic corrosion problems with a brass switch in an aluminum casting in the presence of hot salt water. Their temperature switch is a type that measures the temperature of the manifold by direct contact. They did not do this in the 600's, so I'm going to try to find out how to adapt the hardware to fit my setup. Hopefully it will be simple..... Thanks for the input, guys.