Guys,

This was a mod that I have been wanting to try ever since I read about the hummer guys putting fittings in the rear-head block off plates. They use those fittings to take water out of the heads and dump it back to the radiator return in an attempt to increase flow and help shed heat.

To me that approach is completley ass-backwards. Taking water out of the heads will only make matters worse. What needs to be done is to ADD cool water to the back of the heads.

So what I did was to tap and drill holes in those block-off plates for 1/4" pipe fitting with hose barbs for 3/8" heater hose. Likewise, I drilled and tapped holes the the plate where the water pump mounts at the front of the engine.

Normally, water leaving the pump must pass through the block, absorbing heat, on the way to the heads. These new holes tap into the pressurized water coming directly out of the water pump. This water is as cool as any in the system, as it just came from the radiator.

So far, my engine is still in the break-in phase, so I haven't pushed it hard at all, but in daily driving, there appears to be fucntioning well. Once I get 1000 miles or so on the engine, I will do a towing run. I have figured out a way to measure rear of head, and front of head temperatures, and I can easily block off the bypass lines for comparison.

But for now, here are the pictures

http://www.gatewaydata.com/truck/cooling1.JPG
This shows the fittings installed on the water pump mounting plate


http://www.gatewaydata.com/truck/cooling2.JPG
This picture show the arraingment of the hoses at the back of the motor.


http://www.gatewaydata.com/truck/cooling3.JPG
Front view of the motor, showing the hoses on both sides. The right hose clears the alternator bracket when its installed.

NOTE: I am not sure if the left side fitting will clear the vacuum pump if used.



http://www.gatewaydata.com/truck/cooling5.JPG
A slightly blurry shot of the block off plate detail


Tim

I have figured out a way to measure rear of head, and front of head temperatures, and I can easily block off the bypass lines for comparison.

Care to explain how you are doing this? Maybe with some Pictures

Care to explain how you are doing this? Maybe with some Pictures

The heads are identical from side to side. That means that one side has a hole in the front for the coolant temp sensor, the other has a hole in the rear that is plugged. I plan on installing a thermocouple fitting in those holes and taking my measurements there. It may not be as good as having a front and rear sensor in the same head, but I think it will give some usable data.

I can block off the hoses with simple pipe plugs.

Tim

I was going to tap those rear plates also and install temp sensors for two small gauges for comparing temps and then I was going to do about what you have done and was hoping to figure a way out to monitor temps after the hoses were connected. I had thought bout that other plugged port also.

Tim

I think you're going to have stagnant water there??

From the pictures, I think equal pressure will be at both ends of the hoses??

Bill,

Not possible.

Water will always flow from a higher head (or pressure) to a lower one. The highest head in the coolant circuit is at the outlet of the pump, the lowest is at the inlet of the pump. The total flow of all the water out of the engine is through the upper radiator hose, which is at a lower head than the engine itself. It does not matter if the water goes through the block, or through hoses to get to the back of the cyl head. Once at the rear of the cyl head, the head presssure is higher than at the front, where the cross-over and radiator hose is.

Where there is a difference in head, flow is guaranteed.

Tim

Care to explain how you are doing this? Maybe with some Pictures

Or use cylinder head temp gauges.
work real nice, the sender is a sort of washer that goes under a bolt head.
we use them on outboard racing boats, and lot of guys I know use them on Rotax powered ultralights.
not sure what they cost.

That might be similar to a thermocouple they sell for airplanes that goes under the sparkplug to read cylinder temps, they're a little cheaper than exhaust pyros and the size is right to put under a glow or injector. I think to get the most irrefutable results, you'd put one on each cylinder(dash guage is on cylinder #1, you just need to see the rest).