Greetings,

I purchased a brand new OEM water pressure gauge for my old D7E and hooked it up for a test before mounting it in the dash. I cleaned out the hole for the brass compression fitting really good and I am getting a good solid connection with the wire tubing on the gauge. However, when the engine is running, I am not getting any reading on the gauge. The engine is topped off with coolant and the coolant temp gauge works properly. Any ideas what could be wrong? I have successfully replaced all of the other gauges and this is the last one.

 

I assume you have checked the obvious such as the radiator cap is sealing and you have run it long enough to build up temperature so it can build up pressure.
You could try hooking it up to a water tap (faucet) to check it works just make sure you don't over pressurize it.

PhilC wrote:

I assume you have checked the obvious such as the radiator cap is sealing and you have run it long enough to build up temperature so it can build up pressure.
You could try hooking it up to a water tap (faucet) to check it works just make sure you don't over pressurize it.

The radiator cap is definitely getting a good seal. I didn't run it very long at all. I assumed it would have some kind of pressure reading quickly. I can certainly try again and let it get warm. Is it normal for the gauge not to have any reading at all when the engine is first started?

Hi, ksliger.
Understanding how the water pressure works and why it is there helps to understand your machine. The water pressure gauge WON'T have any pressure to register until the engine warms up a bit and the water in the cooling system expands a bit. It will then go up slowly as the coolant temperature rises and the coolant expands more - always 'assuming' of course that you have no leaks.

The water TEMPERATURE gauge needs to be read in conjunction with the water pressure gauge and both are color-coded to facilitate this. The coolant can get above the UNPRESSURIZED boiling point of water WITHOUT 'ackshully' boiling if it is under pressure. If the temperature gauge goes past the start of the first section of the 'red' range but the pressure gauge is in the same secondary color range as the temperature gauge, the coolant still hasn't boiled 'coz it is under enough pressure to prevent that happening.

Coolant loses a LOTTT of its effectiveness when it boils but still remains effective at temperatures higher than the un-pressurized boiling point if it is prevented from boiling by being under pressure.

Hope this makes it all at least slightly clearer than mud.

Just my 0.02.

Deas wrote:

Hi, ksliger.
Understanding how the water pressure works and why it is there helps to understand your machine. The water pressure gauge WON'T have any pressure to register until the engine warms up a bit and the water in the cooling system expands a bit. It will then go up slowly as the coolant temperature rises and the coolant expands more - always 'assuming' of course that you have no leaks.

The water TEMPERATURE gauge needs to be read in conjunction with the water pressure gauge and both are color-coded to facilitate this. The coolant can get above the UNPRESSURIZED boiling point of water WITHOUT 'ackshully' boiling if it is under pressure. If the temperature gauge goes past the start of the first section of the 'red' range but the pressure gauge is in the same secondary color range as the temperature gauge, the coolant still hasn't boiled 'coz it is under enough pressure to prevent that happening.

Coolant loses a LOTTT of its effectiveness when it boils but still remains effective at temperatures higher than the un-pressurized boiling point if it is prevented from boiling by being under pressure.

Hope this makes it all at least slightly clearer than mud.

Just my 0.02.

Great info, thank you! I will go and do a more thorough test and make sure the engine gets fully warmed up. I will report back my findings.