76 water pump?

[04 Diesel]

My truck temp stays very low in the normal zone but yesterday it got very high in the normal zone so I took it home and shut it down. Opened the hood and felt the top raediator hose and it was not hot, it didnt even feel like there was any antifreeze in the hose. I could squeeze it, there was no pressure on the hose at all. Today I replaced the thermostat, started the truch and there is a rattling sound now. Will a water pump that is going out make a rattling sound?

Also, my oil pressure gauge was reading higher than it normaly does, what is going on?

[75Crew]

water pump issues

You may have more than one issue going on. I say this because your oil pressure gage and your water temp gage both are reading higher than normal. The high gage readings may be a sign your instrument voltage regulator (plugged in to the back of your instrument PC board) may be going out. Common problem. I replaced mine with a solid state unit that I bought on eBay for quite a bit less than the OEM unit sells for. Works very well and has a "lifetime" warranty (for whatever that is worth).

The rattling sound could be a water pump bearing going out. After making sure the battery cable is disconnected so there is no chance of the engine starting, see if there is any "play" in the water pump shaft by loosening the fan belt and shaking the fan blade. If you can feel "play" in the water pump shaft, it is probably time to replace it. Most likely if the bearing is going out, you will also see antifreeze leaking from around the shaft.

However, since you just replaced the T-stat, you may have air in the system which might cause a "rattling" sound (water pump cavitation) until it is purged from the system which should happen after it runs a bit and the thermostat opens up. This may be the likely cause if you didn't hear the rattling until after you replaced the T-stat.

[04 Diesel]

You may have more than one issue going on. I say this because your oil pressure gage and your water temp gage both are reading higher than normal. The high gage readings may be a sign your instrument voltage regulator (plugged in to the back of your instrument PC board) may be going out. Common problem. I replaced mine with a solid state unit that I bought on eBay for quite a bit less than the OEM unit sells for. Works very well and has a "lifetime" warranty (for whatever that is worth).

The rattling sound could be a water pump bearing going out. After making sure the battery cable is disconnected so there is no chance of the engine starting, see if there is any "play" in the water pump shaft by loosening the fan belt and shaking the fan blade. If you can feel "play" in the water pump shaft, it is probably time to replace it. Most likely if the bearing is going out, you will also see antifreeze leaking from around the shaft.

However, since you just replaced the T-stat, you may have air in the system which might cause a "rattling" sound (water pump cavitation) until it is purged from the system which should happen after it runs a bit and the thermostat opens up. This may be the likely cause if you didn't hear the rattling until after you replaced the T-stat.

The rattling did not start until after I replaced the t-stat. I didnt let the truck run that long because I thought I might break something. I will let it run longer tomorrow. Thanks.

[oldmopar]

If the water is not circulating the oil temp will go up becaude the water is not there to keep it cool. When the truck is warmed up enough to open the themostat if you look in the radiator you should see the water flowing if not then a bad pump or something is blocked.

[04 Diesel]

Got home from work today, checked the water pump, the bearings are fine. Started her up and everything was fine, the rattling went away, the temp gauge was down in the normal zone, oil pressure was fine. Then I turned the lights on and the temp gauge started to clime, so did the oil pressure, turned the lights off and both gauges went back to normal. I havent had time to put the high beam foot switch back, there are screws that hold it down to the pan, is that a ground? Tomorrow Im going to putit back and see if that is the problem.

[75Crew]

gage issues

Make a note of what level your fuel gage is indicating when the other gages are reading normal. Then, when the other gages start to rise, watch the fuel gage...if it rises also, you have an instrument voltage regulator that is not regulating properly. It regulates voltage to the oil pressure, coolant temperature and fuel gages. This is a plug-in unit that can be replaced fairly easily. As I said earlier, if you decide to replace it, I would go with a newer solid state unit rather than the OEM type but that is just my preference. Good luck!

[04 Diesel]

All good now, it was the ground on the high beam switch.

[Don Williams]

I have seen poor grounds cause many problems over the years. Some so strange as to make one thing the entire electrical system was suspect. Whenever someone starts describing a strange electrical problem and asks what to do I usually recommend checking the grounds first. Good find.