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Low Coolant Pressure?

R

Raleigh

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Location
Salt Lake City
So it is a bit warmer out today, the ECT was a bit high @ 200, but here is the weird part, there is very little pressure on the upper radiator hose and I opened the reservoir with no issues at all.

How much pressure should be in the cooling system? The cap is rated at 15# so I would assume there should be at least 10-12# which would make the upper hose pretty damn hard!

This is a 94 K2500 vin F TD, no mods done to the truck at all, very little blow by and it runs great, plenty of power.
 
No one ever checks or replaces their radiator caps...

I would test your cap, looks for leaks, and check the oil. In case your cap is good and no pressure is a bad thing!
 
New 15# cap and the oil looks good. I am thinking T-stat or it is just low on coolant. The reservoir is only about half full when the engine is completely warmed up.

There is no smoke and the exhaust doesn't smell like coolant.

Atleast if the head gaskets are toast they are easy to do!
 
I don't know if the 94's have a low coolant sensor in the expansion tank, if they do a warning light would let you know if the level is low.
 
it does have the sensor, I think I will be doing a T-stat in the morning and wee where that goes.

No leaks that I could see, a new cap and I cleaned the radiator stack.
If it were just the heat I could see it being a dirty radiator but I cleaned it anyhow.
 
I ruined an engine over a "new" cap. It would not release pressure until it was way high and then on cool down it sucked the hoses flat. New parts are not always good parts.
 
Unless there is a difference between the 94's and 96's I am ignorant of, while there is some pressure in my system, there is seldom a time when the upper radiator hose is "rock hard." I'm always able to crush the upper and get the fluid in the reseviour tank to bump /bubble a bit with a firm grip....
 
Paveltolz said:
Unless there is a difference between the 94's and 96's I am ignorant of, while there is some pressure in my system, there is seldom a time when the upper radiator hose is "rock hard." I'm always able to crush the upper and get the fluid in the reseviour tank to bump /bubble a bit with a firm grip....
Click to expand...
Okay, that is what I was curious about, I wasn't sure if it would be like that or not.
I am putting in a new 180* Tstat tomorrow anyhow just in case.

Thanks Paul!
 
Raleigh said:
I am putting in a new 180* Tstat tomorrow anyhow just in case.
Click to expand...

In almost all cases, it's better to use a 195 thermostat. A lot of people have said they lose MPG when they switch to a 180 thermostat.

Just FYI before you buy/replace it with a 180.
 
So I put a new 195* tstat in and a new temp sensor. Not much difference, although now I can see that when the temp hits 205* it cools down to 195*, then goes back up.

I did pull the fan clutch and did the fan clutch mod, the clutch is covered with old oil, I wonder if it working all that well. If it has no oil in it, the mechanism will not work, right?

So I am curious if it is the fan clutch engaging too late, or if it is the tstat is opening too late! ARGH!! :cuss:
 
Oh and one other thing, not sure if it makes a difference, it has 5w40 oil in it. I am going to change it later today with 15w40, see if that helps.
 
Sounds like your fan clutch is toast.........For a quickie test....

1. Turn Engine OFF
2. Spin the fan blade by hand
3. If the blade spins freely, without any resistance, your clutch is probably toast.
 
It has very little resistance, when I took it off the check the spring I noticed the oil on it.
It had some resistance, but it turns very easily.
 
Okay so the 2839 fan clutch engages at 170*, which is about 180* coolant temp, that is great, but will the Dmax fan bolt on to it?
And the prices are much higher than what the thread says now. The lowest I found was $116 then the fan.

I found a Heath assembly on Fleabay for $150, might go that route.
 
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