2000 year, C3500 Chevrolet Dually with 7.4 liter engine?

[Big Bubba]

Hello fellow Iboaters,
How is evryone doing this evening. Me I am fine and have a question about my, new to me Chevrolet Dually C3500 with 7.4 liter, 454 engine. Anyway, I have to fill my radiator with water before I drive it. Not that much water but probably a quarter of a gallon of water. Anyway, I noticed that in the front corners of the lower intake that it is wet. I am wondering if the lower intake gasket will fix my loss of water/antifreeze inside the radiator if I replace it? I sure hope it is not the head gasket though but hoping more that it is the intake manifold gasket. Also, if it is, is it very hard to do. I know, I think, the distributor has to be removed from the intake manifold. Is there a good easy way to mark the distributor before taking it out to ensure that when I reinstall it that it will drop back into the same place and guarantee it cranks up after the lower intake manifold changeout? Also, this is a Vortec engine, because there is a plastic cover over the throttle body, Im believe that says vortec on it, anyway are these Vortecs prone to have lower intake gasket problems. Let me know. Thank you for your time and patience, Bob

 

[Bob_VT]

Re: 2000 year, C3500 Chevrolet Dually with 7.4 liter engine?

Yes, Intake Manifold Gasket leaks were common. They leaked coolant......

 

[Big Bubba]

Re: 2000 year, C3500 Chevrolet Dually with 7.4 liter engine?

Bob_Vt,
Thank you sounds like the lower intake manifold gasket will be what I do to fix the loss of antifreeze/water inside the radiator that causes my truck to run a little above the 210 degree mark. Thank you. what are the chances it being a head gasket?

 

[partskenn]

Re: 2000 year, C3500 Chevrolet Dually with 7.4 liter engine?

Possible, but not likely. Intake gaskets are real common, head gaskets not very.

 

[Big Bubba]

Re: 2000 year, C3500 Chevrolet Dually with 7.4 liter engine?

Partskenn,
Thank you very much. I am leaning more towards the Intake Manifold Gasket leaking because the front corners seem wet to me and look like there leaking so that is why I am thinking the Intake Manifold Gasket is my problem and it is causing the water/antifreeze to go down inside my radiator and me having to fill it up everytime I drive it anywhere. It doesn't take too much water/antifreeze to fill it, maybe a little more than half a gallon to fill it. Now my overflow water/antifreeze reservoir does not go down when the fluid inside the radiator goes down. So we still think Intake Manifold gasket is the issue?

 

[Big Bubba]

Re: 2000 year, C3500 Chevrolet Dually with 7.4 liter engine?

//////update/////
Well I might noy have to do and Intake Manifold job after all. Today I took my truck to get the Air Conditioner fixed becuase the high pressure port was leaking very badly and had to get that replaced so the mechanic had to evacuate, swap out the low and high pressure ports or valve stems, then vacuumed and then reserviced the air conditioner. Anyway, to make a long story short the mechanic noticed that the bypass, rubber hose, going from the top of the water pump to the intake manifold where the thermostat is was leaking pretty good. He should me and yes, low and behold, it looked like somebody had cracked open a water faucet inside the house and the fluid was slowly leaking out so I am hoping that is why I was loosing water/antifreeze out of the radiator. Yeap it was comming out under neath the rubber hose so the mechanic tightened the clamp up some more and said it was not leaking anymore. Thank God for that. So I will monitor it and hope that that is what it was the whole time.

 

[RogersJetboat454]

Re: 2000 year, C3500 Chevrolet Dually with 7.4 liter engine?

//////update/////
Well I might noy have to do and Intake Manifold job after all. Today I took my truck to get the Air Conditioner fixed becuase the high pressure port was leaking very badly and had to get that replaced so the mechanic had to evacuate, swap out the low and high pressure ports or valve stems, then vacuumed and then reserviced the air conditioner. Anyway, to make a long story short the mechanic noticed that the bypass, rubber hose, going from the top of the water pump to the intake manifold where the thermostat is was leaking pretty good. He should me and yes, low and behold, it looked like somebody had cracked open a water faucet inside the house and the fluid was slowly leaking out so I am hoping that is why I was loosing water/antifreeze out of the radiator. Yeap it was comming out under neath the rubber hose so the mechanic tightened the clamp up some more and said it was not leaking anymore. Thank God for that. So I will monitor it and hope that that is what it was the whole time.

Probably would be a good idea to take the hose off, and check for corrosion around the connector. Also probably not a bad idea to replace that hose at 12 years old (if original).

Keep an eye on the corners of the intake. Clean them down good with some brake cleaner till their clean and dry, and check them once in a while.
GM was using plastic intake gaskets at this time, and I have personally replaced MANY sets on small blocks, and the V6. Never did a big block, but I wouldn't be at all surprised if they used the same style gasket.

Since they are plastic, the expansion and contraction of the metal parts+heat+time=the plastic failing and allowing the coolant to leak. If you are lucky, the coolant leaks out of the engine. If you are not so lucky, the coolant leaks INTO the engine, contaminating the oil. If left to it's own devices, the oil contaminated with coolant eventually wipes out the bearings. Goes with out saying to also keep an eye on the oil level. If it starts "making oil" you've got problems.

 

[Big Bubba]

Re: 2000 year, C3500 Chevrolet Dually with 7.4 liter engine?

/////yet another update and another problem found causing a coolant leak////
Well I did some more looking for coolant leaks letting the engine run for a while and I found the radiator cap leaking pretty good. Let it cool down and inspected the radiator cap andthe upper gasket that seals the cap the radiator is completely cut not having a closed loop on the gasket. So I replaced it with a stant radiator cap. I am really thinking that the radiator cap, the way it was leaking fluid out of it that it was causing my main coolant loss.leak. Rogersjetboat454, I will watch and hope my oil level DOES NOT!!!! go up as you say. Thank you, Bob