Overlandtowater’s solid axle suburban

[lilkia]

Heres the pics. First is the suburban, second is the from filler, third is into secondary tank, fourth is out of secondary tank, fifth is into main tank. The 6th is the secondary tank. Every single 2500 suburban Ive looked at is set up this way. The perspective sucks but I was laying on my back in the driveway.

Apparently it is both gravity and pump fed. I hadnt dropped the tank but it does have a pump on top or at least fuel lines going there. I hadnt paid any attention to them before. Seems like a piss poor design that it has both but since the fill line between tanks is in the front and about an 1 1/2" above the bottom i guess its needed to scavenge the rest of the tank.

 

[CrazyDrei]

Why is the spare tank a unicorn? It comes stock on every gmt800 2500 suburban.

Lilkia,

I guess you are right, spare tank is not as much of a unicorn as I have originally though, it does come on every GMT800 and GMT900 2500 Suburban.

All the ones I have seen have a pump in them.

Correct, every auxillary tank that sits above the spare tire has a pump and is not gravity fed.

Well the one sitting in my driveway is gravity fed. The filler goes from the quarter panel into the small tank and then theres another 2" line going from the bottom edge of the little tank into the top edge of the main tank. Since there is only one fill on a suburban how do you fill the main tank? It doesnt pump from the secondary tank to the big one. It would never keep up with the gas pump volume.
Did you take that picture you posted or did you get it off the i ternet?

Lilkia,

You are wrong, your tank is not gravity fed, I do challenge you to prove me wrong though. The picture StomperXJ has is the picture he found online (I've seen the same one when I was looking for a second tank) however it is also the picture of the exact tank that is in the GMT800 Suburban sitting in your driveway.

I also happen to have a 2500 Suburban sitting in my driveway and I can't believe that I actually got out and crawled under the truck to double check. LOL. I will take pictures tomorrow, but from the gas fill the 2" fuel line bifurcates: one goes into the main 33gal tank the second goes into the auxiliary 11ga tank. If you actually follow both 2" lines you will see that the one line that looks like is gravity fed is actually the 2" fuel line that sits on top of the auxillary tank and goes into the main tank from the gas fill. Continuing from the top of the tank, you should be able to feel with your hand where the auxillary fuel pump sits and the three lines that go from the auxiliary tank and transfer the fuel into the main tank.

You are also correct that in a 2500 the fuel gauge takes approximately 100 miles longer to get to move or to the fist notch than in 1500s.

 

[CrazyDrei]

Heres the pics. First is the suburban, second is the from filler, third is into secondary tank, fourth is out of secondary tank, fifth is into main tank. The 6th is the secondary tank. Every single 2500 suburban Ive looked at is set up this way. The perspective sucks but I was laying on my back in the driveway.

Apparently it is both gravity and pump fed. I hadnt dropped the tank but it does have a pump on top or at least fuel lines going there. I hadnt paid any attention to them before. Seems like a piss poor design that it has both but since the fill line between tanks is in the front and about an 1 1/2" above the bottom i guess its needed to scavenge the rest of the tank.

Lilkia,

You beat me to the punch and I stand corrected. Weird mine does not have the gravity feed hose, only the fuel pump and little fuel lines.

I will get the pictures up tomorrow morning. I wonder if they changed that design from GMT800 to GMT900 2500 Suburbans.

 

[CrazyDrei]

 

[Overlandtowater]

so to the fuel tanks, are the 2500 main tanks the same as the 1500 tank? Where does the fuel lines for the aux tank enter the main tank? Is the connection in the filler section? If its in the fuel pump area can I put a 2500 fuel pump in the 1500 tank and block the ports until I get the aux tank?

 

[Martinjmpr]

one goes into the main 33gal tank the second goes into the auxiliary 11ga tank.

Where did you get those numbers from? The manual on my '04 says 31 gallons for the 1500 and 37.5 for the 2500.



So if I'm understanding correctly, the 2500 has the same "main" fuel tank as the 1500 but then has an additional tank above the spare tire? I'm just wondering if there is sufficient space in the 1500 above the tire. The only thing I can think of that a 1500 has back there that a 2500 doesn't is the panhard bar for the coil suspension (since the 2500 has leafs it shouldn't need the panhard bar, right?) So is it possible the panhard bar interferes with the aux gas tank?

It's a neat idea but seems like a lot of expense to go through to get (according the the owners manual) just 6.5 more gallons.

 

[Overlandtowater]

I orders a stage1 shift kit for the 4l60e form Oregon performance transmission it should be in today. I will pick up a auxiliary cooler and plumb it in series with the factory trans cooler, I hear heat is the death of the 4l60 but in the farm trucks around hear they seem to burn up the clutches and bands too, so I thought process is I can put the shift kit in it to firm up the shifts and minimize slippage and save the bands and the clutches. 200 is cheap insurance to keep the bands alive as long as the sun gear don't explode on me now.



Also last week I noticed my oil pressure went form running 40+psi all the time to now running 20psi at idle and a lifter tick....I can run it up and get the pressure and the ticking stops and it will run for 5 minutes or so and it starts ticking again. The last oil change I switched form conventional to full synthetic and put on a fram filter. I think Im going to change the oil and use a wix or napa filter but I hate to change the oil and not solve anything. You guys think its worth going ahead and changing the oil pump? 150k on it.

 

[Overlandtowater]

Where did you get those numbers from? The manual on my '04 says 31 gallons for the 1500 and 37.5 for the 2500.

View attachment 503011

So if I'm understanding correctly, the 2500 has the same "main" fuel tank as the 1500 but then has an additional tank above the spare tire? I'm just wondering if there is sufficient space in the 1500 above the tire. The only thing I can think of that a 1500 has back there that a 2500 doesn't is the panhard bar for the coil suspension (since the 2500 has leafs it shouldn't need the panhard bar, right?) So is it possible the panhard bar interferes with the aux gas tank?

It's a neat idea but seems like a lot of expense to go through to get (according the the owners manual) just 6.5 more gallons.

Yeah for the 6 gallons it is a lot of work. That's why its on the last of my list. Do the 2500 sit higher off the frame?

 

[CrazyDrei]

Where did you get those numbers from? The manual on my '04 says 31 gallons for the 1500 and 37.5 for the 2500.

Martinjmpr,

Different sources quote different fuel capacities for the fuel tanks. Just like a gas can there is the recommended volume to which you should fill up the tank to accommodate for volume expansion beyond the evaporation canister. Even though my 1500 has a 31gal tank I have put 33.5gal into it before at the pump.

I'm just wondering if there is sufficient space in the 1500 above the tire. The only thing I can think of that a 1500 has back there that a 2500 doesn't is the panhard bar for the coil suspension (since the 2500 has leafs it shouldn't need the panhard bar, right?) So is it possible the panhard bar interferes with the aux gas tank?

There is virtually no room in the 1500 above the spare tire cross member to squeeze in an aux tank unless you do a 3" body lift, then there might be enough room. I cut out the spare tire cross member to mount my 35" donut spare as high as possible and keep it protected by the hitch. Now I have enough room to mount a 42gal tank from a GMT400 Suburban.

Realistically though, how much of a range do you really need? 1500 will do 500 miles on the highway which is 8-9 hours of non stop cruising. Same 31gal tank lasts 300-350miles off road. 2500 trucks have a larger fuel capacity, I consistently get over 600miles when my fuel light turns on, thats 10-11 hours of non stop driving.

 

[lilkia]

Yeah for the 6 gallons it is a lot of work. That's why its on the last of my list. Do the 2500 sit higher off the frame?

I havent measured but from a quick glance it looks like the 2500 frame is several inches "taller" than the 1500. I havent compared side to side or measured but it looked bigger. If one of you wants to post measurements I will go measure mine. Just indicate where you measure. I do know that the 2500 doesnt have a fully boxed frame. Its only boxed in the front and a few place going back but from what I remember it is a much thicker heavier duty frame with some pretty big cross members. From the stuff Ive read on the Duraburb conversions its the same frame as the 2500/3500hd trucks.

 

[CrazyDrei]

Also last week I noticed my oil pressure went form running 40+psi all the time to now running 20psi at idle and a lifter tick....I can run it up and get the pressure and the ticking stops and it will run for 5 minutes or so and it starts ticking again. The last oil change I switched form conventional to full synthetic and put on a fram filter. I think Im going to change the oil and use a wix or napa filter but I hate to change the oil and not solve anything. You guys think its worth going ahead and changing the oil pump? 150k on it.

Dirtdobberoffroad,

I had a similar issue with mine at around 250k miles. It's now fixed and I did not change the oil pump.

Run one can of either seafom or berrymans in the crank case where the oil goes for about 100-200 miles.
Change the oil and filter, when adding new oil: one quart of automatic transmission fluid, and 4 quarts of motor oil. I have always run 5-30 for high mileage.
After approximately 2,000miles put another 1/2 can of seafoam or berrymans into the crank case for 100-200 miles.
Do a complete oil change with new filter using only 5-30 oil.

This cleaned out all the gunk and sludge in the motor and cleared up the oil flow through the pushrods and got rid of the ticking.

This is usually the simplest fix that does not cost too much. The valve rockers could have come loose too but not very likely unless you have been bouncing your truck off the rev limiter all it's life.

 

[CrazyDrei]

This is how my 2500 came.

Right side of the picture is the fuel fill, which goes to a bifurcation of the 2" fuel line.

From the bifurcation: left fuel line goes into the auxiliary tank, right line continues, sitting on top of the auxiliary tank and continues into the main tank.

On the left is the fuel line from the previous picture that goes in to the main tank, little line is the breather hose that connects to the fuel fill and behind the 2" fuel line are 3 fuel lines, on the right side they attach to the fuel pump inside the auxiliary tank, I can not see how they attach to the main tank.

 

[lilkia]

What year is that 2500?

 

[CrazyDrei]

What year is that 2500?

2011

 

[lilkia]

I orders a stage1 shift kit for the 4l60e form Oregon performance transmission it should be in today. I will pick up a auxiliary cooler and plumb it in series with the factory trans cooler, I hear heat is the death of the 4l60 but in the farm trucks around hear they seem to burn up the clutches and bands too, so I thought process is I can put the shift kit in it to firm up the shifts and minimize slippage and save the bands and the clutches. 200 is cheap insurance to keep the bands alive as long as the sun gear don't explode on me now.



Also last week I noticed my oil pressure went form running 40+psi all the time to now running 20psi at idle and a lifter tick....I can run it up and get the pressure and the ticking stops and it will run for 5 minutes or so and it starts ticking again. The last oil change I switched form conventional to full synthetic and put on a fram filter. I think Im going to change the oil and use a wix or napa filter but I hate to change the oil and not solve anything. You guys think its worth going ahead and changing the oil pump? 150k on it.

First thing is check your oil level if you havent already. Check for leaks. Its a common issue when switching to syn oil to develop leaks around seals and gaskets. Are you using the same viscosity syn as you were dino oil?
Second I would use seafoam l8ke Crazydrei mentioned. Its a good product and can help clean the oil passages. Ive never used ATF in my engine so I cant speak to that. I dont ever run seafoam for more than a few hundred miles before changing it out. Since you just changed oil if its low dump in a can of seafoam and run it then change the oil.