major problems, major fixes (bit rambly)

[magnethead]

My truck had a fuel leak on the return line going from the driver side tank to the switch. I just replaced that line, but it is still leaking, but a whole lot less. I'm currently burning fuel out of the tank so we can drop it...

but that was only 1 thing fixed. I've been watching my fuel gauge, and after 6 3 mile trips, i'm used up a "1/4" tank of fuel. On a 20 gallon tank. Thats telling me i have now gone below 4 MPG(!). I'll get to that later (along with why it's in quote marks).

We went and got some gravel from the local quary. The scale said that with only me in the truck, it weighed 6680 pound. I'm 160, that means the truck weighs 6520. The left side had "3/8" a tank of fuel in it @ 6 pounds per gallon. 6460 pounds. I forget how much the right side tank had.

I've got some sort of whine comming from my truck going down the highway, but I haven't quite spotted where it's comming from. It's a middle pitched whine, not as high as a straight-cut-gears gearbox nor as low as a loose belt. I have previously ran my rear axle (dana 70HD) completely out of lube and still driven it, but it doesn't seem to come from that far back. I've already checked the carrier bearing and all 4 yokes- all are tight.

My rear drums need to be serviced. We have (as previously mentioned) owned this truck since 1990. That's 15 years. We have never had the rear brakes even remotely touched since we've owned it. We're actually not sure when the last time they were serviced was. Is it true you have to remove the differential cover, drain the fluid, and remove the axleshafts to pull the rear brakes off? Also, being that everything (drum, springs, levers, shoes, wheel cylinders) need to be replaced, would it be cheaper converting to disc? I have been told that when this level of replacement is needed, it is over 50 dollars cheaper to do the conversion than to completely replace the drums (luckily GM has always used the 8 on 6.5 pattern, even on newer trucks).




What should I do about my rear Brakes?

What could the UWO (Unidentified Whinging Object)?


How long can I expect these rubber fuel lines to last. We've had the truck since 1990 and this is the first time we plan on replacing both lines going to the left side tank. We've already done said procedure on right side.

My fuel gauge isn't reading correctly. It is reading about 1/4 tank or so off. If it says i'm on empty, I actually have 1/4 tank left. This is true for both tanks. What's a probable cause?

How can I shed weight? I know if I only use 1 tank at a time, i'll have 120 pounds less weight than using both. What about the radiator core support? I've heard of using a hole saw and drilling holes (sometimes up to 5 or even 7). How much would I save per hole with a 1.5" hole saw? What's the biggest I can go, 2"? Being I have 4 different coolers up front (including the 4 core radiator), I'd like to keep it structurally sound. And removing the bed (as much weight as that would save me) is out of the question.

what about removing the tailgate? How many tenths of a mile per gallon is that worth in itself, both aerodynamicly and by taking that amount of weight off the truck?

If I re-install the air tube going to the air cleaner that goes to the grille, how many tenths of a mile per gallon is that, if any (based off denser air)? Or would giving it that denser air make the carburetor actually dump more fuel into the engine?

I probably wouldn't do this, but how much weight could be saved if I took out the front bench seat of my truck and replaced it with a pair of buckets from a newer truck from a junkyard or elsewheres?

Are there any other things that I may have forgotten here than would help me out?

[magnethead]

[magnethead]

[79BIG10]

Lots of questions you have but I'll try to help out and if I miss some maybe someone can jump in as well.

On the fuel gauge it sounds like the gauge itself may be the culprit but every truck of these I've owned seems to play with the gauge where it says empty but I still have a few more miles left in it.

Rubber lines will eventually rot and sounds like it's time to replace them.

Saving gas/body mods- First thing to lose some weight would be at the step rails on both sides of the truck. This would help some for weight reduction towards it. Next thing would be after fixing the fuel line leak(s) to give a tune up, air filter, plugs, wires, and retime to see how it runs then. This will all help out but the biggest thing holding you back is probably the rear axle gear ratio. Being a truck setup for hauling heavy loads it's going to be geared really low compred to other trucks. If you changed out the gear ratio it would help but is it worth doing if you haul trailers etc. enough to need them? Maybe cheaper to get a different tranny with a OD. I wouldn't cut any into the radiator support. It's weakening the frame and not making that much difference on the fuel consumption. I also wouldn't take the tailgate off. Mythbusters proved that it's better to have the tailgate up than down. It creates a vortex while you're driving to deflect wond off the back of the truck with the tailgate up.

With everything you've mentioned on the problems the fuel leak sounds like the main culprit along with the basic maintenance. The brakes could be dragging causing the whining sound you mentioned.

[pumpkin]

I have an 11000lb class A motor home with a 454 and 4.10 gears that I tow my 72 Blazer with. We roll down the road all loaded at 17000lbs and get 7 mpg at 70 to 80 mph. You should be able to get 10 to 12 mpgs without any weigth loss. Your gas milage problem is more like engine condition and or state of tune, and of course raw fuel loss.

Rear discs,,,,,,,,,,,,,,,Hellya! The only thing, is parking brake? There are ways, but if your paying for it and not doing it yourself it will add a lot to the bill,,,,,, if its not all ready included.

[eagle23]

I agree with the tune-up, etc suggested above. The fuel line leak sounds like another culprit, since it doesn't take much to ruin mileage. Also look at getting either geting a really good reman carb or doing it yourself if you can. They have plugs in the bottom that can leak and be another source of lousy mileage (they leak straight into the intake manifold).

From what I know, weight reduction only helps incrementally. The weight on the scale seems right for a crew cab dually. They're heavy, period, so swiss-cheesing anything will produce a marginally lighter truck by <50 lbs, a structurally weaker struck to boot (see above) and a frustrated owner (like now)

I agree that looking at the axle ratio might help. Do you know what it is right now? If you went to an OD trans, get a really stout one given the weight of the truck and any hauling you might want to do.

Circling back...do the tune-up/fuel line/carb and check for any other fuel leaks (like the fuel bowl on the carb overflowing from the float set too high). Easy, basic, less expensive fixes first is my approach. I've done variations of the "deep surgery" first to later discover I had wasted a bunch of money that would have been better spent on less exotic solutions.

Brian

[magnethead]

Originally Posted by 79BIG10

On the fuel gauge it sounds like the gauge itself may be the culprit but every truck of these I've owned seems to play with the gauge where it says empty but I still have a few more miles left in it.

I've actually checked it. Went to the station when the needle hit empty, put 15 gallons in it, pump shut off and needle went past full.

Originally Posted by 79BIG10

Rubber lines will eventually rot and sounds like it's time to replace them.

We've already replaced both lines to the pass. side tank. Doing both lines to driver side tank is all that's left.

Originally Posted by 79BIG10

Next thing would be after fixing the fuel line leak(s) to give a tune up, air filter, plugs, wires, and retime to see how it runs then.

Originally Posted by eagle23

I agree with the tune-up, etc suggested above. The fuel line leak sounds like another culprit, since it doesn't take much to ruin mileage. Also look at getting either geting a really good reman carb or doing it yourself if you can. They have plugs in the bottom that can leak and be another source of lousy mileage (they leak straight into the intake manifold).

Originally Posted by eagle23

Circling back...do the tune-up/fuel line/carb and check for any other fuel leaks (like the fuel bowl on the carb overflowing from the float set too high). Easy, basic, less expensive fixes first is my approach. I've done variations of the "deep surgery" first to later discover I had wasted a bunch of money that would have been better spent on less exotic solutions.

I'm not sure about the float and all that, but we did tune-up the quadrajet round 1997 right after putting the headers on it. It has new plugs, wires, not sure on rotor or dizzy cap (as in under a year and a half or 2 years maybe?). Not sure on the age of the quadrajet itself. I've recorded a best of 11 MPG on the right tank, but that was from here to dallas all highway. As far as local/trips to town, best i've done it 7 on the right tank ~4 on the left. (of course, getting a true readout of mileage over gallons would probabl help, based off the inconsistency of my gauge)

Originally Posted by 79BIG10

This will all help out but the biggest thing holding you back is probably the rear axle gear ratio. Being a truck setup for hauling heavy loads it's going to be geared really low compred to other trucks. If you changed out the gear ratio it would help but is it worth doing if you haul trailers etc. enough to need them? Maybe cheaper to get a different tranny with a OD.

Originally Posted by eagle23

I agree that looking at the axle ratio might help. Do you know what it is right now? If you went to an OD trans, get a really stout one given the weight of the truck and any hauling you might want to do.

It has 4.10's right now in an open D70. I've looked at the gear vendors OD, but they said that trucks like mine hae only seen a 1.5 MPG gain at best. Although that does add up, it would take me over 18,000 miles of saved gas to pay off the unit. I'm lucky if i drive it that much the rest of it's life. A 4L80E is the next closest thing I could find (for around the same price).

Originally Posted by 79BIG10

With everything you've mentioned on the problems the fuel leak sounds like the main culprit along with the basic maintenance. The brakes could be dragging causing the whining sound you mentioned.

The whine changes pitch with the engine RPM, and it only does it in gear-all 3 gears- but I haven't noticed it in park or neutral, and havent thought about listening for it in reverse.

Originally Posted by pumpkin

I have an 11000lb class A motor home with a 454 and 4.10 gears that I tow my 72 Blazer with. We roll down the road all loaded at 17000lbs and get 7 mpg at 70 to 80 mph. You should be able to get 10 to 12 mpgs without any weigth loss. Your gas milage problem is more like engine condition and or state of tune, and of course raw fuel loss.

And I thought a 7000 pound truck towing a 6500-7500 pound bumper tow trailer was a lot of weight doing down the road....(getting 6-8 MPG from 1990 to 1996)

Originally Posted by pumpkin

Rear discs,,,,,,,,,,,,,,,Hellya! The only thing, is parking brake? There are ways, but if your paying for it and not doing it yourself it will add a lot to the bill,,,,,, if its not all ready included.

Yea not sure on parking.. the 1 downside.

[magnethead]

I have video of my truck running..i'm editing and fusing it now. I'll see if i can egt it hosted.. 64 megabytes @ 2 minutes 6 seconds.

[Don Brace]

Have you looked into a new coil? A weak spark will really hurt your milage.
Don

[79BIG10]

I would check the carb floats like mentioned to see about running rich. What's your timing at? Sounds like easy hceap fixes to get it running better along with the hoses.

BTW: Where in N. Texas are you? I'm near W. Falls.

[magnethead]

Gainesville

not sure if the coil's been changed..and aint sure on timing either, dont think we've ever taken a light to it..

VIDEO: (not exactly dial-up safe)

http://www.youtube.com/watch?v=ER_xJq8WYOI

[magnethead]

I'll pop the spark plugs out sometime soon to see how it's running. Last time i looked at the one from the pass. side front cylinder (1 or 2, whichever it is) there was no oil on it and there wasn't any crud on it.

[BigDan3131]

After looking at all those pics,did you actually grease every joint on the driveshaft? Next you want to lose a few pounds? You could get a fiberglass hood and take that old POS stock manifold and quadrajet carb off. Does the airconditioning still work? If it doesnt take everything from the pump to the condensor off. Switch to an aluminum manifold (Edelbrock Performer) and aluminum water pump as well. With the performer get a Holley 750 Vacumn Secondary carb. When you go to replace your plugwires and dist cap and rotor dont buy the cheapest store brand. Buy Accel or Mallory, aftermarket wires and parts are higher quality and have less resistance. What means to you is more spark to burn all your fuel not less like those I saw in the pics. If you dont have to pass a smog test get a ram air box with a big K&N airfilter in it. They cost more but are warrantied for 1,000,000 miles. If you drive in a dusty area alot they have a wrap you put over it to keep the big dirt out.

All total the hood,manifold and water pump should take about 200 pounds off. If you want more you have to switch to narrower tires on aluminum rims. If you take the air-cond off thats another 100 something pounds.

[79BIG10]

On the video it sounds like a vacuum leak on the whining and a belt needing replaced. The timing sounds off with a carb not dialed in as well. Check your plugs, do a vacuum test, and check your timing. This will help you out alot on getting it better tuned.

You can get a vacuum gauge frmo Harbor Freight for like $10. If you were closer I'd stop by and let you use mine.

[magnethead]

Originally Posted by BigDan3131

After looking at all those pics,did you actually grease every joint on the driveshaft?

I aint so sure that things been touched by a grease gun since we changed pinion seals...

Next you want to lose a few pounds? You could get a fiberglass hood and take that old POS stock manifold and quadrajet carb off. Does the airconditioning still work? If it doesnt take everything from the pump to the condensor off. Switch to an aluminum manifold (Edelbrock Performer) and aluminum water pump as well. With the performer get a Holley 750 Vacumn Secondary carb. When you go to replace your plugwires and dist cap and rotor dont buy the cheapest store brand. Buy Accel or Mallory, aftermarket wires and parts are higher quality and have less resistance. What means to you is more spark to burn all your fuel not less like those I saw in the pics. If you dont have to pass a smog test get a ram air box with a big K&N airfilter in it. They cost more but are warrantied for 1,000,000 miles. If you drive in a dusty area alot they have a wrap you put over it to keep the big dirt out.

All total the hood,manifold and water pump should take about 200 pounds off. If you want more you have to switch to narrower tires on aluminum rims. If you take the air-cond off thats another 100 something pounds.

A/C and heater don't work (ducting and other gremlins) but not sure that i want to remove the components. Everything you listed is pricey for the marginal gain (albeit i'd be closer to 6K).

Originally Posted by 79BIG10

On the video it sounds like a vacuum leak on the whining and a belt needing replaced.

the whining i'm talking about doesn't appear in the video...and yes one of the belts is literally screaming for help. EDIT: under further review, mybe it is...

The timing sounds off with a carb not dialed in as well. Check your plugs, do a vacuum test, and check your timing. This will help you out alot on getting it better tuned.

I'm going to pull a couple plugs (i'm going to see if i can pull numbers 6 and 1 without damaging the boot) and check them. I don't think many, if any, vacuum lines are connected. The one to the air cleaner snorkel is unhooked, we have a screw rammed in one (not sure if they go together), and i think there may be 1 or 2 under the air cleaner housing that are unhooked. Our timing light is moody, but i might see if i can get it to work. How hard is it to find the markings to find timing? We have to do the timing almost yearly on our boat, but i can't look down at the crank very well when i got cooler lines and 3 belts all over the place.

You can get a vacuum gauge frmo Harbor Freight for like $10. If you were closer I'd stop by and let you use mine.

knowing my dad he might have one laying around from the race car.

[79BIG10]

Plug the vacuum lines all up whether if connecting them or using caps or screws in the lines themselves. This definately is a sounds that can causing a whining or whistling sound and a drop in power. Here's a good site to help diagnose the issues. http://www.s10blazers.com/vacuumtest.htm

On the balancer you should be able to find the mark on it and take a piece of chalk to help make it easier to find once the timing light is working. You can turn the engine by hand to locate the mark on the balancer.

[BigDan3131]

All the part I listed are about 1k total. I would at least buy the good plugwires and cap and rotor.

[magnethead]

hopefully tomorrow I'll have time and i'll go pull the plugs and check the vacuum lines (i'm pretty sure we dont have a guage). How many vacuum lines are there? I know one goes to the air cleaner snorkel, we have that one broke off and i think thats the one that the bolt is plugging, how many other ones are there floating around under there?

[magnethead]

more ancient pics of the carb/intake.






you can see in the last pic the one thats capped off and i guess goes to the air cleaner since it's part of the choke assembly? What other ones minght there be?

[magnethead]

just looked, and this truck is running

LEAN!

I only pulled plugs 2 and 4- the rest are almost impossible to get at, either from hoses, the headers, or that huge daggum A/C compressor.

The only way I can figure that it's running as lean as it is (i mean, the entire plug is white. I'm amazed this engine is running) is that either the choke isn't working, or because the flipped air cleaner lid, or both combined. I think the choke's working, we just replaced the choke coil.

I only found 1 vacuum line, and it's the one comming off of choke and has the golf tee in it. I didnt realize the air cleaner snorkel choke goes to the air cleaner base, so i don't know where the plugged one goes.

As far as timing, I can't even see the balancer to even try to see the mark, let alone get a piece of chalk on it.

all pictures were with engine off and 85° ambient temp.




Passenger Side Cylinder Bank



Driver side cylinder bank



Driver side cylinder bank



After having a miss in cylinder 1 repeatedly......We found and resolved the problem



I believe that is cylinder 3...







Air Cleaner...Appears clean (i blew it out with the air compressor last month or so)



Bottom of air cleaner housing..everything's connected.

[magnethead]

Carburetor...



Air cleaner snorkel choke..





Distributor





Can you see the balancer?

[magnethead]

Should be Cylinder #2





Should be cylinder #4

[magnethead]

I looked at the belts, the loosest one is the one going to the A/C compressor. Thinking it might be one of the other 2- they had almost no movement in theyre longest lengths.

[BigDan3131]

I think you should take the truck to a self-serve wash station and bring a scraper and 4 cans of degreaser with you. Bring 2 plastic bags,cover the altenator and distributor and hose everything with that cleaner.

Make sure to cover the top of the carb to keep water out.

To get the balancer clean you need to lay under the truck to reach it and if the grease is on heavy use the cleaner with a rag. It took me about 4 hours worth of scraping and using the cleaner to remove 30 years of grime.

Dont just clean the motor, clean everything in the engine compartment. Then lay next to your truck and either use the spray stuff or what ever degreaser the machine has in it.

If you have a pressure washer at home use that.


Once your clean check your carb to make sure all linkage works and the butterflies open. Next you can use carb cleaner all over the carb and in it to clean the gunk out or go old school. By that I mean,when the engine is good and hot take the air cleaner off and move the truck somewhere where you dont mind smoke everywhere and trickle ATF fluid into the carb. It takes 2 people to do that,you pour the other keeps the motor reved up. The fluid cleans the carbon off the combustion chambers and valves in your motor.

[magnethead]

Originally Posted by BigDan3131

I think you should take the truck to a self-serve wash station and bring a scraper and 4 cans of degreaser with you. Bring 2 plastic bags,cover the altenator and distributor and hose everything with that cleaner.

Make sure to cover the top of the carb to keep water out.

To get the balancer clean you need to lay under the truck to reach it and if the grease is on heavy use the cleaner with a rag. It took me about 4 hours worth of scraping and using the cleaner to remove 30 years of grime.

Dont just clean the motor, clean everything in the engine compartment. Then lay next to your truck and either use the spray stuff or what ever degreaser the machine has in it.

If you have a pressure washer at home use that.


Once your clean check your carb to make sure all linkage works and the butterflies open. Next you can use carb cleaner all over the carb and in it to clean the gunk out or go old school. By that I mean,when the engine is good and hot take the air cleaner off and move the truck somewhere where you dont mind smoke everywhere and trickle ATF fluid into the carb. It takes 2 people to do that,you pour the other keeps the motor reved up. The fluid cleans the carbon off the combustion chambers and valves in your motor.

clean my engine? I ain't doing that, it might not run anymore (i'm already running motor oil that looks like more of a "soquid"..that's why my engine doesn't burn oil).

and it's not that the balancer is dirty (but it probably is), i can't see it from anywhere in the engine bay. All my cooler lines (radiator, trans cooler, oil cooler, power steering cooler) and everything else is in the way. That's why my dad never put the light to it, the light would never get to it and even if it did, it'd be impossible to see what mark lighted up.