Hey Vortec Guys! / Sierra pickup / Suburban / Yukon etc - Finally has Index!

[NevadaLover]

I haven't gone through this thread all the way so forgive me if you have but have you pulled apart the vent filter yet? it's the round black cylinder hanging off the back of the charcoal canister in this pic, you can get it apart and it will probably be full of dust and dirt, clean it out and put it back and you should be good to go!!

 

[rayra]

replaced it and the purge valve atop the intake manifold to, and blew all the lines while apart. And verified the new vent valve passed air with key off.

It's acting like the tank isn't venting properly. They only thing I haven't done is back-blown the vent line from the tank to the canister. And should have pumped air into the tank while I had that line disconnected. OR even now, I should try that. Wrap my compressor blowgun in a rag to plug the filler, have the missus goose some air into the tank while I feel around the vent of the vent valve.

The vent tube from the fuel pump is 3/8"? 1/2" rigid plastic pipe. Only thing I can figure is that the tank got overfilled some time and some schmutz is lodged in the orifice at the top of the fuel pump assembly, where that line is connected. That would be about a 1/4" orifice. I'm clean, it's dark, I want to go crawl under there and pull the line off the vent valve solenoid and jam my air hose in it and blow air into the system.



crap, looks like there's another tiny vent / line at the filler side too, right above / behind the filler opening, that I need to check.

And also, there's a rollover protection device that acts like a snorkel ball, built into the vent fitting on the tank. That might be lodged in the shut position, preventing offgassing during filling.

 

[NevadaLover]

Definitely disconnect and blow out those lines and the check ball is easy, use a piece of mechanics wire to push it down next time you fill up, if that helps then you know there is an obstruction in the vent line and the pressure is pushing the check ball up!

 

[rayra]

Tonight I found a lot of references to GM 'roll over valves', typically at the union of the tank top and the source vent line that goes to teh evap canister (the line with the blue fitting in my pics). But I could NOT find any definitive info that the GMT800 Tahoe / Sub have such a device. It's much like a snorkel or toilet valve. Repeated over-filling would transport debris into it, and/or repeatedly move its internal float up into a closed position, sealing that vent tube. If it is stuck in an 'up' / closed position, it would produce the trouble I'm still having. If the vehicle even has one. I guess I'm heading to the Chevy dealer this week to get some parts looked up, by VIN. Only way to be sure. Need to go over there anyway for the rear suspension bump stops for my Sub.

( http://www.tahoeyukonforum.com/thre...able-to-fill-your-tank-look-here.16989/page-4 )



In theory, I can disconnect the tube fitting from the vent valve solenoid - it being the easiest line to get to, seat / seal my compressor blow gun in it and bust some air in there a couple times and that ought to result in the tank-top vent line blowing clear or resetting the roll over float. If I can get this done some evening this week, I can beat the next necessary fill-up, or go attempt the re-fill myself after the air attempt and see what happens. If it fills up without trouble, then everything correlates. And I'll likely have to drop the tank to change the roll over valve. IF it even has one. I have no reason to think there's crap in the tank, other than 12yrs / 183k mi.


Could also be an anti siphon device in the fill neck / pipe. If it's failed or stuck somehow.


Kicker is it has to be some sort of pipe blockage, one way or another. I was getting no codes as would typically happen with the purge and vent solenoids. I called it 'preventative maintenance' and replaced them first, as part of my initial inspection and attempt. I was going to handle them anyway as part of looking for a vent blockage, and I'm a fan of taking the opportunity to refresh parts when I'm already doing 80-90% of the work to replace them, anyway. That also means that everything I've replaced so far was probably working just fine. After I visit the GM dealer for info, I might go ahead and dismantle the filler assembly on my Sub to explore things.

Too, if there is a rollover valve in the top of the tank and I need to replace it, that's a lot of work and requires unshipping the tank. At which point I'd consider changing the fuel pump while I am there. But the missus is making noise about needing a new vehicle. The few niggling repairs hers has needed are starting to put her off. And it would make some sense to sell it off while it is still in (mostly) good working order.


eta
innocuous little thing, $12 on ebay
http://www.ebay.com/itm/NEW-Genuine...alve-911-001-GMC-Chevy-Chevrolet/231846584713


modern anti-siphon device / snorkel ball
https://www.youtube.com/watch?v=k39E2PRofIo

 

[fl0w3n]

well SOB, 'worse than ever'. First time I was pumping. Got any immediate cutoff. That's sometimes happened to me in other vehicles, in very hot conditions. Reset adn started pumping again. cut off 2-3 more times. I held the bellows on the pump clear to allow vapors to escape and again it repeatedly cut off. Lots of splashy frothy noises issuing from teh filler, but no gas splashing out. Got a good run in the middle, thought 'aha, things are cooled off and flowing ok', then cutoff, cutoff, cutoff. All told at least a dozen shutoffs in the course of pumping a little over 18gals. Which by the trip odometer was about spot on, just under 16mpg.


Only thing I can figure is the vent pipe at the fuel pump mount at the top of the tank OR there's some sort of obstruction in the filler pipe. Next wrenching opportunity I'm pulling the fill pipe apart.
And it's back to digging around online for possible solutions. It's a very simple system, it shouldn't be this hard to fix it.
And I might pull the vent solenoid pipe back off and slowly ramp up some compressed air back into the system. Have to find some info on how the fuel pump assemblage is plumbed. I don't want to screw something up putting pressurized air back into it. Not at this late date. 183k+ mi. on the original pump.

"I'm terribly vexed"

I'm with you man, that's how mines been. I still haven't replaced canister/solenoid/valve or anything, just blown it out, but imagine your frustration but then imagine having to put 30+ gallons in haha


Mine got slightly worse/no change after blowing it out, but then after a few weeks its not as bad any more. I only get 2-3 shut offs and need to hold the nozzle at a bit of an angle. I would eventually like to get it fixed for good.

 

[fl0w3n]

So, rayra, I don't recall if it was here or in my own thread where you recommend I replace the main belt tensioner ... well at any rate, when I read the suggestion I was already pretty much wrapped up with the bulk of my work and figured ah it'll be fine.

Fast forward to the trip from Laughlin NV back to LA the other weekend, and sure enough, belt tensioner self destructs into fine particle dust, takes out the belt with it, and I got stuck in Barstow doing a belt and tensioner change in 110* heat. Oh, and the radiator sprung a pinhole leak right before the trip, which progressed into a slightly larger spray, enough to cause some problems.

So, another $400 order from Rock Auto do do some more "preventative maint." over the next two weekends to get ready for the next trip.

I still feel the motor doesn't run quite right, I'm thinking when I messed up the torque sequence on the intake I probably created a leak. So I'll reseat that, and I'm replacing the pcv vent tube because there's a small split in the one now. It just has a kind of shaky/not smooth idle.

 

[Stryder106]

Hey All - quick question on radiator hoses - are the ACDelco hoses on RockAuto.com the same quality as a Genuine GM hose? I know that ACDElco makes the GM stuff, but I also know that ACDelco has 4 different levels of quality for each hose. Since only 1 option is listed for my Av - I'm wondering which quality level it is - or if I should just go to the dealer and pay the $81 for one that I know is not the bottom end of the spectrum.

 

[Stryder106]

So - AC Delco quality goes: OE, Professional, Standard, Specialty. Given that, the professional level hoses on RockAuto, Amazon, Summit, etc are a step below the OE that you get at the dealer.

 

[rayra]

well the RockAuto Delco is a quarter of the price and I doubt the premium dealer part is 400% mo better. And I haven't seen any mention anywhere of any issues with the cooling systems hoses. I would think that the mere fact you put in a new Delco or Gates hose is plenty of improvement. 2-1/2yrs since I torture-tested mine over the Grapevine grade in 100F+ heat, I still haven't got around to changing my hoses or pump.
Recall too that the whole system is basically 'fused' at 15psi via the cap. So they aren't under a huge strain to begin with. Just a refresh of coolant and hoses ought to go a very long way towards 'upgrading' your cooling system.
Having electric cooling fans would go a long way too. I'm looking into retrofitting a 2003+ factory elec. fan setup into my '02

 

[rayra]

So, rayra, I don't recall if it was here or in my own thread where you recommend I replace the main belt tensioner ... well at any rate, when I read the suggestion I was already pretty much wrapped up with the bulk of my work and figured ah it'll be fine.

Fast forward to the trip from Laughlin NV back to LA the other weekend, and sure enough, belt tensioner self destructs into fine particle dust, takes out the belt with it, and I got stuck in Barstow doing a belt and tensioner change in 110* heat. Oh, and the radiator sprung a pinhole leak right before the trip, which progressed into a slightly larger spray, enough to cause some problems.

So, another $400 order from Rock Auto do do some more "preventative maint." over the next two weekends to get ready for the next trip.

I still feel the motor doesn't run quite right, I'm thinking when I messed up the torque sequence on the intake I probably created a leak. So I'll reseat that, and I'm replacing the pcv vent tube because there's a small split in the one now. It just has a kind of shaky/not smooth idle.

Could have been either topic, I was posting then about alternator and main idler swaps around the same time. And also subsequently changed the AC belt and its idler on the missus' Tahoe. I think I ordered those parts right after cautioning you about yours. took my own advice lol

between my two own vehicle and talking with all of you about yours, I'm starting to lose track of what I've done or intend to do to mine. This topic is as much a tracking topic for me, as anything else.

 

[Stryder106]

On the hoses - I bit the bullet and bought them from the dealer (ouch) but figured I've got 15 years and 180K miles on my factory originals so the new ones ought to last me that long again. On the plus side, the new heater hoses came with the new fittings already mounted in them.
//
Any good tricks to bleeding the air out of this thing after I drain it and redo the hoses? 7 quart capacity - right? I feel like I'm losing my mind.
//
Rayra - also check your PM and let me know.

 

[rayra]

There's a TSB recommended procedure after you breach the cooling system, change the pump. IIRC after you've re-assembled and re-filled the system you're supposed to start it up and then hold a higher RPM, north of 2000. That supposedly prevents pump cavitation and gets things moving around under some pressure and I guess move any trapped air.

I also attempted to mostly fill my radiator and upper hose before final mating of those.

I found out after the first (and second) time I did a water pump swap on the Tahoe, a few years ago. Changed pump, thermo, upper and lower, topped it off, idled in the driveway looking for leaks and as the temp started to come up I left for a test drive - and watched the needle go right on climbing thru 230+. Hurried home and shut it down. Wondered if I'd screwed up the thermostat install or had a defective one. Breached the system, pulled the thermo, boiled it on the stove to see if it functioned, which it did. Put it back in and went for another drive and bam sailing into high heat again. Went home and got busy googling and found the technique mentioned above. Worked fine.

I'll see if I can find my bookmark for that procedure.

 

[Stryder106]

Need some urgent advice - over the years I have added the yellow universal coolant that mixes with DexCool and the Green. I purchased all universal for this drain/flush/refill that I'm doing, but I just drained my system and it is still very orange (more DexCool in there than I thought. So - thoughts - go ahead with the universal after flushing or use DexCool?
//
My original; thinking was that if I need coolant out in BFE that I would be more likely to get universal vs DexCool.

 

[rayra]

well if you are going to convert you need to thoroughly flush it anyway. So that becomes moot.

Dexcool's been around for over 20yrs, so I'd expect to find it anywhere I'd find the green.

Southwest Deserts, I quit carrying coolant a long time ago and instead carry a lot of potable water - which I can use in the vehicle if necessary. I can't drink antifreeze. My truck can drink water. And it obviates concerns about mixing coolant types. Patch your leak, top it off with water and keep moving. It's not sechsy 'high performance', but fluids take a lot of volume and weight. I'd just as soon carry 'dual use' water.

 

[Stryder106]

well if you are going to convert you need to thoroughly flush it anyway. So that becomes moot.

Dexcool's been around for over 20yrs, so I'd expect to find it anywhere I'd find the green.

Southwest Deserts, I quit carrying coolant a long time ago and instead carry a lot of potable water - which I can use in the vehicle if necessary. I can't drink antifreeze. My truck can drink water. And it obviates concerns about mixing coolant types. Patch your leak, top it off with water and keep moving. It's not sechsy 'high performance', but fluids take a lot of volume and weight. I'd just as soon carry 'dual use' water.

Agreed. So - for this fluid change - which I'm flushing it - should I stick with DexCool or go ahead and go with the universal? I seriously did not think there was this much DexCool left in my system - was I ever wrong.