brucelimerick

Here is some information that will help when firming up a rusted frame. My frame doesn't have enough metal left to grind down to bare. I was thinking of using this process before I put a protectant over coat on. 9-5TannicAcidTreatm.pdf9-6CleaningIron.pdf 9-5TannicAcidTreatm.pdf 9-6CleaningIron.pdf 9-5TannicAcidTreatm.pdf 9-6CleaningIron.pdf 9-5TannicAcidTreatm.pdf 9-6CleaningIron.pdf

Interesting, actually a study at Purdue shows it is about half as damaging as salt, sodium chloride to bridges. I live on a dirt road and it is used as a dust suppressant and stabilizer. So I get it year round. Every time the road gets wet it splashes on my truck and car. So much for thinking I washed everything off in the spring. The one thing bad for vehicles is it attracts moisture. It will make things stay wet longer meaning the chemical attack will continue for a longer period of time. So even though it may be half as damaging as regular salt, by staying active longer it could be way worse over a year. Plus by using it in the winter for ice control and in the summer for dust control I get it 12 months of the year. I live in a humid area so it has lots of moisture to work year round, it just sucks it out of the air. I had noticed some times even though it was dry out that the dust collecting in areas under my vehicles would be damp. This explains that. You learn something every day. Doesn't let GM off the hook though. If their corrosion protection stayed in place it should prevent this. It seems if you lose a section of the coating, corrosion will run under the rest of it and peel it all off. As you can see on my truck it is all gone. So for everyone else, keep an eye on it and when a section of frame becomes exposed go into the dealer and make them repair it. GM has a bulletin out and will pay for it.

My truck hasn't seen the liquid brine, I haven't driven it in the last 3 winters. I don't know how much worse that is, salt is salt. Mortal enemy of unprotected steel and we use a lot of it here. The problem with the coatings everyone is recommending is they only get one side. You can't get at any of the hydro formed box sections so they continue to rust from the inside out. The only real way to protect these frames properly is hot dip galvanize them. Though that adds weight. The rust protection sprays if done right can get into the hydro formed cavities but too late for that now it seems. Ford is going to aluminium bodies, maybe they will do the frame next. They will have to be careful with that making sure the 2 metals are electrically separated. The basic problem is GM is trying to lighten the truck and sacrificing longevity because their corrosion protection for the frame doesn't work. I would sacrifice a few points in gas mileage for an extra decade of driving my truck. .

I always power washed the underside of my truck extremely well in the spring once it got above freezing. My new car is protected by Krown every year plus 3M stone guard on all the rockers. Most vehicles I have worked on over the years that were rust proofed where in excellent shape frame and body wise. I shouldn't have listened to GM about how great their corrosion crude was. Rust proofing voided their warranty. I my opinion both are crap.

I have a 2001 with about 100,000 miles on it. Frame is the same, junk. Driver side rear spring shackle snapped this winter. The other one is in bad shape and will be replaced soon. In reality the whole frame from the fire wall back is soft. Last summer I replaced all the brake lines, they were history. I have my frame from my 68 Chev that is made into a trailer. It has twice the metal my 01 has. I am totally disappointed with GM and this truck. There are lots of issues with the frames and the corrosion protection right up to 2013. A decade of ignoring the problem. Sound familiar? I won't buy another GM product if this is how they make them and look after their customers. 40 years of liking GM down the tubes.

Yes, you are right MickeyZ. I had forgotten the original post. Here is a pretty good explanation of the probable part of the brake system causing the problem. http://auto.howstuffworks.com/auto-parts/brakes/brake-types/master-brake.htm When the pedal is up and not pushed the whole brake system should be at atmospheric pressure. ie no pressure anywhere in the system. The only way to generate pressure is if something is blocked and the pressure from pressing the brake pedal can't be released when it is released. Pay attention to page 3, the proportioning valve and the metering valve. I believe the differential pressure switch on GM trucks is on the master cylinder. Don't quote me on that. There is a possibility it is the master cylinder but it doesn't sound like it. If it was the brake light should be on on the dash. That would be indicating a leak in the system. Doesn't sound like the problem because both front brakes are getting hot. If there was a leak only one would be getting hot. This could also happen if the master cylinder was having problems and one of the pistons was stuck. I would say your problem is in the combo valve. I don't remember one on my 2001 when I redid the brake lines. The 2 lines coming out of the master went to the ABS unit which means these valves or their function is internal to your ABS system. My 2001 has rotors on all 4 wheels. GM went back to drums on the rear a year or 2 later. They may have added the combo valve back into the system. I would hope so for your sake as the ABS unit is quite expensive. The ABS does have it's own idiot light on the dash but I'm not sure what events make it turn on.

Forget about the rubber flex lines. They have nothing to do with your problem. You have air in your lines. You have to re-bleed the system. Brake fluid does not compress nor build pressure. Bleed all your calipers not just the front.

That was lucky, the tubes shouldn't be melted. My hose problem has been slowly happening over the years. Yes the ends were corroded and no wrench would fit or hold. My brake lines were totaled as well. I had half my truck apart this summer doing them. The bracket test is good. One other thing to check is the metal plates the pads are bonded too. Sometimes the dies that punch them out are worn and there are burrs on them which prevent the pads from sliding on the chrome sliders properly. A little file work can make a big difference. Note I said a little. The pads should be snug on the sliders, not loose. If they are they vibrate and chatter, not good. It should take very firm finger pressure for them to slide. I just touch up the burrs, never open up the gap, they will be obvious. Try to save the grease, I'm not sure if it is hi-temp or not. Some different types of greases don't mix well. I agree with Mikey, I have had corroded pins before when the boot cracked or came off the recess. The bracket should slide smoothly and easily on the pins. The tubes are your problem. Calipers and flex hoses should go 100k miles easy even up here in the heavy salt.

Seems to be a bit of confusion here. The rubber boots that were mentioned, corrugated, go between the caliper and the pad bracket protecting the exposed end of the pin. There are 2 recesses that hold them in place. The rubber tubes I have no idea what they are. Hence my assumption they were for shipping protection. Pull a tire off and have someone apply the brakes. You should see them compress on the rotor and when the pedal is let off they should relax. Most times it is the piston that will wear and begin to stick, but not always. With the probable crud on your pins it may not be a good test now. I would pull one of them apart and see what has happened to the tubes. The pins go on bare. You have a 2004 but no indication of what part of NA you are from. I live in a road salt environment and my calipers lasted about 9 years on the front. I had no problem with the rubber flex lines to the caliper until I had to replace the caliper. The lines were ok but the ends were totalled by the time I got them off with vice grips My ABS and Master are still good. I have a 2001 Sierra.

I have never had rubber tubes come with a brake kit. Sounds like they are protective shipping pieces. The pins slide into the other side of the caliper with nothing on them exept the high temp grease. They are supposed to be bare. They are what is causing your calipers to stick. You are going to have a real b*tch of a time as these rubber pieces have probably melted inside the caliper bore. You may get away with using a proper sized drill bit to clean the holes but even with 1/64" increments you might not get the right size. When you are getting into new territory with brakes just do one side at a time so you have the other side to refer too. You may have to by new rotprs again if you can't get them to slide freely. The pins and calipers have to slide freely, there are no springs to make them retract, just the decrease in pressure. They always slightly touch the rotor. If they stick they heat up fast. I have had sticking pins before and at night when you stop you can see the rotors glow.

It's not technically difficult. You really just need a flaring tool and a little hand bender. The problem is GM installed all the lines on a bare frame with no thought to future maintenance or corrosion. So to do it in your garage is a pain in the butt, but not hard, just frustrating sometimes. Just remember what GM would charge you to do it and have a beer. You will be able to fill the box to over flowing with the money you will save. I would recommend splurging and using the easy bend lines. They are corrosion proof not corrosion resistant, big difference, you can bend them with your fingers and they are almost kink proof.

You are welcome and I'm glad your job went well. I like the garden hose trick. It does make things easier going in when you have an idea of the potential pitfalls. 13 hours and $150, hard to beat that.

After reading the post by 59ih430, I remember the reason I used the brass adapters, the factory aluminum to steel connection is a corrosion nightmare. My steel fittings were toast and there was pitting on the threads of the ABS. I used 6 pt brake fitting wrenches to get them off, a conventional wrench would for sure have rounded them. The pressure I used was scary on a couple of them. I was a little worried as I knew what the ABS was worth if I screwed it up. Bruce

I have a 2001 and just finished replacing all the brake lines. I think they are the same, sure sounds like it. According to my thinking GM really did a poor job of engineering this whole mess. I am a little jaded as I have been dealing with the rear discs since the truck hit 21,000 miles. Rears eat pads, passenger side has to have new pads every 6 months. Pads and rotors once a year. Dealer suggested I shouldn't drive it on gravel roads, lol. A Gucci city boy truck? Stupid designers as far as I'm concerned. The only other complaint I have is no locking rear differential. Should be standard, this truck gets stuck in a flat parking lot in the snow. Anyway I digress. The rear lines are conventional 3/16" after the splitter on the rear axle. The line running to the splitter is 1/4" line and a 1/4" fitting going into the splitter. Where this line goes into the ABS it is a 5/16" fitting taking a 1/4" line. The 2 lines coming from the master cylinder to the abs are 1/4" line with 5/16" fittings drilled out for 1/4" line. The 2 lines to the front cylinders are 1/4 " line with 1/4" fittings at the calipers and 5/16" fittings with 1/4" line at the ABS. You can't buy these lines. All the mechanics I talked to after making the assumption that the 1/4" line would have 1/4" fittings could buy the 5/16" fitting with the 1/4" bore and they made their own lines. I ended up getting 1/4" to 5/16" adapters for the connections to the ABS and ran 1/4" lines. The adapters are a problem, they have to have the small end on the 5/16" side. The big ended ones can be used on the master cylinder. The 5 on the ABS required me to phone and visit every automotive part store in 200 miles. Special orders resulted in the large wrench ends. You just can't fit 5 of them on the ABS and get your wrench on them to tighten them. I have the part number in my truck of the company that still makes the small ones. If you need it let me know. To replace the main line from the ABS to the rear splitter will require you to either drop the gas tank or remove the box. GM hides this line between the gas tank and the top of the frame rail. To remove the gas tank it is also recommended you remove the box first as well. Only 8 bolts and 2 torx screws holding the filler hose to the box. Basically it was a horror show. If your engine light is on it is also the time to replace the solenoid valve vent for the charcoal canister and the ring which holds your fuel pump in the tank should also be replaced. In hindsight I would buy the 1/4 x 5/16 fittings and buy 1/4" Easybend line and make my own flares. The steel lines are junk, even with the "corrosion" coating on them. By the time you get finished bending and routing it there are scratches all over it. The lines at the ABS are a mess. It is jammed between the charcoal filter and the fuel filter. 5 lines have that have 4 to 5 bends in 6" and fit into a 1/2" by 4" space going over the frame and then come together to run up the outside of the frame. You can buy a pre-bent set of lines for about $280 but after doing the job I would think you would have to remove the box, cab and most of the front end to get them in. The Easybend is real cool line. Copper nickel, truely corrosion resistant and bendable by hand. You can almost knot it and not kink it. Unfortunately I found out about it about half way through my job and it was too late to switch. You could run 3/16" steel line from the rear splitter to the rear calipers, plain Jane runs which can be redone easily to have to avoid buying a 25' coil of the easybend. The Easybend seemed to be about $50 for 25'. Cheap believe me. I have abs of steel crawling out from under my truck about 500 times fine tuning the bends on the steel lines. I ended up buying straight steel line with the fittings on them. You pretty much need fittings and joints on the steel lines. Pretty much impossible to run a full line the way GM routes them. And every joint is a potential leak point. The easybend will allow you to run the lines with no joints and just bend as you go by hand. I will NEVER run another steel line, ever! If you want to really know if I'm bullshiting just crawl under the drivers door and have a look at the mess around the ABS on the inside of the frame. Also look at the line that heads to the rear, you can see about 18" and it is gone. The lines are run in the factory with the frame fully exposed and no body parts on. Every mechanic I talked to cursed this truck and most would want $1,000+ to do the job. I expect with a dealer you would be well on your way to $2k. Our dealer shop rate up here in Canada is $115/hr. The only one who was reasonable was the one who showed me the Easybend, he was still $75/hr but had the secret. Too bad I didn't visit him earlier. It would have saved me a week of cursing. I have pics start to finish if you need them. My brakes are great, well as great as GM made them, they have always required more effort than any other vehicle I ever owned. Bruce

I agree with govtech4, I doubt it is the knock sensors. All I have done under the hood of my 2001 is change the oil, everything else is stock and original. Knock is fuel, timing and spark. The engine controler monitors the fuel quality (a sensor to check) and sets the timing. Nothing you can change or adjust there anymore. But to get knock your fuel is igniting early. I doubt it is the plugs, if you have knock they are firing. It would seem to me it could be a fuel issue especially when you mention the 100+ temperatures. You could pull an easy plug and check for deposits. Deposits can give you hot spots in the combustion chamber which can cause pre-ignition. It could be so-so fuel as well. You could try a 1/4 tank of premium and see if that makes a difference. The heat will vapourize the top end of your fuel. It could also be getting some vapour in the fuel line if it is running close to a hot area of the engine. The fuel lines do run close to the exhaust right around your feet and the catalytic converter is right there too.