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.

All this makes sense too, loose parts. All good hints. Also a cheap fix if you find something loose. A mechanic seems to always head for the most expensive fix first. Knock is a distinctive sound as are rattles. Without hearing your problem everything is a guess. A bad oxygen sensor can also cause knock as well. Not trying to beat a dead horse, just a hint if the other stuff doesn't work out. Everything seems to come down to economic interest and yours is not the same as the dealers.

Probably knocking. Pre-ignition. The cylinder is firing a little too early and the knock is caused by the explosion hitting piston before it gets to the top. My 01 will do it sometimes at low speed and low RPM's when it is cold. Unfortunately this stuff is all sensors and computer controlled now. Low octane fuel can cause it too. One way to check this is run your gas tank down near empty and put a part tank of hi-test in, 93 octane. I believe there are sensors on the engine that are supposed to sense knock and tell the computer to adjust the timing a little to get rid of it. The higher octane fuel should make it better. I haven't had this problem so I haven't done much research on it but I'm sure there will be at least a few on this forum who have. Vehicles are very complicated now a days. Some things even get expert mechanics scratching their heads. You are smart enough to have asked the question. I hope you know a good trustworthy mechanic.

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.

You might want to look at this post. http://www.gm-trucks.com/forums/topic/154899-brake-line-size/?do=findComment&comment=1373752 I do have a sketch of the ABS somewhere. I can dig it up this weekend and scan it. I may also have the diagram on my other computer but it isn't handy right now. I think I found that one on this site. Off the top of my head, looking at the face of the ABS, looking towards the back of the truck, the top 3 lines are the output, the one on the top right goes to the rear, the left 2 go to the front wheels. The lower pair go to the master cylinder. The fronts are specific, the wheel sensor has to be the same as the line controlled by the ABS.

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.