Update on an old Burb.

Wa'all, it's been months, again, since I posted on TDP, so - - - Been ignoring the old 95 Suburban 2500 6.5 for some 5 months, now! The 4L80E started some funky shifting, back in April ~ ish, then it started a big whine that we're assuming was the TC, and, at the same time, the Shift 4 controller lost it's display, perhaps control. I sort of gave up, for a while, then ordered a rebuilt TC from Rock Auto, which has been laying around all Summer.
Finally, about a month ago, I put her up on the lift, took out the trans, took it down to SW Transmission and had them check it out. BTW, the trans had been rebuilt, with new TC, 2 years ago, last Apr, and had a 1 year guarantee on it.Trouble is, in those 2 years, I'd put on just 6700 miles! South West found nothing wrong inside and agrees with me that the big whine is most likely from the TC, which still looks factory new.
Last week, I got a little more serious about getting the Burb back on the road. Since I obviously need a controller (mechanical IP) and my US Shift -Shift 4 controller (second one) has always been too complex for my analog brain, plus, no one in this area has ever heard of it, I did some on-line comparisons and ordered a Compushift. Hoping that it'll be more plug-n-play.
Running the Miata out the 2 mile Goat Path for groceries in the Summer has been easy and fun, but we've had a dusting of snow for 3-4 days in a row, and that ultra-fine red volcanic dust turns from concrete-hard to slime, under these conditions. We have six vehicles registered , here, but, right now, we have Lance's (son's) 07 Suburban gasser, needing a very leaky rear-main seal (and have a TC that we're putting in there, while it's on the lift - 200K mi). We have a 2012 Outback that's on the lift, with a new TC in it, and a prayer that the CVT tranny is Okay. Then there's the 95 Burb that's non-functional, so, we're left with Lance's 03 Dually D-Max, the Miata and the Smart Car, which is fun, but only to a limited degee. THAT'S why I'm anxious to get the old Burb back. Wish me luck.

Good luck, Dick!

A little catch-up. Finally got the tranny back in and been going through the wiring process of the Compushift. So, I finally got everything hooked up and re-filled (the trans holds 16 quarts, with the oversized aluminum pan). It always fires right up and settles down fairly quickly. I have manual control of glow time and cold-start advance. Got to the point of ready for a road test, after clearing a TPS sensor code on the phone/Bluetooth Compushift controler. Drove it about 15 miles and the shifting seemed pretty darn good. My son, Lance, held my phone and relayed info. The line pressures seem low, to me; down around 30 psi, or so, at idle and downhill, and, when I really romped on it, the highest we saw was around 180-190. Lockup occurred at about the same speeds and throttle as before, which is all good. So, I'm calling it a successful day. I'll wait for Compushift to open on Monday and call them and have them walk me through the line pressures, etc. The TPS code came back several times, and it says something about "A" Low Signal. I'm thinking that the tip-in voltage is a bit low for the C S controller. No big deal, if that's the problem. Hardest part of adjusting it is taking the intercooler/ intake cover off to access the TPS's two screws. As it is, right now, the voltage is .79V at idle, to 4. 90 at WOT. So, I'm thinking that C S is looking for a min of 1V at idle. ???
Seemed so good to get behind that wheel! That old 2500 has always been a delight to handle. Lance's 07 gas Burb 1500 is a great car, but the 2500 tracks better and the 6.5's torque is something to be sorely missed, solo, or towing. I'm hoping for longevity, now, with that new controller.

Sounds like the Burb is on it's way back to being a daily driver
Looking forward to having ours plated this summer as it gets turned into our road tripper/overlander
In a small way i wish it was converted like yours to a mechanical pump.But i am hoping that seeing how i worked through the bugs it had that i can deal with computer issues if they come up.

As I've said, bfore; Kennedy advised me, nearly 20 years ago, to stay electronic and I wish I had. I had already remote-mounted my PMD on a big heat-sink and was having no problems, that I can remember. If it ain't busted, don't repair it, is good advice. I'll always feel that my cobbled-up throttle/transmission control, ending with the US Shift trans-control and related tuning problems, most likely, or, maybe, caused my trans failure.

I have a large bias against computers...
My brain just doesn't mesh with using them, working on them, ect
I converted my 98 3500 tow truck as it had multiple electronic issues. Going mechanical solved them. But it was a 5 speed so there was much less to deal with.

We had a guy, back in Vermont, who did quite a few mechanical IP swaps, and, far as I know, he always did it on a manual, or swapped a manual in. Believe me, last Spring I came close to making a search for a 5-6 spd manual. Don't think I'd have been much slower about doing the job. Still, at my age, I've gotten sick of crawling around, under and over, vehicles. I'm really hoping for some longevity out of the tranny, now, but, with 195 thousand on the engine, there are no guarantees. The injectors aren't that old, of course, nor the glo-plugs. All such thing are pretty simple, still, but, an engine rebuild? We have a lift, but, I've proven, very recently, that craning my skinny neck around, under there, is a daily, nightly, lesson in soreness.

Four, or five years ago, back in VT, I took the 80 gallon tank out of our Seneca MH, cleaned it and re-installed it and added an after-market pump and filter system. Did it alone., with some plywood, floor Jack's and ratchet straps. I might be able to do it, today, but I don't want to have to find out.

The engine in my burb has been out, it was was part of the big restoration process.
It was an abandoned truck with multiple issues, if i had know the extent of the issues i probably would not have taken on the project.
In the end...
Computer reflash
injector pump
security sytem
dropped valve seat: engine removed and taken apart. A piston from Robyn and a set of good used heads. Had to close my eyes and use the block that had a crack...
Runs very good with a Kennedy Tune
The burb was rust free and the engine was very clean and unmolested so saving it wasn't a lost cause.

As much as I am not a fan of a lot of the computer controls in our rigs..Most of the electronic transmission controls work pretty decent (Factory stuff)
The Interface of the DS4 injection system and how that mess ended up...
The DS4 system was rushed into production waaaaaay too soon and was/is a 5 alarm train wreck.
Yes....WHEN it works it is pretty decent.....The issue is the failure rate is far too high.
I fought several 1994 6.5 rigs....a couple 1995 Burbs and finally the 1995 Dually crew cab.....

Always something going south.....

The 4L80E Trans is a decent box....Pretty much a TH400 with an extra gear and a lockup converter.
The electronics are reliable......

With the diesel ...trying to change the engine to the mechanical pump is easy.

Trying to get the tranny to play nice after the other changes has always been the fly in the ointment.
Looks like Dick has finally got the fix......

Glad to hear things are improving .....

I'm really enjoying the new settup, with a couple of almost-non issues. I'm understanding more about the settings, now that I finally got the tps married up to the Compushift, correctly. Their written instructions had me confused, because it doesn't say, specifically, that CS does, indeed, furnish a ground from their their control to the tps. So, a Q search that I did, to CS, turned out to not be CS, told me that they do not furnish a ground. Eventually, I got the word from Mike, at CS, and my old tps works just fine. Then, once I got to the test run (s) and tuning, my phone (Bluetooth), showed me a lot that their very brief manual leaves my aged analog brain, struggling. After that, I had the thing shifting pretty well. Got on with Mike and the adjustments/settings became more clear. We put on close to 50 miles, this morning and I found things quite to my liking. Upshifts, especially, first to second, might be more OK with a load on, but, solo, I find it wants to rev up more than necessary, so, I lift my foot and it shifts beautifully. I'll get on the program and experiment with the settings until I get it comfy for myself.

The doggone PS pump is still moaning, not as bad as before, but annoying. Looking at the HB brake asm, I see a small diameter tubing loop, near the top, with a a metal block, with a hex cap. Is that maybe for bleeding? The system is full and I didn't see any foam, everything warm, the last time I checked, Walmart parking lot, over in Taylor. Any advise?

The PS pump is self-bleeding. If it's growling, howling, or moaning, it's either low or failed. If you drive it a few miles and use the brakes and steering, it's bled. Trying to bleed the system at the HB will just make a mess, and won't solve anything.

As Maverick said.
The growling PS pump is a sign that the pump is worn.
Our 95 has been making noise for years.....

Left knob on the radio pretty much adjusts out the noise :rolleyes:
The only real fix is to replace the pump......

The extra speed required on the 1-2 shift is a TPS setting .
The throttle pressure the controller is seeing is a tad high and so the shift is late and probably a bit harsh too ????

If you set the TPS to reduce the throttle pressure then the line pressure drops off and this is not really good

"Throttle pressure"
What the controller thinks your throttle setting is (What you are asking the engine to do)

Getting this stuff all tweaked to perfection can be tough.....Always better to error on the side of a tad more T P than needed....

Too little T P and the clutches can start to slip during the shift....BAD JU JU

The original programming on these rigs was very good.....The 1-2 shift was firm yet not obnoxious ....Same with the 2-3 and the 3-4 .

The lockup on the converter was at about 45 mph at moderate throttle and was firm but again not obnoxious.......

A very harsh converter lockup is/can be rough on stuff......Firm is good and allows the converter clutch to engage without slipping ....Long "Mushy" drawn out shifts no matter which ones drastically shorten the tranny life.....

The old TH-400 in the earlier Burbs (1980's) had a vacuum control on the Injection pump that was supplied by a vacuum pump and fed vacuum to the Vacuum modulator on the trans to control the shifts.

Same sort of "Tail chasing" you are doing...../Only it was vacuum and hydraulics instead of electronics.....

We had a 1986 Burb K2500 with the 6.2 and it was a pain to get the shifts in the sweet spot.

From the factory that rig was always a tad late and harsh on the 1-2 shift.

I monkeyed with various ideas to get things the way I wanted.....The vacuum control valve was just not able to be adjusted to that narrow of an adjustment.......I finally replaced the modulator with an adjustable one and after many trips under the rig and tweaking the modulator I finally got that thing onto the happy place.

Still the entire set up used to artificially create and manage vacuum as it relates to throttle pedal position and what the operator was asking.....SKETCHY AT BEST But quite workable as long as you were not being fussy

Factory settings were a good compromise and generally worked fine....
Unless the owner was anal....Like me... :D

Hi, Robyn, Maverick. I guess it was back a few notes that I mentioned this, but, the PS pump is brand new. Regardless, I think the noise is gonna go away, eventually. I think that my biggest problem has been me. I've had too much of a tendency to try to make it purge air when everything is already warmed up and frothy. Yesterday, I'd been parked at Walmart, Taylor for quite some time, so, there was no foam when I came out, and I "worked" it, steering and brakes, leaving Taylor. Noise, still there, but redused. About 6 miles down Bourdon Ranch, it spontaneously reduced again and was pretty close to normal, by the time we pulled in at home.

Compushift's programming allows pretty good control of those parameters. Some of them are given as percentages, so, it's just a matter of experimentation. We'll get there, eventually. As things are, right now, I'm pretty close to overjoyed with the difference, Compushift vs US Shift.

Thought I'd move the PS pump conversation back over to the 6.5 forum.
Weather was pretty good, this afternoon (for a while), so, I fired up the Burb and waited for it to warm for ~2 minutes, or so. Took off, down Eagles Flight, still running the cold-start advance. I used to have a timer on it, but it conked out on me. I ordered a new one, modified the case to fit, just like the old one, and, the doggone thing wouldn't even light up, so I canned it and went back to the toggle. Anyhow, I can get up to 2nd, even 3rd, on EF, and it'll run up to 2000 rpm. The whine was totally absent!������ Got closer to the intersection(.3 miles) of EF and Dry Gulch, and, here comes the whine, gradually increasing. So, I cancelled my plan to turn around and go back and celebrate; turned left, up Dry Gulch Hill and the whine worsened as we climbed out. So, I drove out to Bourden Ranch Road, took a right and drove to Shumway Road and turned around and came home. Wherever I got the chance, I kept on the throttle, to maintain 1500 and exercised the steering and brakes. The brakes definitely change the pitch of the whine, though by only a bit. Both steering and brakes work flawlessly, except that I can actually feel the resonance in the wheel.

After I got back, I grabbed a piece of heater hose and had Jean run the throttle. Incidently, the whine can be heard at idle, but, barely, and it doesn't increase until 1000-1100 rpm. Gets the loudest at 1500. At idle, through the hose, I couldn't tell what I was hearing, but when she took it up past 1000, there was a very high frequency noise that I perceived as having (maybe) the same pitch as in the cabin, but was the result of having my ear right on the steel surface. I checked a lot of areas, and was surprised at how quiet the valve covers engine block and the intake system were. Very hard to tell about the vacuum pump and AC, because the cooling fan moves so much air on that side, near the shroud opening. Oh! The turbo seems to make next to zero noise, through the hose.

So, here we are. I'll probably take the time to remove the serp belt and give her a quick run, out Eagles Flight and back, maybe turn around as soon as I hit 1500 rpm. Must remember to warm it up, though, before I pull the belt, if it's gonna continue to run silent, cold.

I mention these roads, kinda hopin y'all might stop in.������ Just remember; EF and Dry Gulch are just two of the 4 that comprise the "Goat Path" to Bourdon Ranch. The other two are Conastoga and High Plains. And, more than likely, if you follow a GPS, to 8480 Eagles Flight, from Bourdon Ranch, mile marker 10, it'll take you right past Conestoga and all the way up to the other end of Eagles Flight and direct (dump) you onto a stretch of the Goat Path that you won't want your Vette within 5 miles of. Matter of fact, beyond Conestoga (.2 MI from BR -- mm10, left), the next 3-4 miles would permanently modify a Vette's whole undercarriage. Stop in, any time.

The PS pump should be near silent (below engine noise), no load, some load, or max load. If it's growling/whining, it's low on fluid, or it's bad. Even if recent, new or reman, that doesn't change the conditions or the result. A squealing pump, like you'd have at steering lock or both feet on the brakes, is not the same. This is not likely, if the brakes and steering appear to operate normally.

A failing hydrobooster on the brakes can and will cause the PS pump to whine due to pressure fluctuations..

I have seen this.....I had a 94 Burb that had a growling leaking pump...Replaced the PS pump and no more leaks.....Still had a whine...Replaced the booster and quiet as a mouse.....

FOOD FOR THOUGHT

Thanks, Robyn. You're hitting on something tha Lance and I are actually working on. Lance has read some comments on the HB being a problem. He found one site where the guy sealed his system and pressurerized it to just two psi and found his leak, easily. So, I'm in-process of rigging a system to do that.
Question: How did you locate the problem as being in the HB? There's a little canister/cyylinder inboard, and parallel to the steel housing of the HB, that I believe is plastic. It's like 1.250 (IIRC) diameter, by 3 inches.The base of it looks a bit damp, as this very fine red dust clings there, as
opposed to the rest of the cylinder. What's it's function? If it's part of the HB, as opposed to the master cylinder, hydraulic system, it should also be suspect as a source of air.

BTW, the PS pump is, indeed new. I looked up my order. Thirty day warranty, and I laid the Burb up, last Spring, within a day or so of installing the pump. Anyway, there's a lot more leak-checking to do, before I yank that pump. There's one caveat to that statement. I distinctly remember that ished that I had torqued-down the two pressure lines (hidden under the pump), before I installed the pump, because they were ridiculously hard to get to. Another good reason to set myself up with a good leak-check system before I replace anything.

The aluminum (not plastic) cylinder inboard of the HB unit is the reserve accumulator. DO NOT mess with it. It retains full system pressure (until it bleeds down, or is depleted by brake pedal operation with engine off). They all weep a little fluid at the base. I've never seen one that didn't, within a year or two of new. If you find one that isn't moist with fluid, you've found a rare jewel, or the system is dry (not unlike Detroits and oil leaks).

Thanks, Robyn and DMax.
Made up an 1.5 in clear hose, with cap, valve and clamps. Clamped it onto the filler tube and used a battery-powered tire pump. It has a leak, somewhere, but it was late afternoon and I didn't bother with getting a soap/water sprayer out there. Will do that, today, under the hood, from above, then, get it on the lift and check from underneath. Those hidden fittings are on my mind.

Dmax. I could see, right away, once I got back under the hood, that the accumulator is definitely a part of the HB unit. I just didn't remember what I'd seen, at first glance, a few days ago.

Ooooookay. As soon as I came down harder, on my hose clamp at the plastic cap/air valve end of my pressurizer, my leak stopped. A session with a spray bottle, showed no leaks, anywhere, except at the chuck, if I left it connected. Then, disconnecting the return hose from the HB and running the engine, with the hose in the filler tube, resulted in copious foam, every time I pressed the brake pedal! Doing the same with the PS return, had the opposite result; no foam when exercising the steering. It immediately occurred to me that, I now had an explanation of why the pump didn't start making noise, immediately, was the fact that the brakes probably didn't get touched until I approached the first intersection, at .3 mi.

So, do you concur that I need to invest in a new HB? Anything else that I can do to confirm the need? Not being familiar with HB, it baffles me as to the source of air, from a unit that's dry as a bone, all around, under 15 psi of pressure. ??? I suppose I could put the system under a vacuum, but I've seen it sit for 10 minutes, showing no bubbles and .losing only a half psi, from removing the locking chuck. ???

It isn't making sense. Seeing is believing, but I'm not seeing. Air has to come from the pump. If the pump is pushing fluid, everything is under pressure, including the return lines when they're returning. The HB unit can't "pull in" air. It can only push excess flow out the return, or to the PS gearbox. If it's foaming, it's coming from the pump, and it takes very little air to make a lot of foam. If there's air in the system, it will exit the HB unit return first. The PS gearbox return is much lower, and it will take much more volume before any air will show there. The pump is pumping air, from somewhere. Most likely a defective pump, with no evidence of a leak, anywhere.

Okay. Well, then, why doesn't it push foam out the PS return? This is why I posted the question about further testing and possibilities. IIRC (You'd think I'd know,. I was just out there this afternoon!), there's just one pressure line from the pump, which goes to the HB, then the steering gear. So, I think my next step is to lift the car, again, and try the steering, lock to lock a few times. We only tested it , running, today, with wheels on the ground and turning back and forth enough to hear the groaning. I'm inclined to think that I wasn't thorough enough.
BTW, I already have a rebuilt pump, pump-to-HB hose, filter and fluid, so, I'm set to tackle that end, if I do prove that the pump is bad.
Thanks for all your good input.

Update. Got the new (OEM rebuilt) PS pump in. During the process, while using the tank and pully off the year-old pump, I discovered that the magnet was dislocated from the flat side of the casting and was covering the end of the supply through-hole! Not completely, as the surface there is concave. So, I checked my new/rebuilt pump and, sure enough, there's the magnet, covering the hole! Now, having 3 magnets to choose from, I found that the old, original pump, had an obviously stronger magnet, which I cleaned and installed on the proper flat in the pump. Installed, flushed and topped up the system, drove a couple of miles, with nary a moan. Topped it up, took a longer drive and topped it up, again. Have ~40 miles on it, and it looks like Maverick hit it right on the head. I don't know for sure, having never been through the issue, before, but it seems logical to me, that the magnet, nearly blocking the fluid supply on one side, would create a lot of cavitation in the pump, at the very least. Anyway, this pump required no fiddling with purging at all, so far. Unfortunately, there are now other issues, with getting the 30+ year-old 6.5 to keep running (See "Where do I start."), elswhere.