A couple of mid-nineties GMC truck questions...

Still looking for winter wheels, we looked at a '95 GMC K1500 w/ L05 350. Seems to drive OK, no funny noises despite it having 240k on the clock.

There were two things I noticed - one, the brake pedal was soft and had quite a long travel before the brakes would engage. It does however look like the brakes are working OK - is this normal on these or do I need to check the brake system over for problems? Pumping the pedal didn't make a difference, by the way.

Second, the coolant was grotty brown - assuming that I'm not looking at a special new fluid I guess that should be fixable with a coolant flush (especially as it's had a new radiator recently so they might have thrown some gunk in there to stop the old one from leaking).

Any other common problems with these that I should have looked for with one of these?

Bah.

Some googling suggests that soft brake pedals are fairly normal with these.

Unfortunately some Autochecking also revealed that it's had an accident last year. Gah. I don't think 400 bucks below KBB private/good are a reasonable enough discount for that...

My early 90s 2500 always has a soft feeling pedal. They always worked until a rusted line let go, it was ok though since the truck ahead stopped it rather well

Yeah, I'm hoping that's not where the accident record came from

The soft brakes will be improved by adjusting the rear shoes and flushing the brake fluid. They always feel a bit soft, though. The rad will have dexcool in it, which may have developed a sludge on top from having air in the system. If its real brown, you may end up popping out some core plugs and getting very wet with a garden hose.

It's fairly brown - I guess if I ended up buying it, I'd get the coolant flushed to see if it improves matters before I started getting a bit more serious on it.

And straight from the unlucky files, the accident record supposedly came from a little bump that didn't cause any more than a scratch (which I noticed when viewing the vehicle). In a sense it would have been better if it had resulted in a repair bill...

Don't get them. The fuel pump assembly/wiring was VERY poorly designed and melted/caught fire quite often. I worked auto parts for 6 months and literally sold 3 fuel pumps with wiring harnesses per day my entire tenure. It was the #1 part by a looooong shot. If somebody walked in and said "90-98 GMC.Chevy" I'd actually ask "fuel pump" before anything else.

A lot of them burned ALL the way...

Well, I better bone up on the comprehensive cover then (and look at the wiring if I decide to get it).

One odd thing regarding the coolant - the truck had a new radiator installed and had the cooling system flushed. Yet, it's still (or again) showing brown-ish sludge.

Javelin wrote: Don't get them. The fuel pump assembly/wiring was VERY poorly designed and melted/caught fire quite often. I worked auto parts for 6 months and literally sold 3 fuel pumps with wiring harnesses *per day* my entire tenure. It was the #1 part by a looooong shot. If somebody walked in and said "90-98 GMC.Chevy" I'd actually ask "fuel pump" before anything else. A lot of them burned ALL the way...

there are a LOT of 90's Chev/GMC trucks around here, and i've never heard of any of them burning down and the only fuel pumps i know of being chronically bad were the 96-99 vortec pumps.

good example: this spring, i paid $250 for a 95 Suburban 2wd that had 375,000 miles on it that ran and drove beautifully and had full service documentation from day one. the only major repair was a new radiator a couple of years ago- everything else besides normal stuff like brake pads/shoes was original.

the brake pedal was soft when i got it, but a new set of front pads and rear shoes and a brake fluid flush took care of that.

my brother bought it from me for $300 and is averaging 17mpg with it and enjoying more room than he really needs for his 3 and 1 year old daughters.

Streetwiseguy wrote: The soft brakes will be improved by adjusting the rear shoes and flushing the brake fluid. They always feel a bit soft, though. The rad will have dexcool in it, which may have developed a sludge on top from having air in the system. If its real brown, you may end up popping out some core plugs and getting very wet with a garden hose.

1996 was the first year for DexCool. 1995 still had green conventional.

The '95's had the traditional SBC, where the '96 and newer had the Vortec heads. They were a great improvement, although the '95 was decent (I have 195,000 miles on mine).

Like SWG said, the brakes should be flushed and adjusted, which will help.

Other than rust, there's not too much to worry about in these trucks. If it has been decently maintained, you'll have a good truck for many more years.

Oh yeah, if the fuel pump does go bad, which is common, but not as bad as you may think, remove the bed (or at least lift it up on the left side) to change the pump. That will make the job much easier.

I've put one pump on my truck in its 195,000 miles; that's not too bad.

Dexcool = brown sludge. The PO or shop may have "upgraded" their coolant. Flush it, and flush it well. That stuff is garbage.

Well, the quotes from a couple of local places including the Chevy dealer weren't too bad for flushing the system so I think I'll take the risk and make the guy an offer on the truck. He'll probably say no to it anyway.

Service advisor at a Buick/GMC dealer at about that time.

If you do go through with buying it, you need to flush the snot out of the cooling system with chemical flush, not just the drain/refill thing lots of places call a flush. That brown crap will keep coming back if that's not done and you still may get a little even with that.

The aforementioned fuel pump issue was a biggie. I was in a Wendy's drive thru in the Jensen with the top down and the radio going, I kept hearing a buzz. It was the Chevy pickup ahead of me, the fuel pump was howling like a banshee.

That one has probably been fixed already, but the mid '90's Chevy V8's were pretty hard on valve stem seals. The springs on the early design seals would break and voila puffs of blue smoke and high oil consumption.

And to make matters worse, another truck that I have looked at before, decided I like but then misplaced the owner's phone number has just popped up again.

So I've now got a choice between a '77 Ford F150 with camper shell, very little rust that drives nice (for such an old truck) and could double as an off-roader, and the aforementioned '95 GMC. The '77 is similar money as the GMC, will need the driver's side floorpan redoing soon and a new throwout bearing but it's got something like 80k on it and drives like it the mileage is genuine.

Given that a truck for me has to mainly get me to work in winter (hence the AWD), do the occasional trip to Ikea and dragging a trailer with a bike to the DMV, I'm beginning to wonder if an old truck that can be repaired with a hammer and a broken screwdriver would really be such a bad idea.

Jensenman wrote: Service advisor at a Buick/GMC dealer at about that time. If you do go through with buying it, you need to flush the snot out of the cooling system with chemical flush, not just the drain/refill thing lots of places call a flush. That brown crap will keep coming back if that's not done and you still may get a little even with that.

Both places I spoke to (local independent and the local GM dealer) pointed that out so I'd hope their service departments would be able to follow through with that.

I did the fuel pump on my '91 without even fully removing the tank, just lowered it a bit and pulled the sending unit. Of course the pump would have been fine, it was a plugged fuel filter that was the real problem.

I was the third owner of mine, with 280k before it went in on CFC, and I knew both of the previous owners. It went through either a heater core or radiator every year for the first 12 years of it's life. Only after nearly a dozen of each did the owner add a good solid ground strap to both, and it went on to almost twice the replacement interval. Seems they had some electrical issues in the cooling system, and the Dex cool only made it worse.

nasty brown coolant = headgasket?

not unheard of for 240k miles. i had an L03 305 at 212k with nasty brown coolant, tossed it in another car and drove it 6k more miles and it finally let go all the way - 9 hours from home on I-95(world's longest parking lot) in 100 degree weather. pulled the t-stat which kept it just under the red while moving, and did make it home, overheating the crap out of it in the mountains. parked it, when winter came i drove it for 6 more months since it did not overheat under 40 degrees.

patgizz wrote: nasty brown coolant = headgasket?

My thoughts exactly. What's in Dexcool that causes the brown sludge?

alex wrote:

patgizz wrote: nasty brown coolant = headgasket?

My thoughts exactly. What's in Dexcool that causes the brown sludge?

I don't know, and I cannot rule out a headgasket, obviously, but every Dexcool filled vehicle I've worked on had nasty brown sludge in the coolant reservoir. On my parents ride, it actually caused it to overheat because the coolant wasn't liquid anymore. On a very old V8 design that doesn't really have headgasket issues, I'd go with a coolant flush every time.

What concerns me is that the owner's uncle and grandfather (both Chevy mechanics) supposedly took great care flushing the cooling system including the heater when they replaced the radiator earlier this year. Given the condition of the rest of the truck, these people seem to know what they're doing and put a decent amount of effort into maintaining the truck.

Nevertheless it's got brown sludge in the header tank six-odd months after they supposedly flushed the system and refilled it with new coolant.

I got back to the owner and basically suggested that I didn't want to insult him with an offer that was low enough for me to take the risk with the cooling system issue and the accident record and he already knocked about $400 bucks off. Trouble is, we're still about $300 over what I'd be willing to pay, max...

I'm beginning to warm to the idea of that late 70s Ford truck although I'd admit that something a little newer would probably be much nicer to drive.

alex wrote:

patgizz wrote: nasty brown coolant = headgasket?

My thoughts exactly. What's in Dexcool that causes the brown sludge?

The internet is awash with info on this. Dexcool, aka "Deathcool", is said to form the brown sludge whenever it is allowed to come in contact with air, as is the case when the vehicle is operated when the cooling system is less than completely full.

http://www.reuters.com/article/idUSN2735011520080327

Just google "deathcool" or "dexcool sludge" and be amazed at the number of people who have experienced the joy of GM ownership.

BoxheadTim wrote: What concerns me is that the owner's uncle and grandfather (both Chevy mechanics) supposedly took great care flushing the cooling system including the heater when they replaced the radiator earlier this year. Given the condition of the rest of the truck, these people seem to know what they're doing and put a decent amount of effort into maintaining the truck. Nevertheless it's got brown sludge in the header tank six-odd months after they supposedly flushed the system and refilled it with new coolant. I got back to the owner and basically suggested that I didn't want to insult him with an offer that was low enough for me to take the risk with the cooling system issue *and* the accident record and he already knocked about $400 bucks off. Trouble is, we're still about $300 over what I'd be willing to pay, max... I'm beginning to warm to the idea of that late 70s Ford truck although I'd admit that something a little newer would probably be much nicer to drive.

OK fine, so they flushed and refilled it six months ago...

WITH DEXCOOL!

And now you have more brown sludge. What are we surprised about?

Hmm. So I should probably get rid of the orange junk in my 305 GMC, eh? Flush it and go straight to normal stuff?

Well, I'm wondering if I've made a mistake and how bad a mistake I made...

I did end up buying the GMC after getting it down to a more reasonable price (for around here, where the redneck tax seems to be really high).

Had to top up the engine oil (by a quart, hmm), it runs OK and pulled up the pass OK - not spectacular but I wasn't holding up traffic. Despite the brown colour of the coolant the temperature staid right at the 210 mark uphill. So far, so good. Oil pressure around 40 hot off-idle, which seems to be where my Corvette (same engine) also has the oil pressure when the oil is properly hot.

I noticed a little play in the drivetrain - there's an occasional light 'clunk' when transitioning from engine braking to the engine driving again - but it still felt OK.

Trouble is , on the way home the 'service engine soon'[1] light came on and when trying out the 4x4 system I noticed that the transfer case (mechanical floor shifter) was extremely uncooperative once I drove it a few hundred yard with 4H engaged - it made interesting graunching noises when trying to shift between the various settings with the trans in neutral and the engine running plus 4L and 4H seem to be the same ratio. Uh oh. Oddly enough both times when we switched between 4x4 and 2WD during the test drive there were no odd noises from the transfer case.

Anyway, looks like I do need to spin some wrenches tomorrow - basic tuneup, most likely an oil change and I'll see if I can get at the transfer case and at least check the fluid level. Probably check the fluid levels in the diffs, too...

Oh, and then go over the whole thing and see what else I missed before handing over the cash.

[1] I'm assuming that's GM-speak for a check engine light