96 GMC K2500 Suburban Restoration (with a couple of mods)

[Erik the Awful]

I'm guessing that whoever did it cranked the nut down with a wrench and cheater bar, because it might as well be welded in place. I tried various means to get it to loosen up, but finally gave up for fear of wringing it off and possibly damaging the water pump.

Cross threaded the wrong thread pitch, most likely.

 

[OutlawDrifter]

As posted in another thread, my attempt to install the new fan and clutch was thwarted by a 12mm nut that some ‘mechanic’ substituted for one of the ½“ nuts on the fan mount hub. I'm guessing that whoever did it cranked the nut down with a wrench and cheater bar, because it might as well be welded in place. I tried various means to get it to loosen up, but finally gave up for fear of wringing it off and possibly damaging the water pump. At this point I'm not confident enough in my ability to get that done before we leave early Monday morning. And, back in the day, I would have waded in and put everything else on hold to get it done. After all, at worst it's just a water pump replacement. But after thinking about it, particularly about the time involved and everything else going on, I decided I’d be better off to just have Jim’s shop do it. I'm grateful that he's willing to work me in, even though he's pretty much booked a week or two in advance. So I put it back together and will take it in today and let them deal with it while I attend to some other matters. It seems that I'm getting more risk-adverse as I get older.

Also, after 22 years my heretofore trusty Rolair compressor decided to stop working, apparently due to a failed pressure switch. Getting a new switch will take some time, as the compressor is so old. So I'll ask Jim to blow out the stack while it's there for the fan replacement.

So two of the three variables I intended to address before this trip will be attended to. The third, the cooling system drain and flush, will have to wait until we return.

Will the water pump be replaced? Or just trying to remove the offending nut/bolt combo?

 

[South VA]

Will the water pump be replaced? Or just trying to remove the offending nut/bolt combo?

Just trying to remove the nut and stud; but the water pump is potential collateral damage. I wasn't willing to take the risk of having to replace it in the available time frame.

 

[OutlawDrifter]

Just trying to remove the nut and stud; but the water pump is potential collateral damage. I wasn't willing to take the risk of having to replace it in the available time frame.

If the pump has to come off, it's a great time to do the flush...just forward thinking.

 

[South VA]

If the pump has to come off, it's a great time to do the flush...just forward thinking.

I was thinking that as well.

 

[South VA]

Jim did the work himself, which he does when they're backed up or someone is out. He got the nut off, and apparently the threads were ok. Put on a new nut and it's good to go. No new water pump needed. That's a relief.

 

[South VA]

Also, Jim told me the fan clutch was shot. I've had the new one sitting on the shelf for probably six months, and so am glad that wasn't wasted money. I'm really looking forward to seeing how the new fan/clutch combo works. He says it's a much better fan design than the original. Even pulling out of the shop, I could hear a difference.

As I think I've mentioned before, most of the time when I talk with Jim I learn something useful. Yesterday after he finished installing the fan and clutch, we were talking about my daily driver, which has been in his shop for over a month now (!), for a clutch replacement and some other stuff. He's had a heck of a time getting the right clutch slave cylinder, and has had to take it apart multiple times now. The latest iteration is he found what he thinks (and hopes) is the correct one, sourced from an eBay seller in Australia. That doesn't surprise me, as I've searched for other parts for that car and found incorrect listings, even though they had the same part number. It's a particular problem with the HHR SS, which was a comparatively low production vehicle, and many of the parts differ from the regular HHRs.

Anyway, we were talking about port injection vs direct injection (a '96 Suburban is the former, and my '08 HHR is the latter) and the importance of fuel choice in a DI motor. I always run premium in the HHR, which is recommended but not required. This then led to a conversation about fuel type in the Subdivision. He surprised me by saying that I'd be much better off using premium while towing, due to the higher potential for detonation under heavy load, which shortens the life of the motor. More expensive, of course, but well worth it. He said to save some money, a 50/50 mix of regular and premium would be enough to get the octane up to ~90, which would do the trick. FWIW, he also owns a gas station on the premises, but I don't buy my gas there. But he seems to be knowledgeable about fuel.

I'm going to give it a try. While I'm not happy about the higher fuel cost, his explanation made sense to me. Until now, I've used the cheapest regular I could find. At the first fill up on Monday's trip, I'll switch to premium. I'm wondering if it will help with gas mileage. We'll see.

 

[HotWheelsBurban]

Also, Jim told me the fan clutch was shot. I've had the new one sitting on the shelf for probably six months, and so am glad that wasn't wasted money. I'm really looking forward to seeing how the new fan/clutch combo works. He says it's a much better fan design than the original. Even pulling out of the shop, I could hear a difference.

As I think I've mentioned before, most of the time when I talk with Jim I learn something useful. Yesterday after he finished installing the fan and clutch, we were talking about my daily driver, which has been in his shop for over a month now (!), for a clutch replacement and some other stuff. He's had a heck of a time getting the right clutch slave cylinder, and has had to take it apart multiple times now. The latest iteration is he found what he thinks (and hopes) is the correct one, sourced from an eBay seller in Australia. That doesn't surprise me, as I've searched for other parts for that car and found incorrect listings, even though they had the same part number. It's a particular problem with the HHR SS, which was a comparatively low production vehicle, and many of the parts differ from the regular HHRs.

Anyway, we were talking about port injection vs direct injection (a '96 Suburban is the former, and my '08 HHR is the latter) and the importance of fuel choice in a DI motor. I always run premium in the HHR, which is recommended but not required. This then led to a conversation about fuel type in the Subdivision. He surprised me by saying that I'd be much better off using premium while towing, due to the higher potential for detonation under heavy load, which shortens the life of the motor. More expensive, of course, but well worth it. He said to save some money, a 50/50 mix of regular and premium would be enough to get the octane up to ~90, which would do the trick. FWIW, he also owns a gas station on the premises, but I don't buy my gas there. But he seems to be knowledgeable about fuel.

I'm going to give it a try. While I'm not happy about the higher fuel cost, his explanation made sense to me. Until now, I've used the cheapest regular I could find. At the first fill up on Monday's trip, I'll switch to premium. I'm wondering if it will help with gas mileage. We'll see.

When I first switched to mid grade 89 octane gas last year, in my crew cab, I noticed that the mileage went up a couple of mpg, and the first few tanks continued that trend. Then the AC and blower motor started acting up and we had to drive with the windows down for a while till I could afford to fix it. Was still not working then so $$$ was tight.... I ran it for several more tanks once the AC and blower were fixed, but it got to where it was getting about the same mileage as it had with 87 octane. Once I figure out why the idle is still lopey and it's running rich, maybe I'll go back to 89 for loaded runs.

 

[Road Trip]

This then led to a conversation about fuel type in the Subdivision. He surprised me by saying that I'd be much better off using premium while towing, due to the higher potential for detonation under heavy load, which shortens the life of the motor. More expensive, of course, but well worth it. He said to save some money, a 50/50 mix of regular and premium would be enough to get the octane up to ~90, which would do the trick. FWIW, he also owns a gas station on the premises, but I don't buy my gas there. But he seems to be knowledgeable about fuel.

That is sage advice. And if your scan tool supports live data, watching the knock counts would eliminate
any guesswork in this area. In the old days you would hear the death rattle develop on long climbs once
the heat would build in the combustion chambers while max performance was needed to overcome the grade.
(And the more carbon that's built up in the chambers the more this problem would surface.)

Of course the knock sensors and VCM in your Subdivision start pulling the timing once the sound of
detonation/knock is detected. But retarding the timing causes performance to drop when you most need it,
as well as the fact that late timing leads to more heat build up.

Long story short, the higher the octane the slower the burn, which directly helps to avoid detonation = less
knock sensor activity = less timing pulled out. Some will argue that they've always trailered with no problem
running 87, and maybe they had a max-effort cooling system and no carbon build up in the chambers...but if
you are running elevated temps and pulling a heavy load, then your mechanic is on the money & guilty of giving
you good guidance.

Again, if your scan tool supports real time data then monitoring how many knock counts accumulate while
altering the octane you are feeding it will tell you if your combo has a normal/bigger than normal octane appetite
while you are towing.

Safe travels. And I'm looking forward to hearing what kind of temps you are seeing with the new clutch & fan setup.

Cheers --

 

[South VA]

That is sage advice. And if your scan tool supports live data, watching the knock counts would eliminate
any guesswork in this area. In the old days you would hear the death rattle develop on long climbs once
the heat would build in the combustion chambers while max performance was needed to overcome the grade.
(And the more carbon that's built up in the chambers the more this problem would surface.)

Of course the knock sensors and VCM in your Subdivision start pulling the timing once the sound of
detonation/knock is detected. But retarding the timing causes performance to drop when you most need it,
as well as the fact that late timing leads to more heat build up.

Long story short, the higher the octane the slower the burn, which directly helps to avoid detonation = less
knock sensor activity = less timing pulled out. Some will argue that they've always trailered with no problem
running 87, and maybe they had a max-effort cooling system and no carbon build up in the chambers...but if
you are running elevated temps and pulling a heavy load, then your mechanic is on the money & guilty of giving
you good guidance.

Again, if your scan tool supports real time data then monitoring how many knock counts accumulate while
altering the octane you are feeding it will tell you if your combo has a normal/bigger than normal octane appetite
while you are towing.

Safe travels. And I'm looking forward to hearing what kind of temps you are seeing with the new clutch & fan setup.

Cheers --

Thanks! That's exactly how he explained it. Using the scan tool to confirm is a great idea.

My scan tool does read knock sensor data; but out of curiosity, I checked my OBDII app, DashCommand, and was pleased to discover that it appears to have the ability to read knock sensor (KS) counts in real time. If that turns out to be so, I'll be quite impressed.

I just added a gauge to my DashCommand screen to monitor KS count along with Transmission Fluid and Coolant temps. I may wind up with a different gauge type for KS, but this will do for now.

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We'll see if it actually works when I fire up the Subdivision later today.

And I too am really looking forward to this camping trip; both because it's a new (to us) park that a number of folks have recommended, and because traveling there and back will provide an excellent opportunity to get even more real time data, to measure the effects of running premium fuel and the new fan/clutch combo. Makes me feel kind of nerdy.