Cooling System Upgrade/Replacement

[TheRedMamba]

I've seen that plunging behavior when there was an air pocket in the vicinity of the thermostat. Make sure that
you have the overflow tank in place and keep filling it back up to the cold mark until the system quits burping
air/slurping water to replace it. Once the system is 100% coolant I wouldn't be surprise to see the coolant
temp climb to the t-stat opening point and just stay there.

FWIW --

Bet! I just went out and filled the overflow bottle since the drive did drain it after letting her sit all day. The radiator was pretty much tip top full. I also did the usual upper hose burp, etc. initially. The top oil cooler line that puked on the 1st start up after the repair required just a skosh of oil as well.

 

[TheRedMamba]

I work at AutoZone. I HIGHLY recommend against a failsafe thermostat. They are junk. They always fail, and cause issues. I've never had one last more than 6 months.

Appreciate the info. Hopefully you've had good feedback on the Duralast Gold Thermostat? There's a pic posted on page 3 I believe. Cheers

 

[TheRedMamba]

I know this pain...

On my '92 I wanted to upgrade the oil filter housing to the one used with the '97-'99 and ditch the crappy connectors for the oil filter lines coming from the radiator to the housing. I also needed to update the radiator from the same years for it has the correct fittings for the new lines. Everything was found at the treasure yard, had the radiator pressure tested and cleaned, to this day all is great! No more leaks from those plastic connectors BS...lol

I truly hope I see your kind of success with my whole repair and decisions made on parts etc. I'm not a huge fan of wrenching on whips, but I'm a solid wrencher with decent knowledge. Growing up my father repaired and wrenched on semi pro race cars on the weekends and I was expected to be present hence my not being a fan of wrenching, but having the capabilities to make it happen, so I guess the longevity is what justifies and grades your skill. I guess??

 

[TheRedMamba]

I've seen that plunging behavior when there was an air pocket in the vicinity of the thermostat. Make sure that
you have the overflow tank in place and keep filling it back up to the cold mark until the system quits burping
air/slurping water to replace it. Once the system is 100% coolant I wouldn't be surprise to see the coolant
temp climb to the t-stat opening point and just stay there.

Q: What was the original failure? Just a leaky radiator? Or was the cooling system being pressurized >15 lbs
and blowing hoses off? Just trying to understand what's going on with your cooling system.

FWIW --

So like a month ago the upper hose came off while driving, when I removed the hose completely... Like 75% of the attachment on the radiator had broken off and was inside the hose. So 4 super glue and clamp repairs later... Phuck.... Right! I had a few days off so I got my parts, a plan, research, the usual and handled it. Also, 2 days before launch, the water pump started dripping while she was parked and the engine off. Possibly I made this happen with my mind because a new water pump was happening anyway, everything I did was a solid decision I feel since you're going to be up in there anyway and for a tight budget I think the parts are quality and hopefully the workmanship will be quality, then the $168 spent will be well worth it.

 

[Road Trip]

So like a month ago the upper hose came off while driving, when I removed the hose completely... Like 75% of the attachment on the radiator had broken off and was inside the hose. So 4 super glue and clamp repairs later... Phuck.... Right! I had a few days off so I got my parts, a plan, research, the usual and handled it. Also, 2 days before launch, the water pump started dripping while she was parked and the engine off. Possibly I made this happen with my mind because a new water pump was happening anyway, everything I did was a solid decision I feel since you're going to be up in there anyway and for a tight budget I think the parts are quality and hopefully the workmanship will be quality, then the $168 spent will be well worth it.

Sounds good. I much prefer a straightforward parts fatigue type failure as opposed to an
issue where the cooling system is being pressurized from a failing spot in a head gasket.

Sounds like you managed to add some cooling system headroom by a savvy treasure yard
upgrade while you were at it. Good call.

Best of luck keeping your GMT400 on the road --

 

[Dravec]

Appreciate the info. Hopefully you've had good feedback on the Duralast Gold Thermostat? There's a pic posted on page 3 I believe. Cheers

That's actually what I run personally in my trucks. I've had pretty good luck with them, and very few warranty returns on them.

 

[Erik the Awful]

I ran one of those "Safe" radiator caps on my RX-7 for several years. It worked, but they're a gimmick. I think they also work better on older cars that ran lower cooling system pressure. When it comes to removing the cap on a hot engine, they're no safer than a normal cap. (Yes, you can remove a cap from a hot cooling system, but it's really f***ing dangerous if you don't know what you're doing, and it's still pretty f***ing dangerous if you do.)

 

[Schurkey]

1. I just love the concept of the lever-lift radiator caps. I'd have one on EVERY vehicle I own...If I could get them to hold pressure. I've got a few nearly-new lever-style caps back in their boxes, sitting on a shelf in the parts cabinet in the shop. Lift the lever, all the pressure goes to the overflow bottle--and I don't have to touch hot metal ('cause the lever is plastic, which is an insulator) let alone grab the cap firmly enough to twist to the "first notch" before releasing pressure. Once the pressure is released, a copulating anthropoid can safely remove the cap.

MORE important--and this comes from a life lived before the advent of cell-phones--is that SWMBO never had to touch hot metal to release pressure if there were some roadside failure.

Those lever-release caps worked just fine (on other vehicles than the ones I have now.) Which makes me think that they've been cost-cut to the point of failure.

2. I remember when thermostats could be counted-upon to work properly out-of-the-box, and for years if not decades afterwards. At some point they might fail closed, or they might fail open, but a "new" thermostat would immediately fix the problem. Starting perhaps twenty years ago, I've had more "new" thermostat failures than I can count. And even the ones that "work" do so in a sticky, digital manner. The engine gets too hot, the thermostat pops open too far, the engine gets too cold, the thermostat shuts...and it bounces between too hot and too cold for too damn long before it finally stabilizes at a reasonable temperature.

This has happened to me with Stant, Robertshaw, and Motorad thermostats including the Motorad in my '88 K1500. Thermostats have become a high-failure item.

 

[TheRedMamba]

If interested....

Skill Level: Intermediate

Experience: Yes done before. 1st time on a truck. Repair done in visitor parking of an apartment complex I do not reside at.

1. Removed the upper fan cover. 3 bolts across the top, above the grill and 4 bolts (2 on each side) connecting the upper and lower fan cover

2. There were no top radiator anchors on babygirl. So I removed the upper radiator hose from the radiator side, overflow bottle hose, and a 3/4" hose below the overflow bottle connection, not sure what it handles, from the radiator side as well. It's easy to stick them behind something to keep them from leaking

3. Removed the upper and lower oil cooler lines (driver side) and transmission cooler lines (passenger side) of the radiator. Stuffed small rags in each to keep from leaking

4. Eye balled the catch bucket for the cooling system drain. Removed lower radiator hose (passenger side) from radiator and directed the flow into the bucket (no spillage)

5. Removed radiator completely with no additional hardware to remove

6. Removed lower radiator hose (passenger side) from engine block

7. Removed the serpentine belt. My tensioner is located on the upper passenger side of center of the engine block

8. Removed fan blade from water pump (center of engine block) 4 bolts between back of fan and pulley for water pump. ***I did loosen with the serpentine belt still in place because you need the tension to loosen the fan blade bolts, also if you have the factory metal 5 blade fan, there's a larger gap between two of the blades for easier access to each bolt

9. Removed all 4 studs by tightening down each bolt all the way then backing them out, cleaned them up and installed into the new water pump pulley using orange thread locker. Then removed the water pump (center of engine block). 4 bolts, 2 each, driver and passenger side. I did get a small amount of seepage so be aware

10. Cleaned all engine block mating surfaces for the water pump with a brass wire brush, both hand and drill operated, a metal scraper and rag. Important to take your time. No scratches and no old gasket residue, cleaned all bolts as well.

10.5. Yes there are still some things some of you would have done already, but bare with me.

11. Applied gasket sealer to water pump, let stand 5 mins to get tacky per instructions, applied new gaskets, applied thread sealer with PFT to 2 bolts

12. While the gasket sealer is getting tacky, applied the same gasket sealer to the engine block and installed new radiator moving bottom rubber supports outward and using upper radiator supports. Got them from boneyard with new radiator

13. Installed the new water pump by placing 2 bolts into the top water pump holes and attached to the engine block, finger tight, then did the same to lower bolts, torqued to 30 lbs per service manual. Let dry overnight

14. Removed upper radiator hose from thermostat housing along with thermostat housing and old gaskets, cleaned mounting surface. Moved ground to a new ground location just below the original mount. Doesn't make sense it's a good ground with a gasket between block and ground

15. Painted thermostat housing, fan blades, and water pump pulley cover black before reinstalling. After paint, installed pulley cover and fan torqued to 30 lbs. (Must have serpentine belt reinstalled to tighten and torque fan blades to pulley cover) along with new thermostat and Thermostat housing torqued to 20 lbs.

16. Installed new lower radiator hose along with oil cooler lines and transmission cooler lines

17. Installed new upper radiator hose along with new fluids

4 hour job to completion
Hope this helps. Cheers

 

[Schurkey]

but bare with me.

I will remain fully-clothed, thankyouverymuch.