...Interesting comment about pink versus green coolant. Yes, I am running pink coolant in the Suburban. Doing so means I only have to keep up with one type of coolant. I never thought it could cause an over heating problem...
Forum member ROBERT CROSS replied to a PM I sent him about DexCool:
Quote:
... Probably the biggest mistake people make with antifreeze is the mixture. It needs to be a 50/50 mixture, without the proper amount of water a straight mixture will not cool properly.
Just that the impeller on the water pump is a couple of inches from the block, with a steel plate on the back of the pump. I would think if the impeller were slipping, it would do so more at higher engine speeds, as there would be more resistance to movement from the natural viscousity of the coolant.
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Meddle not in the affairs of dragons, for you are crunchy, and taste good with ketchup.
Terry
Forum member ROBERT CROSS replied to a PM I sent him about DexCool:
Anyone have anthing to add?
Tom
That PDF link posted recommended a 44/56 antifreeze/water mix caught my eye.
I had read a good coolant article many years ago in Car & Driver and it had a lot of good info about Red verses green and mixtures including a 40/60 for warmer climates.
One thing I remember about that article is NEVER put Red in an older vehicle.
have you checked the radiator for blockage ? you have hit on everything but that.A BLOCKED RADIATOR STILL SHOWS FLOW HAVE A hand held heat sensor movineing along the rad checking the temp from top to bottom and side to side.on that year vechile with milage you can expect some blockage. it happened to my truck and I change my antifreeze evey 2 yrs.had the rad recored and no more problems.boiling it out weakened the core on mine thats why the recore.
The fan clutch is brand-new, and operates like I think it should.
The last one lasted about three years before leaking all it's silicone fluid out and doing nothing but freewheel.
The one before it seized on my Overlander's first trip.
My Quadrajet has the throttle shaft play you mentioned. If I could find a decent machinest AND new bushings, I would fix it. Care to recommend anyone?
Thanks for your insight - I do appreciate it.
Tom
Tom;
I checked for all applicable TSB's on '84 model w/7.4 engine for overheating.
There are 3 TSB's (Technical Service Bulletins). They include pictures which for some reason don't open up in PDF format (?). I'll break this into 2 posts as follows; this post has 2 PDF's. One is a supplement to the other. Both have the same illustrations, so I won't duplicate. I would give serious consideration to an add-on GM electric cooling fan (part # in TSB) as this is an identified problem that relates to your symptoms in your 1st post.
As far as the Rochester Quad goes, I would suggest a machinest that has worked with aluminum and have some brass bushings made to fit the throttle plate/shaft. The only other quad issue has been the power valve has been known to stick in the down position resulting in noticeable loss of power. #0000 steel wool takes the scoring out of the brass valve restoring free up and down travel. No parts needed providing the air horn gasket isn't damaged.
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Larry & Sandy
08 Classic 30
05 GMC K2500 Duramax Four Courners Unit
WBCCI # 2460 AIR # 17259
Tom;
Here is the last TSB, which you should read first. Take note of the dates of each TSB. Before I spent any $, I'd verify good airflow through any coolers, condenser and lastly the radiator. There should be no debris causing any restriction. Per this TSB, I wouldn't worry about casting flash. With high miles, head gasket deteration would be a last resort possibilty. Hopefully this wil provide some direction for a cure to your woes with minimal expense.
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Larry & Sandy
08 Classic 30
05 GMC K2500 Duramax Four Courners Unit
WBCCI # 2460 AIR # 17259
Last week I got O'Reilly's Auto Parts to order me a new, heavy duty water pump:
Quote:
Originally Posted by O'Reilly's web site
MASTER PARTS DIVISION - New Water Pump
Limited lifetime warranty
HEAVY DUTY WATER PUMP
INCREASED COOLING CAPACITY/HEAVY DUTY COMPONENTS
It came in on Friday, and the Store Manager laid it out on the counter beside a regular duty water pump for my inspection. Without taking the backing plate off (did you catch that, Terry ), I couldn't see any difference between the two pumps. I was hoping the super-duper pump would at least have a glitzy paint job.
The manager, who appeared to have turned a few wrenches in his life, could not shed any additional light on the subject and admitted this was the first one of these pumps he had seen. Hoping that the pump might help, I went ahead and bought it.
Here is a picture of the old water pump with the backing plate removed:
There does not appear to be anything wrong with it. The impeller neither loose on the shaft nor rotted away. Several threads from another forum drove me to look at the impellor clearance, which was measured to be [about] 0.070":
Pulling the backing plate off of the super-duper water pump, there was one immediate, noticable difference - a round plate riveted to the impeller:
With my limited knowledge of hydrodynamics, I can see that plate making a difference in the pump's efficiency. Since the plate is there at all AND it is riveted on, I must assume this was the manufacturer's concession for "increased cooling capacity". My reasoning here is that nowadays, manufacturers don't add parts that are not essential to operation or to back up a claim.
Everything on the HD pump I could measure was the same size on the regular pump.
I also flushed the system and went back to green coolant.
Although the Overlander's next trip is still a week-and-a-half away, I will drive the Suburban to work this week to get all the bubbles out of the cooling system and gauge the truck's "unloaded" performance.
Check for either plugged tubes inside the radiator, or the cooling fins coming loose from the tubes. The other thing it could be is dirt plugging the fins.
Tom, the plate on the back of the impeller is to reduce cavitation, and increase coolant flow.
For those who don't know, but do care, cavitation is caused by extremely low pressure allowing water to boil at very low temperatures, hence the bubbles (boiling water). That is one of the reasons submarines travel in very deep water, the higher pressure from the water decreases the tendency to cavitate behind the propeller (boiling water is noisy). The boiling cold water can cause damage to metal parts as well as noise, and cause a loss in efficiency of the device moving the water.
__________________
Meddle not in the affairs of dragons, for you are crunchy, and taste good with ketchup.
Terry
Although the Overlander's next trip is still a week-and-a-half away
It's onward ho to Jackson MS with all the replacements/improvements. We're staying at a new Camp Jellystone near the area while attending my Uncle Bill's 70th birthday party (read: family reunion).
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The impeller neither loose on the shaft nor rotted away. Several threads from another forum drove me to look at the impellor clearance, which was measured to be [about] 0.070":
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