Running warm (Nearing Hot) and radiator questions (SBC)

[Cataldo]

Michel, that is a good article, it explains things nicely. Yeah I need to go through and replace a lot of the vacuum lines as a whole, when I do so I'll figure out the best place to plumb it in, probably a t fitting as you mentioned unless I can figure out a 'cleaner' way to rout it. I am kinda picky on wires/hoses/vacuum lines running all over the place, so I am going to spend the day and mess up well established success. haha

Although 210* is not too hot, it is past the point of peak efficiency, new cars run that hot for emissions reasons. They run thermostats that high for that reason, and with a proper cooling system it should stay at the regulated temperature (Thermostat setting) within a few degrees through thick and thin. With a low load 'high speed' (Basically not idling or low speeds) the engine should run on the thermostat setting, within a few degrees. This is where I am having my issues.

Running down my mental check list of what it could be's:
-Blocked/damaged radiator
-damaged water pump (Impeller damaged)
-Improper air flow through radiator, like Kenne Mentioned, where at a certain speed the air coming into the radiator is more than what is able to evacuate from under the hood. This could be caused by a few things to my understanding: a lack of a path for the air to escape (Like under engine mats and air diffusers), a mechanical fan that is spinning at whatever RPM allowing X amount of air through when >X is trying to go through from the vehicles speed (Usually with mechanical fans and not clutch fans), or restrictive fan shrouds (That cover the whole radiator and have too small of fan openings, many electric fan shrouds have little flaps that will open up at speed but close up when not going fast enough so that the fans pull all their air through the radiator core).

The problem is discovering what/which is the pending issue.

EDIT: I drove the Wagoneer to work today with my vacuum advance unhooked, just for S&G's. Other than getting poor...er fuel mileage it ran nearly the same and got just as hot, about 210* maybe 215*.

[Tatsadasayago]

Can't underestimate the value of a good clean radiator...

I passed smog here in Sacramento with the 76 401 Wagoneer but it ran VERY warm (220+) in the 100+ degree heat. I switched everything back to manifold vacuum, reset the base timing and it ran much better, but was still too hot. The radiator didn't leak, but was showing some white corrosion in the tubes so I ordered a new replacement from Eagle Radiator (My friend Ben) up in Diamond Springs.
I made no other changes besides using fresh coolant and immediately the 401 ran at a max of 195F sitting in traffic on I-80 or running 75Mph down Hwy 99 in the heat of the day.
I suspect the old rad was just not very efficient any longer.

Something to ponder anyway.

[letank]

Can't underestimate the value of a good clean radiator

X2, and the cheap approach is to clean the system with some Presto--- or other brand chemical for neglected cooling system. I did this on both wagoneers, and the amount of rusty water that is coming out was mindboggling, especially that the 74 has been mine for over 30 years and I only used distilled water, in fact, before I used the chemical flush, when I redid the intake manifold gasket, there was some serious sludge in the back. It took about 50 gallons of garden hose flush to obtain clear water, and yes the average temp dipped from half to 1/4.

There is a video here

https://www.youtube.com/watch?v=2JBm72fqK00

or this approach

https://www.youtube.com/watch?v=s--5ft5YiHg

[Cataldo]

Yes good idea on the radiator flush. It looks fairly new but flushing it never hurts

[letank]

Yes good idea on the radiator flush. It looks fairly new but flushing it never hurts

The radiator can be new, but the flush works on all the other parts of the cooling system. I was talking to a retired mechanic today, and he uses some detergent used to clean walls, not TSP, it a non sudding detergent....

http://www.leguidedunettoyage.fr/lessive-multi-usages



Cannot find the back passage picts, but this was close this:

[tgreese]

Before the days of the EPA, mechanics used oxalic acid, followed by a neutralizing wash, to clean cooling systems. Prestone sold a two-part kit for this. This material is no longer available as radiator flush, but you can still buy the materials and follow the procedure.

There was also a GM TSB for this - it's reprinted here - http://www.corvetteforum.com/forums/c3- ... flush.html

"Prestone used to make a cleaner for GM P/N 12346500.
It was also sold under Prestone P/N AS100 Heavy Duty Cooling System Cleaner
Here is the GM TSB and Instructions #99-06-02-012D (Online or at a GM dealer)
It is not made anymore but these are the components.
9 dry oz of Oxalic Acid (DAP Wood Bleach)
2 dry oz of Sodium Carbonate (Arm & Hammer Super Washing Soda)"

Then the TSB instructions follow.

Usual cautions apply. Oxalic acid can be dangerous if mishandled, so read the Wikipedia page https://en.wikipedia.org/wiki/Oxalic_acid and its attached MSDS about it. Dispose of the waste water conscientiously. I would gather the rinse water, neutralize it, and pour it down the drain. Don't let it drain on your lawn or garden or drain into the storm drain.

[SJTD]

I wondered if the two part flush was still available.

It works well because oxalic acid reduces, in the chemical sense, the rust back to iron. In doing so the rust shrinks since a rust molecule larger than an iron molecule and tends to break loose.

[Cataldo]

Huh! I like this idea a lot! Just need to figure out a proper disposal plan. I have yet to actually use a flush kit, always just used a water hose and pressure washer.

[letank]

try the available in a bottle at your part store: Prestone super flush and cleaner

After draining your current coolant, fill with distilled water and the super flush for a few hours, IIRC 300 miles or 6hrs

[Cataldo]

Yes sounds easier, and lest caustic

[letank]

Yes sounds easier, and lest caustic

Very easy, the recovered original coolant can be disposed at your local waste station.

[Cataldo]

Thanks for the heads up!