dr bob

Rolled the car over into the workbay from its winter hibernation spot last evening. Our early snowstorm the week of Thanksgiving terminated driving season a bit early, so some of the normal pre-storage prep was delayed, including coolant change-out. It was last changed exactly two years ago, just before the car made the trek from the Los Angeles area to central Oregon. So no concern about the extra time really, and a pH test confirmed that it was not acidic.

With the car raised, I pulled the trays, then each of the block plugs one by one. Reservoir cap was left in place to slow the drain flow and help control the secondary splash area. Then the radiator drain. Got lots of coolant out but didn't look like four gallons in the catch pan. With all the plugs back in, lowered the car and... Discovered that the reservoir was still full. Leaving the cap on while draining kept the reservoir from draining.

So back up it went, and another round of pulling the drains and letting another half a gallon or more drain into the tub. Now it looks a lot more like four gallons in there.

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The drain plugs came out easily, thanks to the TFE thread sealing paste and reduced torque applied when they were last installed. Bolts and block threads look brand new, so back in they went with another dose of paste and 20 lbs/ft of torque again.

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Hope this helps someone who might otherwise leave a gallon of old coolant in the block by accident.

the flyin' scotsman

gr8 info, thx doc Bob.

Given the car now lives in cooler climes do you increase the a/f to water ratio? Assume you use a modern aluminium friendly coolant with distilled h2o.

dr bob

Used 25% with Water Wetter in distilled water the near-arctic climate found in the northern-most Los Angeles suburbs. At maybe 8 miles due north as the crow flies, so not the coldest spot in the world but had to be close.

Moving to central Oregon where it does get wintry cold once in a while, increased concentration to 50%. No need for Water Wetter at that concentration, at least so far. I haven't experienced anything close to 100ºF+ SoCal temps while here, so there hasn't been any real hot-weather test of that concentration's performance without Water Wetter. I don't intentionally drive the car at freezing temps, but keep the appropriate protection just in case.

The car has had Zerex G05 for all but the first couple years of my stewardship period, when it had a yellow/green coolant installed as part of a dealer TB/WP done prepurchase. The car had a full dealership history prior to my purchase.

Mrmerlin

Bob the Zerex coolant I have been using has a note on the label good for 5 years and 100 K miles,
if you tested it and found it not acidic why change it in 2 years?
The change the coolant every 2 years was made back when the coolant additive packages didnt have the properties that the modern coolants now have
I mix mine with 2 gallons of Zerex to 2 gallons of distilled water

hacker-pschorr

+1

Also, issues rise when different kinds of coolant are mixed. If you previously flushed the system and re-filled with Zerex, you know nothing else was added.

On that note, on a car I'm flushing for the first time I also take off the two lines going to the heater core and pour distilled water through them to make sure any previous coolant is flushed out.

Adk46

I sometimes get into discussions with fellow brass instrument players about the virtues of different alloys. I have strong opinions when it comes to the acoustical effects - it's all straightforward from basic physical properties. (I'm viewed as a heretic, though, since my opinion is contrary to lore and marketing campaigns.)

If the subject turns to matters of corrosion, however, I can only say "It's complicated". Corrosion is horrifically complicated and dependent on specific conditions. In brass instruments, there is a phenomenon called "red rot" - very bad. It remains rather mysterious to this day, but it is strongly linked to stagnant conditions. The chemistry of the fluid in a highly localized spot becomes harmful, and is not flushed away - or something like that.

The pitting sometimes seen on our engines might be due to something similar - who knows? If one is inclined to be extra cautious, it would not be silly to run an engine every so often, just in case. I won't argue with anyone on the subject of corrosion.

hacker-pschorr

Regularly starting up an engine and not allowing it to reach full operating temperature (meaning the oil reaches 212F to boil off moisture) you can do more harm than good.

Use good coolant, check for acidity levels. This doesn't need to get complicated.

dr bob

My fluid-life philosophy has been to plan on no more than 50% of the "expected" life, and change accordingly. I really don't want to wait until the pH has gone low to change coolant, because by then the corrosion devils have started their work. Coolant swap every couple years costs $30 for a couple gallons of G05 and a few gallons of distilled water from the local Wal-Mart, very very cheap insurance especially considering the damage we've seen in neglected systems. Corrosion is like any other wear, cumulative over the life of the metal. Changing coolant twice as often in the second half of life doesn't make up for a first half that only had coolant changes half as often as recommended.

Engine oil, transmission and differential fluids, brake and power steering fluids, all deserve a chance to work well. With the possible exception of the differential oil in my car, the car seems to benefit from avoided damage. I still change the differential oil, but the car is driven gently so I'm not sure how the differential gears and bearings know the difference. Meanwhile, I've participated in more than enough SoCal "resto" projects, where the outside of a car looks great due to the mild climate, yet the mechanicals inside suffered from serious neglect. Cooling and hydraulic (brake and clutch) systems seem to suffer the most. The systems are easy to forget. Damage in those systems is invisible until failure, with the obvious failure points just tips of much larger damage icebergs. If you can see the color of your brake fluid through the reservoir wall for instance, it's way past due; the color is from corroded metal parts inside.

A few years ago now, while visiting 928 International for some suspension bolts and fitments for a clinic car's suspension work, Mark invited us to do a walking tour to point out the pieces we needed. His boneyard includes some pretty seriously corrosion-damaged assemblies as scrap. Those who have ordered parts from 928 International know that used parts are only different from new parts in cost. The stuff that doesn't clean up to that standard is scrap. The tour was a reminder that, even though he buys only good dry-climate examples for salvage, only a percentage of those parts are eligible for remarketing.


Did I mention that coolant changes are really really cheap?

dr bob

Take a look at Kevin's thread on head gasket failure to see how corrosion can do a number on the aluminum heads.

https://rennlist.com/forums/928-foru...d-gaskets.html


Did I mention that coolant changes are really cheap?

mike77

I seem to be dumping mine every 6 months at the moment. Water pump then coolant bridge and now to change the high pressure power steering hose. Not 100% sure I had to but I decided to drain the radiator so I could get the coolant hose and fan shroud out of the way of the alternator bolt. Ideally I would like to only do it every 2 years.

dr bob

Mike--

Not knowing what year your car is... I find that the alternator pivot bolt comes out when the engine is at or at least close to normal height in the chassis. Sagging motor mounts make removal tough with the fan console in place. Short term, you can lift the engine slightly to make things easier on that bolt. Longer term, replacing sagged mounts has even more benefits.

Dark Blue

I'm going to hijack this thread a bit on a related topic. One of my block plugs is stuck and on my last two coolant changes I decided discretion was the better part of valor and I just left it, drained everything else and re-filled. I don't want to get involved with a helicoil in my block. Any good advice on getting ot out w/o risking anything. I used copper anti-seize the last time I had it out and I guess that was incorrect. I cahnge coolant every two yrs so I figure I'm fine leaving some in the block. Thanks!

Steve

'89 S4 Auto

dr bob

Steve--

Generally, any anti-seize is better than none, but copper between aluminum and steel is the key to making a great battery. As you've discovered.

Depending which side the plug is on and therefore the stuff around it that would otherwise burn, I'd start off with a MAPP gas torch on the plug and the boss. Cycle the heat a few times locally and stand a chance of breaking the weld that the corrosion has created. The aluminum will carry the heat awy quickly so no worries about melting anything really. Just watch for what's above. Let it all cool again. Then a shallow 13mm 6pt socket with a long 1/2"-drive handle on it. Make sure the socket fits completely and snugly on the bolt head. A sharp pull on the long handle will get it loose if it's going to move.

Risks, in ascending "aw gosh!" order: (1) Wrench slides off and rounds the hex head. (4) Bolt pulls corroded threads with it as it comes out, requiring a longer bolt or threaded insert. (911) Boss on the block breaks off, requiring you to build a new one or have the old one reattached. Last is way into "aw gosh!" territory.

You can moderate the probability of these some with the heat-shock using the torch. Manage the effort on the bar, knowing that in a perfect world, your hard snap-pull on the bar will be rewarded with a similar snap-release from the plug. If it starts to move but is really hard, use the STAR process - Stop, Think, Assess, Respond. Inspect the boss and the bolt as you move them back and forth to verify that you aren't ripping the aluminum boss.


You can flush the crap (literally) out of it with the thermostat removed and the garden hose pushing down through the water pump, out the top outlet, and reverse of that with the crossover passage in the bridge completely blocked. Stuff a rag or even one of those expanding drain-cleaner bulbs in there to seal the passages enough to stir the old stuff out. I did this at my first coolant change as I was concerned for the amount of torque required to remove what appeared to be 8mm threads under the 13mm head. Turns out the threads are bigger, 14mm IIRC, so the 13mm hex is there to remind you not to overtighten.

Teflon thread sealing paste from the hardware store (white-and-grey "Oatey" brand in the plumbing section at Home Depot) is my weapon of choice on the threads and the washer faces. I use 16 lbs/ft (std torque for 8mm bolts/13mm boltheads into aluminum) on them and have no issues. Dave C shared some similar guidance in a recent thread, except he may have a different torque recommendation. You could use Hylomar or HondaBond/YamaBond/DreiBond on them in a pinch if you don't have access to the Teflon thread sealing paste. The paste limits the metal-to-metal contact area between the plug and the block, and also limits liquid contact with the plug that would otherwise encourage galvanic activity at the junction.

Dark Blue

Thanks for great advice! I'll see how brave I feel next time I change coolant.

Steve

ramcram

Have you considered 'waterless synthetic' coolant? Evans is made in the states and is approved for some aircraft.
Freezes at about -80C, boils at about +200C, doesn't corrode any metal, so it doesn't need additives for that, doesn't need wetting agents and is good for life.
If you have to remove the radiator or water pump, just drain and save it and then put it back.
Because it doesn't have a boiling problem, it doesn't need to be run under pressure to artificially alter the boiling point. So you can use a radiator cap say 5psi instead of 14psi. This reduces load on hoses, hose clamp joints, radiator and of course, the water pump seals.
I've been running the Aussie version [Liquid Intelligence] in my SC 86 5.0l for some years now and never needed to top it up and never the slightest cooling issue.