rosenfe

My new purchase had coolant flushed 5 years ago with 5k driven since. When is it due again. This a 1980. Good history of previous flushes

linderpat

Now. The coolant grows acidic and eats at the aluminum block and heads. It is time dependent, not miles dependent.

polecat702

Every 2 years.

FredR

3 years ago!

The glycol is not the problem- it is the anti corrosion chemical package that exhausts and then acids form that ultimately nibble away at the alloy block. Changes every two years are probably very conservative but safe. Also the coolant used will factor into this given they are not all equal.

davek9

IMO the more a car sits w/o running / driving to stir the coolant cuts the recommended change time, so a 3 year coolant is only good for 1.5 years if the car is stored during the winter and not driven every day.

So yes to the every two years suggestions.

SwayBar

No need to guess, buy this ph tester:

https://m.summitracing.com/parts/otc-75134

AO

I have NEVER seen a block with any issues from coolant (except some scaling). That's not say it can't happen, but the Alusil seems to be much more resistant to this phenomena. The heads, however, YIKES! Pitting and corrosion up the Ying Yang! In fact, of the two head gasket failures I've personally experienced, it wasn't really a head gasket failure per se, but rather a head failure from pitting around the fire ring of the gasket allowing coolant into the combustion chamber.

Just setting the record straight.

Erik N

1996 MBZ S500. Also is alusil.

Was fortunate enough to locate an aircraft welder willing to come out to the shop and fill it in. Bought a 14% Si Al rod (IIRC) for the filler on ebay. Guy had to use some sort of inert gas to do it properly.

NoVector

Just looked it up in my maintenance book

Coolant every 2 years
Brake fluid every 3 years
ATF 30,000 miles
Oil 15,000 miles
Rear differential 60,000 miles

polecat702

The problem is that most of us didn't buy our cars new, and the maintenance history is sketchy at best, with little to zero documentation.

All we can do is change all the fluids, TB/WP, top end refresh, tend to the factory recommended maintenance schedule, hope for the best.

I know for a fact that my 89 was neglected, and I'm paying the price in real dollars to bring it back to being reliable.

polecat702

Argon, is the preferred backing gas for Heli-Arc welding.

dr bob

Makes me wonder why it isn't called Argo-Arc welding.

For history buffs, the reason we don't use helium (as was the root cause of the name Heli-Arc...) is because of a relatively limited supply. Argon, OTOH, is more easily recoverable from sea-level air that we breath. The Hindenburg lighter-than-air ship was filled with hydrogen because we were hoarding helium as the second war-to-end-all-wars started in Europe.

dr bob

Separately, I found some pH test strips for cheap enough that I can test coolant in seconds. Grabbed them for testing neighbor Jim C's now-sold OB. Used 1 of the 100 strips for that. Just this morning tested the Toyota HOAT stuff in K's 4Runner as part of a minor inspection/planning tour through the car. Testing takes seconds -- just dip the little test strip into the coolant, shake it off, compare the color to the chart. Test shows pH at 8, when it should be 9 minimum. So new coolant is on the way, along with hoses, serpentine belt and such.

The test strips were a few dollars for 100, worth it for just a few tests.

AO

Not all Alusil is the same there are many different recipes - but that looks kind of like whatI've seen on the 928 heads. For engine blocks, I'm told they like to use 16% to 20% silicon, plus a dash of magnesium and copper. Probably a little rosemary and salt and pepper too.

Charley B

I recently did a coolant drain and refill with G 05, Rad, block and heater core. 25% coolant.

Tested for PH and came out with an 8. WTF!?