jpitman1

Somebody recently posted re long term coolant loss (> 3 months?), wondering whats happening, as engine doesnt seem to have problems.
I had a similar slow loss, with high water in the tank very slowly going down, but no sign of drops or stains underneath. Finally one day I looked down on the RH side with some lighting for something else, and noticed a wet area on the front undershield (alloy plate covering gap from front X member to engine pan). I finally found I could tighten up the top hose clamp some, and inspection over the last few weeks shows no recurrence. Looks like the leak was so slow, and only when hot, that the coolant wouuld evaporate before it could run off the shield.
jp

Normy

Pitman...

I've lost about 1-2 quarts every 3000 miles or so, nothing that I've worried about. I'm from Orlando, and it gets hot here (!) in the summer, so a German car can be excused for sweating a little h2o!

My concern in my post was about using Prestone Lo-Tox coolant. I've been running it for the past two years, and it is about change time, so I am curious about what it is going to look like when it came out. The stuff the PO put in it came out kind of hazy, kind of whitish. Looking in the cap now, it seems quite clean. I posted asking if anyone had heard any bad things about using Lo-Tox, as it is made from propylene glycol instead of ethylene glycol.

But on the evaporation front....I'm running a 75%/25% distilled water/coolant mix, as the higher water portion aids in heat transfer to the radiator. Bear in mind, this car is never subject to below-freezing conditions since it is in Central Florida. This higher concentration of water to coolant is probably responsible for my water loss. The car seems to run a bit cool- one needle width below center on the water temp gauge...even on hot days with the a/c pumping.

Normy

Sab

I had a slow coolant leak for a while and then finally broke down on the Turnpike with a massive leak. That was the only time I ever broke down with my car. It turned out to be a small 3 inch hose connecting to the valve which regulates the water to the heater. It seems to get pretty hot back there and I was surprised that the hose lasted that long in the condition it was in.
regards,
Sab.

Greg86andahalf

Hi Normy,

What was the determination on using propylene glycol instead of ethylene glycol?

I'm about to refill my cooling system (and prof. freshly cleaned and tested radiator) after a timing belt/water pump job.

In this small town I live in, my choice for off the shelf is:
Dexcool (no way I'm using it!!)

store-brand "no phosphate safe for all engines including aluminum"

Sierra propylene glycol.

There are some other "GM Dexcool approved" coolants on the shelf, but I'm not sure what to use. No 450 or other coolant over $6/gal available loacally. I may order online if needed.


I want to do this right. Any advice?

Thanks

WallyP

While I am not trying to persuade anyone to use it, DexCool should be fine in a 928.

On the subject of propylene glycol, the only advantage that I know of is a reduction in toxicity compared to ethylene glycol. My only comment is that airports routinely pump thousands of gallons of de-icing liquids containing ethylene glycol over airpanes every winter. While they try to capture/recycle it, no one, including the state or federal EPAs, gets too concerned about some escaping into the streams.

GM has finally accepted propylene glycol, though. This is supposedly from a bulletin to their dealers:

General Motors has been reviewing data supplied on the performance of propylene glycol engine coolant in GM vehicles. It is our conclusion that propylene glycol engine coolant will perform adequately under most vehicle operating conditions. As a result, propylene glycol (meeting performance specification GM1825M) may be used in GM vehicles and will not affect the warranty coverage.

Prior to adding propylene glycol engine coolant to the cooling system, all the existing (ethylene glycol) coolant must be removed. This can be acomplished either by utilizing water-based coolant flushing equipment or "waterless quick change" equipment available in the GMDE program. As with any coolant change procedure, be sure to thoroughly purge the heater core and block as well as the radiator before attempting to convert the system to propylene glycol coolant.

Freeze/boil point levels are different for propylene glycol than for ethylene glycol engine
coolant. To accurately determine freeze/boil protection level, it is imperative that coolants
not be mixed. Removing all the used coolant as previously discussed resolves this concern.

Freeze protection of propylene glycol cannot be determined using a standar hydrometer. Rather a refractometer or test strip must be used.

Greg86andahalf

Thanks Wally.

So it seems that there is no compelling reason to do a switch to propylene glycol coolant.

Please see my question about coolants under a seperate heading as I do not want to take this thread off-topic.

Normy

Greg-

My interest in propylene glycol based coolant versus ethylene glycol is indeed based around toxicity. Before putting this in my system, I did basic research and determined that it probably was safe for aluminum components. Off I went. I mean, if the stuff keeps the engine from boiling over or getting crusty, and has the added benefit of not killing the stray cats that wander into my garage and like to lick the various bottles of cleaner/wax/castrol on my shelves....

(by the way, deicing fluid used at airports is a mixture of surfactants and propylene glycol, as ethylene glycol is considered toxic waste by the EPA.)

In a previous life I drove a turbocharged VW Scirocco. Due to problems with high coolant temperatures, I elected to try "Mecca/Evans Cooling", with less than good results. This system used 100% coolant! No water, just a propylene glycol based coolant and a zero pressure cap on the expansion tank. Great for the hoses, as there was no pressure and the system was supposed to be superior because of the lack of "nucleate boiling", or boiling spots in the head and block. Well, it got hot nonetheless and phone calls to Mecca were not satisfactory- they claimed that I needed to buy their special hi-flow water pump (at $350..., infering that VW was at fault for their product not working! I promptly changed back to regular coolant. I'm not sure this company is in business any longer, but it peaked my interest.

HOPE this helps!

n

I've been running a 75/25 water/coolant mix in Florida, and have had good results while using "water whetter" additive. This high mix of distilled water can probably be blamed for my coolant loss.

Greg86andahalf

Thanks Normy.

I may be overly concerned, but between the posts I've read on the 'net about aluminum engine cooling, and a recent discussion with the professional radiator shop owner who inspected and cleaned my 928 raiator (this guy is making a living off of 98-2000 GM radiators), I simply do not want to make a mistake. All of the info provided by you, Wally and others is great!

Thanks much.

Normy

GREG-

If there is one thing I can recommend to you...

DITCH THE DAMN BEHR PLASTIC RADIATOR!

-My Scirocco developed leaks in it's plastic radiator, primarily due to heat.

-My VR6 Corrado had similar coolant problems in Central Florida heat.

-I bought the car of my dreams. It peed green on my garage floor the first day.

I vowed "NEVER AGAIN!"

Devek's radiator is Winston Cup spec and it WONT leak. There are no seams...

Anyway, that and water Whetter! My coolant gauge consistantly reads low. My gas mileage sucks as a result! And as to coolant...Keep it topped off and use the cheap brand, or PG based like mine and you cant go wrong. Attention to maintenance is everything with a 928- if you maintain these things they are cheaper than Jettas.

Normy

Ed Ruiz

I had a DEVEK radiator that began leaking 13 months after I bought it. The leak was from where the core is (that's right, it's) epoxy glued to the side tanks.

I switched back to the Behr and have never looked back. When the seals start to fail on the Behr radiator, it costs about $100 to fix. YMMV.

BTW, I know of two others who had the same problem with their DEVEK radiators.

Normy

Well, my Devek radiator has no glued seams....It looks like everything is welded aluminum, which is why I bought it! It wasn't any cheaper...but no more expensive either and I've had good results.

Normy

Greg86andahalf

Thanks Normy. I don't like the plastic radiator idea either. Especialy as it related to cross-contamination of atf/oil/coolant. I'd rather see seperate coolers for oil/atf.

At this point though, I have just re-installed (2am this morning) the freshly cleaned and checked radiator while doing the timming belt.

I left the hoses off so I can hand-flush the block and heater core (without the crap going through the radiator). Then, attach hoses, fill, burp, (the system) start engine (see how my timing belt replacement worked)run, etc.

The Devek does seem reasonably priced.

BTW, I did Wally's viscus oil for the fan clutch job. Cool. It took a while for the oil to go in, heating, spinning, cooling, etc. If you stare at the fins in the fan clutch while spinning it for a while, then look up, the room bends and wobbles. That too was cool. I entertain myself.

The clutch was noticably more resistant after the oil was added.

Thanks for the advice.

Normy

That sounds like fun Greg...I need to try the fan thing!

Normy <img src="graemlins/roflmao.gif" border="0" alt="[hiha]" />

Ed Ruiz

Unless they've changed their building process, all DEVEK cores are epoxy glued to the aluminum ends. You just may not be able to see it.

The new OEM Behr radiator actually cost me $200 less than the DEVEK radiator. YMMV. Moreover, it's much easier to fix, and it fits perfectly without any modification.