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Discussion Starter · #1 ·
My '86 Spider's owner's manual says to use a special antifreeze for aluminum alloy engines. Is there a recommended brand for this? Does the entire cooling system need to be flushed rather than just adding to the already existing antifreeze?
 

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ya you should flush. but its a bit more involved than many cars. there is a bit of bleeding that needs to be done to avoid air-bubbles. the bleed plug is brass and on the drivers-side of the engine at the back, behind the exhaust manifold and pipes.

Prestone works good. its really important that you mix with DISTILLED water and not just tap-water.
 

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A thorough flush is a good idea. Although most brands of antifreeze will be compatable with others (meaning they won't turn into a slug of goo), mixing different types does minimize any advantage of any particular brand.

All the major antifreeze brands have products compatable with aluminium. I use Havoline or Prestone because I can get them anywhere.

The bleeding procedure is described in IAP's tech page: bleeding the cooling system.

To flush I drain the system then use lots of water (plain old tap water is fine for flushing) with the drains open. Then I close the drains and fill with distilled water (you can buy it for about $1/gallon) - use the bleeding procedure - and run the engine until it is warm enough to open the thermostat and circulate the clean water. Let it cool and drain that out. Do that once or twice more until what drains out is fairly clean.

Finish by adding the specified quantity of coolant and top up with distilled water. Bleed the system and you'll be all set. If you drain and re-fill every couple of years and use the same product to re-fill you won't need to do such a thorough flushing every time.

BTW, here's a tip for cleaning out the coolant reservoir: rinse it out then put in a handful of crushed ice. Shake that around inside the reservoir - the ice is abrasive enough to scour the inside without harming the plastic reservoir. Then rinse it out with hot water and the ice and scum will come out easily.

BTW #2, it is also a good idea to remove the radiator and take it to radiator shop (look for an 'old fashioned' shop that actually works on radiators vs a shop that just replaces them with new). They can either chemically clean & flush the innards or open it up to physically scrape it clean ("rod it out').


P.S. the Sicilian is describing the block drain (behind the exhaust manifold). The bleed screws are on the top of the water pump and the top of the intake plenum.
 

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System Flush Chemical

A thorough flush is a good idea. Although most brands of antifreeze will be compatable with others (meaning they won't turn into a slug of goo), mixing different types does minimize any advantage of any particular brand.
Follow-up #1 - do you suggest using a packaged system flush chemical such as Prestone makes? Thanks, Bruce
 

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I suppose a flushing chemical might help. Hopefully it wouldn't hurt...

My suggestion is a thorough water flush of the block and taking the radiator to a radiator shop for a cleaning. That's what I did with our '84 Spider (and MGA & MGB) and haven't had any problems with cooling efficiency. From then on proper maintanance will keep the system functioning well for a long while. Ignore the system (let the coolant stay in there too long) and then you'll have problems.
 

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The type of antifreeze can be important. The common polyethylene glycol, yellow, is not as easy on aluminum as polypropylene glycol, green, the stuff that dogs can drink. I use the green stuff. I'm sure others will work. Just read the bottle to be sure that you are satisfied before filling the cooling system.
 

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Discussion Starter · #7 ·
Thanks, all of you. I agree that a good flushing seems a good thing and I appreciate the directions on how to do this. I really wanted to know specifics about antifreeze for aluminum alloy engines and Geezer has outlined the differences.
 

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There was an extensive thread on the various options for antifreeze about a year or so ago, perhaps in the engine rebuilding forum. From memory, the OEM antifreeze from Honda dealerships came out well ahead of the generic versions. There was also a useful discussion about the compatibility of 'Water-Wetter' style products, too, if I remember correctly. Do a search! :)

Alex.
 

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ya, the reason i dont know the bleeding screws is because 90+ motronic engines have a bleed-valve built into the system at the top of the intake manifold. (the return hose directly to the coolant overflow reservoir. my mechanic tells me that bleeding is absolete in late spiders. does that sound right?
 

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It doesn't sound far fetched.

Newer cooling systems are designed to sort of 'burp' themselves when an air pocket comes through.

Old systems used the resevoir as a catch tank, so no real participation other than to prevent spillage in the event of a boilover.

New systems let the catch tank actually participate by feeding or bleeding the system as neccisary, hence the 'full cold' and 'full hot' level indicators instead of a simple singular 'full'.
 

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great idea Willie. im going to be swapping out my thermostat on my 74 and will be reviewing this mod for myself.

very smart sir
 

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Grazie, io uso un serbatoio di un Volvo 343 1984, perche quello è bastanza stretto. I am using a bowl from a Volvo 343 1984, they are small enough to fit on the firewall. Never blown a gasket since i did this arrangement.

Cordiali saluti Wille R.
 

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Discussion Starter · #14 ·
Geezer,
Can't seem to find any polypropylene glycol antifreeze that you mentioned. Is there a particular brand that you use? Although it still contains ethyline (plus other ingredients), Prestone's top of the line 50-50 (use as is with water already in it) claims to be good for ALL engines, including aluminum alloys that we have. What do you think?
 

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Geezer,
Can't seem to find any polypropylene glycol antifreeze that you mentioned. Is there a particular brand that you use? Although it still contains ethyline (plus other ingredients), Prestone's top of the line 50-50 (use as is with water already in it) claims to be good for ALL engines, including aluminum alloys that we have. What do you think?
I've found it under the names Sierra & Prestone Low Tox. Never tried the Prestone 50/50 stuff. I also saw GM 50/50 antifreeze, Dexcool I believe, that claims to be good with aluminum.

BTW I just pulled the head off of my '91 Mazda B2600. The original head gasket finally failed. 274,000 miles and no corrosion using polypropylene anti freeze.
 

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the antifreeze for later model VWs comes highly recomended, not sure of exact name, but go to a VW or Audi site and look for the stuff for like 2002 forward VW's. It is expensive and some versions are not compatible with other products, so a thorouggh flush is needed. Also, especially if you have hard or well water, bu sure to use distilled water to mix with the antifreeze. Alfa has suggested this for a while. I have heard bad t hings about "Dex-Cool" so would stay away from that.
 

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It's ethylene glycol and proplylene glycol, not poly. Polypropylene glycol is a different compound: it's the polymer of propylene glycol and isn't used in antifreeze.

In either case, the glycol is just the intert carrier and doesn't have anything to do with fitness for aluminum engines. That's a function of the anticorrosion and other additives in the antifreeze. Most antifreezes these days are fine with aluminum.

The advantage of propylene glycol is that it's non-toxic, and thus safer.
 

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Geezer,
Can't seem to find any polypropylene glycol antifreeze that you mentioned. Is there a particular brand that you use? Although it still contains ethyline (plus other ingredients), Prestone's top of the line 50-50 (use as is with water already in it) claims to be good for ALL engines, including aluminum alloys that we have. What do you think?
Thats because there is no such thing as polyethylene glycol.......for antifreeze, I believe. PEG is used in the cosmetics and medical products industry, not the automotive.

GUBI is right.

Ethylene glycol (EG )is the preferred because of its higher specific heat, over propylene glycol (PG), although, it is toxic to animals. And as far as distilled water, distilled OR deionized is virtually the same thing, if you are offered this choice in the supermarket. Both pure water sources good for batteries/radiators.
 

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If you want to avoid spending extra for someone already having added the water for you, dont but the 50/50 ready to use stuff. They WANT you to buy that over their straight EG cuz they make more $ on it.

And compare price with brand name with store brand EG (I like Advance brand extended life). EG is EG. Additives are debatable issue, but maybe I am biased, but most generic drugs are as good as the Pharmaceutical rip off brand name. Dont buy Motrin, but Stop-and-Shop brand Ibuprophin. I will never pay for Prestone. And the OEM will have plenty of lubricants/anti corrosion additives in it. This stuff is not nanotechnology.

I do OEM specialty chemicals for a living, and OEM for the big supply houses in th northeast, but ironically, compete with them with SAME product with my own label on it. At half price!!!!!!!!!
 

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My bad. I guess that I should read the label carefully instead of relying on my feeble memory.

 
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