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coolant additives to prevent head gasket problems........


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12 replies to this topic

#1 Rooster2

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Posted 31 July 2007 - 08:03 PM

I recently bought a '99 OBW with the 2.5 motor with 149K miles on the odometer. I took the car to my favorite mechanic who has his own shop. I had him change the tb, front crank seal, water pump, and fan belts. He was very aware that 2.5 Subie motors have a tendency to blow out head gaskets. To help prevent this, he added some GM Cadillac sealant pellets to the cooling system. He said that Cadillac adds these pellets to their new cars at time of manufacture to prevent head gasket blow out problems on their cars. Has anyone here used this product? Was this the best product to use, or is there something better that I should be using on my 2.5 motor? Also, Subie dealers sell some coolant additive product designed to save head gaskets. Is that product good?

#2 rweddy

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Posted 31 July 2007 - 08:14 PM

I recently bought a '99 OBW with the 2.5 motor with 149K miles on the odometer. I took the car to my favorite mechanic who has his own shop. I had him change the tb, front crank seal, water pump, and fan belts. He was very aware that 2.5 Subie motors have a tendency to blow out head gaskets. To help prevent this, he added some GM Cadillac sealant pellets to the cooling system. He said that Cadillac adds these pellets to their new cars at time of manufacture to prevent head gasket blow out problems on their cars. Has anyone here used this product? Was this the best product to use, or is there something better that I should be using on my 2.5 motor? Also, Subie dealers sell some coolant additive product designed to save head gaskets. Is that product good?

The Subaru additive is for phase II (00-04) 2.5 motors that blow HG externally, the phase I (96-99) blow them internally. There is not much you can do but cross you fingers and hope for the best. With Phase I motors it is not a matter of if they will blow but when they will blow.

#3 nipper

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Posted 31 July 2007 - 09:06 PM

Well you can also service your cooling system when its called for. There are a few things to help avoid it, new radiator cap, new T stat, flush the system and fresh antifreeze. Change the waterpump with every timing belt.

And learn to scan your dash so you read the temp gauge regularly.


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#4 porcupine73

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Posted 01 August 2007 - 07:29 AM

The Subaru coolant additive is relabelled holts radweld from the U.K. It costs $1.50 on up depending on how much the dealer marks it up. This stuff doesn't do much for the phase I exhaust blowing into coolant type failures. It may be more effective for the phase II external peeping leak. IIRC Subaru did retrospectively say to use this additive in all Subaru engines and it is added to all new Subaru's at the factory.
Posted Image
Not sure if I'd use the GM pellets....since GM uses that potentially glopulous oat dexcool coolant.

#5 Rooster2

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Posted 01 August 2007 - 09:14 AM

Thanks to all about coolant additives to help lessen hg problems. Has Subaru ever said what percentage of stage 1, 2.5 motors will develop head gasket trouble? Was there ever a recall offering a permanent fix? If I ever have to replace hg, is there a revised hg that is better then OEM?

#6 nipper

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Posted 01 August 2007 - 09:23 AM

Thanks to all about coolant additives to help lessen hg problems. Has Subaru ever said what percentage of stage 1, 2.5 motors will develop head gasket trouble? Was there ever a recall offering a permanent fix? If I ever have to replace hg, is there a revised hg that is better then OEM?


Percentage is 15-20 % from real world failures. Subaru wont admit to any number. The higher end seems to be in germany where they like to drive hard and fast.

No recall just an extented warrenty on phase II engines. If you have under 100,000 and a good dealer to back you up you can usually get it for free even if your not technically under the extented warrenty. You need to use the subaru additive to protect yourself in phase II engines if you wish to make a future warrenty claim.

SUbaru only offers the newest and (fixed) design of the head gaskets. Some here have gotten after market HG just to discover (the hard way) that they were old stock, not the newest.

In defense of subaru, and other mfgs, the head gasket is the hardest part of the engine to design. Its amazing how many opposit forces and temperitures it has to deal with all at the same time. There is no accelerated life testing on a Head gasket, unlike other parts of the car.
Neons have a 100% failure rate at about 60,000 miles. Almost all mfgs have or had one engine with a bad head gasket design. The present design should hold up well untill there is another emission standard change, then the learning curve starts all over again.

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#7 porcupine73

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Posted 01 August 2007 - 09:28 AM

I don't think Subaru ever said what percentage have HG issues. Many of the phase I 2.5L engines are up there in mileage at this point since they're like at least 8 years old now. There was an offer from Subaru to extend the warranty to 8 years or 100,000 miles if the conditioner was added per the TSB and some other conditions, but I think that was on the phase II's.

If the HG's need replacing, typically you want to get the new style OEM HG's. These are multi-layer steel. But you don't want some old stock from the shelf. Not sure about aftermarket Subaru HG's; I did hear someone say they had been using cometic gaskets in Subaru's with good results.

#8 grossgary

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Posted 01 August 2007 - 09:46 AM

you should check yours and see if it's been replaced or not, you may already have the new style headgaskets, you can tell just by popping the hood and looking in the right spot. either underneath by the exhaust manifold or just behidn the power steering pump. at the head to block mating surface, part of the gasket protrudes and you can tell if it's a multi layer metal style or just the old standard headgasket. and yes...the newer style headgasket is far superior to the original.

i haven't seen any reliable sources quoting percentage of failures. that's not to say nipper isn't reliable, he's one of the most reliable sources on this forum, but i haven't seen a solid analysis anywhere. it might be 5%, it might be 40%, i don't think there's a solid method for assessing that. when i stop into the subaru shops they typically have a few HG jobs going on simultaneously (3 last time i was there), in a very small city of less than 40,000 people. i am constantly looking and buying subaru's and blown headgasket 2.5's are not hard to find at all. the last legacy i bought actually had new headgaskets on it...which is why you should check yours like i mentioned before worrying about conditioning it, etc.

i would not use that cadillac conditioner. they use some junk engines in their cars, i wouldn't want any of their additives in a subaru. and like they said, additives really only help the late phase II 'external leaking' engines. additives have not been known to help the phase I engines at all. timely replacement of cooling system components like nipper mentioned and flushing your system is more valuable in this case.

#9 PAezb

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Posted 01 August 2007 - 09:59 AM

http://users.sisna.c...headgasket.html

http://www.scoobymod...16&d=1120308813

#10 nipper

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Posted 01 August 2007 - 10:29 AM

There are many many GM coolant issues that are being traced back the to coolant themsleves. Some think (you think subaru is tough to get info from try GM) that the coolant is actually causing the gaskets to leak.

Dont use anything GM. Thankfuly subaru still uses nice standard old-fashioned off the shelf coolant.

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#11 porcupine73

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Posted 01 August 2007 - 10:52 AM

Right on, GM uses the 'dexcool' OAT coolant. This type of coolant Subaru specifically says not to use. This is the stuff that has caused glooping/gelling issues in some vehicles, especially if any air is getting sucked into the system. The closest parts-store available match to genuine SUBARU coolant is BASF G-05, licensed to Zerex and some others.

#12 uniberp

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Posted 02 August 2007 - 10:44 AM

dupe

#13 uniberp

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Posted 02 August 2007 - 10:48 AM

The Subaru coolant additive is relabelled holts radweld from the U.K. It costs $1.50 on up depending on how much the dealer marks it up. This stuff doesn't do much for the phase I exhaust blowing into coolant type failures. It may be more effective for the phase II external peeping leak. IIRC Subaru did retrospectively say to use this additive in all Subaru engines and it is added to all new Subaru's at the factory.
Posted Image
Not sure if I'd use the GM pellets....since GM uses that potentially glopulous oat dexcool coolant.


Yep, "Holts" is molded right right on the bottle.
Just an FYI: I think I noticed on the inside of that label that it contains "linseed husk". Somehow that appealed to me. It worked, stopped my drivers side HG exteral drip up the 99sohc PII.




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