OEM radiator construction ?? Alu-plastic parts pressed or glued together?

Mi_ka · 10-31-2012, 03:10 PM

After I almost had a heart attack

when I had intermittent HG failure symptoms in our virtually unused EL15 equipped '08 Impreza,
the good folks at the repair shop found out that OEM radiator was leaking coolant / inserting air along the plastic-aluminum parts mating surfaces

Does someone know if the OEM radiator plastic parts are press-fit to the aluminum body
with maybe some gasket or O-ring sealing the mating surfaces or are they just glued together with some special sealing glue ?

I still wonder WTF happened

as I was driving the car hard but much less than much lesser cars on the same 300 miles route and I was deeply disappointed by this failure for a car that has just 10K miles on the clock in the 4 years we have it (belongs to a disabled fellow) and was virtually exactly as delivered to us with the OEM blue long life coolant.

I also wonder if high thermal loads during high speed driving in freezing temperatures (rushing to make it before a mountain pass was closed due to snow) could damage the radiator as the plastic and the aluminum parts must have different expanding-contracting rates compromising the plastic-aluminum seal so it started leaking/taking air 6 months later in hot weather driving.

Opinions of guys-in-the-know? (thanx!)

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NH8991 · 10-31-2012, 09:09 PM

I can't comment on the radiator construction, but living in Montreal where winter gets down to -30 degrees C and summer can be around mid 30s, I don't think air temperature is a concern, i've had my car 4 years and no issues so far....

kay95 · 11-01-2012, 08:48 AM

From what I have seen on the older models the rad has a oring under the plastic endtank and crimped by the aluminum part. From what I have heard rad shops can uncrimp and replace the oring.

Mi_ka · 11-01-2012, 12:11 PM

Thanx for the feedback guys!

Quote:

Originally Posted by NH8991

... living in Montreal where winter gets down to -30 degrees C and summer can be around mid 30s, I don't think air temperature is a concern...

By any chance, have you driven the car on the highway WOT for 2-3 minutes in freezing temps? This should maximize thermal differences on the alu-plastic parts I suppose..

Quote:

Originally Posted by kay95

From what I have seen on the older models the rad has a oring under the plastic endtank and crimped by the aluminum part.

What year models are you referring to?
No glue, just crimped-to-fit should explain different thermal expansion rate parts matching.
O-ring seal could explain intermittent symptoms if it has moved out of position when hot due to manufacturing misalignment or less than optimum crimping tolerances.

NH8991 · 11-01-2012, 12:53 PM

Quote:

Originally Posted by Mi_ka

By any chance, have you driven the car on the highway WOT for 2-3 minutes in freezing temps? This should maximize thermal differences on the alu-plastic parts I suppose..

For me, WOT on the highway would mean leaving the car in 2nd gear

(4EAT, it pulls 112km/h in 2nd), so no, but in the winter mornings I go from a garage at +15 degrees C straight into outdoor temperatures in the minus twenties and i'm on the highway within 3 minutes....
I also did plenty of WOT pulls in sub-zero temps when the car was in the process of being tuned.
Subarus are very popular in this part of the world because of the winter conditions, and i've never heard of people having this type of radiator issue. Which doesn't mean that it never happens.....

Mi_ka · 11-01-2012, 02:21 PM

Well said, it should be a common issue if it was winter related.
I had been pushing the small 1.5 EL15 engine with 3rd (4EAT) WOT in 5.5K-6.5K rpm for maybe 3-4 minutes when the damage must have happened (red temp led went on much later while normal driving) and I am trying to guess why as I suppose the cooling system must be the same as the 2.5 you get there so the radiator *should* be an overkill for the small engine.

kay95 · 11-01-2012, 05:52 PM

Well my 96 outback has a rad like that and so does my buddy's 02 WRX. He even told me that is how he fixed his. It is common for them to leak like that. Any shop that can fix it for you will tell you any OEM rad like that will have problems. Well more than a welded or brazed full metal unit anyway.

10-31-2012, 03:10 PM	#1
Mi_ka Scooby Newbie Member#: 289270 Join Date: Jul 2011 Location: Thessaly, Greece	OEM radiator construction ?? Alu-plastic parts pressed or glued together? After I almost had a heart attack when I had intermittent HG failure symptoms in our virtually unused EL15 equipped '08 Impreza, the good folks at the repair shop found out that OEM radiator was leaking coolant / inserting air along the plastic-aluminum parts mating surfaces Does someone know if the OEM radiator plastic parts are press-fit to the aluminum body with maybe some gasket or O-ring sealing the mating surfaces or are they just glued together with some special sealing glue ? I still wonder WTF happened as I was driving the car hard but much less than much lesser cars on the same 300 miles route and I was deeply disappointed by this failure for a car that has just 10K miles on the clock in the 4 years we have it (belongs to a disabled fellow) and was virtually exactly as delivered to us with the OEM blue long life coolant. I also wonder if high thermal loads during high speed driving in freezing temperatures (rushing to make it before a mountain pass was closed due to snow) could damage the radiator as the plastic and the aluminum parts must have different expanding-contracting rates compromising the plastic-aluminum seal so it started leaking/taking air 6 months later in hot weather driving. Opinions of guys-in-the-know? (thanx!) * Registered users of the site do not see these ads.

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10-31-2012, 09:09 PM	#2
NH8991 Scooby Newbie Member#: 197937 Join Date: Dec 2008 Chapter/Region: E. Canada Location: Montreal, QC Vehicle: 2009 Impreza 2.5i Sport, DGM	I can't comment on the radiator construction, but living in Montreal where winter gets down to -30 degrees C and summer can be around mid 30s, I don't think air temperature is a concern, i've had my car 4 years and no issues so far....

11-01-2012, 08:48 AM	#3
kay95 Scooby Newbie Member#: 45494 Join Date: Oct 2003 Location: glen rock, pa Vehicle: 95 impreza L awd green	From what I have seen on the older models the rad has a oring under the plastic endtank and crimped by the aluminum part. From what I have heard rad shops can uncrimp and replace the oring.

11-01-2012, 02:21 PM	#6
Mi_ka Scooby Newbie Member#: 289270 Join Date: Jul 2011 Location: Thessaly, Greece	Well said, it should be a common issue if it was winter related. I had been pushing the small 1.5 EL15 engine with 3rd (4EAT) WOT in 5.5K-6.5K rpm for maybe 3-4 minutes when the damage must have happened (red temp led went on much later while normal driving) and I am trying to guess why as I suppose the cooling system must be the same as the 2.5 you get there so the radiator should be an overkill for the small engine.

11-01-2012, 05:52 PM	#7
kay95 Scooby Newbie Member#: 45494 Join Date: Oct 2003 Location: glen rock, pa Vehicle: 95 impreza L awd green	Well my 96 outback has a rad like that and so does my buddy's 02 WRX. He even told me that is how he fixed his. It is common for them to leak like that. Any shop that can fix it for you will tell you any OEM rad like that will have problems. Well more than a welded or brazed full metal unit anyway.