Hey everyone I am new here so just wanted to say hello and ask a peculiar question. I have a 1988 GL turbo wagon that I have had absolutely everything done to it I.e. water pump, thermostat, timing belts, and head gaskets, multiple coolant flushes. The car still runs hot and overheats on the highway so was just wondering if anyone on here has ever experienced this problem or if someone may know where else to turn? Head gaskets were done 3 weeks ago properly with heads machined, took car on road trip out to the gorge in Washington, car ran perfect going there but overheated catastrophically on the return trip home. Thank you

catastrophically overheating - that's bad.  might be more wrong with it now than before.

 

clogged radiator.  test it - run a garden hose through it and see how much comes out compared to what goes in.

 

are the cooling/radiator fans coming on?

 

do you see white smoke coming out of the exhaust?

 

were the heads pressure tested?  drop the exhaust manifolds and see if there's cooling coming through the exhaust ports.

 

EA82T's don't have coolant lines going to the turbo right?

 

was this a craigslist special you bought with coolant and oil blown all up through the crank case, PCV, and intake hoses and saturating the filter - before you repaired it?  the engine might be suspect.

Remove the radiator and flush it out with hose pressure.  In place radiator flushes are worthless.  Turbo's usually require a double core radiator, especially in the summer time when the A/C is running.  I have seen sticky thermostats that stay stuck in one position.  You could remove yours and put it in a pan of water and boil it, in order to see if and how much it opens.  The primary cause is loose cylinder head bolts allowing the head gasket to blow hot air into the cooling system.  When I tighten cylinder head bolts, I first tighten them to their maximum, then I let them sit overnight, and the retighten them the next day before slapping on the cam towers.

Edited October 10, 201510 yr by scoobiedubie

Ya I also replaced the radiator and temp switch for coolant fan awhile ago and those are all good it doesn't overheat in town just out on the highway I've had the car for almost a year and have been dealing with this cooling problem it has been pressure tested again I thought maybe I blew out the brand new head gaskets but that's not the case it's been tested and there are no exhaust gases in antifreeze no oil in antifreeze no white smoke none of that stuff

Oh I forgot grossgary that there are coolant lines going to the turbo one supply and one return

Scoobiedoobie the thermostat has been replaced twice and that's a good note about the cylinder head bolts I had a really reputable shop do all of this work from where I am from and that is where it is at now and they have done all kinds of stuff and can't figure out what is going on

Do you know where to get a dual core radiator because to my knowledge they only make a single row for them and was wondering if there was anyway to get rid of turbo or bypass it without screwing electronics up

not much left other than replace radiator , to check current one and put back together may cost half the price of a newie.

 

then there is - cat converter blocking up ? which would affect the performance

 

or the simplest - is radiator cap the original and not holding correct pressure no more ?

 

Knowing the ignition timing is correct is a no parts check.

Ya the radiator and cap are brand new have never seen a problem like this before but I appreciate all of the quick responses thanks guys!

Are you loosing any coolant (besides what boils out when it overheats)?  For instance, what would happen if you did this:

 

1.  as soon as it starts to run hot, pull over.

2.  let it cool down

3.  check coolant level in radiator and overflow tank.

 

I'd like to know if the overheating is caused by, related too, or completely independent of coolant level.

 

When it's starting to run hot - pull over and look in the overflow tank - are there bubbles?

I've never seen that symptom on older gen's but it's common in newer gen.

And what brand headgasket was used?

 

The factory service manual calls for the headgaskets to be retorqued.  I'm not sure if that matters, is OEM gasket specific only, or really matters though...

OEM are supposed to be re torqued.  Fel Pro permatorque don't need to be.

Every turbo EA82 I have owned (3) have had the 2 core radiator. I don't believe that radiator can be bought new anymore. Seems odd to me that it runs cool in town but only overheats on the highway. 

genuine OEM from Subaru headgaskets , done four now, and on retorque, did not budge a bit. I ran non retorque required non OEM for 20,000km and were still fine in operation, yet took some when i did retorque them.

 

What are the air temps when you are around town and on highway ? I find sometimes when it is hot outside mid 30 C and loaded up a hill, will run a few degrees more corrsponding warmer outside air.

Maybe make an air dam to force more air in up from valance panel to rad meanwhile ?

 

Just don't cook the baby !.

I had exactly the same problem on my '88 Turbo sedan. It ran fine around town and anywhere that you stayed under 50 mph but on the highway it would overheat at anything over 50 mph, especially climbing hills such as I90 out of Vantage in the gorge. I checked and replace everything cooling related except the radiator because it seamed to flow well and had been replace by the previous owner in the last year.I still could not solve the problem until I realized that the new radiator was a single core. I installed a new 2 core and the problem went away.

 

A good radiator shop might be able to recore yours to 2 core or do a search. A quick search found one here https://www.radiatorexpress.com/product.asp?part=1988+SUBARU+GL-10++-+1%2E8+liter+H4+RADIATOR+TURBO+REPLACEMENT+W%2F+STRAIGHT+OUTLET&part_id=40020&aaia_id=1268704

Awesome not sure what brand head gaskets were used exactly since a shop in my town did them and I trust the guys who did it I was wondering about a 2 row radiator but searched and couldn't find one and the original one that I replaced was a single row but awesome thank you for the link I am going to buy one and try it. And I have checked levels of coolant when it overheats and am not losing antifreeze otherwise but thank you everyone for your responses I really appreciate the help!

Look for mice nests between the main radiator and the A/C radiator.