Some ideas and questions on HGs problem - your feedback is much appreciated

[New Subaru Fan]

Hi all,

 

a few months ago I bought a 2.0 GT 1990 Legacy (automatic transmission). I paid 500 NZ $ for it, and though the guy told me there was no problems with overheating I kinda new that was the case. Anyway I used to take this car to the mountains for snowboarding many times and one day the car overheated and I observed an external coolant loss from the bottom radiator hose. I could also see quite big bubbles coming out of the overflow bottle and then I knew immediately the HGs were bad so I took the thermostat out.

Since then car hasn't overheated anymore but undercooled. Now I want to put the thermostat back.

The question is:

1) What hole(s) size should I drill in the thermostat to make it pass just enough coolant (and all exhaust gases) so the engine does not overheat?

Also:

2) What do you think of using "liquid" gasket (in the hope it would "seal" the cracks in the HGs with the engine idling) and then re-tightening the head bolts?

3) Do you think that carbon dioxide which gets into the cooling system (when the HGs are leaking) would make the coolant acidic and therefore further deteriorate HGs (and other components)?

4) If you agree with 3), what would be the way to prevent the coolant from becoming acidic (e.g. using certain additives)?

5) And finally, is there any chance of replacing the HGs without taking out the engine?

 

Some of these ideas might sound a bit fancy but even the craziest ideas can be correct. Anyway I would be glad if this thread would cause an interesting and healthy discussion.

 

Cheers

[ricky santana]

I have a similar problem with my HG leaking oil into the coolant. Though it's verry little oil that seeps through over time it allows air to build up causing an air lock on the thermostat resulting in overheating. I've tried BLUE DEVIL sealant as a temporary fix until spring so I can replace the HGs but it did not work for me. It actually clogged my radiator twice!!! I'm running without a thermostat for now but will attempt to put it back in this weekend. I drilled 3 holes in the face of the thermostat in hopes that this will allow the coolant to continue to flow just enough to prvent an air lock while still allowing the thermostat to open & close as designed. If this doesn't work it will be a long cold winter. I'll let you know how it goes. I think I used a 5/8 stainless steel drill bit.

[subikid90]

There is no way to fix the problem without replacing them. They will only get worse. Coolant is not a good lubricant like oil so coolant in your oil if going to be your main problem. Its headgaskets now or motor later, I personally choose headgaskets lol

[New Subaru Fan]

I have a similar problem with my HG leaking oil into the coolant. Though it's verry little oil that seeps through over time it allows air to build up causing an air lock on the thermostat resulting in overheating. I've tried BLUE DEVIL sealant as a temporary fix until spring so I can replace the HGs but it did not work for me. It actually clogged my radiator twice!!! I'm running without a thermostat for now but will attempt to put it back in this weekend. I drilled 3 holes in the face of the thermostat in hopes that this will allow the coolant to continue to flow just enough to prvent an air lock while still allowing the thermostat to open & close as designed. If this doesn't work it will be a long cold winter. I'll let you know how it goes. I think I used a 5/8 stainless steel drill bit.

 

Yeh, it would be cool! Pls let me know how it goes, because I'm still driving without a thermostat. Cheers

[SBT]

1) Your subaru engine is a special aluminum alloy as is the radiator. Adding anything other than Subaru-specific coolant and conditioner (very important BTW where you HGs are concerned), will cause the alloy to leach / corrode, further compounding your issue(s). The stuff collects in your radiator, blocking flow and ultimately corrupting your entiner cooling system, including the water pump.

 

2) Leaking HGs cause all kinds of issues beyond the acidic / degraded coolant ones. They cause misfires, cylinder scoring, coolant in your oilpan, etc. - all not good for your motor's normal operation or longevity

 

3) Drilling a hole in your thermostat is foolish if not downright crazy. The thermostat is there to keep the engine temp stable and creating any kind of by-pass will not come to any good

 

4) HGs can be replaced with the engine in the car...much easier out, obviously, but there's more than enough room to replace the heads. Just need to get the stuff out of the way to do it. Can't recall whether your version of the 1990 2.0GT is forced induction or normally aspirated. If FI, then even more reason to get the HGs fixed ASAP as pressurized cylinders need to be "tight" to operate properly.

 

GL with this.