Massive coolant headache

Mattst165

New member
Picked up an st165 over the weekend, drove it 4 hours home with no issue, ran absolutely flawless, no leaks. Well, next morning I drive an hour or so, get home and notice coolant is pouring from the heater core outlet as soon as I shut the car off. Decided to just bypass it to avoid messing with the heater core. Drove it for an hour or so again, runs perfect and holds temp just fine. As soon as I shut the car off coolant is leaking from the tstat housing. After that I just assumed the thermostat was what was originally bad, replaced it and drove for another hour checking every ten minutes to be certain it wasn't leaking, it was fine. Shut the car off after that long drive and another different hose burst as soon as I shut it off.
I'm new to 3sgtes and wondering if any of you have experienced this. As I said the car runs perfect, idles perfect, doesn't smoke, and pulls hard so I have a hard time believing it's the head gasket. Any ideas before I give it a compression test tomorrow?
 

underscore

Well-known member
I'd start with the rad cap, if it's stuck or someone put a high pressure one on it them it could be causing excess pressure making other parts fail.
 

Mattst165

New member
underscore":3mpxhclc said:
I'd start with the rad cap, if it's stuck or someone put a high pressure one on it them it could be causing excess pressure making other parts fail.

I hope it's that easy, I'll be picking one up today. Something I noticed is that the previous owner added Toyota red coolant to the green it had previously, you can tell they have obviously been mixed. I've heard mixed results about using the two together, I'm wondering if this could be the issue.
 

alltrac801

New member
I had this issue with my St185 when I first got it. First my radiator started leaking so I changed that. Then my upper radiator hose burst so I changed that. After that one of the hoses on my water neck burst. I think my hoses were just old so once I fixed the radiator they couldn't handle the pressure so I just changed every coolant hose and I haven't had a problem in 3 years.
 

underscore

Well-known member
I'd flush out the coolant and get one type in there (don't forget to clean the heater if you reconnect it), like you I've been told that the different coolant types don't play nice and mixing them can cause all kinds of issues. Depending on how the hoses look you many want to replace all of those as well since some might be 30 years old now.
 
Was the ST165 sitting for a long time (years) without being used? Sitting outside with the hood open for a very long time? Are any plastics in the engine compartment very brittle? Heat and sun weather and harden hoses and plastics very quickly. If your temperature did not go above normal, that’s good (so the original thermostat was working properly). Cap release pressure should not be greater than 14 psi.
 
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