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Rb20 Oil In Coolant

Timtim123
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Timtim123 Explorer

Timtim123

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I purchased my 90 gtst in August and noticed that the coolant was a little brown colored. I searched around and it actually sounded as if it was fairly common for these motors as they are prone to a little rust in the system. This car especially shows signs that it likely sat a good while before it was shipped here to the US. So I drained the coolant out through the radiator plug and refilled and moved on. It didn't look too bad just discolored.

Just the other day I decided to start on my timing belt and waterpump change and drained the coolant. This time I drained via the bottom rad hose and noticed the coolant looked much worse and was pretty thick. See picture below. I'm thinking this is much more than just rust and possibly oil. It also looks to be sitting on top of the coolant, which again makes me believe it's oil. So before I put on my new water pump and new radiator/hoses, I'd like to fix the issue. Sounds like it could be either head gasket or cracked head/block. The local parts store here rents out a coolant pressure testing kit -- Do you guys recommend I start there to see if it's losing pressure? If so, I guess start with the head gasket?

Has anyone used a pressure testing kit on their rb motor and have any advice/direction on doing so? Thanks for the help, I'm hoping it's only the gasket unless anyone can shed any good news on something else or less minor. My original plan was to just flush it real well a few times until clean then move forward to see if it comes back. But, I figure I shouldn't try to hide from a potentially bigger issue. Also, the motor itself seems strong. I did a compression test just last weekend and got about 158-160 across all six.

24909569182_e26eb314e7_c.jpg

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Timtim123 Explorer

Timtim123

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Oil looks good, at least when it was replaced about 100km ago. No glitter and no signs of coolant. Wondering if this has been in the system for awhile and just didn't make its way out the first time I flushed it, as I don't think I even got the plug completely out the first time I drained and just let it drip out of a loose plug. I'm picking up the pressure tester tonight and going to test that tomorrow or sometime this week. I dug around a good while last night and it appears to be pretty simple and can be done with an empty system too.

Timtim123 Explorer

Timtim123

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Its worth noting that draining the coolant from the radiator hose only drains about half of it, there's a plug on the rear passenger side of the block behind the dump that you can use to drain the rest

Good to know, thanks. That will be good to see how it looks on that half of the system as well. I'm currently pressure testing it and so far it's holding pressure fine (after chasing a couple of small hose leaks). Hoping it holds pressure. If so, my only guess is that it's old gunk that wasn't properly flushed before. Whether that came from a previous issue with the motor, or nasty water/coolant mixes, I guess I'll never know. I do know the car sat a good while over in Japan, so who knows.

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