Hey guys,

i have an rb25det, all stock everything and im pretty sure i have oil in my cooling system. i flushed the coolant today and it comes out dark, dark, dark green, almost black. however, it(the supposid oil) doesnt float on top. i tought oil would still float on top of coolant, but its all mixed in together. anyways, the black s*** in my reservior is a lot more like motor oil so yeah, its oil...damnet.

so heres my question, what are the chances that its my stock rb25det turbo leaking oil into the water system and not a blown head gasket or worse...dare i say it...cracked block? im really really hoping its just the turbo but after some searching, i still dont know if thats possible with that turbo or any water and oil turbo.

if i do a leak down and/or compression test, would either of those point out a blown HG or cracked block? also, i checked the dip stick and it looks pretty clean with just oil so it looks like its just oil in the coolant and not coolant in the oil. i guess ill drain the oil some time this week and see if i see any coolant. if there was coolant in the oil, will there be traces on the dip stick?

anyways, any advise on how to proceed would be great. if its the turbo, sweet, cause i've been looking to upgrade that mofo anyways! blown HG, ok, that sucks, but i can fix that. cracked block, damn, what a waste.

thanks,

michael

PS. car runs fine and temp stays in the middle. no smoke, no noticable power loss, no over heating.

you can have a BHG with none of the 'expected' BHG issues...my xjr has a blown hg but does not overheat or consume coolant via combustion chambers...instead it just leaks it down the side of the block along with oil.

there is simply no way in hell that the turbo can be a source of coolant and oil mixing, the two systems are isolated within the turbo from one another and never mix, EVER.

you need to do a leakdown test to determine if there is a hg leak, just because the stock temp gauge does not indicate you are overheating it is far from accurated...my car got to 120*c before the stock needle even began to move.
are you sure your cooling system isnt just full of trash?
when engines sit on a boat for months, rust and such builds up...i have even seen crystalized coolant/iron in an engine i just tore down from being half full of coolant for god knows how long.

I would drain the coolant and do a proper flush once again...and this time drain the block before you refill...the drain plug is on the drivers side near the coolant feed from the block.

Do what he said a Leak down test and honestly I have some black s*** in my cooling system sometimes too. even did on the KA when it sat for A LONG peroid of time without running, flush again maybe and take a deep breath.

I mean if you got your eye on the temp gauge for the coolant and the oil pressure gauge and she runs fine, boosts fine, etc,

say f*** it and just that head gasket to you do a build up or have spare time to pull it all apart.

Buddy of mine has an RB25 with a BHG that just leaks a little bit of coolant, he overheats SOMETIMES in heavy traffic on a hot day, but otherwise his car is fine, faster than mine, and his is 100% factory

cool, thanks guys! ill be picking up a leak down tester this weekend and see whats up. i checked the reservoir again tonight and sure enough, its black again. ill be doing another flush this weekend. hopefully it was just cause i didt get all of it out. its actually coating the reservoir walls pretty good, so im guessing its coating the block walls, pipes, heater core walls pretty good. is there anything i can run though the system that will break up the oil/sludge and flush it out? simple green?

also, heres the weird part. i didnt do too well in chemistry, but im pretty sure oil floats on water. so i drained it into a bottle and yesterday, it was all mixed together and when i dipped my finger in it, no oil coated my fingers. so tonight, i looked at those bottles. if my chemitry is right, the dark liquid would have floated to the top but no, the dark stuff settled to the botom and the green water/coolant floated to the top. wtf? so anyways, i put half of the oil/sludge in a water bottle and filled the rest with the coolant. ill post a poicture tmorrow and see if you guys think its actually oil. it actually look lik dirt or some other crap other than oil, which is good! i duuno, has anyone had mixed oil and coolant? does the oil float on top of it?

thanks for all the advise guys!

michael

hey guys,

sorry to keep bugging you with this. so i put half of the dark stuff in a water bottle and filled the other half with coolant/water and left it over night. so the "dark stuff" sank to the bottom while the green water floated on top of it. here i have a picture of it seperated and after i shook it up. its gets completely opaque after mixing, no light what so ever gets through.

looking at it, it doesnt look to be oil, but more like just black dirt or crud....which is better than a BHG or cracked block! so if it isnt oil or 100% oil, then ill just do a bunch of flushes and hopefully clear that crap out.

i dunno, what do you guys think? oil or just crud? think i still got a BHG?







thanks for the advise guys!

michael

i have no idea what that its...looks to be particulate matter but I am not sure.
Its possible that you have a water/oil emulsion going on but if it seperates out completely then that may not be the case.
might just be junk in the system...if thats the case then a good flush or two should clear it out.

u got oil in the coolant. Time for new hg. i had that same issue with my ka motor and it never leaked any oil or coolant but had a small hg leak and that is exactly how the crap looked when i drained the coolant

If oil is less dense than water, how would it settle out? I'm going to vote for crud in the block.

USMCgetsome wrote:u got oil in the coolant. Time for new hg. i had that same issue with my ka motor and it never leaked any oil or coolant but had a small hg leak and that is exactly how the crap looked when i drained the coolant

hmm...damn, i was starting to feel a little better thinking it wasnt oil so i wouldnt have a BHG. by any chance, did you notice if the fluid you drained also seperated like mine where the black crud went to the bottom?

i kind of think its not oil...at least not all oil. i was draining the coolant again today and took the radiator out and shook it around with water in it. then i noticed something that looked like a little black rock. i pulled it out and its not a rock, its a bit softer cause it started to fall apart in my fingers. i dont know what it is, but i think its contributing.

but heres my (stupid) question of the day. so i wanted to drain it at the block as well, but i cant find the damn drain plug on the block. i have the FSM and it only shows me this vague picture and i cant figure out where the plug is. Carl H said above that its on the driveside by the feed line. i see an oil feed and return, and then if i look the right (towards the back of the car), i see one of the lines for the coolant, but im not sure if this is the feed or return. the other line connected to the turbo goes around the back of the motor, possibly to the other side. if you look at the picture below, the bolt it pointing at, i see a bolt that may be in that general vacinity, but it has a bracket bolted to it that holds one of the coolant lines that go to the turbo. is that the drain plug, the one with the bracket attached to it? Carl H, im assuming you mean the left side of th motor when you say its on the driverside, and not JDM driver side corret? is it towards the back or front of the motor? can someone take a picture of that plug and say if its on the left, right, front, back, close to the top, closer to the very bottom, etc please?



sorry to be a noob but much thanks for the help!

michael

It is exactly where the diagram shows it. Beneath the #5 and #6 exhaust ports. You can't miss it. It is not the bolt that holds one of the coolant lines to the block. It is all on its own. Look harder

Yeah the diagram is exactly correct, the real thing is about 14.5in from this keyboard, and its just sitting right under the coolant feed.

~Alex

cool, thanks guys, i found it. turns out i had to pull my head out of my a** first, who'da thought? i dont have a jack low enough to get under the car so i had to look from the top. at that angle, the exhaust headers was blocking it. i had to stick my digicam in there, just behind the elbow and just randomly fire shots away. 2nd shot and bam, there it was, just like the diagram says.

its official, im a noob...

hey man i have the SAME EXACT ISSUE. except it overheats too and no matte how many times i do a coolant flush the water goes back to black/brownish color. I thought it was the turbo too and it can definitely be but most unlikely. in my case it was the turbo also. the seals went bad and it was mixing in there. but yeah just replace the headgasket. im in the process of doing that now. and i dont have that much of experience. just following the fsm with some tools. gluck to both of us

thrasher324 wrote:hey man i have the SAME EXACT ISSUE. except it overheats too and no matte how many times i do a coolant flush the water goes back to black/brownish color. I thought it was the turbo too and it can definitely be but most unlikely. in my case it was the turbo also. the seals went bad and it was mixing in there. but yeah just replace the headgasket. im in the process of doing that now. and i dont have that much of experience. just following the fsm with some tools. gluck to both of us

as carl h said. theres no way that oil is mixing with coolant in the turbo. they are completely separate chambers. coolant only goes through the casting on a water jacket around the CHRA. the oil gets injected and passes directly through the CHRA, if you look in the oil ports you can see shaft. just to clear that up. you just blew you oil seals. there are no coolant seals in a turbo

How is your turbo mixing oil and coolant? Did some one drill a hole in it?

hey guys,

just an update, that stuff in that bottle, im like 99.9% sure it isnt oil. i made another bottle of that stuff, with half the dark stuff and half coolant, and the i added about 1 oz of used motor oil and sure enough, my physics/chemistry serves me right, the oil floats to the top and that dark stuff settles. some of it may have got trapped in the oil, but the oil definately does seperate and float to the top, every time, no matter how hard or long i shake it for. ill post a picture of it if anyones interested. when i did my swap, the guy gave me an old s14 radiator. its prob been sitting for years collecting dirt...prob the motor as well...

anyways, ive flushed it many times but it still has more. in order for me to get the block drain bolt off, i need to take the turbo elbow off or get some 6-side short sockets because my long impact ones wont fit. can i just take out the thermostat, stick the hose in the outlet hose and flush everything through?

your 15year old radiator cap is probably deteriorating. rub the rubber piece under the cap with your finger and see if the blackness rubs off
your coolant should be in ok condition since the dirt really only gets into the reservoir when the coolant expands.