I've Got Milky Coolant But Not Overheating

[Nismo37]

I recently picked up a 240z from an old guy that's had it for decades.  It's in really great shape but hasn't been driven in awhile.  I changed th oil when I got it home and have put a couple hundred miles on it.  I noticed that it's leaking coolant in several places, one spot seems to be coming from where the head and block meet but definitely from a couple of the hoses.  I started draining the coolant to flush it and found it to be very milky.  I've attached a pic.  It's not smoking or overheating so if there is something going on with the head gasket it doesn't appear to be severe yet.  Anyone have any ideas of what the issue could be?

[rcb280z]

Have you checked the oil after the oil change to make sure it isn't "milky" looking? You didn't mention changing the coolant...did you? If not maybe you should. Don't stop with the engine oil. Do all fluids especially if its been sitting for as long as you say. It looks really dirty to me. Not sure if I'm looking at rusty water or extremely dirty coolant. Either way, you need to change it.

[Nismo37]

I changed the oil and it seems fine but the coolant is NASTY!  Check out the attached image of the thermostat.  I'm assuming it's just really old coolant that's coagulated.  If I've got rust issues in there are there any additives to help remedy that or slow it down?  Could it be that I have a head gasket problem?  Any good flushes besides good old water that anyone would recommend?  I'm assuming the previous owner used tap water with the coolant.

[Patcon]

Antifreeze has antirust properties. That is why it is important to not run straight water.

[rcb280z]

Looks ugly. I have never personally experienced your situation but if I were you I would take it and get a coolant system flush done. I get it done on all my cars. Coolant is always clean looking. Find a shop close to you. I wouldn't want to drive that any distance just in case it did start to over heat. There are do-it-yourself kits but it can get messy and then you have to find a place to dispose of it. Thats up to you. PITA in my opinion. Keep us posted. And I would replace that thermostat also.

Fix your hose leaks before you go.

Edited September 8, 2015 by rcb280z

[Nismo37]

I flushed it out as best I could in my garage today and got clean water coming out but I didn't do a complete flush through the block drain.  I probably need that.  I'm just hoping I don't have a head gasket problem.

[Chickenman]

With coolant looking like that and the muck on the Thermostat it would probably be a good idea to pull the Rad and have it " Boiled " out at a Rad shop.

 

You may have to do the same with the heater core.

 

On second thought, with aluminum rads so cheap on E-Bay these days it may be worthwhile just getting a new Rad. Depends what condition the current Rad is in.

 

Re-torque the head bolts and see if that stops the coolant leak at the head and block.

[bartsscooterservice]

You could use something like Wynn's coolant system flush, you just add that to the coolant and drive for a while, after that you flush the system and refill with new coolant.

 

I would recommend ready to use coolant, don't mix it yourself with water.

 

Good idea to maybe also check the water pump ( bearing could suddenly fail from sitting so long, I had this myself  ), and replace the thermostat like allready said here.

[hr369]

Looks like he ran it with water right out of the tap.  All those dissolved minerals in regular tap water love to eat aluminum heads. If it were mine, i'de pull the head and look

for erosion in and around all the water jackets. 

[Chickenman]

^ Yeah... agree 100%. Pull the Timing Cover and W/Pump and inspect those for corrosion as well.

[rossiz]

just an fyi - beware re-torquing head bolts that have sat for 30+ years and been exposed to corrosion such as in your photos. very easy to snap one.

last time i checked, a new set of turbo bolts from courtesy nissan are less than $75 and way cheaper than dealing with a broken stud buried in the block. if you do replace the bolts (recommended) be sure to chase the threads with a good quality bottoming spiral tap (don't waste your time with a fluted hardware-store one as they chip/break as well) so you get a nice, accurate torque.

 

yes, pulling the head is a day's job the first time you do it (gets easier once you've dealt w/all the rusted, crusted bolts) but in the end you'll have a nice clean head, new gaskets at the head, manifolds and t-stat and after you clean off all the crud you'll find in there you'll be happy you did it. i've got a thread on here showing the poop that came out of my block when i did just this (my PO ran straight tap water and my coolant was rusty like yours) and it was shocking how nasty it was inside the block. if you're leaking around the head, it wouldn't surprise me if the PO used some "stop-leak" additives at one point, which tend to make a nice, goopy jelly-like mess in there. i wound up using a pressure washer to blow it all out of the freeze-plug holes and down through the coolant galleries in the top of the block.

 

do a search for my thread and you may want to consider doing this work...

[Zed Head]

If you want to drive it the most cost-effective route is to refill it with the proper water-coolant blend, drive it, and monitor the situation.  If you want to work on it, there are myriad paths you can choose to address the ugly coolant.  Not being sarcastic, just saying, some of us buy to drive and some of use buy for garage projects.  Either way, a refill and some driving will tell you a lot about the situation.  Only cost, with proper monitoring, is the coolant.  You might find that the coolant maintains its proper color and clarity and the engine runs fine.