Reserve Bottle Coolant Level

[Mayuri Krab]

Hi guys

Just spent several hours reading up on old threads of the wonderful world of cooling problems in Skylines...

But couldn't find many similar incidents to mine (the few that looked similarly didn't have much info on it).

Background info

I had 2 past cooling system related problems.

1st incident occurred early February after getting my A/C fixed, I noticed a slight over-heating (stock temperature needle went slightly over 1/2 way), noticed coolant was bubbling when I granny-ed back home. Got it checked out & turned out to be a worn-out thermostat & Radiator cap, replaced both & car seemed fine (needle always stays just below 1/2 way point).

2nd incident occurred about 2 weeks later, the top plastic radiator tank has developed a hair line crack & pissed out a little bit of coolant, took it to the local mechanic and got a reconditioned top tank fitted (thought about using a new OEM one, however lady on the phone from Nissan couldn't find one for a automatic Skyline).

The issue

Ever since then I've kept a close eye on the temperature & cooling system & it appears that the coolant level is going down at a very slow rate from the reserve bottle. I've marked the bottle & it seems to be losing a coupe mm down the marked line every time I check it (every couple of days in the morning when the engine is cold). The actual radiator is always full with the coolant level up around the neck area.

It has being about a month & the coolant level in the overflow bottle has gone down from about ~80% (between the min & max line) to ~60%.

Last week I took the car to Natrad, they pressure tested the system & didn't find any leaks & it held a steady 15psi with no drop in pressure. Also I haven't seen any of the usual head gasket issues (oil is nice golden colour, coolant is nice green, no white smoke or bubbles from radiator, car hasn't over-heated).

So now I'm stuck on whats causing the coolant level to drop ever so slight from the overflow bottle, only thing I can think off now from reading some old threads on the issue was that it could be some air that wasn't fully bled out when the new top tank went in & is ever so slowly coming out & hence slight drop in coolant levels? (how long does this take anyway? Since it has being a month already.)

Is there anything else I should look at?

Cheers

EDIT: Also noticed the replacement rad cap they put on was some generic one which didn't state the pressure, all it had was the number "130" written on it, does that mean its 1.3 bar cap? After reading some extra info here, I'm thinking off buying new OEM 0.8 bar cap from Nissan later this week (which hopefully doesn't cost me an arm like what they tried to charge me for a plastic bottle cap for the window washer bottle).

Edited March 22, 2011 by Mayuri Krab

[turael]

You can get a rad cap from supercheap or something, don't pay for an OEM one

Coolant level dropping means you are losing coolant somewhere generally. you can bleed the system properly with the bleed screw up the top near the throttlebody, loosen it all the way until either bubbles or water come out (might want a toewel to mop up the mess).

I guess it would only take the smallest leak to do what you are describing - maybe it's only evident when its warmed up.

[Mayuri Krab]

you can bleed the system properly with the bleed screw up the top near the throttlebody, loosen it all the way until either bubbles or water come out (might want a toewel to mop up the mess).

How much torque do you need to move that bolt?

Was trying this morning but the bitch won't budge at all! I'm using some generic spanner & anymore force I apply I feel that I'm going to snap either the spanner or the metal joints that connects to the bolt...

[Mayuri Krab]

Also every time I start the car up & drive it for the 1st time or so I can hear a "Glup" noise behind the dash (comming from the front of the car), could that be the air stuck in the cooling system?

Since I can't seem to undo the bleeder bolt, I followed what someone else suggested on an old thread & parked the car on my steep car park with the front end on the high ground & let it idle with the radiator cap off till the engine was up to operating temperature (aftermarket gauge showed it was at the mid 80 degs) but no bubbles ever came out.

While I was doing this, the coolant keeps on raising above the neck of the radiator & flowing out & splatting onto the clutch fan (which ended up on my face... ). Is this normal?

Edited March 27, 2011 by Mayuri Krab

[Socrates]

The glup sound you are hearing i believe is the airconditioning motor that selects where the air is directed to.

It might have lost a tooth in the motor.

Common r33 problem i have read.

Edited March 27, 2011 by Socrates

[turael]

Hit the bolt with some penetrating oil like wd40 and let it sit for a bit

maybe tap it with a hammer...

its just rusted inside and seized.

As far as I know, coolant coming out of the rad means it's having issues flowing, like its pushing water into the rad but it can't flow out back into the engine. This can be caused by airlocks, happened to me on my rb buggy.

Definitely need to get that bleed screw undone first. brace the bracket with something and get a breaker bar on it.

[Mayuri Krab]

Will try the wd40 tomorrow, can't believe I didn't think about that! I was even using that stuff to on Saturday cleaning off some rust in the back boot.

Finally with the min & max line on the bottle, is the max for when the coolant is cold or when it is hot (engine at operating temperature?) on the old threads there seem to be a conflict of answers...

[turael]

When it's hot it will be at its fullest, pretty much when you turn off a warm car your coolant will be at its warmest as it's not being cooled/circulated, so it will increase the pressure in the system and flow out the rad into the overflow. As it cools down the water gets sucked back into the rad.

Tbh I don't understand how the coolant can flow back in, never really thought about that - surely it gets stopped by the rad cap... maybe it only sucks back in while the pressure is still high enough to open the cap.

Really don't think it matters how high the level is on the overflow, as long as there's enough. If it's too high while cold it could overflow once warm and come out the overflow bottles overflow part. dawg. just my 2c of course not very informed on this topic

[Mayuri Krab]

The glup sound you are hearing i believe is the air conditioning motor that selects where the air is directed to.

It might have lost a tooth in the motor.

Common r33 problem i have read.

Does the motor move even if I have the entire system off?

Since mine still makes that 'gulp' sound shortly after I start the car even if I have the entire air vent system off.

[Socrates]

I've never owned an R33 to know for sure.

I think it does it regardless if system is on or not.

hopefully some R33 owners can chime in with some info.

[Mayuri Krab]

Update

I started to notice some small coolant marks on the undercover of the car so I had a more through look around the engine bay & noticed a trail of coolant marks on the areas underneath the water pump.

I guess the water pump seal is gone & it's new pump time, dam Murphy's law is coming back to bite me in the ass now.

While the pump is getting changed I guess I will also get the bearings/pulleys changed too at the same time (timing belt was done 30,000kms ago).

I'm going to be poor again...

[Mayuri Krab]

Noob question:

When your water pump seal is gone, how fast is coolant suppose to leak from the hole underneath the water pump, Driping or pissing out?

My leak seem to only occur when the car cooling down or warming up, doesn't seem to notice any leaks when the engine running at operating temperature?

[turael]

Do you mean it's leaking from where the pump attaches to the block or through the spinning part? the seal from block to pump is just a gasket goo - could try tightening the bolts up a bit maybe?

[t_revz]

Noob question:

When your water pump seal is gone, how fast is coolant suppose to leak from the hole underneath the water pump, Driping or pissing out?

My leak seem to only occur when the car cooling down or warming up, doesn't seem to notice any leaks when the engine running at operating temperature?

my pump leaked out of the tell tale hole twice in 3 months while it was parked up for 2 weeks each time when i was away working. the day i finally saw it first hand it was a fast drip almost a stream. must depend on pump position when engine is stopped. never leaked when running

[Mayuri Krab]

Got my car back with new water pump, idler bearings & 3 new drive belts. No more leaks from underneath the pump.

With some luck, hopefully no more other leaks/problems would occur in the near future, as I need to drive to Albany this coming easter...

<fingers crossed>

[Mayuri Krab]

Quick question for everyone:

What level does your coolant sits at in the radiator?

Mine always seem to settle about an inch below the neck. Is that normal?

If I top it up all the way to the neck, after a drive & letting it cool down all the way (next day) it will be back down to this level again. I don't think its leaking anywhere since I had it pressure tested just a week ago & the shop reported no leaks & it seem to be maintaining the coolant at this level for almost a week now.

Just a bit paranoid with the recent cooling system issues I had...

[Socrates]

i think air is just still coming out, keep topping up

[Mayuri Krab]

Hey guys, need your help/opinion again, sorry

So after my last fix (replace the O-ring seal on the top radiator tank due to a minor leak) I drove the car to Albany (~400km) before Easter break & it had no problem (& I give it a bit of WOT from time to time when overtaking road trains & Caravans).

For the past week the car has just being mainly sitting there, with the exception of 1 trip I made to Denmark (~100km round) I checked the overflow bottle level from time to time & it appears to be stable around the max mark (when cold).

Today before heading back to Perth I did one last routine check before handing out & I found what appears to be a white/semi-transparent film on the top layer of the coolant in the overflow tank (see picture below), I checked the coolant in the radiator & it doesn't have the same 'film layer' there.

What is this film? Is this what oil in coolant looks like? Did a a couple of google image searches but those appeared to be more browny cream colour instead?

I checked the other usuals (oil dipstick, oil cap & auto trans dip stick) & all of those appeared normal and rad cap doesn't have white stuff neither.

While driving the car back to Perth today, keeping an eye on temperature & it was all normal (never went past 82 deg C when stationary, usually sits in the low 70s when moving along at 100-110km/h) & nothing was unusual here, car was smooth (no misfire) even when I go WOT (when overtaking) & hit 6k rpm etc etc

I also pulled over & checked the coolant bottle every 100km or so & nothing else was unusual, I noticed that once the coolant has warmed up the white film disappeared & I could only spot some small 'white flakes' if I flash a LED torch.

So yeah, is that white film what oil (or ATF) look like in coolant?

Cheers.

Going to check it again 2morrow, this car is giving me a headache atm