Help! Cracked Head/head Gasket

[doylej]

On Thursday car started over heating got a little over half way turned it off let it cool down and topped it up drove home, next day checked it out had crack in top radiator bought new radiator installed it did the bleed thing well think I did seemed sweet drove 10min down road started over heating turned heater on full and kept it at normal temp drove 2 hours like that sweet, checked fluid in morn didn't need topping up and will still start getting hot if heater not on, cracked head?

[Hadouken]

didnt bleed properly?!

[doylej]

Well that's what I thought but I looked at the videos and did what they did.

[Hadouken]

have you tried bleeding it some more and see if any air bubbles out?

[doylej]

I tried again this morning, didn't see any air bubbles will let cool down and have another go, when the bleed cap is off should that be full with coolant running through it cause mine wasn't.

[(Locky)]

is your overflow correctly topped up?

Rad cap new?

could be sucking air back in

[nickcorr]

Is there a bleed point in the pipe at the back of the engine? Did you open it?

With the M35's it's a complete arse of a job, and the rear bleed point needs to be used to ensure minimum of airlocks. It is even used for the last few topping up..

Edited January 19, 2013 by nickcorr

[doylej]

yup got that open

[scotty nm35]

But did you fill it completely from the bleed point? It needs to be done cold, then drive around to release the bubbles from the block. Once it's cooled again you need to re-check the rear bleed point. Same issue at the moment in the Stagea forum...http://www.skylinesaustralia.com/forums/topic/418050-overheating-gearbox-something-else/

If it's in need of bleeding you can hear a waterfall sound behind the dash, and the heater won't work properly. (not that you would know at this time of the year) One cupful of coolant missing is enough to airlock the system.

I have designed a VQ coolant mod to get around this issue if anyone wants to stop this happening, and make it easier to bleed...

http://www.skylinesaustralia.com/forums/topic/413471-m35-coolant-bypass-mod-install/page__st__20__p__6651111__hl__coolant%20mod__fromsearch__1#entry6651111

http://www.skylinesaustralia.com/forums/topic/410876-m35-coolant-bypass-kit/page__st__20__p__6572366__hl__coolant%20mod__fromsearch__1#entry6572366

[doylej]

I filled from main radiator, havnt got new cap, so do I need To flush and refill via the bleed valve?

Edited January 19, 2013 by doylej

[scotty nm35]

The rear bleed point is where you want to fill from, once the radiator is full. Just leave the radiator cap on and crack the bleeder, I use a large syringe to fill it.

As I said, make sure the car is cold (overnight) before checking and filling. You will have to do it a few times as the bubbles get trapped in the block, and are only released from driving around. It's a pita, but once bled you should be fine if the system is still sealed.

[doylej]

Ok thanks ill leave over night and try that in the morning.

[sonicii]

I have never had much problem changing coolant in any car I have had.

When filling I usually open the heater tap if possible, crack open the bleader and fill at the radiator. Normally the radiator cap is high enough so some coolant bubbles out of the bleader when it fills. then I squeeze the top radiator hose which causes the coolant to move around a bit and gets rid of most of the bubbles. Then refit the radiator cap, squeeze the top hose again until coolant starts coming out the bleader, hold the hose in this position and close the bleader. Then top up the radiator and overflow tank. I usually find the overflow tank drops a little over the next few days, so I just top off. Never had any issues doing it this way..

[scotty nm35]

That method will likely see you with a blown head gasket on the VQ's, I have rebuilt two engines now due to overheating lifting the head from simply not having water flow (airlocked system) Another V35 I worked on was bled 3 times and still overheated on the way home.

You can't get rid of the air from the block as it has nowhere to go, there is a blanking plate over the most logical (highest) point to bleed the block, which my bypass mod design gets around. Even if the stock setup didn't airlock it would never bleed fully.

[doylej]

Update bleed again this morning got a lot of air bubbles out, but still over heating until I put heaters on will let cool Down will try again tonight

Edited January 19, 2013 by doylej

[sonicii]

That method will likely see you with a blown head gasket on the VQ's,

I have done it twice now on a VQ without issue.. but I will keep an eye on it in the future.. thanks.

[scotty nm35]

Update bleed again this morning got a lot of air bubbles out, but still over heating until I put heaters on will let cool Down will try again tonight

You don't just bleed the air out, you need to fill the bleeder completely first with coolant then start the engine. Keep topping it up until it overflows without bubbles for a while.(heater off) There may be air trapped in the heater lines too so you will have to turn it on and off at some points but I have found the air bubbles make their way up the heater pipe easier with no water flowing.

If the engine temp gets hot during all this bleeding, or the thermo fan kicks in, you have an airlock and no water is flowing through the block. Sometimes turning the engine off will release the air but it has taken me over an hour to get it out on a few occasions.

[doylej]

So just keep the car running with bleed valve open until no bubbles are coming out

[doylej]

gave up and took it to Nissan today, they wont look at it till tomorrow but he said he thinks itl be head gasket, and will cost around 5k+ to fix because have to replace cam chain to, seems like a lot to me, can anyone shed some light to what sorta price I should be looking or where to take it in nz, Auckland or Tauranga.

[Hadouken]

Take it someone who isnt a nissan dealer/mechanic. But yes it will cost a bit of cash.