is it a BLOWN HEAD GASKET or CRACKED HEAD

i have an 04 str with the zd30 motor.
recently had new water pump and radiator cap replaced because it was over heating.

After that i done a c02 test and it was fine but than i went on a trip and on the way home i could smell coolant had a look and it was the little line that comes off radiator just below the cap that came off, put it back on didnt think much of it.

couple days later after a short 10min drive i turn the ute off and popped the bonnet cause i could hear the overflow tank bubbling but the coolant wasnt really hot to touch?

I than changed the radiator cap to the origiinal one which seem to have stop the problem but than it started leaking a little bit off coolant around the overflow tank but there is no hole or crack in the tank i think it was coming out of the top of the overflow bottle

i than done another c02 test which was fine until the motor got to operating temp than the c02 tester turned green but the motor still is not overheating it runs around the half way mark which it always has.

I need to know if i have a blown head gasket or much worse a cracked head?

can anyone tell me which head gasket the zd30 has as i have been told there are 2 different types?

I can get it fixed for about $1200

Hi Kerrie,
had the same sort of issue about a year ago, was losing coolant constantly and finally after a lot of chasing found a leak from the radiator only running temp.
Fixed the radiator and a week later the engine did hydraulic lock in a carpark. The problem came down to a cracked head through number 4 which leaked the fluid into the cylinder, thankfully i was with some mechanics at the time who spoted the issue.
Not much more to say but about $7000 later it was back on the road.

James

wow or should i say ouch... id you dnt mind me asking why did it cost you so much

Total rebuild of the top end, the head alone was around 1800. Most i spoke to would not repair the head and if they would they would not give any warraty on it.
included glow plugs($100), injectors($1000), thermostat($50) and head gaskets($350).
took nearly 2 days for the job to be done.

ok thats alot of mony to spend.i dont think i need to do that work i just either need to replace the head gasket or head.i can get the following

1. complete recon head with new valves that has been milled/crack n pressure tested for $850
2. i can get a bare head for $615
3. head gasket $100
4. head bolts $45

my next question is if i go with the recon head should i get the thicker head gasket since the head has been milled?

Was the test for CO2 or just CO? A diesel engine won't always indicate properly on a Tee-kay type tester.

not sure it says on the box combustion leak tester- you pour blue dye into the hand pump and put it over the radiator and pump it if it turns green there is an exhaust leak which is what happen but only turned green when at normal operating temp, it stayed blue when cold.
I also done a coolant pressure test when the motor was off and it was holding pressure and when i started the motor it incresed in pressure

Do you have steam constantly coming out of the exhaust or is your oil a milky grey colour.

Hi mate, I had the same problem, was pushing water out of overflow and getting an airlock in radiator. I did a co2 test but it showed nothing. Replaced thermostat and radiator cap. No good. Bit the bullet and decided to pull it down as I suspected a cracked head. Stripped it down and got head checked. They couldn't fault it. Could see some marks where possible leak on head gasket. Replaced head gasket (2 notch gasket from memory) .05mm thicker, new head studs, new water pump and decided to do timing chain and sprockets while I had it apart... All up cost me about 900. But 6500kms later and all is good!

I think what you are describing is a cracked head, when cold you are getting no change on the co2 test but once the motor warms up it changes colour, this could be as it heats up a hairline crack opens up, these heads are prone to cracking through to the glow plug. These are the exact symPtoms my motor was showing. I assumed the worst... But got away with the head gasket!!! Hope this helps

ok so we pulled down the motor and found the head cracking around 4 exhaust valves n 4 intake valves n 8 valves badly pited caused from water leakin past head gasket.By the looks of things it all started from number 4 the valves were getting eatin away.

after some ringing around i can get a complete new head minus the cams for 1500 delivery or i can get a second hand complete head that has been crack/pressure tested with all new parts.

Last option is to buy the parts all seperate for about $1000 - $1200 but the only trouble that way is trying to put everything into the new head without stuffing things up like the shims.

how dirty was the intake manifold?
need to find why its got excessive egt's.

yea the intake was covered in soot and oil but before the head cracked it was a great motor run really well had good response but our str has 270,000kms but has a complete service history from the 1st service to the very last

Kerrie,

I had mine done last year at 140,000km and there was no sign at all that anything was wrong. I checked the coolant one day and it was missing and oil around the top of the radiator cap. Got it checked and it tested fine through a compression test, no cracks/gasket issues.
Ran it for another month or so, maybe more, and oil appeared back in the radiator fluid. Took it in and it was cracked in two places, near number 4. Fortunately no damage to piston they could see.

I have an EGT gauge now and it runs up to 600+ pre turbo in what I assume would be a normal uphill drive. Sure makes me back off and sit on 2000-2500 rpm in the next gear down.

Do as much as you can because it cost me $7000 for everything to be done again.

tweak'e said:

how dirty was the intake manifold?
need to find why its got excessive egt's.

Click to expand...

Tweak not sure how dirty mine was, I did ask and they said not overly. It seems that these get very hot when laboring in the incorrect gear selection, even slightly. I was very surprised at the high temps and I have been told that all it takes is a small amount of time, at any stage, at too high a temp, to push it to far.

No one can say what that temp is though...

Is this a good reason to do the EGR Blocking off mod? Does it help reduce the temp of things in that part of the engine?

It will help.

Just drive it hard, they love it.

I still rev mine out often, even with 250,000km's on the clock.

She loves it, plus I only use Delo 400 oil aswell.

Afternoon guys, its been a while since I have been in for a look. Work has been chaotic.

I think I have some serious issues with my Nav, and just thought I would pick some brains on here. My old girl hasn't been doing a lot lately due to me away all the time, but over the last 12 months or more I felt it was loosing power (or, down on power) but couldn't quantify that as I have never had it dyno'd either. Then a few months ago I get sporadic coolant loss. Sometimes it will loose half a litre in a few hundred km's, other times it will not loose any for a few 1000 km's. Nothing showing up either in the oil, or oil in the coolant. No residue in the rocker cover from moisture either.

Now the last few times I have gone home to start it after an extended break (I leave it for a month at a time) it has not wanted to turn over straight away, like a flat battery, which is what I thought at first (even though I have the battery on float while I am away). Tested the battery, its fine. I found if I held the key on start it would then slowly start to turn over, and once moving was fine. It would then start normally, run normally, and start every time like normal as long as its less than a few days between each start. I have now noticed that after it starts for the first time from the month off, I am getting a lot of white smoke. Water. So after reading this thread, and putting together all my symptoms, I am not willing to start it again once I get home from this swing as I don't want to hydraulic lock it and do any more damage than is already there. I am thinking that its a cracked head, or headgasket leak, and water is slowly leaking in to one of the cylinders over time, or possibly corrosion caused by the moisture is growing over the month away and making it difficult to turn over?

I would have thought if the coolant was going to leak and build up, it would do it immediately after shutdown while the coolant system was still hot and help pressure? There fore there should only be as much water in it after a month as there would be after an overnight shut down? Hence my possible corrosion theory? Either way, next swing home looks like I willl have to knock the top off and have a look. Just wondering what else people recommend doing at the same time, where to get parts from etc. I want to source a reco head if possible before I head home so that if I need to get it I can get on to them straight away.

Other things like my rear seal leaking I thought I might as well do at the same time, so taking the g/box out. Then if I am there, the clutch has been slipping a bit under load for a while so might as well do that. Then if I am doing that, should I be doing the bigend bearings and bolts as I heard these were not so flash from factory, and the cause of a lot of the nissan handgreandes?? FML, the list never stops. What would you be doing? And where would you go to get parts, reco or new? I have a few weeks before heading home again so wanted to gather as much stuff ready, parts and knowledge, before I get in to it to save down time with out wheel. Any special tools?

Lots of questions, I know, but I know you lot are most generous with your knowledge

Cheers,

White smoke is also unburnt fuel, but the loss of coolant does tend to point in the direction of the head gasket.

Best bet is to take a sample of the coolant to a radiator specialist and have it tested. If any combustion gases have contaminated it, they can tell.

As for cranking it over - as batteries age, they can't hold as much depth of charge nor can they summon power as well as they used to, although they can still show a surface voltage making one think it's in good condition. When a battery reaches this stage, you can use a discharge tester (most auto electricians have one) and you'll often find that they'll start delivering power but will fall away rapidly.

Thanks Tony, and its been so long since I have been on here, I don't even know how long you have been a bossman on here for... congratulations, or commiserations, one of the two.
Yeah, the battery is fine (Big cranker, new only a month or two ago). I should have elaborated a bit more. It throws out and starts to turn the motor, and then stops dead. The first few times I let the key off and tried again, and every now and again the starter would miss the teeth and make a horrible noise. Not wanting to shear teeth off the flywheel, I held the key once it engaged properly instead of trying multiple more times, there was a pause after the intial fraction of a second turn of the engine, and then after a second or two it laboured around (Slight hissing sound), slowly building up speed to normal cranking speed. Every other start from then on when I am driving it regularly is fine. The loss of coolant has been getting worse and worse as time goes on, but still not regular. Last time I noticed it the overflow bottle still had the normal amount, however the radiator need nearly a litre in it.
Also makes a horrible knock and misses and carries on for the first few seconds after that first start that I have issues with.

It sounds like the starter motor is giving up the ghost in that case.

Still worth taking a little coolant from the drain and getting it tested - at least for a small fee you will know whether or not the head gasket is leaking into the water jacket.

If you take a look inside the camshaft housing, is there any milky appearance in there?

The only other place coolant can go is the heater matrix inside the cabin and I guess you'd notice that by the smell, so for my money I'd be taking that sample for testing.

Not sure on the knock either - could be liquid in the combustion chamber, or a cylinder not firing properly (perhaps a glow is out?).

It could have water entering a cylinder and causing it to "hydraulic lock" which puts an enormous amount of strain on the starter if you keep trying to start it, but once the piston has compressed the water and you stop trying to start it it will allow the water to pass by the piston and therefor releasing the cause of the "hydraulic lock" problem and allows you to start it.
Once you do get it started you will get a puff or allot of white smoke from the water in the system.

Some cracks in the heads can be almost impossible to detect making it very hard to get results from pressure testing and Co2 tests and sometimes the only way is to remove it an have it
X-rayed, some cracks will only let water passed when the engine is really hot and under load and if turned off at the right moment will allow water to enter the cylinder, But alternatively wont happen at all on some occasions although generally it will get worse and worse the more you use it.