Water leak at no. 6

[240znz]

I always check out the Zed before taking it for a spin. Noticed last weekend that the block has rusty water stain on the left hand side (LHS).

Traced it to the back of the head, right behind no6 cylinder. Then noticed that the stain is on the RHS of the block as well but not as much.

Check rad for water and......heart lept out and stopped for the 5 seconds......CRAP....it was dry. I put 1.5 litres in it to get it up to level. Started it up and a very small trickle emerged on the LHS. Let it warm up and checked again....nothing....dry...no leak.....hmmmmmm.

Took it for a mild drive, stopping and checking LHS every so often. Dry each time and also RHS. It could still have a leak and the heat of the block will be evaporating instantly.

Checked levels today and all OK. Did exactly what I did last week in checking after start-up and when warm but no leak. Rad level still OK. Cleaned all the rusty trails off and took for another drive. Zip...no new trails....what the? Rad level OK after the run too.

I was thinking of re-torqing the head as the PO has rebuilt this engine some 1500 miles ago. Head as been shaved and it was a lumpy cam in there also.

Any ideas? I have a new head gasket and I'm thinking of pulling the head to make sure that it isn't serious....last thing I need is a warped head.

Your input/ideas/help is appreciated.

[280zx Fever]

Watch the temp gauge ! but if you have time i would take the head off and check could be a cracked water gallery or something..

[Gav240z]

hmm strange what does a compression test show?

Have you checked your spark plugs for water getting into combustion chamber?

Your theory that it may require retorquing is a good one especially after a rebuild.

Whats your radiators condition or the hoses attached?

How about your heater radiator there is a tap inside the car that is prone to leaking also might be something to check.

I almost pulled the head on my car recently to find the cause of all my problems was a dizzy module.(note your car will not have this BTW if your using points). So before you go pulling it apart check the other possiblities.

Try running the car a bit hotter maybe the metal only expands enough to allow it to leak at higher temps have you been watching your water guage lately?

Have you also checked your oil for water?

[280zx Fever]

if you havent had the head retorqued after the rebuild you should do !

rule of thumb 1000km/h after the heads been off you need to re torque it

[sjcurtis]

240znz,

Have you confirmed the leak is from the head gasket area. the pre heater plumbing in the intake manifold is susceptible to corrosion. A leak onto the block on the left hand side at six could be a leak from the rear pre heater hose fitting, dripping onto the block. A leak at six right hand could be the rear head hose adaptor leaking down and staining the block. Non of the above is very likely, when it is happening at the same time, but like Gav240z is saying check every thing before pulling it up. Be very careful with that temp getting to high, when it goes its all gone. I hope you sort it quickly.

cheers

steve:classic:

[2ManyZs]

I would definately re-torque the head before you do anything else.

It almost sounds as if it may be a cold water leak, which could come from the head not being re-torqued. When the engine cools, the block and head will contract just enought to allow standing water in the water jacket to leak out between the head and block mating surface. If after re-torquing, you still notice dampness, then you may end up having to replace the gasket.

[Bambikiller240]

I had a leak at the rear of the engine in this same area for over 3 years. Water stains on the block at the rear near the fitting for the heater hose. It definately came from the head gasket, but only put water out to the atmosphere, no water in the cylinders or oil. Compression on all cyls in the 155 to 165 range. I retorqued the head to no avail, so after worrying about it for 3 years, I elected to pull the head and replace the timing components at the same time. 150K on the motor, so it was about time. I ended up having the short block rebuilt (bored .5 mm over) at the same time, even though it was not necessary to stop the leak. Just got the engine fired up two days ago.

[240znz]

Spark plug looks great. No water in the engine oil. I'll do a compression test tomorrow. Weird.

Maybe as you suggest Keith. Don't really want to rip the head off but it might just have to be.

Should I retorque when hot or cold?

[2ManyZs]

I would re-torque when cold. It's one of those "either/or" choices.

The aluminum head will expand and contract with temp changes differently than the iron block, so by torquing cold, you will be doing it when the aluminum is contracted the most.

[beandip]

I bought a Maxama brand new in '80 and it had a 240 engine . Factory said to retorque the head at 1K . Might just as well .

[kyteler]

I have a similar problem on my L24 in the Skyline, if you get your head shaved or simply retorqued or any work done by a shop, could you let me know the price you paid? Being you're in NZ I can expect to pay a similar amount I'm guessing.

It's a small leak, there's no water in oil, compression test is pretty much identical in all cylinders no watery spark plugs so yeah, except it's not at the back of 6. It's at the RHS of 5.

But yes, if you get anything done I'd be most appreciative if you could let me know the costs involved.

[240znz]

Finally got around to doing a compression test tonight.

The results were 1-6: 130;125;130;125;120;125. I thought this was OK but I was expecting a little higher in the 170's-80's. Then I read the manual and it says that I should have done this with the engine hot. DOH! Engine cranker has gone to bed so it'll have to wait until tomorrow. But the readings are 95% of each other so it can't be all that bad. It does suggest that the PO did do a rebuild.

So I'm hoping that the readings will come up tomorrow or I will have other things to consider, like did the PO really rebuild this engine? If he did then why does it have a low compression with new rings??? It does have a chunky ground cam in there though...maybe that has something to do with it. It is a L24 block running a E88 head. The PO told me that the head had been shaved but I don't recall by how much, so I am thinking that the combo of the two might result in a lower compression.

Still no more leaks. Rad level remains unchanged. Oil levels also remain unchanged.

Any ideas? Should I be checking else where?