Head gasket leak.

[Rocket88]

My son's 74 260Z has a bit of a coolant leak between the head and block on the passenger's side.

It is worst when you first fire it up and stops once the engine is up to temperature.

The engine is original with 92,000 miles, runs strong.

No white smoke coming out the exhaust, so I don't think I'm burning any coolant.

Can I try re-torquing the head, or should I just bite the bullet and do the head gasket?

[d240zx2]

If you've got an external coolant leak, re-torquing will not help. Bite the bullet....

[Zed Head]

My son's 74 260Z has a bit of a coolant leak between the head and block on the passenger's side.

It is worst when you first fire it up and stops once the engine is up to temperature.

The engine is original with 92,000 miles, runs strong.

No white smoke coming out the exhaust, so I don't think I'm burning any coolant.

Can I try re-torquing the head, or should I just bite the bullet and do the head gasket?

You could try some of that "magic" leak stopping powder, like Bar's or other. I had a small external leak from the back of my engine and one bottle of Bar's stopped it.

[ozconnection]

You could try some of that "magic" leak stopping powder, like Bar's or other. I had a small external leak from the back of my engine and one bottle of Bar's stopped it.

Yeah mate, try Bar's first.

HG's do weep sometimes, and this may be all that's needed to sort things out.

Your boys HG weeping is worse when the engine is cold because the coolant/block pressure is higher before the thermostat opens. Does that year use the coolant bypass from the thermostat to the water pump inlet? (The bypass was designed to reduce coolant block pressure for those who ran straight out onto a freeway with WOT and a cold engine. It would work to reduce HG weepage, like your seeing).

Still, try the solution in a can first especially if there are no other symptoms of a wasted HG.

Cheers.

[Oiluj]

Given it's an aluminum head and will warp if overheated, I'd replace the head gasket sooner than later. Replacing the head costs a lot more than a head gasket. You can R&R the head in an afternoon.

[ozconnection]

Given it's an aluminum head and will warp if overheated, I'd replace the head gasket sooner than later. Replacing the head costs a lot more than a head gasket. You can R&R the head in an afternoon.

I can only assume that whatever Rocket88 has told us in his introduction is what is actually happening. However he hasn't pointed out how much is leaking and whether or not there have been overheating problems. Why are we to assume there are other problems with the engine if they have not been mentioned by the author?

This forum is a great place to help people but lets not pretend to know what is happening unless we are actually told so by the author! We could save this guy some money (yes, he may have to replace his HG eventually but not yet as I can see) and time if all he needs to do is stop some coolant weepage.

Rocket88 you need to fill in the blanks for us now please.

Good luck with the car.

[Zed Head]

Agreeing with the man from OZ...

The original post described a very small problem. A "bit of a coolant leak." It goes away completely when the motor warms up. No mention of overheating, oil burning, etc. The post even says "no white smoke" so there is some awareness of the various bad head gasket issues.

Just taking off the head can cost extra money and time, for gaskets, broken bolts/studs, possibly failing to secure the timing chain, etc.

I would apply the KISS principle here.

Edited May 22, 2010 by Zed Head

[Z train]

You have water leaking from the head.The HG is FAULTY.Anything other than replacing the HG and making sure the head is "flat" is a shade-tree mechanic HACK-job.

[ozconnection]

You have water leaking from the head.The HG is FAULTY.Anything other than replacing the HG and making sure the head is "flat" is a shade-tree mechanic HACK-job.

Hang on a tick, I'm talking from personal experience.

Let me fill you in on why I make the comments I make. My L28 had a new NISSAN gasket put on by me approximately 30K kms ago. In that time it has performed over 60 individual dyno pulls, gone on holidays with the family twice (3500km round trips each time) and has had many subsequent performance improvements to the engine and cooling system (LD28 water pump, reconditioned 3 core radiator, thermo fan, water wetter etc). Compression tests recently proved that all my cylinder pressures are spot on too.

The point I'm making is that all of this is on "the HG that was weeping after I installed it". I solved the weeping problem with a dose of Bars leaks and have never looked back. I could've replaced the gasket at the time with another but I'm glad I waited and have had zero problems since then.

"You don't need your appendix out if it's been so far diagnosed as pain in the guts" Treat your symptoms and see what the resolution is. Go from there.

Like Zed Head suggested in his post........K.I.S.S.

[prilofx]

might be that the break in the gasket is small, and once the engine warms up, the gasket swells enough to seal itself.

[Gary in NJ]

You have water leaking from the head.The HG is FAULTY.Anything other than replacing the HG and making sure the head is "flat" is a shade-tree mechanic HACK-job.

I'm kind of in this camp as well. What scares me about Bars and other sealant products are; what else are they sealing? I'm sure that the sealant doesn't only cling to the leaking problem, so by using these products you may fix one problem, but may create another.

[ozconnection]

I'm kind of in this camp as well. What scares me about Bars and other sealant products are; what else are they sealing? I'm sure that the sealant doesn't only cling to the leaking problem, so by using these products you may fix one problem, but may create another.

Such as....?

There is definately a place for a product like Bars leaks. If the the HG was 'blown' in that it was leaking compression/cylinder pressure I would have no problem recommending that Rocket88 repair the leak by changing out the HG. The main usage of Bars leaks is not to correct a blown HG.

Now we'll start debating the term 'blown headgasket'. OMG!

Just one more thing before I let this go...I have replaced my engine coolant many times since the original installation of the new HG. Never since have I needed to re-use any more Bars leaks to stop renewed weepage.

I have written about this extensively on HybridZ and have even tested the pressure head generated by the mechanical LD28 water pump as being around 30 psi at 4000 rpm. I have a 20 psi radiator cap on my radiator to prevent nucleate boiling after shutdown. With these cooling system modifications, I'm happy to say that Bars leaks does a wonderful job of stopping HG weepage!!!!

Probably more important is to keep your cooling system clean.....many don't change their coolant for very long periods, allowing scale to build up and clog radiators. I thing neglect causes far more problems than the appropriate use of Bars leaks mate!

Edited May 22, 2010 by ozconnection