Head gasket mis-adventures. Part 1

[zbane]

A little bit of background…

Some time ago I noticed that I was loosing coolant. At first, it wasn’t much, but the amount continued to increase, yet I couldn’t find the source of the leak.

One day, as I was driving to school, I heard a pop! but assumed that I had hit an empty can or some such. Knowing that I had been loosing fluid, I checked the reservoir once I had parked. What I found was that my reservoir had popped open and belched fluid all over the place. Once the radiator was cool enough, I opened it and found that enough fluid had been evacuated to allow me to see the top row of the radiator.

I filled it up and drove home to see if the situation would happen again, and it did, though this time the temperature gauge moved up to three quarters for about twenty seconds, then went down to a normal reading, pointing strait up. I figured it was a faulty thermostat, so the next day I purchased a new one.

The new thermostat didn’t do a thing to change the condition, as it happened again the next day. I kept driving as it was, checking and filling as needed.

After going through more and more fluid, I installed a back-flush kit and back-flushed the system as per the instructions, yet this didn’t help either, so I installed my spare radiator, thinking that the original was the problem, and back-flushed again.

Alas, while the “new” radiator did indeed help, the problem of the popping reservoir continued.

I watched the engine warm up, and saw air bubbling into the reservoir, and also found a small leak from the J-tube.

I replaced the leaking hose segment and while I was at it I ran new hosing to/from the thermal vacuum switch (removed the funky metal tubing and replaced it with FI hosing).

Again, things were fine for a few days. In fact, the car was running incredibly strong, full of power, though the gauge was still doing its thing of going up to three quarters and then moving back down to normal within a few seconds.

Then, on Friday, January 11 things went terribly wrong.

I drove to work third shift, and the car was wonderful. It was a beautiful day, and the car was acting like a kid on the first day of Spring Break.

However, when I went to start the car the following morning, all I got was the “rarr, rarr, rarr” of the car trying to start up, but not doing so.

The starter had been grinding from time to time (pinion gear not completely engaging), so I left the car at work and went home.

Not sure if the problem was indeed the starter, I grabbed all the spare parts I had that would have anything to do with starting the car (starter, distributor, cap, AFM, electrical contact cleaner, etc.) and went to replacing these things the following night at work. I checked relays, fusible links, and fuel pressure. I pulled and cleaned the plugs.

I had spark and fuel, but no starting.

[zbane]

After fiddling, switching around, and basically making a mess of things, I finally came to the decision that I had to get professional help.

I called my insurance and had a truck sent out. We took the car to the shop I’ve been using for several years, about 30 miles away. After fiddling with it while I told them of the things I had done (with them checking some things over again), they told me what I was hoping they wouldn’t (but had a sneaking suspicion it was), blown head gasket.

And then they told me that they wouldn’t touch it.

“We’ve never done anything like that on an engine like yours” was the reason I was given.

So I called a couple recommended shops (we’d love to do it, can you stop by in two weeks?).

I called my “local” Nissan dealership. “Head gasket? Sure, that’ll be $86, and it’ll be here in a week. And to have it installed will run @ $870.”

Call the insurance back to arrange towing back home. Keep in mind that the zx is my daily driver, and school starts up the next day. Things are not looking good.

Tow truck will arrive in about 3 hours.

At least I have time to get a rental.

Off to the rental place, only to find out that my license had expired (in November, yikes!). Off to the license place (across town, but they drove me) for new license.

Finally get the rental, the tow shows up, and back home we go.

Disassembly:

Day 1- Tuesday. Parts have been ordered directly from Fel-Pro (though Advance Auto).

All external hoses and connections are disconnected, except for the EGR valve (won’t budge-heavy PB blaster applied).

Day 2- Wednesday. is manifold day. All four intake bolts come out smoothly. Manifold doesn’t budge. Not even a little. Pressure from all directions is applied. No effect, just a little movement. I call Will for advice, and follow all that is offered to no avail. Snow is in the forecast for the evening.

I start removing all the bolts holding the heat shield to the intake, thinking that was the problem and round one off in the process. Good thing that unit is only attached to the intake (I was mistaken about that, the FSM barely discusses it). I continue to try to remove the EGR valve. More PB blaster.

Day 3- Thursday. Standing in 5 inches of snow, I continue to try to remove the intake. I grab an old sturdy chef knife and drive it down between the gasket and mani, I work it from end to end by tapping it with a hammer (concerned about the injectors, I removed the fuel rail assy. first). No discernable change.

I start removing the bolts that I can feel (but not see) from underneath the intake, thinking that they are pass-throughs from intake to exhaust. They are not, and my knuckles are raw.

Day 4- Friday (rental is due). I finally start to see progress with the EGR. By applying much force (hard to do when standing on ICE), I manage to get the upper fitting to move a little. Over the course of an hour, I manage to get the thing loose from the intake. Really, it took about an hour.

The manifold really has absolutely no reason to be stuck like it is. I remove the throttle body so that I can slide my breaker bar inside for more leverage. Doesn’t help at all. Out of desperation, I grab my little hydraulic jack and fit it under the mani. I brace it and start jacking. The entire engine and transmission are listing to the right (to the extent that I could have removed the mount), and finally it breaks loose. I repeat further up on the mani, and get it loose. I immediately call Will with the news.

The exhaust manifold comes loose quite easily; as does the head itself (I used an old pair of pliers to brace the tensioners).

I drive off to Brevard to return the rental (they weren’t happy about giving me a ride back. Don’t know why…it’s only 30 miles one way).

Obvious washing of cylinder 3, though the gasket seems intact. No cracks are visible in either the block or head.

We will see what adventures reassembly brings (hopefully none).

[zbane]

Here are the photos of the block.

[zbane]

And of the head and gasket (kind of).

My apologies for being so long winded (worded?), and thanks for making it this far.

Any and all thoughts on this are appreciated, so long as your advice isn't "get a garage." (unless I can borrow yours).

My thanks go out to Will and AJ (by extension) for helping with this mess!

[Cracker Jack]

Ok, you may or may not appreciate my responses but here they are:

1. Garage yes you need one, so do I, joys of living on a fixed income!!

2. That butcher knife stuck between the manifold and head is a CLASSIC!

(True "surgery" on the ole z car)

3. If you ever need help, I will try my best to assist, I know I am up the road a little ways, but maybe I can give you moral support at least

Last but not least, thank you VERY much for the details and the pictures, they will be a huge help when I do the head on my '81 280zx although I will be doing mine after I yank the engine.

[ktm]

Your head may be slightyly warped, which is why you had coolant in #3. I experienced the same thing on my car - HG was fine, head showed no cracking, but the head was warped 0.02". Make sure you have the head checked out by a competant shop.

The fire ring on #3 does not look round but rather sliiiiiightly oval. This is indicative of a loss of clamping force/pressure which could be a result of a warped head.

[zbane]

Bo-thanks for the suggestion, unfortunately, I don't think there is a competent shop in the area...

[ktm]

It does not have to be a Z shop, just a good "head" shop. Call around to your local hot rod stores/shops and see if they recommend any body. If you get 2 or 3 shops recommending the same place, you are golden.

You are not asking them to rebuild the head, simply check for straightness and, if you want, a pressure test.

[Zedyone_kenobi]

Agreed. You have done so much work up to this point, it would be a shame not to get the head checked for straightness. Its relatively painless and inexpensive. But to not do it, may mean that all your work is in vain.

[bradyzq]

When you re-attach the head, you WILL be using new hardware, right?

Ideally, use head studs, especially if you don't find someone to check your head for straightness. You can torque the head down tighter with the studs than you can with head bolts. They're only a bit more expensive than head bolts.

Summit sells a kit for $135.

http://store.summitracing.com/partdetail.asp?part=ARP%2D202%2D4206&autoview=sku

I had suspect compression in neighouring cylinders on a 5 cylinder Audi motor of mine. On the Audi, like the Datsun, the head bolts are stretch bolts. In theory, single use. So, with the head still attached, out came the old bolts, and in went the head studs, which can safely be torqued down more tightly.

I took another compression test, and I had regained the lost compression. In my case it was a band-aid temporary solution til the head comes off.

In your situation, it could straighten out a _slightly_ warped head, and, if you can find a competent machine shop to check your head, you will have done it completely right, with the best chances for long life!

[JimmyZ]

It's probably not warped but...

An engine machine shop will check flatness for free if you're nice. It takes a minute with a proper straightedge and feeler blades. While you're there ask them about the mating face. If it needs milling then the valves, cam towers etc willl have to come off. It will be cheaper for you to do the disassembly/reassembly. Just keep all parts labeled to the right # port. (Dixie cups are good) The price my shop used to charge for disassembly was around $150.

Here's a link which might help you in understanding how to help your head gasket seal.

http://www.enginebuildermag.com/Article/2434/gaskets_sealing_todayx2019s_engines.aspx

More than likely it's just some corrosion in the aluminum. (Mating face of head)Probably some pitting near the water passage letting things get by. It could also be internal corrosion which has eaten through to one of the ports. (Zyglo or good visual inspection would detect this) If it is corrosion in the face of the head a new head gasket may not/probably won't cure it. (not for very long anyway ) The face of the head will need to be milled in this case.

It's interesting when you start reading about heads and the surface finishes required on the mating surfaces. Today's standards of finish are greater than those in the past and modern car's head gaskets are designed for said finishes. As the head heats up it expands more than the iron block does so things slide. This is why it's good to have flat/smooth mating surfaces. "Smooth" is reffering to the "ra" or microfinish imparted during machining. Using sandpaper or other abrasives will damage the flatness.

2c

Jim