How to access a HEAD GASKET to replace it?

I have an '87 Nissan Sentra that I believe has a leak in the head gasket (major water leakage; water leaks out muffler & tailpipe whenever I fill the radiator, and car is very hard to start unless there’s very little water in radiator). I tried to take the cover off but am not sure how; there were only a couple bolts which I unscrewed, but the cover was sealed tight. I’ve heard you’re not supposed to pry it off if it’s stuck. Then how do I get it off??? For a 22 year old car, I’d expect it to be stuck. I just don’t want to go ruining anything in the process of trying to remove the cover. Any tips on how best to do this?

You NEED to buy a shop manual. A factory shop manual is best (try Ebay). A Haynes repair manual will work for this (parts store for $17.95). The cover your trying to get off is the valve cover. Do not pry. Tap on the side with a soft rubber mallet or the palm of your hand. This is only the beginning!! You still need to drain all the fluids, remove the exhaust manifold, intake manifold, timing belt/chain, maybe the valve lifters to access the head bolts. Then remove the head bolts in order as instructed by the manual. The head may need to be pried off, but FOLLOW THE INSTRUCTIONS IN THE MANUAL TO PREVENT DAMAGE TO THE HEAD AND BLOCK. Usually there are ears designed for prying to prevent damage. Use them only.

Once off, I suggest you take the cylinder head to a machine shop to check and correct the flatness of the head and to get the valves and seats ground. They can also replace the valve seals from you gasket set. Reinstallation requires the cylinder head and block surface to be clean and dry. The block NEEDS to be scraped to remove any remaining gasket material, cleaned with a good degreaser, then wiped down with alcohol to get it super clean and dry. Same with the head BEFORE the new gasket is placed on. Place the cylinder head SQUARELY back on the gasket and block to prevent gasket damage. A second pair of hands is great for this step. Then, replace the head bolts as instructed by the manual, and replace the other parts you removed as instructed.

TIP: If the torque specs for the head bolts requires a final step of turning by a specific angle, you have Torque-To-Yield bolts, and they MUST be replaced once removed. Do not reuse them. If the manual calls for new bolts, buy them.

I Like The Advice Given By Busted Knuckles . . .
. . . especially the part about the NEED for a manual. However, I think he is being too kind. He makes it sound too easy. That’s because for him, it is. There’s a reason an experienced mechanic charges hundreds of dollars to do this.

You also need proper tools, including but not limited to a torque wrench, all kinds of wrenches, etcetera. You also have to have quite a bit of experience with tools, stubborn fasteners, gaskets, belts, etcetera.

The advice about the extra hands is good, too. I would take that a step further and say that those hands should be attached to a person who has successfully done a head gasket replacement before. I did my first head gasket without assistance, but I had all of the above and knew the difference between a valve/rocker cover gasket and a head gasket before proceeding and I knew what causes “water” to pour from a tailpipe.

This is not a good solo project for a person of limited knowledge (and possibly limited tools) without at least advice from somebody with experience at different stages of the operation.

It’s commendable that you want to do this yourself and the the fact that the car is 22 years old makes it almost monetarily necessary without totaling the vehicle. However, proceed cautiously or the project could end in a “basket case” that nobody would want to mess with.

Is there somebody with experience you can call on for some help?


I agree with CSA, as I frequently do. The OP clearly has little automotive expertise, and this is not a job for someone with no experience–even with a repair manual to guide him. At the very least, he needs someone with the proper expertise to work with him.

I agree with the others. This is not a job for a novice DIY’r. It sounds like you’re trying to take the valve cover off, this is just the tip of the iceberg, if you are having difficulty with that, then the rest of the job will be an ordeal for you.

You need over-the-shoulder instructions on this one. The task is too complex for you to handle alone. Maybe, there is a good Smartin mechanic in your 'hood who will do this over-the-shoulder?

Other than agreeing that it sounds like you have near zero aptitude for performing this job my feeling is that the engine is likely trashed and it’s simply not even worth putting a head gasket in.

If the head gasket is so bad that the engine won’t start when the radiator is full, water is running out the tailpipe, etc. then odds are the piston rings, crankshaft/crank bearings, cam bearings and lobes, etc. are all washed out and in bad shape. You’re better off finding another engine; new or used.

There’s a LOT to replacing a head gasket…obviously a lot more then you thought about…ESPECIALLY for a OHC (Over Head Cam) engine. I believe this engine has a timing chain which will have to be removed.

Here’s a partial list of parts you’ll have to remove just to get to head gasket.
. Radiator
. All drive belts.
. Timing belt/chain cover.
. If a chain…you may have to drop the oil pan.
. Intake manifold.
. Exhaust manifold.
. Fuel line.
. Fuel injector rail.

And that’s just a partial list. An experience mechanic will take the better half of a day to replace one. I’ve done them before, but not in years. It will take me over a day…Obviously you don’t have even close to MY experience…expect to take 2-3 days and there’s a good chance you won’t do it right.

Second that OK4450 . . . and the price of a used '87 Nissan Sentra engine will probably be less than doing the head on the old one. Look around . . . maybe you’ll get a decent one. Rocketman

Oh I have plenty of aptitude, you wanker. There’s plenty of difference between aptitude versus experience. If I had experience, I wouldn’t have posted on here. So you worry about yourself and your “aptitude”, ok? Thanks.

You’re not on a HUGE ego trip, are you?!! No, certainly not you. Man I posted on here expecting to hear from genuinely well meaning people, not arrogant assholes like you.

Obviously I DID think about what it would take to do this, otherwise I wouldn’t have posted on here. My post asked a simple question. An arrogant answer was not called for.

And furthermore, you really would have zero knowledge of my experience, abilities, OR “aptitudes”. So mind your own business, prick.

The manual I have is Chilton. Not sure why you put “water” in quotation marks (?)—that’s exactly what it is. I stopped using antifreeze because it’s too expensive use every time when it’s just going to go out the tail pipe within 5 minutes. I have the tools too. Just not sure if I want to devote the time and energy to it but I don’t have money for another car, so trying to salvage this one is a last step before junking it. It’s either this or take the bus.