Foo - How hard is it to change a head gasket?

Anyone ever done this before? Seams easy enough, remove the lid, slap gasket in, cover the lid :D

Is it that easy? Huh? Please?

I think she is blown, sux too because I just paid 300 for new exhaust which BTW I am hypothesizing that the new exhaust puts more back pressure into the engine and caused the already weak failing gasket to blow. Sound reasonable or is that a wild hair brained idea?

I have but it was a lot easier on the old stuff:

http://i263.photobucket.com/albums/ii132/pgoat/Cars/Lizzie3.jpg

there was a lot less to get in the way back then....if i recall the hardest part was making sure all of the old one was removed cleanly. And then you want to tighten evenly, obviously.

Sounds like a valve cover gasket, which is easy. Head gasket, not so easy. Increased back pressure leading to failure is doubtful.

Fixed the spelling error in the title for you. ;)

ah - good catch. He said head gasket; obviously I was thinking valve cover also.

Unless you are driving an old flathead, it isn't quite that easy :)


http://www.heal-a-seal.com/ENGINE6500X491.jpg

Oh yeah I guess there is actually two of them in a V-8 which mine is. The oil is coming out on the passenger side. Do people generally just do both of them at the same time while you have it all taken apart? It's an old car, 1994, but still has lots of bells and whistles.

The think about the muffler question is it literally started happening the day I got it back from the shop. Don't ya love that :rolleyes:

The think about the muffler question is it literally started happening the day I got it back from the shop. Don't ya love that :rolleyes:
There is some possibility that in manipulating the manifold the gasket was disturbed, but it was most likely ready to fail if that was the case.

valve cover gasket was the job that led me to buy my torque wrench, which I'm not sure I've ever used since.

Are you sure it's a head gasket? Or is it a valve cover gasket? If you aren't sure, what are the symptoms? Is it spewing white smoke out the tail pipe? What kind of engine/car is it?

Ha, my dad always said: If you have to ask how difficult it is, don't do it. ;) (Hmmm, in Dutch it works better :p )

There's some truth to that, if you cannot see all the ins and outs, you might want to find someone to hold your hand and help you through it. Or maybe just forego the whole thing and have someone else do it.

Of course, the exception is if this is a non-vital vehicle and completely blowing it up wouldn't be a major problem.

Also, the man imparted me with the wisdom that everything that man put together, can be taken apart and put back together by another man. ;) Just be sure to:

1) Inventory all nuts, bolts and other bits you have to remove. Make sure you have all the tools before you start.

2) Inventory the smaller, cheaper things you might break and have replacements at hand. Things such connectors, rubber hoses (old ones), hose clamps.

3) Find the manual for the car, look up what they say about needed tools and bits. (It's a second hand I assume, therefore, never trust the manual)

4) Make a gameplan based on the manual, what to take apart and in what order.

5) Start taking it apart, labeling every screw, bolt and nut to it's respective hole.

6) When all is apart, replace damaged stuff and clean everything (while you're in there).

7) Replace the part you went in for (Head gasket in your case).

8) Check, double check and check again....make sure everything fits the way it should, is in place, that nothing fell into places where it shouldn't be,etc.

9) Check again!

10) Decide how best to put things back together, should some parts be assembled first and then put back?

11) Put things back together.

12) Check to see if everything fits and was put back together well!

13) Cross your fingers and start the engine.

Remember also to have your heads checked for warping, if you are actually needing to change out the head gaskets.

Remember also to have your heads checked for warping, if you are actually needing to change out the head gaskets.

Yes. Most shops now rountinely machine the heads before replacing the gaskets.

If you have a Subaru, you're gonna have to pull the engine out.

Can I post here just to say I have absolutely no idea what you're talking about?

Are you sure it's a head gasket? Or is it a valve cover gasket? If you aren't sure, what are the symptoms? Is it spewing white smoke out the tail pipe? What kind of engine/car is it?

It's a Mercedes M119 4.2L V8. It's in the shop right now getting diagnosed. I was thinking head gasket but certainly could be wrong. What happens is that once the engine warms up oil starts leaking out and burning on the engine. If I have the heater on the stench comes inside the car if I am at a stop light, moving causes enough airflow to blow the smoke away.

Looking under the hood I can see where the oil is dripping onto the hot engine but not exactly where it's coming from. With a mirror and a flash light I reached in as far as I could, it's tight in there, on the passenger side of the engine down almost under the engine and oil was dripping on the mirror.





Ha, my dad always said: If you have to ask how difficult it is, don't do it. ;) (Hmmm, in Dutch it works better :p )



Ha great post thank you. I am mechanically inclined. I figure if it is the head gasket and thats going to cost over a thousand dollars then I will first try a miracle in a can and if/when that fails try to fix it my self and if/when that fails have it towed to the dump :D

If you have a blown head gasket the car would be overheating. You would be loosing coolent into the oil. Or the car would be smoking so bad you would have noticed it.

Might be valve covers, might be oil sending unit...

Let us know what the shop tells you.

Nice car $ to get worked on.

if it was a blown HEAD gasket, your vehicle would be losing power as soon as it starts to warm up from a dead cold crank and not to mention it would overheat, further irritating the gasjet and not to mention possibly blowing the head itself.

it is your valve covers which is nothing and very typical of all vehicles, especially older ones.

and who told you that back pressure would get into your valve areas? that's what your catalytic converter is for and that is in your exhaust line. granted you may need a special one (if you have one) designed for a heavier dose of recycled exhaust air now that you've changed the exhaust but not anywhere in your valve covers would or should there be that kind of pressure.

Ok cool so it's probably not the head gasket. The whole thing about the back pressure is my idea :) Just odd that it happened as soon as I got it back so I had to come up with some logic. ;)

I should find out some time today or tomorrow.

since it's a modern DOHC V8 with variable valve timing on the intake camshaft: too hard.

wait for the mechanic's advice. and if he says it needs to be changed, pay him to do it.

even though the bill is going to hurt.

keep us updated...be cool to find out what the problem is.

As others have said, it's likely the valve cover gasket and if so, you can do it and have fun.

It's unlikely the head gasket because you would be spewing white smoke and you wouldn't have to worry about mosquitoes for a while. But if it were the head gasket, pay the shop $1500+ to do it. :)

valve cover gasket was the job that led me to buy my torque wrench, which I'm not sure I've ever used since.

That may have been why I bought mine as well, but it's since gotten tons of use for bike repairs.

That may have been why I bought mine as well, but it's since gotten tons of use for bike repairs.

I've tried using it on stem bolts but I don't put a lot of faith in the results. Although the stems and bars have remained attached to date.

I've tried using it on stem bolts but I don't put a lot of faith in the results. Although the stems and bars have remained attached to date.

For bikes, it seems to me that the foot pounds kind that you would normally use on a car would be a bit much for a bike. Not nearly sensitive enough. But I wouldn't know, I've never bothered torquing anything on a bike.

even though the bill is going to hurt.There's a reason you see so many cheap cars in the classifieds that say something to the effect of "Just needs a new head gasket!" :)

Jfmckenna, first let me say beware the car advice you get on the internet. Next, please answer a few questions:
What is the year and model of the car?
What exactly is the symptom, in detail?
Can the symptom be photographed and posted here?

Jfmckenna, first let me say beware the car advice you get on the internet. Next, please answer a few questions:
What is the year and model of the car?
What exactly is the symptom, in detail?
Can the symptom be photographed and posted here?

Here ya go.


It's an old car, 1994


It's a Mercedes M119 4.2L V8. It's in the shop right now getting diagnosed. I was thinking head gasket but certainly could be wrong. What happens is that once the engine warms up oil starts leaking out and burning on the engine. If I have the heater on the stench comes inside the car if I am at a stop light, moving causes enough airflow to blow the smoke away.

Looking under the hood I can see where the oil is dripping onto the hot engine but not exactly where it's coming from. With a mirror and a flash light I reached in as far as I could, it's tight in there, on the passenger side of the engine down almost under the engine and oil was dripping on the mirror.

OK, I'm a lazy reader, I admit.

OK, so burning oil enough that you get oil smoke collecting under the hood usually indicates a significant amount of oil dripping onto the exhaust manifold. The exh manifold attaches to the side of the head, and continues usually straight down or out to the sides as it makes its way back. The likelihood of a head gasket, which is below the manifold, dumping that kind of oil on the exh manifold is pretty remote, as it would have to squirt it out the side ala the Black Knight's fleshwounds in Monty Python's The Holy Grail. It's most likely that your valve cover gasket is leaking, and oil is pooling on top of the manifold.

A VCG may still be outside the do it yourself realm on that motor, the pictures I found looked pretty crowded in there.

Yeah it's really tight in there. I used a mirror and a flashlight and could barely manipulate it enough to see around but the oil is dripping like you said and burning up. I could see where the oil was dripping on to but not where it was coming from, it actually dripped on the mirror as I was searching for it. If I knew the names of the engine parts I'd probably be more helpful. The shop was really busy yesterday so they will get to looking at it today and I will find out more.

This is sounding more and more like a valve cover gasket. Be happy, that's a relatively inexpensive repair. :D

This is sounding more and more like a valve cover gasket. Be happy, that's a relatively inexpensive repair. :D

It can be pretty much free if you properly use gasket glue. ;)

It can be pretty much free if you properly use gasket glue. ;)

Yup, my brother made a set of valve cover gaskets out of cardboard! :lol: He had a 69 Chevy Impala that started leaking oil from the drivers side valve cover, he found some cardboard (non corragated) cut them out to the shape of the gasket, slapped some gasket glue on both sides and the car was fine and leak free for about three years. :thumb: Then one day he was late to work and kinda speeding thru an intersection and another speeding driver went thru the red light and "T" boned my brothers car, the impact was so hard that it sent him shooting thru a brick walled row home and right into the living room! (Thank goodness no one lived in the house!) when I got there the car was still on! It was a total wreck but the valve covers still didnt leak oil! :lol: (I knew this because the hood of the car was in the kitchen!)

Sweet! So it turns out to be a valve cover gasket and also he said the oil sending unit is leaking. So I am looking at $310. I can handle that :)

Thanks for your replies and crazy car stories ;)

Getting out of a Mercedes shop for 300 shmooks is a victory in itself! I'm glad it worked out for you.

This isn't the dealership mind you OMG no way. I was forced to go there a few years ago with an electrical problem and it was like $700 to install a freakin switch. This is a local mechanic, very honest, real nice guy who happens to know foreign cars. If he told me it was going to be $1500 then I'd trust him it was the cheapest he could get. It's good to have some one like this especially when you have old cars like I always do.

i hate Bosch oil sending units. they always leak, and half the time you can't reach them. plus, they make the sending unit body larger than the wrench flats, so you can't stick a socket over them.

Well, it depends upon the model of car and where they placed the oil-pressure sensor in the engine. Usually it's on the side near the front close to the oil-pump so you can usually reach it from underneath.

I've changed a headgakset twice in one day at the track once. Running too much boost and the headstuds were stretching, letting the combustion-pressure out. Ended up replacing the factory 12mm studs with 14mm ones during the rebuild and torquing them down to 140lb*ft... heh, heh... :)