How important is it to remove the studs when taking off the head?

[Baltimore Sailor]

I'm facing the prospect of replacing the head gasket on my A4, and I see from the sticker on it that Moyer Marine rebuilt it back in 1993; I'm hoping that means it'll be fairly easy to get the head off, as it hasn't been 33 years in place (the engine is a 1975). Is there a good reason to remove the studs when taking the head off? I'm going to be working on this with the engine still in the boat, and if I snap off a stud there's going to be no way to get a drill in there to drill it out; it'll have to come out of the boat to get to it.

Does removing the studs make it easier to get the head off? Or is it more a matter of checking them at the same time to make sure they haven't corroded too much?

Thanks!

[David Masury]

If all you are doing is replacing the head gasket, then I see no reason to remove the studs..... I didn't when I did mine three years ago... I actually did it twice in the same month (don't ask).. and I left the studs in place.

The engine has been running great with no leaks since that time ..over three years,

David

[Charles Taylor]

I just pulled my head off today and it came off rather easily. Before doing it, I sprayed the head nuts with WD-40, let them soak for a little while, and they came right off. I don't know whether the WD-40 was necessary or not, but I didnt have any problems removing the nuts. The head itself also came off with only using screwdrivers to pry into the head gasket.

After reading some of the other posts on the subject, I guess I was rather lucky. I'm going to take the head to a machine shop tomorrow.

As my studs appear to be rust-free, I don't see any reason to remove them.

Good luck on your head removal,

Charles

[adab1402]

stud removal

dont worry about the studs that are left ,if you really feel compelled to pull the studs use a stud puller . the only reason would be to make cleaning the block surface easier to clean ,use a small scrapper take your time and dont sweat to much ., put a little anti-sieze on the threads upon installation of the new gasket ,follow don,s words of wisdom and all will be well . fair winds ken "albatross"

[Don Moyer]

There's no compelling reason to remove studs when replacing a head gasket as
long as the head comes off without doing so, but can I ask why you believe
you need to replace the head gasket?

Don

[Baltimore Sailor]

I have only about 5-6 psi in cylinders 3 and 4, while 1-2 are up around 110 psi. The book says close to zero psi in two adjoining cylinders is probably head gasket failure. However, I wasn't seeing any milky oil or anything, so I was hoping that it was just a couple of stuck valves.

This weekend I took off the valve cover and had my helper turn the crank while I watched the valves, and all of there were smoothly moving up and down. I didn't put the feeler gauge to them, but I was more interested in seeing if the valves for #3 and 4 were moving at all. However, the tolerances looked sane, and the engine never did have any valve tap to it. I'll definitely check them before putting everything away again.

Since they're all moving OK, I figure the next step is to take the head off and have a look. I suppose something could be preventing the valves from closing completely, rather than a bad head gasket. Still, the head's gonna have to come off anyway, right?

Inside the valve cover it looked beautiful. No gunk or rust or anything, just gleaming metal. The engine was rebuilt by you back in 1993, so I expect it doesn't even really have very many hours on it -- maybe 700 or so, allowing for 50 hrs/year? So I'm really, really hoping that the head will come off fairly easily.

[Baltimore Sailor]

Here's my full history with this engine, in an nutshell:

Bought the boat in April 2007, it ran fine. Took it up to over 2000 rpms on a test sail, no problems.

A few weeks later I was running the engine at the dock at about 1200 rpms to charge up the batteries (I wasn't sailing every weekend, so I thought I should charge them weekly if I didn't take her out). After running for about 20 minutes I glanced at the gauges and noticed that the temp was up to about 220 -- not pegged yet, but close to it. I instantly realized I hadn't opened the raw water intake, and shut the engine down immediately. I did not open up the intake valve because I figured the worst thing I could do is send cold Chesapeake Bay water into an extremely hot engine. I figured the best thing to do was let it cool down gradually.

The next time out -- ran fine, good rpms.

The next time out -- no problems. Long sail, used the engine quite a bit on a calm day.

The next time out -- no problems. Stalled out coming back in. Would start and run for a few seconds, then die. Repeated this several times. The gas gauge was down near 1/4 tank, so figured it might be low enough to need some. Put in the gas from the portable can, then realized that the PO had said he had no idea how old that gas was -- could have been two years old, and he had no idea if it had been stabilized. The engine started and ran, but there must have been something wrong with the gas, because the engine would only run with the choke partially out.

Had the same problem next time I tried to run the engine -- needed the choke out, then gradually it got so bad it wouldn't run at all. It would just sputter and die after a few seconds.

Ultimately replaced the carb (new one, didn't do a rebuild), put in a bunch of fresh, stabilized gas, hoping to dilute the bad stuff enough so it wouldn't matter. Started her up, ran great! Revved nicely, right up to 2000+ rpm. However, when I put her into gear the rpms wouldn't go up over 800 or so.

Many posts to here later and a prop cleaning, I did a compression test and got numbers like 110 on #1, 110 on #2, 5 on #3, 5 on #4. The book says that low/zero psi on adjacent cylinders is probably the head gasket. I wasn't seeing any water in the oil, so I hoped it was just a stuck valve, but after looking at them this past weekend it looks like it's something in the head.

Could the overheating for 20 minutes kill the head gasket, or maybe warp the head, or even crack the block? Whatever is wrong, there was still no water in the oil, or oil or water spurting out of the engine when it ran. And I ran it a couple more times on 2 cylinders just to finish out the season.

So that's where I am: I figure I gotta take the head of to have a look-see, which I hope will let me figure out if it's a gasket, or warped/cracked head, or cracked block.

And and all advice is welcome! Thanks for taking the time to read this tome.

[tenders]

If the valves are all moving smoothly and you have low compression in adjacent cylinders I agree the next logical step would be to suspect the head gasket.

[Don Moyer]

As long as the valves have retained any reasonable clearance, you're
probably correct to assume that the head needs to come off.

Don

[Baltimore Sailor]

Does anyone have any guesstimates as to any damage the overheating might have caused? Melted head gasket? Warped head? Cracked block?

Did I do the right thing by shutting down immediately and letting it cool naturally -- though I can't imagine that pumping 60 degree Bay water into an overheated engine would have done anything but bad stuff to it.

Are these A4s tough enough to take some abuse?

Can you tell I desperately want to hear I don't have a cracked block? A head I can replace, but the block... I don't wanna think about it.

[Don Moyer]

The Atomic 4 seems to be very forgiving of severe overheating (much higher
and longer than you're reporting). The one thing we do hear failing in the
aftermath of a severe overheating is the head gasket, but only if the gasket
were one of the green variety sold by Universal dealers through most of the
1980's and early 1990's. Most of these gaskets have failed by this time and
are out of the fleet.

Don

[Baltimore Sailor]

That sounds good. I guess my final question would be that, as the engine was rebuilt by Moyer Marine back in early '93, do you remember which kind of head gaskets you were using back then? Had you moved to the good kind yet?

Really doesn't matter I suppose, except as a matter of curiosity.

Thanks for all your info and advice!

[Don Moyer]

We actually began using Victor steel reinforced prototypes in 1994 but were delayed in being able to buy them on the open market until around a year later (1995). In 1993, we were still using a gasket that was being made by Victor which wasn't much better than the very unreliable and now infamous "green" head gaskets.

Given the high number of head gasket failures by the late 1980's and early 1990's, it's highly unlikely that the Atomic 4 fleet would have survived much longer due to the growing conviction on the street that the engine had somehow outlived its useful life. "You can't even keep head gaskets in it" became a common complaint. The development of these improved gaskets by Victor therefore arguably played a vital role in saving the Atomic 4 fleet.

Don

[Baltimore Sailor]

That means I have the "old unreliable" gasket in my engine. Perversely, that makes me feel GOOD, knowing that's the probable point of failure.

Thanks again for all the info and advice. I'll keep you posted as to how it all turns out.