Head gasket replacement

The friendliest place on the web for anyone who enjoys boating.
If you have answers, please help by responding to the unanswered posts.
If if anyone is talking to me, I am way past all that. With plenty of expert advice and all the usual remedies.

It was retorqued on schedule then several times to eliminate the leak and the coolant changed several times.
Last edited:
"Any tips or suggestions?"

I would take the head to a good machine shop and have it trued.

This is not milling the head for a go fast , it is a tiny cut of a few thousands to be sure the surface is really flat.

Might even get the exhaust done at the same time.
If if anyone is talking to me, I am way past all that. With plenty of expert advice and all the usual remedies.

It was retorqued on schedule then several times to eliminate the leak and the coolant changed several times.

are the bubbles and signs of oil gone with all that flushing?

I found this thread and hoped for a bit more detail, perhaps a few pictures. I will be doing a head gasket soon.
Nope .....bubbles and oil/oily soot maybe arf back and still bubbles.

Never did the second head job.

Funny thing, the more mechs I talked to. Got completely different answers.

All the highly experienced with great reputations said don't worry about it, keep an eye on the oil analysis.....all the young hard chargers said my engine needed as immediate head job.

After 1000 or so hours after the bubbles returned, still great oil samples and seems to run fine.

What would you like pics of? They really don't show much except the obvious pieces you remove in a head job and some light carbon right at the fire rings of the old gasket.
The unbolting part is sop. I read the head is 120lbs. As I have twins it is tucked under floor preventing direct up lift with aid. any pics of lifting head off and out may give me ideas.

Did you test or replace your oil cooler? Picture of oil and bubbles?
Have you checked the rubber gasket between the exhaust elbow and the exhaust manifold? (This was recommended by Brian as an early T/S check when I got the sooty substance in my coolant.)

Btw, I ended up renewing the head on mine. Upon taking it off, it didn’t appear the head gasket was compromised. But the shop noted some of my valves were gummed up. At the same time, I replaced the above mentioned rubber gasket at the exhaust elbow and added 3M nbr 2 gasket sealer. Engine runs much better and now immediately starts, as if compression was an issue. Of course, it would have been better to do one t/s solution at a time.
Isn't the exhaust manifold fresh water cooled and sealed from the elbow. That would leave a crack in manifold or the manifold gasket. I will be tearing mine down in October and will remember to look for that rubber gasket at elbow end
Having read all the posts and suggestions may I just raise a point worth considering ?
Having checked all the usual joints, gaskets etc and not found the cause of the bubbles I would suggest a separate radiator and cylinder pressure test.

The same thing happened to me with a Volvo TAMD 6 engine, we discovered that the No 1 cylinder liner was porous.
The jet of water entering the block from the water pump was directed at No1 cylinder liner and because the previous owner only used fresh water in the radiator the tiny particles in the water had in fact 'water blasted' the cylinder wall.
Once we discovered it we simply replaced the liners and rebuilt the engine and it was perfect for years after.
If buying a s/h boat I always recommend cleaning the cooling water system and only using anti-freeze mixture all year round, even in the tropics !
I'm simply trying to explain what baffled me until by process of elimination the problem was isolated.
I hope I don't offend you by giving my experiences.
Last edited:
Irish Rambler....were you not losing coolant or getting coolant in oil?

At some point there would be no pressure in the cylinder but pressure on the coolant side.

The hole(s) would have to be akin to GoreTex fabric size I am guessing to allow air but no water even under slight pressure.
Yes I was losing coolant through the pressure cap, it started slowly and built up over 3 weeks. When the engine got very hot there was a slight oil film.
We used engine leak 'magic' fixes all no avail. Having checked every possible cause we just bit the bullet and stripped it down as we couldn't afford it out of service any longer.
I had meant through the cylinders after shutdown. I added recovery bottles so I am just pushing fluid around while running but not loosing any after shutdown by having it leak back into the cylinders.
No, a perforated cylinder wall is like a 'one way valve in the early stages' as it pushes compression out into the coolant but is too fine to let water back in.
Having got the cylinder head checked did you check the head is true flat. I've also come across fine hair cracks between cylinders.
Good luck tracking it down, patience will get you there.
Had the head totally redone...it was the block top that wasn't checked as closely as maybe it should have been.

But I thought it was good enough so did a mech that the gasket should have been enough.

Manifold was pressure checked. New gaskets including to exhaust elbow.

Because the next 1000 hours of so will be intracoastal...going with the top pros suggestion to wait for a secondary symptom in addition to the current tiny stream of bubbles in the recovery tank.
I'd go with that for your next bit of cruising.
I've a steel straight edge ruler which has served me well over the years whenever I take a head off.
I would have thought the gasket would have done the trick but sometimes the darn things can be capricious and I've been caught out myself a time or two on the learning curve.
Much sweat and tears to get there but when she cracks off and runs like a mouse chawing tissue paper it gives a great sense of pride of a job well done.
At 2900 hours SMOH your engine is still quite young. I would install new pushrods at the least. Probably new adjusting screws for the rockers, pull a couple out completely and see if the nice round ball on the end is becoming lopsided. Also for $185.00 each I would probably replace the rocker shafts unless you are positive they are not worn, mic. them. The rockers themselves are very expensive ($185.00 per each, times 12) They are very tough but they can wear, check them out, there should be very little, if any play between them and the shaft.

It's a PIA to get the injectors out because the bleed-off tube must come out, don't bother trying to get them out without taking off the tube. If my memory serves me though, I don't think the injectors need to come out but it is a very good idea to remove them and have them "pop tested" or just rebuild them. The head is so heavy and the injectors extend beyond the surface of the head that you will probably damage them just moving the head from boat to truck to shop.

There are little caps inside the end of the rocker shaft. You can knock them out and reuse them although they are cheap. The caps go on the front end of the front shaft and in the back end of the rear shaft.

While the head is off, make certain the bleeder valve on the port side of the exhaust manifold is free and working. You will need to open it to allow antifreeze to flow into the cooling tube which runs at an angle along the starboard side of the engine. Overheating will result due to an airlock if you don't get the tube filled.

Removing the head is actually quite straightforward. If it is in the way remove it.

American Diesel is your source for parts and information.

Good Luck, send pictures

There are a few on here now with ongoing or possible head gasket replacements. So any further posts one might want to specify who they are giving advice to and make sure all the right repair jobs are lumped into the same barrel.

I am done and did all that needed to be done for a head gasket. Not sure if that was the issue but am way past injector, valves stuff.

As I said, waiting to see what happens next based on lots of good advice.

PS....lots of good advice available when American Diesel doesn't have the answer.
The gasket leaked for a reason. If the head is going to a machine shop a very light cut will make sure it is really flat.

While its out , I would look at the valve seats , lapping them in is really simple.
That's all what I had done at a locally famous speed shop.

Thus my thoughts it was the block top....or an install error on my part (remote but possible)....

Of it could be a block/liner issue.....as I think I ruled out manifold ones.
Update. In August the starboard engine locked up after a few cranks. On checking there was a loss of coolant. Logic suggested a head gasket with water sitting in a cyclinder(s).
Did more reading and came across dampers losing springs and jamming up flywheel to bell housing. That seemed like an easier re & re than tearing into the head. Besides dampers should be replaced about 1500 hours operation. Sure enough that was the problem. Problem is gone, runs great again.

Latest posts

Top Bottom