Cracked Head ?

[anglosax]

Hi Don et al
I have an early model 1965 A4 and have a persistant weeping of cooling water from under the alternator bracket on the cylinder head. I first thought that it was weeping up the head studs at cruising revs under load, at idle it does not leak. On further inspection there is a 1 inch hairline crack in the cylinder head adjacent to the center row of studs, oozing cooling water at cruising revs. Obviously it needs considerable pressure to make the leak. The engine runs well but I have noticed an increase in steam/white smoke in the exhaust.
Bottom Line - is there a hopeful fix without having to buy a new Head. Anyone had any experience with either welding , or automotive type sealer compounds

[Don Moyer]

Clean the area really well around the crack, and then apply a fiberglass patch using one of the small fiberglass repair kits available through West Marine. If the head is otherwise in good condition, such a repair will commonly last a couple years at least.

Don

[Fishguy]

Sorry to bring up such an old post, but I couldn't find much regarding my problem and since Don himself made a recommendation to the original poster I thought it would be a good start.


I have a late model with raw water cooling that I brought back to life this summer with considerable help from this forum (Thanks again!!!) the engine now starts and runs beautifully! We have used it moderately with zero issues. So this weekend I went to change the racor fuel filter to a all metal model for safety sake and to bring it to code. I noticed some corrosion on the top of the head and around the plugs. I checked hose clamps etc then started the engine. Nothing until I increased the rpms. Then a small stream of water shot up from a pinhole leak. I found some information on the MMI site and planned to drill out and tap the hole for a brass plug. After gathering tools and materials I scraped the area clean and started it up again to make sure I drilled the correct location. Then I found the hairline crack...

I'm looking for advice. Do I fiberglass as Don suggested the OP? Jb weld? Solder? Weld? Etc? Try an internal sealer? Please help, I did not find any water in the oil or any other problems(I'm dealing with water in the oil of my fishing boat right now and would like to keep the sailboat functional.

Thanks,
Tim

[Marty Levenson]

Sorry for your troubles...

Not saying it is impossible to fix, but I think the odds are against you.

Having gone to great lengths in an unsuccessful repair attempt on a similar, smaller crack, I would look for a "good enough" used head. Even if you get this to stop leaking it will never be trustworthy.

Others may well have a different experience and other advice....

[edwardc]

I agree with Marty. I had a similar crack on my original A4. Ground it down to bare metal, dressed it out with a Dremel and a dental tool, and filled it over with JB weld. The crack just kept extending out past the edge of the repair.

And who knows how thin the rest of the head's cooling passages are? Your best bet in the long run is to buy a new replacement head from MMI. Its what I ended up having to do.

[Easy Rider]

Good advice from Marty and Ed. I had the same problem a few years ago and in the same place on the head. I took it to a shop who claimed they could fix everything except the break of day. Well, it lasted until the engine got up to temperature and then it really let go. I replaced it with a new head from our hosts and never regretted it. IMHO is that when a raw water cooled head cracks it's time to replace it.

[sdemore]

One of the things we had to do in the Army for crack repair, was to drill a hole at each end of the crack. The hole will stop it from spreading any further, while leaving it undressed will just allow it to continue running along. I haven't had any experience with it on an A4 head, so no idea how the heat, vibration, and corrosive nature of the environment will impact it, but it worked really well on airplane propellers.

[ndutton]

You're getting a new head sooner or later, why not sooner?

[CamaroMan]

Clean the area really well around the crack, and then apply a fiberglass patch using one of the small fiberglass repair kits available through West Marine. If the head is otherwise in good condition, such a repair will commonly last a couple years at least.

Don

VERY late reply - but a real good tip ive used in the past is to use radiator sealer/repair stuff from any parts store. You would have to use a temporary solution for raw cooled as the stuff has to circulate for about 5 mins (ive never needed more than that) - I guess u would shut off the sea water valve and run a loop thru a bucket?

Anyway - a GREAT, cheap and easy way to block cracks. I used it on a VERY high performance kawasaki motorbike that spins to 20 000 rpms - 4 yrs later and not a drop of water used.

Just thought Id throw it out there since google finds these (old) threads alot -

[sastanley]

Ugh, c'mon, man...Bar's Leaks? Really?

CamaroMan, no offense, but I am trying to figure out where that gunk would apply, and why it would be recommended in this situation?? I will admit to using it when I was a teenager and had a cracked radiator and didn't know any better in my first car and had no money. I am not sure I'd trust it in a cracked head, and especially in a raw water cooled system where, as you stated, it is likely to not circulate for very long. That stuff is like hair clogging a drain, except in this case it is all flying out the exhaust.

We all like to save a few $$, but I think here the correct solution is a new/used head if one of the other remedies doesn't work. I wouldn't waste my $$, or want to deal with the aftermath of that stuff collecting in the nooks and crannies on this motor.

[CamaroMan]

it's actually quite good stuff.. It doesn't collect anywhere unless there's a crack. Take it or leave it. I'm not some kid trying to save a buck.. In some instances it will last year's, others more severe maybe not.

It's worked for me real well just thought id put it out there..

Been wrenching 20 yrs.. It can work, sometimes for years..

[tenders]

Take it or leave it.

I vote “leave it” unless perhaps the engine is FWC and being coaxed to life on a bench.

If the engine is in a car or motorcycle and the kludge fails, the vehicle slowly rolls to a stop and you sit by the side of the road waiting for AAA.

If the engine is on a boat and fails, it fails while you are underway but not sailing, ie you have determined that the wind, current, water depth, nearby boat and ship traffic, etc. are not conducive to safe or efficient propulsion by sail. To depend on a clot-in-a-can to keep your engine running under those circumstances is the kind of decision that puts people on the rocks, or worse. Why take that chance?

In a RWC engine with salt water that doesn’t circulate and rust and scale in various degrees throughout the cooling passages, the clotting goo has no chance of even getting where it’s intended to go. Using it is like using duct tape, or gum, to try to patch a leak halfway down the inside of a water slide tube.

[JOHN COOKSON]

I vote “leave it” unless perhaps the engine is FWC and being coaxed to life on a bench.

If the engine is in a car or motorcycle and the kludge fails, the vehicle slowly rolls to a stop and you sit by the side of the road waiting for AAA.

If the engine is on a boat and fails, it fails while you are underway but not sailing, ie you have determined that the wind, current, water depth, nearby boat and ship traffic, etc. are not conducive to safe or efficient propulsion by sail. To depend on a clot-in-a-can to keep your engine running under those circumstances is the kind of decision that puts people on the rocks, or worse. Why take that chance?

In a RWC engine with salt water that doesn’t circulate and rust and scale in various degrees throughout the cooling passages, the clotting goo has no chance of even getting where it’s intended to go. Using it is like using duct tape, or gum, to try to patch a leak halfway down the inside of a water slide tube.

Good post.
If the engine cooling passages were already somewhat narrowed - this happens in a RWC engine - blocking them even more could totally finish off the engine cooling system.

TRUE GRIT