Head removal - reasons?

[rigspelt]

Now that I have removed the water pump (new one arrived from MMI), thermostat housing (ditto), side plate (plan to order new one), alternator, starter (OK, just in the way) and distributor (to replace flyweight springs), I'm on a roll and eying the head. Boat is on the hard for a year anyway - bought it in the spring and doing a major refit -- my last boat, I reckon. Now is the time to do a solid engine maintenance job, along with everything else I'm doing to the boat.

I am very suspicious of rust around the head/block seam aft starboard corner: head gasket water leak? See photo below: the only other place on the engine with rust was under the old leaking water pump. Otherwise I have no real reason to pull the head. There was no thermostat in the housing, which makes me suspect they had an overheating problem, so I would like to give the water jacket and manifold a solid cleaning. The compression was 110-117 in all four cylinders. I don't have enough reason to pull the whole engine for a block rebuild, I'm pretty sure of that.

If I pull the head, I can clean out the water jacket and manifold, check and set the valves, check the head gasket, and end up more secure about the engine than I am now. I don't think it has had much maintenance in the past decade. Downsides: risk of major stud issue or damage to block/head.

So, have I got enough reason to pull the head?

[Don Moyer]

I don't think so. With good compression on all four cylinders and no real signs of any leaks, I'd stick to the other maintenance you refer to first. My guess is that after cleaning out the water jacket (as you are now doing) and subsequently flushing the engine - probably first an acid flush and then a pressure flush - any heating problems encountered by the prior owner will be remediated.

Don

[Kelly]

Just two comments.

You mention "checking the head gasket" if you remove the head. I understand (and this was my case) that removing the head pretty much means replacing the head gasket. Fairly pricey item to replace if it's not necessary.

Also, "check and set the valves". With your good compression reading your valves are likely seating well. Adjusting their tolerances can be done by accessing the valve stems from the cover plate opposite the water jacket cover plate.

Hope this helps.

Kelly

[rigspelt]

You mention "checking the head gasket" if you remove the head. I understand (and this was my case) that removing the head pretty much means replacing the head gasket. Fairly pricey item to replace if it's not necessary.

Sorry, I should have written it more clearly to mean "inspect and replace". There are two head gaskets in there, but in places I wonder if they are damaged.

Also, "check and set the valves". With your good compression reading your valves are likely seating well. Adjusting their tolerances can be done by accessing the valve stems from the cover plate opposite the water jacket cover plate.Hope this helps.

Aha, that clears up that point. All three A4 manuals talk about removing the plate, but do not seem to specify precisely where it is. I understand now.

Hope this helps.

Yes, all the comments help, thanks. In the end it is the skipper's decision (me), adding all the factors together. I am still leaning toward removing the head and manifold to really give the cooling system a good going over before starting life with this old boat. I don't know where else that limited area of corrosion could be coming from. But only having done one other head myself before, I am naturally uneasy about taking the plunge unnecessarily. So I have to decide whether to tackle it now as part of this year-long refit, or leave it and have to tackle it between sailing seasons.

[rigspelt]

I don't think so. With good compression on all four cylinders and no real signs of any leaks, I'd stick to the other maintenance you refer to first. My guess is that after cleaning out the water jacket (as you are now doing) and subsequently flushing the engine - probably first an acid flush and then a pressure flush - any heating problems encountered by the prior owner will be remediated.Don

Thanks Don. I know it is very hard to make the judgement call from just looking at a limited photo, so thanks for offering your valued opinion. The thing I'm struggling with is whether that corrosion is indeed a sign of a leak. It is the only place on the engine that is lumpy and rusty (except for the area under the leaking water pump), which makes me wonder what caused that corrosion. In general, can a head gasket leak seawater in that spot to cause corrosion along that part of the head/block seam (this engine is not FWC)?

[Kelly]

Here are two photos that might interest/help you. The first shows the top of the block with the head removed. You can see the water passages and where you may have to do some cleaning and scraping. The second shows the underside of the head. Same comments.

Maybe someone else can post a picture of the valve stems and springs; I can't seem to be able to find mine...

Kelly

[msauntry]

Can you take a wire brush to this area and maybe do some stiff poking with an awl? I might be seeing things but in the top photo, just above and to the right of the heavy orange rust line looks like a crack. Maybe the head has rotted away in this area.

[High Hopes]

I am very suspicious of rust around the head/block seam aft starboard corner: head gasket water leak? See photo below.. . . So, have I got enough reason to pull the head?

Hi Rigsy,

Well, everybody has an opinion. I had a suspicious looking place like that on my head near the thermostat housing and thought there might be a leak. I pulled the head out of curiosity, quite frankly. I also had the engine out of the boat sitting in my garage at the time.

I found no evidence at all of any gasket leaks. In your case, it looks like some rust/crud stained the excess gasket edge that is sticking out. Also, notice that the rust /crud is also above the gasket. Water doesn't run uphill, so the water/sludge/whatever came from above.

I would pop freeze plugs and dig out the gunk. That will be quite an adventure in itself.

IMHO,

Steve

[rigspelt]

Can you take a wire brush to this area and maybe do some stiff poking with an awl? I might be seeing things but in the top photo, just above and to the right of the heavy orange rust line looks like a crack. Maybe the head has rotted away in this area.

I did that, and the metal is very solid. I decided not to pull the head. When I took off the manifold and cleaned up behind the side plate, I was very impressed with the good condition of the cooling passages. Twenty five years in freshwater before coming to the salt made a world of differnce, judging by images of other engines here and there. So, I plan to put the engine back together over the winter, do some painting, add some of the A4 mods from MMI and Indigo, and then next spring flush it out and do sea trials.

[rigspelt]

No leak

After repainting last winter and the first summer in the water: no sign of a leak on that joint.