Remove head and manifold or leave well enough alone?
 

Hi All,
I recently acquired a boat with an A4 and have since removed the engine for repair of the boat and engine. The question is this: The exhaust manifold has some pretty bad flaking on the inside, at least what I can see from the exhaust port, and am considering removing it and the head for further inspection. The studs for both actually look decent from what I can see, and I dont see any leaking. Should I leave them on and risk further issues after reinstalling the engine, or should I remove the head, manifold and studs and replace all of the studs?
This boat has been in a fresh water lake since it was new 1n 1974 and has never seen salt water.

It is not a bad idea to open the engine up to inspect in most cases. Did it run before? Does it spin on the starter? You may even want to do a pressure check which may not be necessary for a fresh water engine.

It is not difficult to cobble a stand for an A-4 and once on the stand (or even on the floor) you could do a compression check. If the compression is suspect it's a lot easier to tear down out of the boat. And with a stand you can even run the engine before reinstalling.

Do you know anything about how it does or doesn't run?

Dave Neptune :cool:

Marty - welcome..it is always a process, but we got you. From another thread, sounds like you pulled the engine. Gaskets are cheap, relatively speaking. I pulled my manifold (salt water motor for many years) and discovered a leaky stud on the block side..I never would have seen it with the manifold intact and it explained the slow loss of antifreeze on the fresh water side. That being said, I have not needed to pull my head off my engine yet, and once I got the #4 cyl valves freed up with various concoctions in the spark plug hole, she runs pretty well. Compression test maybe to see where you are at?

it all depends how far you want to dig into it, but a lot easier on a stand and not in the boat. Start snapping some pics and adding to your posts..it helps us a lot...many members have seen it all before..:cool:

There are conflicting stories about whether this boat ran before. It does turn over (by hand) and feels pretty smooth, and appears to have compression, but I have not checked it yet. I have been working allot of hours and have not had time to check it out yet. I was told that when the carb was gravity fed fuel it would run. That would explain how it could run with the fuel pump disconnected.
Also I will try to take some pictures and post them. I will also build a stand for the engine and try to get it running in my shop. I have it sitting on boards right now and would not be stable enough to run without falling over. Overall, from the OUTSIDE, it looks decent. The OCD part of me wants to pull the head, manifold and reverser cover in the hopes of revealing any hidden leaks or problems, then I thought, I might as well replace the studs if i do that.
I will take some pictures either tonight or tomorrow and see what you guys think. Thanks again for all of your advice.

I have a project motor in my shop too. It would bind up during hand rotation, so I took off the head to avoid damage..turns out a little rain must have gotten into #2 spark plug hole, and there was some rust on the cylinder wall. Sprayed it with a little stuff, and loosened right up. Now I gotta scrape the gasket and all that stuff...shoulda just sprayed some stuff in the plug holes, and it might have loosened up without yanking the head. I might try a compression test before you pull the head..unless you enjoy the tedious scraping. I have not touched mine since last fall now..too many other projects. :-)

Hi Marty,
Welcome to the forum!
Not sure of your goals here. An engine that runs, ASAP (I need to get it reinstalled)? Perhaps an engine that you'll be happy with for years to come. The quick course is to just get it running but then you risk the surprise of finding out that it leaks oil and coolant and smokes up the cabin.
The engine is out of the boat. That's one of the hard parts of doing a full overhaul and upgrade. Let us know your goals and we can advise.

I had not really planned on a full engine rebuild. I would like for the engine to be sound. I have read so much about head bolts leaking and thought I would replace them while I had it out. I have no check compression yet. Along with the pictures of the engine, I included one looking into the exhaust manifold. I thought I would do what I could to remove the flakes from it, using a pressure washer and various brushes. (after removing it)
This engine was at one time (I think) a heat exchanger/coolant cooled engine and was then changed to a raw water cooled engine. It has lived its life in a fresh water lake so I plan on using only raw water and removing the associated plumbing for coolant.
If I remove the head and manifold, and find issues, or have a compression issue, I will rebuild, otherwise, reassemble. I will then sort out the fuel system, remove the remainder of the front water pump pulley from the crank, clean, paint, test, tune and reinstall. Thank you all for your help.

Looks like it got hot at one time. I would remove the side plate behind the alternator and clean out around the cylinder walls. My fresh water engine always ran hot - ~210 F for about 10 years after I bought it. I couldn't figure out why until I removed my side plate and found 30 years of gunk around the cylinder walls. Cleaned that stuff out with a screwdriver and a dentist pick and it started running at 140 F.

Go easy removing the side plate bolts. I broke two off. Other than drilling out the broken bolts, it was probably a 1 hour job.

Thanks for the info.

I would like to see better picture of exhaust manifold...
 

Something about the shadows or the impression of erosion on top of the manifold. Pressure check as other have stated for block and exhaust manifold just to see what you have got. Probably time to at minimum do a flush and more beneficially, with necessary risk, manually clear the coolant passages behind the water jacket (be prepared to replace bolts and possibly water jacket depending on internal scouring). Based on pressure test and if you are pulling the manifold anyway, maybe have it machined then remount it or replace it if it has degraded to a point of future failure risk. I would do everything I could while the engine is out, maybe even convert back to FWC. Good luck!

Down the road as you are getting close to running it again, I would consider changing the fuel line from the pump to the carb. Personally I don't like seeing the pinched hose. Planning to add in a fuel gage and polishing filter while replacing the hose I think would help you in the long run avoid trouble and help you trouble shoot any fuel issues.

Don't forget to hook up the scavenge tube from the carb to the manifold before you run it! :D

Thanks for everyone's reply. The pictures are exactly as I received it. I have not made any repairs yet. I plan on re-plumbing and rewiring everything. At this point I am thinking I will at a minimum, remove and clean the head and manifold. If I break one stud, I will remove and replace them all. I will as suggested, remove the water jacket plate and clean inside as best i can. I have been advised to replace the water pump, which is the original with one from MMI, and will make that decision after I give it a look.
The thing I am very short on right now is time to work on it. I am concentrating on the boat right now and once some progress is made on it, will circle back to the engine. Thanks again for the help and great information!

Where are you located...and couple trailing thoughts...
 

Quick follow-up...

I live near Boston and have helped others work on their engines gratis to help me learn about my own. The favor has been returned many times as well.

If you decide to dump your heat exchanger, pump, reservoir from FWC system would like to see what you have.

Whatever is the white gunk at the flange side of manifold. I have seen numerous penetrating erosion points exactly in that area toward the last cylinder port and the exhaust outlet. I bought a grab box of parts and two of the manifolds had thinned to the point of seeing daylight through penetrations in the same area.

Best with your work. Tim

Hi Tim,
I don't know how I missed this post until now but I did. I have since removed the additional raw water pump and plumbing. It did not come with a heat exchanger, it was removed before I got the boat. Unfortunately I have not had time to make much progress on the engine yet. I will post here when I do. Thanks for your help.