need help-rust in cylynder block

[mrellis]

Im new at this. I have a volvo aq 125a. I bought the boat last summer and did not know anything about boats. I took it out on the lake thinking it only used fresh water to cool the engine--I was wrong. It overheated, so i put some coolant in it and ran it for the rest of the day and it did not get hot. when i got home i checked the oil and it was milky. well i did not do anything to the boat since then. just this week i pulled the heads and found a little corosion in the cylinder head and cleaned itlooks ok but the cylinders in the block has rust on the sides. my question is, is my engine ruined or can this be fixed? can i sand the rust????

 

[littlebookworm]

Re: need help-rust in cylynder block

Nope. That engine is shot. Time for a replacement. Good luck. Hy

 

[Ride The Lightning]

Re: need help-rust in cylynder block

Hi!

Of course you can not use your engine until an reparation.
You have to take the engine out of your boat. After that remove the oilpan. How does the engine look inside (crank shaft, camshaft, bearings etc)? Then remove the pistons. How do the piston rings look like, are they free to move?
After that you have to hone the cylinders and install everything the other way around.
There are several possibilities you have got the milky oil:
- the seal at the impeller shaft is broken-down
- the cylinder head has a draft
- the exhaust gas-header is rusted through
...

You said this is you first motor so have a look for a professional engineer.
Do not use the engine, you will have even more problems otherwise.

Regards
Lars

 

[rndn]

Re: need help-rust in cylynder block

Welcome to the forum and sorry your first boating experience was not a better one.

 

[45Auto]

Re: need help-rust in cylynder block

Your engine might not be ruined if it is only very light surface rust in the cylinders. If you are very lucky, running a hone through them a couple of times will clean them up. You don't want to sand them. Borrow or buy the correct size "cylinder hone" (fits in a hand drill) and run it up and down the cylinders a couple of times with plenty of oil. If the cylinders are too badly scarred to clean up with a light honing you will need to rebuild (have cylinders bored out and fit oversize pistons) that engine or get a replacement engine.

Another important question is "How did the oil get in the water?". If the engine overheated it is a very good chance you have a blown head gasket and a warped cylinder head that let the water into the oil. It is also possible that you have a cracked block or cracked cylinder head.

You need to determine how the water got into the oil and correct it so it doesn't happen again as soon as you put the engine back together.

 

[Coors]

Re: need help-rust in cylynder block

Search for Don's leak-down test in here.

 

[littlebookworm]

Re: need help-rust in cylynder block

I apologize. I didn't mean to seem flip in my response. The advice you've gotten here is correct and what I should have said myself. I was having a bad day and typed without really thinking my answer through. I've gotten good advice on this site from people with far more marine knowledge than I have, so follow what they suggest. Check out the engine; it might be capable of being saved, but a rebuild is a definite possibility. Anyway, welcome to iboats, my apologies again, and good luck. Hy

 

[mrellis]

Re: need help-rust in cylynder block

thanks everyone for your replies. i am going to try the hone.

 

[Coors]

Re: need help-rust in cylynder block

If that's all you're gonna do, just seal the top of the piston with grease, and hand sand it with 300 grit.
What about the area between the top of the piston and the top ring?
I give it a 50/50 chance, as the original problem is not being addressed.