Topic: Water in crankcase, motor Toast?

[Impala]

So my new 70 CB750 had a stuck motor. soaked with penetrating oil, warmed up cylinders nice with bullet heater, and voila! she came loose! But then I drained motor oil and she was full of at least 2 quarts of clear running water, then some drabs of oil. Big Bummer. Removed motor side covers drained them of water also. Tranny still shifts. Where did the water get in? Dont know history but obviously sat outside.[sank in a lake maybe?] Is there any hope motor survived the water bath? Wont be able to tear down motor anytime soon, so I was thinking of flushing out motor with WD40 or something to try to dry it/lubricate internal parts to minimize further damage. Is there a way to easily access crankcase to fill it with oil to do the flush. Or do i have to fill oil reservoir tank and pump lubricant thru motor that way? Any suggestion where to go from here? besides returning it to the lake.  Thanks, Paul.

[chewbacca5000]

So my new 70 CB750 had a stuck motor. soaked with penetrating oil, warmed up cylinders nice with bullet heater, and voila! she came loose! But then I drained motor oil and she was full of at least 2 quarts of clear running water, then some drabs of oil. Big Bummer. Removed motor side covers drained them of water also. Tranny still shifts. Where did the water get in? Dont know history but obviously sat outside.[sank in a lake maybe?] Is there any hope motor survived the water bath? Wont be able to tear down motor anytime soon, so I was thinking of flushing out motor with WD40 or something to try to dry it/lubricate internal parts to minimize further damage. Is there a way to easily access crankcase to fill it with oil to do the flush. Or do i have to fill oil reservoir tank and pump lubricant thru motor that way? Any suggestion where to go from here? besides returning it to the lake.  Thanks, Paul.

Simply drop the oil pan and have a look up in there with a powerful LED light and see what it looks like.  Is it all rusty or shiny.  Who know water could be condensation or got in from rain.  It does not automatically mean it is trashed.

Kerosene is a good cleaner de greaser.  You can put some in the spark plug holes it will seep down into the crank case.  Then give it an oil change if you are not planning on doing anything now.  Neither WD-40 or Kerosene will stop rust long term that is what the oil is for.

[mrbreeze]

Might have hurt some bearings/ journals but you won't really know without disassembly. Best thing to do would be to do what Chewy says and have a look see through the bottom, flush thoroughly. I've used diesel in auto engines. Don't really know if it would have a bad effect on the clutch. Drain & refill with oil/new filter. Run it and hope you don't start hearing any knocking. Keep a close eye on oil pressure. Put a fan on it if you run it for any amount of time. If all is well....change oil/ filter again and enjoy!

[SOHC4 Cafe Racer Fan]

That, at minimum, sounds like a good idea. You have to have a look-see inside to see if your transmission, crank, rods, etc. are rusty-crusty.  If so, running the motor and praying for the best is not a good plan.

[mrbreeze]

Yeah if there is lots of rust it will still create problems as it flakes off into the bearings and plugs passages. Best case scenario`............rebuild! It's your call but if you do it like I said you would still want to change the oil & filter often and check for crap in the oil. It don't take much to kill a bearing.

[754]

Often sprinklers are the culprit..
 I open a KO I have... The main bearingsm looked ok at first glance, but looking close had a Wrinkly look.. The moisure must have got them
 You will see a lne where tye water level as, once you get into it,rods, crank..probably useable if not submerged..  All the tranny bearings will be suspect.. Used tranny, probably less money than bearings... Probably use most of it anyway ..youbwill have spare parts left.
 You will get beeter idea as soon as you open it up..

[HondaMan]

I once opened a K4 like that (it's on the cover of my book, top and bottom bike are the same one). When I got the junkyard refugee home and pulled off the oil lines from the engine, water ran out because the oil cap had been removed some 10 years prior. Water had leaked through the oil pump (slowly) to a height about 1/2 the height of the countershaft. Those lower ball bearings were rusty, but interestingly the gears were fine (oil and zinc still plated them). In the end, all that was needed was a detailed cleaning and 2 new bearings for the countershaft.

Oh...and a rebore, the pistons were stuck but good!

[70CB750]

Your best bet is to take it all apart and build from bottom up - get Hondaman's book and follow it.

[01Thomas]

I have rebuilt a crashed Moto Guzzi 850 LeMans (the one in my signature) after it stood in the open with a crashed-open tappet cover for about 3 years. Then it stood in a garage for another ten years until I got hold of it and restored it.
Draining the oil revealed about 4 litres of fluid, of which about half was water. The crankcase components were all covered with a slimey red goo... which I rubbed off with my bare fingers to reveal clean metal underneath.
The anti-rust additives in the oil truly did their job. And every semi-decent el-cheapo oil will have anti-rust additives. I even reused the original big-end and main bearing shells.

But the fact remains for peace of mind your bike will need a strip and rebuild.

[mrbreeze]

This guy said he wouldn't be tearing the motor down anytime soon so I thought he wanted to see if he could run it without a teardown. I guess what he was asking was if he could flush it out and it would be OK. I'll change my answer to what 01 Thomas said. For peace of mind tear it down. Running it like that might have a slim chance of being OK but why risk burning up good parts to save time and a gasket set/ bearings.