coolant in the engine oil. how bad can it be?

This thread is meant to either scare me a bit, or put my mind to rest a bit. And maybe get some good advice of what the problem can be, and what should i tell the mechanic to throughly do on my bike, as i will not start digging so deep into my motorcycle by my self (lacking the tools and the time to do so).

Let's get things straight: i'm talking about a 1993 Kawasaki EN500A (Vulcan 500), 41000 km (25 476 miles), but i cannot guarantee for this as i am about the 4th owner of this bike. I've had it for one year now.

About a month ago I couldn't see enough oil through the little round glass that helps me check the oil level. I thought my engine was consuming the oil so i went to my mechanic to have some more oil put in it. It turned out that it was some white-grey foam that was preventing me to see oil through the little glass. He told me i had coolant mixed with the oil. From the bikes history (he had been looking for the bike the past 3 years) he told me it has to be a worn cylinder head gasket. I ordered a new one along with a clutch cover gasket and oil pan gasket (as the mechanic told me he wants to throughly clean the water from the engine).

I never got around to taking the bike to him as it sat 2 weeks without turning it on, and when finally i tried to do it i discovered i had some electrical problems that i could only recently solve(see my other thread on the repair forum)

My intention was warming the engine up, taking out the oil+coolant mixture and putting in some cheap oil just until i could get the motorcycle to the repair shop. So i wasn't able to do that. But come the new year I will do that right away.

So here are my questions:
1. How bad is for the engine having the mixture sit in it for 3-4 weeks? I can imagine the oil has already separated from the coolant. Having this situation, what should my mechanic do about it?

2. What are possible causes for my problem that I should ask my mechanic to look for ? I have been told that the cylinder head gasket is just one of the possible causes. Another one would be the water pump. Any other ideas?

3. If the cylinder head gasket it the cause, then what caused the cylinder head gasket to get worn? I have never gotten any signs of overheating from my temperature sensor. It's true though that we have very warm summers here. This last summer i used to ride the bike in traffic jams at at least 40 degrees Celsius (104 Fahrenheit). So i wouldn't rule out the overheating problem. If it turns out to be an overheating problem is it true that the cylinder head gets deformed and that it should be mechanically reshaped in order to restore it's flatness.(this is something someone told me and i can not be sure of the accuracy of the technical info as i am not a auto/moto mechanical guru)

4. Any other ideas on how the current problem should be treated from now on? How should the engine be cleaned, what other parts need cleaning, any special treatment that should be applied to engine parts and all this considering the engine has been sitting with the oil/coolant mixture inside it for about one month?

Thanks in advance for all of you showing interest in this thread. Have a happy new year and may the road incidents avoid all of us!

I whould drane the oil to prevent part's from rusting and the coolant so more don't leak into the engine.It is most likly to be the head gasket leaking so make sure the head is not warped before replacing the gasket.If the bike is hard to start then there is proably coolant ontop of the piston.I whould pull the top end down and check for any damage to the engine and clean it.

the bike isn't hard to start. it's impossible to start. so it might be the case with the coolant on top of the piston

Don't try to run it! The working fact of hydraulic pressure is that fluids (oil, water, coolant, etc) do not compress! You can bend things, like connecting rods! Pull a plug(s) and then cycle the engine to satisfy your curiosity - watch for any fluid coming out the plug's port. That will show you there is fluid above the poston.

Blown head gaskets can cause the problem - that is the cheapest and easiest fix; but as said above check the sealing surfaces for warpage. I know nothing about your bike specifically, but a lurication system is a closed system. A cooling system is a closed system. When the two mix - it's a serious problem. I've seen cylinder fractures and head fractures cause this problem too.

If you don't have the ability to deal with the problem right now I would recommend you drain both the cooling and lubrication systems. Find someone with a pickup or trailer to get the bike to the shop when you're ready.

I've had several Kawi's of various makes and models and several had coolant mix with the oil, with one bike it happened after a mere 3500 miles!

I had one that did it every summer too.

Every time, however, it wasn't the head gasket, rather it was the water pump impeller seal. See, it's driven by a gear off the crank, the shaft that the impeller sits on passes through the case into the pump housing. It has a seal behind the impeller (little centrifugal pump blade) that keeps the coolant from running into the crank case (and thus mixing with oil). Considering the age of your motor, I would guess that the seal got hard with time and let go.

If that seal isn't 100% pristine and perfect, when the system heats up and starts to build pressure, it will force coolant past the seal and into the crank case where it mixes with the oil and makes a gross oil/coolant froth.

I would check that FIRST!!!!! Waaaaaaaay more likely than a head gasket.

If you're coolant's pretty fresh and not too old, you shouldn't have to worry about corrosion too much. Coolant (antifreeze) has anti-corrosion additives mixed with it to protect your cooling system. Not only will these additives protect your cooling system, they will prevent the coolant from rusting your engine's guts too. But, if your coolant's old, or not mixed properly (50% water, 50% antifreeze), you're making rust soup out motor giblets.

The bigger problem (bigger than corrosion) is that you stand a good chance of blowing up your engine by running it with coolant in your oil. The gray ick is actually air bubbles. Since air compresses, when this mix finds it's way into your bearings, every time a cylinder fires, it will push through those bubbles and pound the living snot out of your bearings. What's more, oil has very, VERY diminished oiling ability mixed with coolant. It's better to run an engine with coolant in your oil than with no oil, but not MUCH better. With 2 strokes, it's not a big deal (the crank, rods, etc is lubed by oil in the fuel, only the tranny has oil in it), but on a 4 stroke, it can be a VERY big deal.

What's probably happened is either that some of that oil/coolant mix has made its way into your cylinders (because there's way more oil in there than there should be because of the added coolant) and your plugs have fouled and need to be replaced or cleaned, orrrrrrr so much coolant has found it's way into the crankcase that there's so much in there, the pistons cant move up or down, or there's enough that it's covered the pistons and they can't move all the way up into their bores.

Right now you have GOT to do some damage control RIGHT NOW!! Drain your coolant and don't add any. Drain the engine oil and remove the spark plugs, refill with some nice, clean, fresh oil and a new filter, and spray copious amounts of WD-40 down the plug holes. Let the plugs rest up against the engine case (to ground them) and crank your starter for a good 30 seconds. That will blow the WD-40/water mix out of the cylinders, and distribute the oil around the engine. Put in new plugs and start it. Only let it run for 30-40 seconds, tops (there's no coolant in there). Let it cool for an hour or so, change the oil (there will still be oil and water in it that you didn't get out the first time), start it and let it run another 30-40 seconds and kill it.

If you don't have a shop manual, get one.

Now, first I would recommend you buy a new water pump seal from your dealer and install it, it's only a couple bucks. Be sure to oil the pump shaft when you install the seal. Check out your local auto parts stores, one of them should have a pump/gauge that you can use to pressure test your cooling system. If it holds pressure, you should be good. Refill your coolant and go on your marry way. If not, then start looking at the head gasket.

the motorcycle has an overheating history, it seems.
the previous owner used to ride it while it was constantly overheating. it finally got to it's current mechanic and he found to be a dirty radiator. so he solved that problem. but i suppose that the overheating started the ireversible process of the failing head gasket. so this is my best guess: that the failed headgasket is the problem.

nevertheless i will not dismiss your theory and the water pump is something i want to have checked. i have the service manual and i think i could take the job of checking the water pump by myself. the only concern i have is this: if i try to get to the waterpump, the impeller and the impeller seal i have to open two covers that have gaskets on them: the water pump housing cover and the waterpump cover. can i reuse the 2 gaskets or should i use new ones.

and above all theese, fingers crossed not to have internal damage to engine parts. i'll post some more details as the story of the repair unfolds. maybe someone will find them useful at some point

An overheat can pretty readily toast a head gasket, but it can also warp the head beyond repair or even crack it. If you, or your mechanic, pull the head, be sure to check for warpage and cracks. It would suck to get it all back together only to fill your case with coolant again.

I am guessing that the problem is probably a bad water water pump seal. There are 2 from your waterpump, one that prevents coolant from leaking into your oil and the other that prevents oil from leaking into your coolant. It is a good idea to replace both seals at the same time for preventative maitenance.

the conclusion:
it was a blown head gasket. the mechanic got it replaced, took the head to solve the warpage, did something to the valves (i think it was lapping them he was talking about) and valve guides, replaced oil, oil filter, coolant, flushed the engine with some cheap oil, cleaned and synchronized the carbs, replaced the spark plugs. the engine feels a lot more powerful now, and sounds great too.