Logo
FULL SITE MENU

Oil contamination? Water or fuel?

L

leomillan

New member
I have a Honda 90 about 2001 vintage. Seems like about every few tankfuls of fuel I go thru, my oil turns white but smells a little like fuel. If it is water, where could it be coming from? If it is fuel would it also turn white and where would that be coming from? Any ideas?
Leo
 
It may just be a matter of semantics but my description of water contaminated oil is gray, not white. I don't have much experience with synthetic oils and fuel contamination so that could explain the difference if you're running syn oil.

My first thought when you say the oil smells of fuel would be the engine is operating at too low a temperature for complete combustion and raw fuel is getting past the piston rings and dumping in the crankcase. We see it with outboards quite a bit where the owner doesn't service the thermostats as required.

That's where I would concentrate my initial investigation, determining if the engine is coming up to proper operating temp.

In your case that would be above 160*f (72c). The thermostat is designed to START TO OPEN at that setting so the cylinder head temperature should be around 170*f. You could check this in many ways but the quickest and easiest is to use a non contact thermal heat gun. They sell an inexpensive one at Harbor Freight. Just take the gun out with you and leave the engine cover off for a good run. After the engine has had a good workout, slow down and shoot the head temp while at idle. I'm betting you'll find that you are way too cool.
 
Agree with Jimmy - engine temperature would be the first line of investigation.

I assume no warning lights are coming on and your oil pressure light is staying on, green. Is that correct? The reason I ask is that another, more remote, possibility is that your VTEC is not kicking in as it is supposed to - around 4400 - 4600 rpm.
 
I may have two things going on here... I drained the oil yesterday and there is definitely water in with it... yes it is grayish, and also smells like fuel in it. Is there a way to determine (water) if it is a cracked or warped head, blown gasquet, or much worse a cracked block? The engine runs fine mostly, the green light stays on as meant to (unless the level increases enough to send a warning) and no other warning lights go on. When the level gets high the green light goes off and a buzzer sounds at startup, I think that's what the manual says it does when there's a problem.
 
I would still check engine temp as Jimmy suggested. But you should not be getting water in the oil even if it is running cold unless from excessive condensation in the cylinder heads OR you still have the old (original) exhaust pipes and water is getting in from that route. Typically, that will blow the HO2 sensor, first.

At this point I would run the diagnostics off the EPROM to see if anything shows up, or take it to a dealer and have them hook up the HDS computer.
 
Sorry... what's the EPROM. And wouldn't the temp issue be addressed cheaper by just replacing the thermostat? And what about those exhaust pipes? It could be coming up those somehow? How could I tell if this modification has or has not been done?
Leo
 
Last edited:
The EPROM is the erasable programmable read only memory - the computer chip that is at the heart of the onboard ECM - Electronic Control module. It is the devise that all of your sensors feed into, and adjusts engine performance accordingly. The EPROM stores fault codes. You can pull those fault codes using a special service connector (Part number 070PZ-ZY30100) plugged into the red, 4-prong service connector plug under the electronics cover on the front of your engine. Alternatively, you can use a paper clip to shunt the lime-green/white wire to the black wire on that plug. The fault code, or codes, are given by the number of blinks on the MIL (malfunction indicator light) on your console. If this is all very new to you, I would recommend taking the engine to a dealer and have them run diagnostics with their computer.

Not cheaper to replace the T-stats, but may be easier to do.

Forget what I said about the exhaust pipes - that problem was for the BF200 and BF225, only.
 
Thanx for all the info... either way water in the oil is a pretty bad deal, and I'm screwed. I'll take it in to see if it is going to be worth the money to get it right, wether I do the work or have someone $$$else do it.
Thanx,
Leo
 
Leo - Not necessarily. Find the problem, first, then evaluate the fix. Those 90's are pretty tough engines, and unless you have cracked a block or permanently screwed up the crank shaft, then a fix may well be worth it. In and of itself, water in the oil is not fatal. Just find out how it got there.
 
Is this a fuel injected engine?
Anyway, if you are getting water in the oil, it is unlikely that it is a head gasket or warped head or block surface. I say that because combustion pressures are so much higher than cooling system pressures. I'm not the expert here and hopefully, hondadude might be monitering this thread to give you his opinion as to where water ingression to the crankcase is most likely. I do know, from reading some of hondadude's other posts, that some of these engines have water passages that pass closely to the oil fill adapter and there is a seal there that can fail. On the smaller engines I work on, there is a seal on the bottom of the block that could fail and allow water from the water tube to enter the crankcase relatively easy.
 
It is carburated. You guys are giving me some hope, I have an appointment to take it in for diagnostics on Monday. We'll see how they view the problem.
Leo
 
Back
Top