1992 90 V4 - Water in exhaust :(

Hi folks!
Got an Evinrude 1992 v4 90hp and had it for a couple of years. It?s always started but really never reved out as it should. Max rpm is around 4400.
After winter conservation and impeller change did I notice quite a lot of water in the exhaust. See http://www.youtube.com/watch?v=3FrLpdTW9tI&feature=youtu.be.
The engine runs as before but maybe idles a bit more rough. Been browsing the forum and talked to a mechanic. The mech said that it's most likely some problem with the inner exhaust plate (head gasket blown are quite rare). He recommended me lookin for a new motor...
Have a few questions:
1. Seems like quite a lot of water comin through - is it dangerous to run the motor?
2. Whats your opinion on the most likely reason?
3. Got a service manual and in that is the outer and inner exhaust plate accessible if you remove the power head. When I look at my motor it looks like it could be removed without lifting the whole powerhead - true?
I suspect I always had some leakage and that may have affected the top rev and that it got worse with the new impeller (and higher pressure). I like this motor and would really like to give it a go.

Cheers

/Mikael

Re: 1992 90 V4 - Water in exhaust

Peaking out at only 4400 rpm at full throttle creates a lugging effect on the engine that will result in a heavy residue buildup of carbon within the cylinders.... a waxy looking carbon substance that one could hold in the palm of ones hand (a lot!).

Have you checked the compression and spark? It would be a good idea to do so. If the compression is up around 100+ psi on all cylinders and the spark will jump a 7/16" gap with a strong blue flame, I would suspect either a carburetor problem or you have a prop with too much pitch.

The water problem......

(Exhaust Relief Ports - Exhaust Housing (Inner/Outer)
(J Reeves)

The long housing between the powerhead and the lower unit is called the exhaust housing. There is a inner housing within it that has a heavy duty seal around the bottom of it, or heavy duty seals around a inner extension between the housing and the lower unit.

The red hot exhaust travels down thru that inner tube and out the propeller with a somewhat supply of water to cool the propeller hub. A good amount of water surrounds and fills the space between the outer and inner tube, otherwise the outer housing would get so hot that the paint would burn off.

Some water pumps, for some reason (differing even when new) exert a great amount of water pressure, and if the exhaust housing seals are in perfect condition, the water fills the tube to a point of overflowing.

This brings into play those two holes or slots, whichever the engine might have, at the top rear portion of the exhaust housing just below the powerhead.

Now, if those two holes/slots weren't there, water would continue to flow up into the cylinders. Water not flowing out of those holes is no concern for alarm UNLESS that outer housing suddenly becomes extremely hot..... the warning horn should sound long before that happens.

The main reason for those holes being there (exhaust relief holes) is that when at an idle, there is an extreme amount of resistance encountered by the exhaust trying to escape due the fact that the outlet via the propeller is now blocked by a wall of water. The escape route in this case is for the exhaust to escape out those two holes, otherwise the engine would slow down quite quickly and die. If exhaust cannot escape, air/fuel cannot gain entrance to the engine.

--------------------
However, that does look like a huge amount of water existing those relief holes, BUT you just installed a new high capacity water pump impeller and the boat is not moving thru the water but just sitting at an idle. As long as water does not enter the bottom cylinders, that would not create a problem.

Re: 1992 90 V4 - Water in exhaust

The water flow in the video looks normal to me. I'd be concerned it you didn't have that water coming out the exhaust relief ports. That visible water flow should increase significantly when the boat gets on plane.

Re: 1992 90 V4 - Water in exhaust

Ok, many thanks for this extensive explanation. This forum is fantastic. I know understand the releif holes function.

The mechanic had made a compression test that was good (according to him). He said that the indicatior on "water in exhaust was that the lower plug (cyl 4) was "clean". I pulled the 3 and 4 plugs and compared them with the 1 and 2 plugs and they are a little bit whiter on the insulator but the difference is not really big. (see attached pic)



I have good sparc. Had some problems last autumn with first no charging and then no spark at all, but that is fine now after I've replaced both the recitfier and the stator.

So I'm thinkin is the potential water leakage really a problem or should I start lookin at my carbs (or both)?

Happy easter!

/Mikael

Re: 1992 90 V4 - Water in exhaust

Go to WalMart, K-Mart, just about anywhere and pick up a cheap compression gauge. Have all of the spark plugs removed then take a compression test/reading yourself, then let us know what those psi readings are as per cylinder. Standing in back of your engine, facing the spark plugs, the cylinders are numbered as follows.

2.....1
4.....3

Then, still with the spark plugs removed, rig a spark tester whereas you can set a gap of 7/16" for the spark to jump. It should jump that gap with a strong blue lightning like flame... a real SNAP! Does it?

Generalities such as... the compression is good and so is the spark just doesn't do it, tells us nothing.

No tester, build the following:

(Spark Tester - Home Made)
(J. Reeves)

A spark tester can be made with a piece of 1x4 or 1x6, drive a few finishing nails through it, then bend the pointed ends at a right angle. You can then adjust the gap by simply twisting the nail(s). Solder a spark plug wire to one which you can connect to the spark plug boots, and a ground wire of some kind to the other to connect to the powerhead somewhere. Use small alligator clips on the other end of the wires to connect to ground and to the spark plug connector that exists inside of the rubber plug boot.

Using the above, one could easily build a spark tester whereas they could connect 2, 4, 6, or 8 cylinders all at one time. The ground nail being straight up, the others being bent, aimed at the ground nail. A typical 4 cylinder tester follows:


..........X1..........X2

.................X..(grd)

..........X3..........X4

Did that engine ever run properly with that present propeller?

Re: 1992 90 V4 - Water in exhaust

Diffferent colorations on the spark plugs can also be related to fuel. Too little fuel and the plugs turn a lighter/paler color. White plugs are not usually considered "normal". Restrictons in the main jets can reduce the fuel/oil to a cylinder, causing it's plug to look different from the others. It that's what you are seeing, it's worth investigating before something catastrophic occurs.

Re: 1992 90 V4 - Water in exhaust

Fwiw my same motor does not do that...spew water out of releif holes. That exhaust gasget in exhaust housing may be ot of place possibly from last time lu was pulled

Re: 1992 90 V4 - Water in exhaust

Hi!
Thanks again. Lots of replies. Will do a proper compression and spark test and get back with the result.
The prop should be OK, I have quite good torque and get her up in plane even with a lot of people in the boat (had like 7 adults). Will check the main jets as well.

Cheers

/Mikael

Re: 1992 90 V4 - Water in exhaust

The way I should have posed a previous question..... Did that engine every run properly and exceed that quoted 4400 rpm mentioned in this post? If so, what rpm did it reach?

Re: 1992 90 V4 - Water in exhaust

No. I've had it for 3,5 years and it's never run well on full throttle. It runs quite smooth and well up until around 80% throttle but if I push the throttle to bottom you can hear on the intake sound that the carbs fully open but there is no increase in speed/torque.

Re: 1992 90 V4 - Water in exhaust

oebb said:

No. I've had it for 3,5 years and it's never run well on full throttle. It runs quite smooth and well up until around 80% throttle but if I push the throttle to bottom you can hear on the intake sound that the carbs fully open but there is no increase in speed/torque.

Click to expand...

On the propeller right in back of the prop nut, there will be numbers indicating exactly what the diameter and pitch of the prop is. If you would list those numbers and also the make and length of the boat the engine is on, someone here (not me) will be able to tell you if that propeller is a good match or not to your boat.